. I ¥ Sf □ ' Division of Flshti, U. S. National Museum U. S. DEPARTMENT OF COMMERCE R. P. LAMONT, Secretary BULLETIN OF THE UNITED STATES BUREAU OF FISHERIES VOL, XLV 1929 HENRY O’MALLEY COMMISSIONER UNITED STATES GOVERNMENT PRINTING OFFICE WASHINGTON : 1930 CONTENTS J- Salmon-tagging experiments in Alaska 1927 and 1928. By Willis H. Rich and Frederick G. Morton. (Document No. 1057, issued October 2, 1929.) Review of experiments on artificial culture of diamond-back terrapin. By Samuel F. Hildebrand. (Document No. 1060, issued October 2, 1929.) Review of the weakfishes (Ctnoscion) of the Atlantic and Gulf coasts of the United States, with a description of a new species. By Isaac Ginsburg. (Docu- ment No. 1058, issued October 30, 1929.) Keokuk Dam and the fisheries of the upper Mississippi River. By Robert E. Coker. (Document No. 1063, issued October 26, 1929.) Studies of common fishes of the Mississippi River at Keokuk. By Robert E. Coker. (Document No. 1072, issued March 31, 1930.) Contribution to the biology of the Pacific herring, Clupea pallasii, and the con- dition of the fishery in Alaska. By George A. Rounsefell. (Document No. 1080, issued July 23, 1930.) Page 1-23 25-70 71-85 87-139 141-225 227-320 12924—30 III ERRATA Page 4, Table 2, under Icy Strait: North end of Chicago f Island should read North end of Chichagof Island. Page 5, Table 3, second line under Icy Strait: Gul should be Gulf. Page 14, Table 11, eighth line: C arence should be Clarence. Page 122, first paragraph, third line: Spriodela should be Spirodela. Page 218, paragrajjh No. 12, last line: (pp. 156 and 216) should be inserted after the word River. Page 305, third line from bottom: A comma should follow the word depletion at the end of the line. IV SALMON-TAGGING EXPERIMENTS IN ALASKA, 1927 AND 1928 1 ■jA By Willis H. Rich, Ph. D., In charge, Pacific Coast Fishery Investigations Frederick G. Morton, Warden, Alaska Fisheries Service U. S. Bureau of Fisheries <£• CONTENTS Page Introduction 1 Southeastern Alaska, 1927 2 Icy Strait 4 Chatham Strait : 7 Frederick Sound 10 Stephens Passage 13 Sumner Strait 13 Page Southeastern Alaska, 1927 — Continued. Cape Decision 15 Clarence Strait 17 Conclusions 18 Uganik Bay, 1927 18 Nicholaski Spit, 1928 21 INTRODUCTION The series of salmon-tagging experiments in Alaska, which was begun in 1922, was continued during the two years covered by this report. In 1927 a number of ex- periments were conducted in southeastern Alaska and one in Uganik Bay, Kodiak Island. In 1928 an experiment was carried out at Nicholaski Spit on the Alaska Peninsula. The experiments in southeastern Alaska were designed to fill in some of the gaps in the information that had been secured from previous experiments in this district. The other experiments were designed to settle specific questions that had arisen in connection with the administration of the fisheries. Although many details of the salmon migrations yet remain to be discovered, it is our opinion that the general features are now well enough known so that there is little need to continue general tagging experiments of the nature of those performed in southeastern Alaska in 1924 to 1927. It is planned, therefore, to use the method of tagging in the future only in connection with specific problems, such as those at Uganik Bay and Nicholaski Spit, which are covered by this report. The method of tagging and the results of the earlier experiments have been covered adequately in previous reports.2 The experiments in southeastern Alaska in 1927 were conducted by the junior author, who also collected and tabulated the data. 1 Submitted for publication Mar. 8, 1929. 2 Experiments in Tagging Adult Red Salmon, Alaska Peninsula Fisheries Reservation, Summer of 1922. By Charles H. Gil- bert. Bulletin, U. S. Bureau of Fisheries, Vol. XXXIX, 1923-24 (1924), pp. 39-50, 1 fig. Washington, 1923. Second Experiment in Tagging Salmon in the Alaska Peninsula Fisheries Reservation, Summer of 1923. By Charles II. Gilbert and Willis H. Rich. Ibid, Vol. XLII, 1920 (1927), pp. 27-75, 12 figs. Washington, 1925. Salmon-Tagging Experiments in Alaska, 1924 and 1925. By Willis H. Rich. Ibid, pp. 109-146, 1 fig. Washington, 1926. Salmon-Tagging Experiments in Alaska, 1926. By Willis H. Rich and Arnie J. Suomela. Ibid, Vol. XLIII, 1927, Pt. II (1929), pp. 71-104, 17 figs. Washington, 1927. 1 2 BULLETIN OF THE BUREAU OF FISHERIES The experiment at Uganik Bay was made by the senior author and that at Nicholaski Spit by L. G. Wingard, assistant agent, Alaska Fisheries Service. SOUTHEASTERN ALASKA, 1927 These experiments were designed primarily to supplement the data secured in 1924, 1925, and 1926. While, in general, the results have merely confirmed those of previous experiments, it has seemed best to publish the data in full on account of the importance of corroborating our findings. It may be pointed out here that when the results of two or more entirely independent experiments run parallel the probability that they are valid is greater than in the case of a single experiment involving an equal number of individuals. Whenever the new data agree closely with those secured previously, the reader will merely be referred to the earlier reports, which contain adequate discussions that need not be repeated here. Owing to the exceptionally light run and the late appearance of the fish in all districts, only 4,668 salmon were tagged during the entire season. Commencing in the Chatham Strait and Icy Strait districts, operations were moved gradually south- ward with the appearance of the fish. The salmon run in the southern district, however, proved to be exceptionally light, and only a few hundred fish were tagged in the vicinity of Gravina Island in Clarence Strait. In all districts the experiments showed the fishing gear to be working very efficiently, and in some instances more than 50 per cent of the fish tagged were recaptured. It was the policy of the bureau to tag the salmon when conditions were most favorable and, whenever possible, just prior to a weekly closed period, thereby giving the fish every opportunity to make headway on their course. A close watch was kept of the fish tagged, and at no time did they appear sluggish or linger around the scene of operations after they were liberated. The two previous reports (Rich, 1926, and Rich and Suomela, 1927) contain maps showing the distribution of the tagged fish, and it has not seemed necessary to republish these maps here. Those reports also contain lists of minor localities not shown on the maps. SUPPLEMENTARY LIST OF MINOR LOCALITIES FROM WHICH TAGGED SALMON WERE RECORDED Abraham Island. Northern end of Clarence Strait near Etolin Island. Ansley Point. Near eastern entrance to Icy Strait, northern shore. Benita Passage. Lower end of Etolin Island, between Etolin and Stone Islands. Big Johns Bay. Keku Strait. Blashke Islands. Kashevarof Passage, northern end of Clarence Strait. Bluff Point. Western arm of Behm Canal at the entrance to Yes Bay. Boulder Point. Sumner Strait at southern entrance to Keku Strait. Breakwater, North and South. ' Revillagigedo Channel, north of Cape Fox, about latitude 54° 50'. Cedar Point. Western shore of Annette Island. Clear Point. Northern point of entrance to Funter Bay, Lynn Canal. Cosmos Cove. Baranof Island, Chatham Strait, latitude 55° 15'. Cube, Point. Admiralty Island, Chatham Strait, latitude 57° 58'. Decision, Cape. Southern end of Kuiu Island, Sumner Strait. Deer Island. Ernest Sound, latitude 56° 05'. Dry Bay. In Portage Bay, Frederick Sound. Dry Point. Eastern shore of Stephens Passage, latitude 57° 37'. SALMON-TAGGING EXPERIMENTS 3 Eagle Creek. Eastern shore of Prince of Wales Island, 1 mile south of Luck Point. Eagle River. Bradfield Canal. Ellis, Point. Chatham Strait, northern entrance to Tebenkof Bay. Escape Point. Western arm of Behm Canal, latitude 55° 39'. False Island. Cleveland Peninsula, Clarence Strait, below Niblack Point. Frederick, Port. Icy Strait, Chichagof Island, longitude 135° 30'. Grand Rapids. Stikine River. Guard Island. Clarence Strait near northern entrance to Behm Canal. Gull Point. Onslow Island, Clarence Strait, near the northern end. Gypsum. Near North Passage Point, Chatham Strait. Harrington, Point. Etolin Island, Clarence Strait. Hepburn, Point. Admiralty Island, Chatham Strait, latitude 57° 57'. Herbert, Port. Chatham Strait, Baranof Island, latitude 56° 25'. Hollis. Western shore of Twelve Mile Arm, Kasaan Bay. Inian Pass, North. Between Inian Islands and the mainland, Cross Sound. Italio River. Near Yakutat. Karheen Cove. Karheen Passage, between Hecata and Tuxekan Islands. Kashevarof Passage. Northern end of Clarence Strait. Kasnyku Bay. Chatham Strait, Baranof Island, latitude 57° 12'. Ketchikan Creek. Entering Revillagigedo Channel at Ketchikan. Kitchen Island. British Columbia. Exact location doubtful. Kittens, The. Near Funter Bay, Chatham Strait. Little Pybus Bay. Just south of Pybus Bay, Frederick Sound. Mansfield Point. Same as Mansfield Peninsula, northern end of Admiralty Island. March, Point. Southern end of Prince of Wales Island, eastern entrance to Cordova Bay. Misery Island. Clarence Strait near Lemesurier Point. Mole Harbor. In Seymour Canal. Moonshine Point. Chatham Strait, near Point Caution, southern entrance to Hood Bay. Nelson Point. Behm Canal, entrance to Smeaton Bay. Peninsular Point. Chatham Strait just north of entrance to Peril Strait. Pleasant Bay. Seymour Canal, Stephens Passage. Portage Creek. Kake Harbor, Keku Strait. Ratz Point. Clarence Strait, north end of Prince of Wales Island, latitude 55° 55'. Red Bluff Bay. Chatham Strait, Baranof Island, latitude 56° 50'. Saginaw Channel. Separating Shelter Island from Admiralty Island. Salisbury Sound. At the western end of Peril Strait. Sclwyn Inlet. Queen Charlotte Islands, British Columbia. Shelter Island. Saginaw Channel, southern end of Lynn Canal. Ship Harbor. Clarence Strait, approximately latitude 55° 37' and longitude 132° 12'. Snipe Bay. Outer coast of Baranof Island, latitude 56° 25'. Spacious Bay. Northern arm of Behm Canal near Yes Bay. Square Cove. Chatham Strait near Cube Point. St. John Point. Zarembo Island, Sumner Strait. Three Islands. Clarence Strait, approximately latitude 55° 42' and longitude 132° 14'. Vandeput Point. Northern shore of Frederick Sound, longitude 133°. Vegas Islands. Between Duke and Annette Islands, Clarence Strait. Wolf Creek. Clarence Strait 3 miles north of Ship Island. Woody Point. Admiralty Island, Chatham Strait, latitude 57° 15'. Wrangell Island, south end. Ernest Sound. Wright Sound. British Columbia, mainland, latitude 53° 20'. 4 BULLETIN OF THE BUREAU OF FISHERIES The following table gives the data for the tags attached in southeastern Alaska during 1927 : Table 1. — Tags attached in southeastern Alaska, 1927 Experiment No. Date Serial Nos. Species of fish tagged Locality Red Pink Chum Coho King ]_ . July 1 1-100 29 16 53 1 Parker Point, Chatham Strait. 2 July 9 101-400 32 107 158 2 Hourigan Point, Frederick Sound. 3 401-475 3 17 55 Carroll Island, Frederick Sound. 4 July 12 501-700 18 90 73 10 9 Marble Bluffs, Chatham Strait. 5 ..do 701-900 13 112 65 7 3 Parker Point, Chatham Strait. 6 July 14 901-1200 40 212 15 33 Inian Islands, Icy Strait. 7 July 16 1201-1700 101 362 8 27 Pleasant Island, Icy Strait. 8 _ .do 1701-1900 30 186 3 1 Inian Islands, Icy Strait. 9 1901-2300 20 164 189 27 Hourigan Point, Frederick Sound. 10.... July 20 2301-2800 30 347 98 21 3 Cape Bendel, Frederick Sound. 11 July 21 2801-3000 28 115 40 17 Point Hobart, Stephens Passage. 12 July 26 3001-3500 198 271 4 26 1 Point Colpoys, Sumner Strait. 13. 3501-4000 185 306 6 2 Do. 14_ 4001-4300 29 164 82 24 Cape Decision, Sumner Strait. 15 Aug. 5 4301-4450 7 86 51 6 Dali Head, Gravina Island. 16 Aug. 6 4451-4700 4 240 i 5 Nelson Cove, Gravina Island. RETURNS FROM EXPERIMENTS IN ICY STRAIT RED SALMON One hundred and fifty-one red salmon were tagged in Icy Strait during 1927, 41 of which were recaptured (27.1 per cent). The data are presented in Table 2. Table 2.- — Returns from red salmon tagged in Icy Strait, 1927 [In this and subsequent tables the figures in the columns headed “ Days” represent the least and the greatest time that elapsed between tagging and reported recapture. The figures in the columns headed “Number” represent the number offish recaptured in the given locality] Locality and date of tagging Locality of recapture Inian Islands Pleasant Island Total number recap- tured July 14 July 16 July 16 Number Days Number Days Number Days Icy Strait: 1 6 1 1 9 1 1 5 1 Pleasant Island 1 6 1 Point Adolphus - .. 1 7 1 1 4 1 2 2 1 4 1 West of Rocky Island 1 4 1 North end of Chicago! Island. _ 1 9 1 Lynn Canal: 1 4 1 1 9 1 Tee Harbor.. ... . . 1 10 1 Chatham Strait: Mansfield Point .. . 1 7 1 South of Clear Point . ._ 1 6 1 N orth of Hawk Inlet 4 1-5 4 2 5-6 1 1 3 Square Cove 2 2 South of Passage Point 2 4-5 2 Marble Bluffs .. 2 7-9 2 1 7 1 4 2 Distant Point 1 15 1 Village Point ... 1 6 1 Near Kingsmill Point. . .. 1 23 1 Peril Strait: llooniah Sound . 1 19 1 Frederick Sound: Deepwater Point 1 8 1 Stephens Passage: Snettisham Inlet 1 10 3 4 4 1 42 1 West Coast Prince of Wales Island: Nichols Bay 1 37 i 10 2 29 41 Percentage returned 40 20 18.1 27. 1 SALMON-TAGGING EXPERIMENTS 5 Previous experiments had shown that the red-salmon runs entering Icy Strait early in the season (the latter part of June) contained fish bound for the Chilkat and Chil- koot Rivers. Later in the season (July 24 to 29) the Chilkat and Chilkoot fish appear to be gone, but Taku River fish appear in appreciable numbers. The Icy Strait exper- iments of 1927 were designed to test the distribution of the run at an intermediate period. The results are similar to those obtained from the experiments of July 24 to 29, 1926 (Rich and Suomela, p. 94), and indicate that the Chilkat and Chilkoot fish have passed through Icy Strait by the middle of July. There is, however, a relatively large migration south into Chatham Strait, and in this respect the experiments of 1927 resemble those of the latter part of June, 1926. (Rich, p. 119.) PINK SALMON Seven hundred and sixty pink salmon wer6 tagged in Icy Strait during 1927, of which 287 were recaptured (37.7 per cent). The data are presented in Table 3. Table 3. — Returns from pink salmon tagged in Icy Strait, 1927 Locality and date of tagging Locality of recapture Inian Islands Pleasant Island, Total number July 14 July 10 July 10 recap- tured Number Days Number Days Number Days Cross Sound: 1 2 i North of Inian Pass 1 5 Inian Pass 1 6 i Dundas Bay 1 5 1 Icy Strait: 4 2-11 2 4 3 4-20 3 9 2 2 2 3 5 2 1 3 1 7 1-5 3 - 2-9 s 2-4 18 9 G 2-30 3 4-7 1 7 6 3 5 5-12 4-5 12 6 4 2 3-5 2 4-0 2 4 2-16 4 4 6-11 2 4-5 3 9 1 9 1 1 1 6 2 21 4 1 1 10 1 6 3 4 6 4 Lynn Canal: 4 6-13 4 1 6 3 4 1 6 i 4 2 1 10 3-11 13-22 2-4 1-10 1-11 1-11 4-5 4-7 1 4 3 11 19 Chatham Strait: 1 3 3 1 13 2 3 4 5 4-9 3 7 2-17 3 3-9 9 3 3-6 3 3-7 11 2 2 9 4 6 1 2 4 8 15 3 2 3 1 4 11 4 4-7 5 1 9 3 1 8 1 4 4 1 1 12 1 12 26 7-9 4-15 1 28 1 26 2 4 7-10 4 2 7 4 4-22 9 1 8 1 15 1 1 6 1 4 2 4-6 1 1 2 8-9 2 7-15 4-8 2 6-9 3 4-7 6 4 5-7 3 11-13 1 12 1 2 Rocky Bay 3 6-25 Kingsmill Point - 2 6-10 2 6-20 O 4 6 BULLETIN OF THE BUREAU OF FISHERIES Table 3. — Returns from pink salmon tagged in Icy Strait, 1927 — Continued Locality and date of tagging Locality of recapture Inian Islands Pleasant Island, Total number July 14 July 16 July 16 recap- tured N umber Days Number Days Number Days Peril Strait: 1 13 2 13-19 3 1 15 1 Frederick Sound: 1 6 i Deepwater Point 2 8-12 2 1 23 1 Cape Bendel. 1 19 1 Fanshaw Bay. 1 14 1 Stephens Passage: Point Hobart 1 10 1 Windham Bav_ 1 17 2 9-16 3 * 3 13-17 3 1 5 1 Shoal Point 1 12 2 12 3 2 4-19 2 1 11 1 1 15 1 13 2 2 6-14 1 6 1 7 4 Groundhog Bay 3 4-5 i 5 4 i 12 1 Salisbury Sound i 8 1 i 35 1 68 73 146 287 31.6 39.2 40.3 37.7 The results are, in every important respect, the same as those secured from the previous experiments, indicating that the main route of migration is south into Chatham Strait and Frederick Sound. CHUM SALMON Twenty-six chum salmon were tagged in Icy Strait during 1927, five of which were recaptured (19.2 per cent). One was taken in Icy Strait, two in Chatham Strait, and two in Stephens Passage. These results, although few, agree with the earlier experiments. COHO SALMON Sixty-one coho salmon were tagged in Icy Strait during 1927, 11 of which were recaptured (18 per cent). The data are presented in Table 4. The results again corroborate the earlier experiments, showing the chief route of migration to be into Chatham Strait. It is also to be noted that the relatively slow migration of cohos is again shown clearly. Table 4. — Returns from coho salmon tagged in Icy Strait in 1927 Locality of recapture Locality and date of tagging Total num- ber recap- tured Locality of recapture Locality and date of tagging Total num- ber recap- tured Inian Islands, July 14 Pleasant Island, July 16 Inian Islands, July 14 Pleasant Island, July 16 Num- ber Days Num- ber Days Num- ber Days Num- ber Days 1 60 1 Chatham Strait— Continued. 1 47 1 Wilson Cove 1 26 1 1 25 1 1 4 1 Baranof Island: Snipe Bay 1 42 1 1 13 1 1 19 1 Total-- - 2 9 11 2 4-7 2 Percentage returned 6 33.3 18 Point Caution.. i 29 i SALMON-TAGGING EXPERIMENTS 7 RETURNS FROM EXPERIMENTS IN CHATHAM STRAIT RED SALMON Sixty red salmon were tagged in Chatham Strait during 1927, 15 of which were recaptured (25 per cent). The data are presented in Table 5 and are very similar to those secured in 1926: Both series indicate migrations both north and south from the point of tagging. In the experiments of 1924 and 1925 red salmon were tagged in Chatham Strait south of Frederick Sound. None of these fish were taken in Chatham Strait north of Frederick Sound, and yet both the experiments of 1926 and 1927 indicate a migration north from the region of Parker Point and Marble Bluffs. These facts may indicate that a considerable run of salmon enters southeastern Alaska through Peril Strait. Table 5. — Returns from red salmon tagged in Chatham Strait, 1927 Locality and date of tagging Locality of recapture Parker Point Marble Bluffs, Total number July 1 July 12 July 12 re- captured N umber Days Number Days Number Days Chatham Strait, north of Parker Point: South of Passage Point-.. 1 3 1 Fishery Point 1 3 1 Hawk Inlet. _ 1 2 1 North of Hawk Inlet 2 2-5 1 2 3 Icy Strait.. . . . . .. _. ... 1 5 1 Lynn Canal: Point Retreat . .. . . 1 12 1 Chatham Strait, south of Parker Point: Basket Bay 1 7 1 12 2 Village Point 1 10 1 Stephens passage: Snettisham Inlet _ i 18 1 Taku Inlet ... 1 26 1 Taku River- 1 3 1 Stikine River: North Arm 1 _ 1 (?) i Total 4 4 7 15 Percentage returned 13.7 30.7 38.8 25 1 Reported captured before date of tagging. PINK SALMON Two hundred and eighteen pink salmon were tagged in Chatham Strait during 1927, 70 of which were recaptured (32.1 per cent). The data are presented in Table 6. They corroborate the data secured in 1926 but add nothing new. 41438—29 2 8 BULLETIN OF THE BUREAU OF FISHERIES Table 6. — Returns from pink salmon tagged in Chatham Strait, 1927 Locality and date of tagging Locality of recapture Parker Point Marble Bluffs, Total number July 1 July 12 July 12 re- captured Number Days Number Days Number Days Chatham Strait, north of Parker Point: 1 3 1 2 1-3 7 1-16 9 i 30 4 3 • 5 1 4 1 1 4 2 2 3 1 13 2 3 2 3 5 1 4 1 2 1 4 3 Icy Strait: 2 5 1 8 3 1 6 1 1 10 1 Lynn Canal: 1 5 1 1 1 1 1 7 1 8 2 Chatham Strait, south of Parker Point: 7 3-16 7 3 3-4 3 1 3 1 1 22 1 1 9 1 5 2 1 16 6 1 2 1 1 1 1 2 8-34 2 Frederick Sound: 1 9 1 1 2 1 Stephens Passage: 1 10 1 4 8-17 4 2 9-14 2 1 17 1 Tain Inlet i 8 1 3 43 24 70 18.7 38.3 26. G 32. 1 CHUM SALMON One hundred and ninety-one chum salmon were tagged in Chatham Strait during 1927, 64 of which were recaptured (33.5 per cent). The data are presented in Table 7. Table 7. — Returns from chum salmon tagged in Chatham Strait, 1927 Locality and date of tagging Locality of recapture Parker Point Marble Bluffs, Total number July 1 July 12 July 12 re- captured Number Days Number Days Number Days Chatham Strait, north of Parker Point: 2 2-16 4 1-16 6 3 1-14 3 8-14 4 3-14 10 1 14 1 1 3 1 1 13 1 1 13 1 4 2 1 3 i Icy Strait: 1 24 1 1 4 i Point Adolphus. 2 3-10 i 6 3 SALMON-TAGGING EXPERIMENTS 9 Table 7. — Returns from chum salmon tagged in Chatham Strait, 1927 — Continued Locality and date of tagging Locality of recapture Parker Point Marble Bluffs, Total number July 1 July 12 July 12 re- captured Number Days Number Days Number Days Lynn Canal: 1 3 1 4 2 3 7-12 3 Chatham Strait, south of Parker Point: 1 14 1 3 2 Hood Bay 3 6-9 2 6 1 9 1 2 15-22 2 1 2 1 Point Caution __ 2 1 8-20 5 1 2 1 1 4 7 4 2 Peril Strait - 1 17 1 Salisbury Sound 1 4 1 Frederick Sound: 1 24 1 Point Briehtman _ _ _ __ 2 8-13 Hourigan Point. _ ... _ 1 9 1 Cane Fanshaw. 1 10 1 Stephens Passage: 6 1 2 19-34 2 Mole Harbor _ _ _ ... _ _ __ 1 12 1 Windfall Harbor _ _ . 1 1 1 Dry Bav . 1 20 1 1 Total... 17 18 29 64 Percentage returned... 32. 1 27.6 39.7 33.5 Very few chums were tagged in previous experiments at this point, so that the information contained in the table is virtually all new. The distribution of this species is, however, very similar to that of the pinks. Two important routes of migration are shown. The main migration followed a northerly route through Chat- ham Strait to its junction with Icy Strait, from whence four returns were reported. The southerly migration showed a tendency to follow the Admiralty Island shore of Chatham Strait to Frederick Sound, where five tagged fish were recaptured. One individual crossed Frederick Sound and was recaptured at Hourigan Point on the Kuiu Island shore. Seven returns were reported from Stephens Passage, of which four were recaptured in Seymour Canal. One individual was reported from Peril Strait and another from Salisbury Sound. COHO SALMON Seventeen coho salmon were tagged in Chatham Strait at Marble Bluffs and Parker Point during 1927, of which three were recaptured (17.6 per cent). One each was reported from the following localities: North of Hawk Inlet, Chatham Strait, 2 days; Marble Bluffs, Chatham Strait, 3 days; Point Gardner, Chatham Strait, 56 days. KING SALMON Thirteen king salmon were tagged in Chatham Strait at Marble Bluffs and Parker Point during 1927, two of which were recaptured (15.3) per cent, one each from the following localities: Wilson Cove, Chatham Strait, 29 days; Point Adolphus, Icy Strait, 10 days. 10 BULLETIN OF THE BUREAU OF FISHERIES RETURNS FROM EXPERIMENTS IN FREDERICK SOUND Four tagging experiments were made here in 1927, the greater number of the tagged fish being pinks and chums. Two hundred and ninety-nine fish were tagged at Hourigan Point on July 1, 75 at Carroll Island on July 9, 400 at Hourigan Point on July 19, and 499 at Cape Bendel on July 20. Although there are some distinct differences in the results obtained from these experiments, the general similarities are sufficient to warrant considering them together. RED SALMON Only 14 fish of this species were recaptured, and no important additions were made to our previous knowledge of their migration. Four of those tagged near the western end of Frederick Sound were taken later in Chatham Strait. One was taken in Clarence Strait, one in the Stikine River at Grand Rapids, and the other eight in Frederick Sound and Stephens Passage. PINK SALMON Six hundred and thirty-five pink salmon were tagged in Frederick Sound and 307 (48.4 per cent) were recaptured later. The data are presented in Table 8. Table 8. — Returns from pink salmon tagged in Frederick Sound, 1927 Locality of recapture Frederick Sound: Hourigan Point ,,- Security Bay Saginaw Bay Carroll Island. , Herring Bay Point Highland Deepwater Point Point Macartney Cape Bendel Little Pybus Bay Pybus Bay Point Pybus Keku Strait . Cape Fanshaw Fanshaw Bay Dry Bay Point Vandeput Cape Strait - . Thomas Bay Chatham Strait, north of Frederick Sound: No details Kasnyku Bay ltoeky Bay.. Peril Strait . Point Caution .. Cosmos Cove Distant Point-, Hood Bay Basket Bay Marble Bluffs Cube Point Point Marsden Hawk Inlet., Funter Bay Icy Strait: West of Rocky Island Chatham Strait, south of Frederick Sound: Kingsmill Point South of Kingsmill Point North of Washington Bay .. Tebenkof Bay.. Locality and date of tagging Hourigan Point July 9 Number Days 7 32 5-7 July 19 N umber Days 2-20 9-22 1 10 18 5 2- 9 3- 6 10 6 10 2-18 4-9 IS 7 19 3-4 4-8 1-20 1-9 Carroll Island July 9 Number Days Cape Bendel July 20 Total number recap- tured Number Days 1-10 10 7-9 1-19 1-21 1- 17 2- 16 9-18 2-37 4-5 21 1-15 2-8 5-14 8-23 7-15 9 13 16 5 2-4 5-13 7 1 3 1 6 9 30 14 12 5 6 4 1 35 13 4 1 1 1 1 1 2 3 3 2 2 1 1 2 1 1 2 1 1 13 13 SALMON-TAGGING EXPERIMENTS 11 Table 8. — Returns from pink salmon tagged in Frederick Sound, 1927 — Continued Locality and date of tagging Locality of recapture Hourigan Point Carroll Island Cape Bendel Total number July 9 July 19 July 9 July 20 recap- tured N umber Days Number Days Number Days Number Days Stephens Passage: 2 13-30 4 5-23 5 2-15 11 i 10 1 5 2 2 9-10 2 3 5-19 1 6 13 4-17 17 Seymour Canal 7 7-13 7 1-18 2 11-20 20 1-22 36 Mole Harbor - 2 10-13 1 10 4 6 7 Windfall Harbor. . . 2 11-18 3 7 5 Pleasant Bay 1 19 2 3-8 3 Limestone Inlet 1 4 2 15 1 14 4 Taku River 1 (?) 5 1 Shelter Cove 1 1 Salisbury Sound i 5 1 4 2 Clarence Strait: Snow Passage. _ 1 14 1 i 20 1 Ernest Sound: Watkins Point 1 11 1 West Coast Prince of Wales Island: Karheen. i 31 i Total 44 92 4 167 307 Percentage returned . ... . . 41. 1 56.0 23.5 48.2 48.4 These data fully confirm the results of previous experiments in showing that the pinks of Frederick Sound are distributed chiefly among the streams of that locality and Stephens Passage. Virtually every experiment, however, has shown a slight movement out of the sound and both north and south in Chatham Strait. No new facts of importance were brought out by the tagging experiments of 1927. CHUM SALMON Five hundred chum salmon were tagged in Frederick Sound during 1927, of which 117 were recaptured later. The data are presented in Table 9. Table 9. — Returns from chum salmon tagged in Ferderick Sound, 1927 Locality of recapture Locality and date of tagging Total number recap- tured Hourigan Point Carroll Inlet, July 9 Cape Bendel July 20 July 9 July 19 Number Days Number Days Number Days Number Days Frederick Sound: Hourigan Point 3 1-11 3 Security Bay... 4 10-26 11 4-15 1 10 16 Herring Bay.. .. .. 2 10 1 6 3 Deepwater Point i 15 3 2-16 1 15 1 (?) 6 Big Johns Bay 3 19-21 4 10-23 1 11 8 Keku Strait. 2 18-22 4 12-25 1 21 7 Kake Harbor 1 10 1 Portage Creek, Kake 1 16 1 Point Macartney 1 2 2 4-9 3 Cape Bendel . .. 1 21 1 Little Pybus Bay 1 27 2 9 3 Pybus Bay 1 22 1 Fanshaw Bay 1 9 1 Cape Fanshaw ... 2 13-21 1 9 3 Chatham Strait, north of Frederick Sound: Point Gardner 1 33 1 Point Caution 2 20 1 12 1 17 4 Cosmos Cove 1 7 1 Distant Point 3 3-4 3 41438—29 3 12 BULLETIN OF THE BUREAU OF FISHERIES Table 9. — Returns from chum salmon tagged in Frederick Sound, 1927 — Continued Locality and date of tagging Locality of recapture Hourigan Point Carroll Inlet, Cape Bendel, Total number July 9 July 19 July 9 July 20 recap- tured Number Days Number Days Number Days Number Days Chatham Strait, north of Frederick Sound — Con. 1 7 1 1 11 1 1 6 1 Chatham Strait, south of Frederick Sound: 5 2-10 2 2-9 7 4 1-32 4 3 9-10 1 (?) 4 3 8-24 3 Tebenkof Bay 1 13 6 3-13 1 7 8 Stephens Passage: 1 26 1 i 10 I 4 11-16 I 33 2 8-13 7 1 20 1 i 18 i 7 2 1 9 1 Limestone Inlet 1 10 1 1 7 i 10 2 1 6 1 Sumner Strait: 1 33 1 1 31 1 I 25 1 1 15 1 Breakwater, North, Revillagigedo Channel __ i 17 1 To*al 27 62 8 20 117 17. 1 32.8 14.5 20.4 23.4 These data provide new information relative to the migration of chum salmon taken in Frederick Sound, as comparatively few chums had been tagged here in the previous experiments. The main migration of chum salmon tagged at Hourigan Point and Carroll Island traversed Frederick Sound to its junction with Stephens Passage, thence northerly, where 12 returns are shown from various points in Stephens Passage. Nine returns are reported from Chatham Strait north of Kingsmill Point and 24 from Chatham Strait south of that point. Two returns are shown from Sumner Strait and one from Stikine River. One was reported at McNamara Point, Clarence Strait, and another individual was recaptured at North Breakwater in Revillagigedo Channel. The returns from the chums tagged at Cape Bendel, Frederick Sound, show two distinct migrations. The main migration followed through Frederick Sound, partic- ularly along the Admiralty Island shore, to its junction with Chatham Strait, from whence three of the fish took a northerly route extending as far north in Chatham Strait as Hawk Inlet. Two followed the Kuiu Island shore of Chatham Strait and were recaptured north of Washington Bay and in Tebenkof Bay, respectively. The other important migration was into Stephens Passage, from which place one-fourth of the returns were secured. COHOS Fifty cohos were tagged and nine were recaptured later. Five were taken in Frederick Sound and Stephens Passage ; 2 in Chatham Strait ; 1 in Clarence Strait ; and 1 in Selwyn Inlet, Queen Charlotte Islands, British Columbia. SALMON-TAGGING EXPERIMENTS 13 RETURNS FROM EXPERIMENTS AT POINT HOBART, STEPHENS PASSAGE Two hundred salmon were tagged at Point Hobart, Stephens Passage, on July 21. Of this number 28 were reds, 115 pinks, 40 chums, and 17 cohos. None of the cohos were returned. Five red salmon were recaptured (17.8 per cent). Two of these were taken at Snettisham, Stephens Passage, one in 2 and the other in 9 days ; two others were taken in Herring Bay, Frederick Sound; one in 2 and the other in 8 days; and one was reported taken in Icy Strait after an interval of 7 days. Seven chums were recaptured (17.5 per cent). Three were taken in Stephens Passage, three in Frederick Sound, and one at Point Ellis, Chatham Strait. PINK SALMON The returns from pinks tagged at Point Hobart, Stephens Passage, are shown in Table 10 and indicate two distinct migrations. The heaviest of these was in a north- erly direction into the waters of Stephens Passage. More than half of the returns from this migration were from Seymour Canal. The second and lighter migration was through Frederick Sound, both south and west from Point Hobart. One indi- vidual was recaptured in Basket Bay, Chatham Strait. This is an interesting addition to our knowledge of the salmon migrations in southeastern Alaska, as no experiments had been conducted previously in the southern part of Stephens Pas- sage. It is evident that most of the fish taken in this region belong in Stephens Passage and doubtless have entered through Frederick Sound. The fish that went westward from Point Hobart may possibly have come down Stephens Passage from the north, but it seems much more probable that this movement represents more or less chance wandering of fish that are still feeding. Table 10.- — Returns from finks tagged at Point Hobart, July 21 — 115 tagged, 1^2 returns ( 86.5 per cent) Locality of recapture Number Days Locality of recapture Number Days Stephens Passage: Frederick Sound: Point Hobart 2 1-3 Fanshaw Bay 1 2 Port Houghton 2 3-14 Cape Fanshaw 4 3-8 Hobart Bay 1 3 Point Pybus 1 5 Windham Bay 10 3-7 Pybus Bay. - 4 4 Mole Harbor 1 5 Deepwater Point 2 3 1 2 1 8 Seymour Canal 6 1-20 Saginaw Bay. _ 1 7 Twin Point 1 3 Chatham Strait: Basket Bay 1 7 Snettisham i 5 Shoal Point 1 11 Limestone Inlet . . . . . . ... . i 17 RETURNS FROM EXPERIMENTS AT POINT COLPOYS, SUMNER STRAIT RED SALMON Three hundred and eighty-three salmon were tagged at Point Colpoys, Sumner Strait, on July 26 and 30, 118 of which were recaptured (30.8 per cent). The data are presented in Table 11. They support in detail the conclusions reached through the previous experiments but add nothing new to our knowledge of the migrations in this region. 14 BULLETIN OF THE BUREAU OF FISHERIES Table 11. — Returns from red salmon tagged at Point Colpoys, 1927 Locality of recapture Locality (Point Colpoys) and date of tagging Total num- ber recap- tured Locality of recapture Locality (Point Colpoys) and date of tagging Tota num- ber recap- tured July 26 July 30 July 26 July 30 Num- ber Days Num- ber Days Num- ber Days Num- ber Days Sumner Strait: Clarence Strait, South of Point Colpoys 9 6-25 3 4 12 Ernest Sound — Continued. Red Bay 5 3 5 Wolf Creek 1 5 1 Point Baker. 1 6 1 Ship Island 2 8-10 2 6 4 Stikine Flats.. 1 (') 1 Ship Harbor 1 10 1 Frederick Sound: Boulder False Island 1 5 1 Point . . .. 1 10 1 Caamano Point 2 4-10 2 C arence Strait, north of Ernest Grindall Point 1 10 1 Sound: Clover Passage 1 8 1 Snow Passage 1 15 1 Guard Islands 1 14 1 Point Nesbitt 5 3-6 2 7-14 7 Gravina Island 1 11 1 10 2 West entrance, Stikine Dali Head 1 6 1 Strait 1 4 1 Cedar Point 1 5 1 Etolin Island 1 1 Driest Point .. 1 13 1 Point Harrington .. 1 3 1 Point Davison 2 4-12 1 6 3 Marsh Island 1 2 1 Hotspur Island 2 8-13 2 1 3 1 Point Percy 3 4-7 3 Coffman Island 3 3-5 3 Sealed Passage... . . . 1 8 1 6 2 Whale Passage 3 2 3 3 6 Ingraham Bay 1 10 1 2 3-4 2 South Kendrick Bay 1 4 1 Eagle Creek 3 4-14 i 20 4 Cape Chacon . . . i 12 1 Ratz Point ... 2 3-12 3 4 5 Cordova Bay: Point Marsh. _ 1 23 1 Narrow Point 1 5 5 4-8 6 Behm Canal: Yes Bav 1 55 1 Ernest Sound: Revillagigedo Channel: 1 5 1 15 2 Kirk Point... __ i 14 1 1 8 1 Boat Harbor 2 5-10 2 Watkins Point 1 5 i Kanagunut Island i 3 i Seward Passage. 1 8 1 British Columbia: Portland Inlet 1 9 1 1 8 1 Mouth of Skeena River. . i 8 i 2 2 1 4 1 Kitchen Island i 6 Smith Island i 6 i Skeena or Nass Rivers 2 7 (?) 7 1 1 1 1 Meyers Chuck... 1 3 1 Total 60 58 118 2 4 2 Percentage returned 30.3 31.3 30.8 1 Reported captured before date of tagging. 2 7 tags recovered near Skeena River, Nass River, and Lowe Inlet, British Columbia, July and August. PINK SALMON Five hundred and seventy-seven pink salmon were tagged at Point Colpoys, Sumner Strait, during 1927, 232 of which were recaptured (40.2 per cent). The data presented in Table 12 show the same general distribution of pink salmon from Sumner Strait as was shown by the previous experiments. It is interesting to note, however, that none of the fish tagged in 1927 were recaptured on the west coast of Prince of Wales Island. This agrees with the experiments of 1926, but both differ in this respect from the experiments of 1924 and 1925, which were made at Ruins Point. It is evident that the fish that enter the strait as far as Point Colpoys are pursuing a definite migration, while those as far out as Ruins Point may or may not be definitely entering Sumner Strait. SALMON-TAGGING EXPERIMENTS 15 Table 12. — Returns from pink salmon tagged at Point Colpoys, 1927 Locality (Point Colpoys) and date of tagging Total Locality of recapture July 26 July 30 num- ber recap- tured Locality of recapture July 26 July 30 num- ber recap- tured Num- ber Days Num- ber Days Num- ber Days Num- ber Days Sumner Strait: Clarence Strait, South of Point Colpoys 3 6-13 5 2-6 8 Ernest Sound— Continued. 1 3 i Wolf Creek ... . ... 2 5 1 7 3 Point St. John ... 1 1 1 2 miles north of Ship 1 5 1 Island . ... 1 10 1 1 3 1 Tolstoi Bay 1 4 1 Ship Island _ 5 4-10 5 1 4 1 False Island 2 7-9 4 6-10 6 Clarence Strait: Caamano Point.. 3 8 4 4-8 7 2 4-6 2 Behm Canal: 1 15 2 6-11 3 Bctton Island 1 15 1 11 2 4 3-6 2 8-9 6 Point Higgins 1 7 1 Helm Bay 1 6 1 3 10-17 3 Traitors Cove 2 7-12 2 1 3 1 Clarence Strait south of Behm Screen Islands.,. 4 3-9 1 4 5 Canal: 2 3 i 7 3 Island Point 1 14 1 1 2 1 Skin Island 1 10 1 2 7-9 2 Grant Cove 1 12 1 Whale Passage ... ... ... 3 2-3 2 3 5 Nelson Cove . 1 12 1 Coffman Island 2 3-5 2 Gravina Island. 1 17 3 4-7 4 Eagle Creek 2 3-14 2 Dali Head ._ 3 8 3 1 4 1 1 5 1 1 3 1 Point Davison 1 6 1 Ratz Point 4 4-18 4 Hotspur Island ... _. 1 4 1 Gull Point. 1 7 1 Vegas Islands 2 16 1 12 3 3 7-12 1 3 4 Sealed Passage 2 8 2 2 5 1 5 3 Duke Island _. . 1 6 1 Ernest Sound: Cape Chacon . _ 2 12 9 Union Bay.. 1 14 4 5 5 Nichols Passage: Bostwick In- Union Point ._ 6 8 3-10 14 let 3 10-16 3 Vixen Inlet 1 7 1 3 2 Revillagigedo Channel: Eaton Point 7 5-12 7 3-19 14 Crab Bay.. 1 13 1 Watkins Point 4 5-10 6 4-14 10 Point Sykes 1 10 1 West side of Deer Island.. i 8 1 Breakwater, south. _ _ _ _ 1 10 1 Seward Passage 0 7-12 6 3-8 12 Ivah Shakes Point 1 4 1 South end of Wrangell Foggy Bay ... ..... 1 6 1 Island 14 5-8 6 5-10 20 2 12 1 5 3 Point Warde 1 8 3 4-7 4 Cape Fox. 1 9 1 Anan Creek 4 4-15 1 6 British Columbia: Clarence Strait, south of Nass River _ ... ... 1 8 1 Ernest Sound: Wright Sound 1 43 1 1 r 1 Meyers Chuck __ 6 2-11 6 Total 108 123 231 Misery Island... . . .. . 5 4 5 39. 8 40. 5 40. 2 Three Islands _ 2 4-7 3 3-13 5 Locality (Point Colpoys) and date of tagging Total COHO SALMON Twenty-eight coho salmon were tagged at Point Colpoys, Sumner Strait, during 1927, six of which were recaptured (21.4 per cent). One was taken at Point Colpoys after 18 days, and the others were taken in various localities in Clarence Strait after 8 to 17 days. RETURNS FROM EXPERIMENTS AT CAPE DECISION, SUMNER STRAIT Two hundred and ninety-nine salmon were tagged at Cape Decision, Sumner Strait, on July 30. Of this number 29 were reds, 164 pinks, 82 chums, and 24 cohos. RED SALMON Of the 29 reds tagged at Cape Decision on July 30 only 4 were recaptured. One was taken in each of the following localities: Barrier Islands, Sumner Strait, 12 days; Tebenkof Bay, Chatham Strait, 11 days. Two were taken in or near the Skeena and Nass Rivers and Lowe Inlet, British Columbia, during July and August, but no definite dates or locations were recorded. 16 BULLETIN OF THE BUREAU OF FISHERIES PINK SALMON The returns from pinks tagged at Cape Decision, Sumner Strait, are presented in Table 13. These data would indicate two important migrations. The main migra- tion traversed the waters of Sumner Strait to its junction with Clarence Strait, thence southerly in Clarence Strait. Two individuals of this migration were recap- tured in Ernest Sound. One return is noted from Skeena River, British Columbia. The second and minor migration was northerly into Chatham Strait, whence 16 returns are reported. Table 13. — Returns from -pinks tagged at Cape Decision, July 30 — 16 4 tagged, fl returns {25 per cent ) Locality of recapture Number Days Locality of recapture Number Days Sumner Strait: Frederick Sound: Cape Fanshaw 1 2 Cape Decision 2 4-8 Clarence Strait: 2 13 1 6 1 11 1 12 Cape Pole.- . ... ... i 7 Blashke Island _ 1 8 Ruins Point _ _ 1 6 1 11 Point Colpoys _ 5 4-13 Ernest Sound: 1 12 1 8 9 G-9 1 14 Chatham Strait: Clarence Strait, south of Ernest Sound: Gedney Harbor .. ... .. l 14 1 8 1 14 Wolf Creek. _ 1 6 Tebenkof Bay . . 2 11-13 Turn Point 1 ... ... 1 19 North of Washington Bay. 3 4 British Columbia: Skeena River.. 1 21 South of Kingsmill Point- . . . 5 4-9 Red Bluff Bav i 5 Basket Bay- 1 G North of Hawk Inlet. _ . ------ 1 8 • 1 Location doubtful. These results differ materially from those secured from the experiments of 1924 and 1925 at Ruins Point, although this locality is just across Sumner Strait from Cape Decision. In the experiments at Ruins Point a large number of pink salmon went to various localities along the west coast of Prince of Wales Island, and comparatively few went north into Chatham Strait. The conditions were just reversed in this experiment at Cape Decision. None of the pinks tagged there were taken along the west coast of Prince of Wales Island, and a large percentage went north in Chatham Strait. These differences may, of course, be due to chance, but it seems more likely that they are indicative of a distinct difference in the com- position of the schools from which the tagged fish were taken. It seems unlikely, however, that such marked differences would be found between the fish at two points so close together at any one time, and we are inclined to ascribe these differences to differences in the runs of 1924 and 1925 as compared with that of 1927. Since the fishery was virtually a failure on the west coast of Prince of Wales Island in 1927, it is not particularly surprising that few fish bound for this region were found among the catches at Cape Decision. CHUM SALMON The chums tagged at Cape Decision and again captured followed a northerly route into Chatham Strait without exception. Three individuals were recaptured at Cape Decision 5 to 15 days from the date of tagging. One entered Frederick Sound and was recaptured at Security Bay; four were taken along the Chatham Strait shore of Ivuiu Island; and one was recaptured at Point Hepburn on Admiralty Island. SALMON-TAGGING EXPERIMENTS 17 COHO SALMON Twenty-four coho salmon were tagged at Cape Decision on July 30. Only one was recaptured, and this was taken near Washington Bay, Chatham Strait, in four days. RETURNS FROM EXPERIMENTS IN CLARENCE STRAIT RED SALMON Eleven red salmon were tagged at Gravina Island during 1927, six of which were recaptured (54.5 per cent). Two were taken in Clarence Strait, one in Revillagigedo Channel, and three in Behm Canal. One of those taken in Behm Canal was found at the Yes Bay hatchery of the Bureau of Fisheries during spawning operations. PINK SALMON Three hundred and twenty-six pink salmon were tagged at Gravina Island during 1927, 77 of which were recaptured (23.6 per cent). The data are presented in Table 14. Table 14. — Returns from pink salmon tagged at Gravina Island, 1927 Locality of recapture Locality and date of tagging Total num- ber recap- tured Locality of recapture Locality and date of tagging Total num- ber recap- tured Dali Head, Aug. 5 Nelson Cove, Aug. 6 Dali Head, Aug. 5 Nelson Cove, Aug. 6 Num- ber Days Num- ber Days Num- ber Days Num- ber Days Clarence. Strait, north of Dali Clarence Strait north of Behm Head: Canal— Continued. Dali Head-- 2 1-4 2 Onslow Island 2 4-9 2 1 2 5 1-7 6 Ratz Point 1 11 1 Gravina Island 3 8-9 i 3 4 F.rncst Sound: East coast, Prince of Wales Union Bav._ ... . 2 3-8 2 1 5 1 Eaton Point, 1 11 6 3-12 7 Guard Islands, _ ... 3 7 3 South end of Wrangell 1 8 1 Island 1 7 1 Behm Canal: Clarence Strait, south of Dali Betton Island 1 4 1 Head: 1 4 1 Polk Island. .. 1 8 1 Smugglers Cove 1 2 1 II otspur Island 1 1 Helm Bay 1 6 7 2-6 8 Cedar Point _ _ 1 5 1 Escape Point 1 8 1 Percy Islands __ 1 3 1 Spacious Bay 1 3 1 Duke Island 1 5 1 Bluff Point 1 2 1 South Kendrick Bay. 1 6 1 Clarence Strait north of Behm Cape Chacon 1 G 1 Canal: Nichols Passage: Bostwick In- Caamano Point __ 2 3-6 2 3 4 let ... 2 4-10 2 1 3 1 3 1-4 3 Slate Islands... 1 8 1 7 2 False Island 1 8 1 Foggv Bav... . . 1 7 1 2 miles north of Ship Boat Harbor i n i 3 Island 2 4 2 3 4 Behm Canal, east end: Point Three Islands. _ __ _ 1 4 i 3 2 Nelson ... 1 3 1 1 4 1 Meyers Island 1 4 i Total 24 53 77 Lemesurier Point i 4 i Percentage returned. 27.9 22 23. 6 The returns indicate two lines of migration — the main one northerly into Clarence Strait, traversing this body of water to its junction with Behm Canal and also to its junction with Ernest Sound, and a minor one in a southerly direction from the point of tagging. Part of this latter migration crossed Clarence Strait to the Prince of Wales Island shore, where three fish were recaptured. The majority, however, followed the Gravina Island shore and then took an easterly course, scattering to various points 18 BULLETIN OF THE BUREAU OF FISHERIES in Felice Strait and Revillagigedo Channel. The time of travel is noticeably short, the minimum being 1 day and the maximum 12 days. CHUM SALMON Fifty-two chum salmon were tagged at Gravina Island during 1927. Only three were recaptured (5.7 per cent), one each from the following localities: Seal Cove, Gravina Island, 5 days; Vegas Islands, Felice Strait, 6 days; Clover Passage, Behm Canal, 1 day. COHO SALMON Eleven coho salmon were tagged at Gravina Island during 1927. Only one was recaptured, which was taken at Guard Islands, Clarence Strait, in eight days. CONCLUSIONS Although the experiments of 1927 involved the tagging of relatively few fish distributed among eight quite distinct localities, the results have corroborated the previous experiments to a remarkable degree. The percentages of recoveries are approximately the same as those obtained in 1924, 1925, and 1926, and are collected in Table 15. Table 15. — Percentage of tagged fish recaptured, 1927. Total number tagged, 4,668; total number recaptured, 1,506; percentage recaptured, 32.2 Locality whore tagged Red Pink Chum Coho King Locality whero tagged Red Pink Chum Coho King Icy Strait.. 27. 1 37.7 19.2 1S.0 Point Hobart ... . 17.8 30. 5 17. 5 Chatham Strait 25.0 32. 1 33.5 17. 6 15. 3 Point Colpoys _ 30. 8 40. 2 21.4 Hourigan Point and Carroll Cape Decision 13. 7 25.0 10. 9 4. 1 20.0 48. 6 26. 1 20.6 Gravina Island 54. 5 23. 6 5.7 9.0 Cape Bendel 10.0 45.2 20.4 14.2 33.3 The routes of migration are virtually identical with those shown in the earlier work, and in most instances the percentages of fish taking the various routes from a given tagging station are as nearly the same as might be expected. These were discussed in some detail in the report dealing with the experiments in 1926 (Rich and Suomela), and it does not, therefore, seem necessa^ to repeat that treatment here. The partic- ular value of the experiments described in this report lies in the fact that they support so strongly the previous studies of the migration of salmon in the intricate channels of southeastern Alaska. UGANIK BAY, 1927 Red salmon are taken in fairly large numbers in the fishery in Uganik Bay on the northern shore of Kodiak Island, particularly in two traps on the western shore. During the season of 1927 126,000 red salmon were reported as captured in this bay, and in 1926 the catch was over 274,000. It was suspected that these might belong to the Karluk River run, and to test this 700 red salmon were tagged and released on August 19 and 20, 1927, from the Broken Point trap of the San Juan Fishing & Packing Co. Three hundred and seventeen tags were taken later in the commercial fishery and were returned with data as to when and where the fish were captured. In addition to those taken in the commercial fishery 86 were observed to reach the Karluk count- ing weir on their way to the spawning grounds. Some of these were captured, but SALMON-TAGGING EXPERIMENTS 19 the majority continued past the weir and doubtless ultimately reached the lake. The recoveries are shown in Table 16. Table 16. — Returns from lags attached August 19 and 20, 1927, at San Juan trap No. 1, Broken Point, Uganik Bay, Kodiak Island, Alaska * Locality of recapture * Ugan- ik Bay South Arm, Ugan- ik Bay Spiri- don Bay Uyak Bay or Seven- mile Beach Kar- luk Beach Kar- luk River Cape Ugat Chiefs Point Uyak Bay Lazy Bay Vie- koda Bay Rasp- berry Strait Cook Inlet Un- known 1 1 5 1 5 7 3 6 58 8 3 3 1 4 10 12 1 5 4 2 8 3 5 4 14 1G 6 1 11 5 2 1 ii i 5 2 1 1 2 21 3 3 13 1 21 i 2 1 1 1 2 1 2 11 5 1 > 8 a 7 3 2 3 47 3 3 1 1 54 13 8 7 9 44 47 124 86 3 3 2 2 1 Date of recapture Total Aug. 19.. Aug. 20. . Aug. 21- Aug. 22.. Aug. 23.. Aug. 24.. Aug. 25.. Aug. 26- Aug. 27.. Aug. 29.. Aug. 30.. Aug. 31- Sept. 1.. Sept. 2__ Sept. 3. . Sept. 4. . Sept. 5.. Sept. 6.. Sept. 7.. Sept. 8_. Sept. 9.. Sept. 10- Sept. 14. Sept. 15. _ Sept. 17.. Sept. 18. . Sept. 19. . Sept. 20. . Doubtful. Total. 2 5 6 74 14 28 11 16 41 11 7 12 8 2 2 21 19 1 21 3 1 2 2 1 2 11 5 1 74 403 1 Reported taken between Aug. 24 and 27. 1 Reported taken between Aug. 20 and 22. 3 Reported taken between Aug. 20 and 27. 1 Reported taken between Aug. 20 and 30. 1 Reported taken between Aug. 27 and 28. An examination of this table shows conclusively that the red salmon taken during the latter part of August in the traps along the western shore of Uganik Bay are predominantly derived from the Karluk River run. The 13 that were taken in the southern arm of Uganik Bay were probably, although not certainly, bound for a stream entering the east arm of the bay, which was formerly very productive but is now depleted so seriously that the run amounts to very little. Three were taken in the region of Alitak and presumably represent an element of the Alitak run that passes the northern shore of Kodiak Island during the spawning migration. Seven were taken to the eastward of Uganik Bay, including two taken in Cook Inlet, and one was returned without data as to when and where it had been recaptured. All of the others — 399 out of a total of 423 (94.5 per cent) — were taken either at Karluk or at some point between the place where the tagging was done and Karluk, or were reported on their way up Karluk River to the spawning grounds. The percentage of recoveries was unusally high — 57.6 per cent- — but this includes 86 fish that were counted through the weir maintained by the Bureau of Fisheries in Karluk River. If we consider only the fish that were taken in the commercial 20 BULLETIN OF THE BUREAU OF FISHERIES fisheries, the number of recaptures is 317, or 45.2 per cent. Although this is still a higher percentage of recovery than has usually been reported from similar tagging experiments, it is within the range of the previous results. The recovery of so many tagged fish shows that the fishery is carried on with a considerable intensity in this district, and it can not be doubted that, were it not for the controlled escapement, the catch of Karluk red salmon would be greatly in excess of the 50 per cent required by law. It will be noted that over 40 per cent of the tagged salmon were not accounted for, in spite of the facts that the results show that a majority of the fish were bound for the Karluk River, and that the weir in the Karluk River gives opportunity to observe the fish that entered this stream. Without much doubt, this discrepancy is due to the fact that it is impossible to observe carefully all of the fish as they pass through the weir. They are usually moving rapidly and may be as much as 3 feet below the surface of the water. Under such conditions it is inevitable that tagged fish would pass through without being noted, and we believe that this accounts for a large part of the 40 per cent that was unaccounted for. The rate of travel indicated by the returns is fairly rapid, corresponding, in general, to the rate observed in the experiments on the Alaska Peninsula in 1922 and SALMON-TAGGING EXPERIMENTS 21 1923. Uyak Bay is only some 20 miles from the point of tagging, and Karluk Beach, where most of the tagged fish were recaptured, is about 20 miles farther on to the westward. Fifty-eight tagged fish were taken at Karluk Beach on the 22d, having traveled about 30 miles in 2 or 3 days. The actual rate of travel is more rapid than is indicated by the figures on account of the lapse of time between the actual capture and the finding of the tags. (See Gilbert and Rich.) It is not known whether these traps in Uganik Bay take Karluk red salmon throughout the season, and it is purposed to secure data that will solve this problem. In the light of our present definite knowledge, however, we must include the Uganik catch of red salmon in the total for the Karluk run, just as is done in the case of the red salmon taken in Uyak Bay. NICHOLASKI SPIT, 1928 This experiment was designed to test the theory that the red salmon taken at Nicholaski Spit were part of the same run that passes the Shumagin Islands and Morzhovoi and Ikatan Bays, which has been shown by the experiments of 1922 and 1923 to consist largely of Bristol Bay fish. Nicholaski Spit is situated on the western shore of Pavlof Bay, Alaska Peninsula, about halfway between the Shumagin Islands and the end of the peninsula. The fishery here is of recent development, a trap having been driven in 1924 and operated every year since. The late Dr. C. H. Gilbert examined scales of red salmon from this locality and found indications that the catches contained a considerable percentage of Bristol Bay fish. More recent statistical studies also have shown a distinct correlation in the size of the catches at Nicholaski Spit and in Ikatan and Morzhovoi Bays,3 a fact that lent further probability to this theory. As originally planned, this experiment was to have been carried out during the height of the red-salmon run in the Ikatan-Shumagin Island district, but additional regulations prevented fishing at Nicholaski Spit until after the 1st of July. Other circumstances made it impossible to tag immediately after the fishing season opened, and it was not until July 11 that the first tags were attached. The main part of the Bristol Bay run has passed through the Ikatan-Shumagin Island district before this time, so that the experiments can not be taken as accurately representing the condi- tion at Nicholaski Spit earlier in the season. In spite of these deficiencies, however, the data show a distinct migration to the westward and into Bering Sea, where tags were taken at Bear River and in Bristol Bay. It seems safe to conclude, in view of all the lines of evidence available, that the fish that pass Nicholaski Spit earlier in the season include Bristol Bay fish, probably in about the same proportion as do the runs in the Shumagin Islands and at Ikatan. Four hundred and sixty-one tags were attached as follows: 300 on July 11, 74 on July 12, and 87 on July 17. Only 30 tags were recovered (6.5 per cent). This relatively low percentage of recaptures is probably due to the fact that the tagging was done so late in the season. The returns are given in Table 17. 3 Statistical Review of the Alaska Salmon Fisheries. Part I: Bristol Bay and the Alaska Peninsula. By Willis H. Rich and Edward M. Ball. Bulletin, U. S. Bureau Of Fisheries, Vol. XLIV, 1928, pp. 41-95. Bureau of Fisheries Document No. 1041. 22 BULLETIN OF THE BUREAU OF FISHERIES Figure 2.— Part of the Alaska Peninsula SALMON-TAGGING EXPERIMENTS 23 Table 17. — Returns from 462 red salmon tagged at Nicholaski Spit, Alaska Peninsula, July 11, 12, and 17, 1928 It will be seen at once that the most important migration is to the westward and particularly into the region of Ikatan and Morzhovoi Bays. Approximately one-fourth of the recaptured tags came from these two localities. The movement from Nicholaski Spit to Ikatan and Morzhovoi Bays was very prompt — from four to five days — and in this respect the migration resembles that of the Bristol Bay fish that pass from the Shumagin Islands to Ikatan and Morzhovoi Bays. (See Gilbert, 1923, and Gilbert and Rich, 1925.) These facts lend strong support to the theory that many of the red salmon that pass Nicholaski Spit belong to the same schools that provide the fishery in the Shumagin Islands, and the single return from Bristol Bay is conclusive evidence that at least some of these fish were bound for the streams in that district. It is not surprising that more fish were not taken in Bristol Bay, because the red-salmon fishery there closed on July 23 — only 12 days after the first fish were tagged at Nicholaski Spit. Although the evidence points conclusively to the Bristol Bay origin of a large percentage of the Nicholaski Spit fish, there is also a surprisingly large migration to the eastward, fish being taken at Chignik, Kodiak Island, and Cook Inlet. The earlier experiments in the Alaska Peninsula region had given no indication of any such extensive migration to the east. Most of these earlier experiments were con- ducted earlier in the season, however, and so were not directly comparable. Some of the later experiments in 1923, however, did show a distinct tendency toward an easterly migration, although by no means as well marked as in the case of the experi- ments of 1928, in which more than 25 per cent of the returns came from Chignik, Kodiak, and Cook Inlet. There is obviously some indication here that the fishery in the Ikatan-Shumagin Island district does draw to a considerable extent, at least after about the 10th of July, upon the runs originating in streams, such as Chignik, situated to the eastward. •V ■ ' : v; . ■ • - < • • : •' fo- ■ ■■ ■. i •- - - : ! ■. - to; ; ■ ' ■ -■ ... ; ... i : - ■ ' . _ . : - • '‘to ' . to- i;! " ■: ' • : rifif/; : . - i- ■■■•■ ■ I REVIEW OF EXPERIMENTS ON ARTIFICIAL CULTURE OF DIAMOND-BACK TERRAPIN 1 By SAMUEL F. HILDEBRAND Director, U. S. Fisheries Biological Station, Beaufort, N. C. CONTENTS Page Introduction 25 Explanations 27 Distribution of terrapins 27 Experiments conducted and sources of information 28 Production of eggs 28 Fertility of eggs 32 Records of survival 36 Rate of growth 44 Growth of young terrapins kept warm and fed during the winter. _ 45 Food 52 Crowding , 53 Comparison of the size of winter-fed and hibernating terrapins at about 1 year of age 54 Page Rate of growth — Continued. Growth of terrapins past 1 year of age. 54 Conclusions 58 Period of activity 64 Food, feeding, and cost of food 64 Copulation, laying season, and incubation period 65 Space requirements 65 Sex ratio 66 Summary 68 Bibliography 70 INTRODUCTION It is a well-known fact that the diamond-back terrapin (Malaclemmys) once was plentiful. When this animal first came into demand only the terrapins taken in Chesapeake Bay and northward brought a good price, and the more southern terrapins frequently were shipped to dealers at certain points on Chesapeake Bay, to be re- shipped from thence to the larger cities as “Cliesapeakes.” Gradually the Carolina terrapins gained in favor, and more often they were shipped directly to the larger markets. The practice of sending southern terrapins to dealers on Chesapeake Bay, however, appears not to have been discontinued entirely, as the writer has been in- formed authoritatively that some southern animals are still sent there to be reshipped. It is not known to the writer whether the more northern terrapins actually excel in flavor. It seems probable, though, that the difference is not great or Chesapeake dealers would not, for many years, have been able to sell animals from the South as “Chesapeakes.” 1 Submitted for publication Nov. 16, 1928. 25 26 BULLETIN OF THE BUREAU OF FISHERIES The catch of terrapins, soon after the flesh came into demand, exceeded produc- tion, for the animals could not stand a heavy drain, as they do not reproduce rapidly and growth is gained slowly. The natural supply, therefore, was quickly dimin- ished. It was quite evident by the beginning of the present century that these valuable creatures were being reduced so rapidly that very soon they would be so scarce as to make fishing for them unremunerative, if, indeed, the animals were not doomed to extinction. In view of the rapid depletion the Bureau of Fisheries (then the Fish Commission) instituted an investigation in 1902 on Chesapeake Bay, which had for its principal object the determination of the adaptability of the diamond- back terrapin to artificial propagation (Hay, 1905). About the same time the State of North Carolina, in cooperation with the United States Fish Commission at the United States Fisheries Biological Station at Beaufort, N. C., undertook another investigation, which consisted principally of an inquiry into the habits and life his- tory of the terrapin and the condition of the terrapin industry in North Carolina (Coker, 1906). The investigation at Beaufort was discontinued in 1903, but the investigations on the Chesapeake Bay were made more comprehensive. In 1904 a comparatively large wooden pound was built at Lloyds, Md., which provided facili- ties for holding both young and adult terrapins, and suitable sand beds, in which the terrapins might lay their eggs, were furnished. The experimental work at Lloyds was continued until 1909, when activities were transferred to Beaufort. The series of experiments upon which the present report is based dates from that year.2 It was learned from the early experiments conducted at Beaufort, N. C., and at Lloyds, Md., that adult terrapins would produce eggs when confined in pens; also, that the eggs could be transferred from where they were laid to “suitable hatching boxes,” where most of them would hatch. Raising the young, however, appears not to have been successful prior to the transfer of the work to Beaufort and the beginning of the present series of experiments in 1909. A number of attempts to raise terrapins in captivity have been made by private individuals. Most of the private terrapin “farms,” however, consist of pens, often called “crawls,” in which the animals are placed and fed in order to gain growth or merely to be held for a better market. However, in 1913 a company was organ- ized in Beaufort, which built concrete pounds and a terrapin nursery house and provided itself with all the facilities necessary for raising terrapins. A large brood stock was obtained, and within a few years from 15,000 to 20,000 terrapins per annum were being hatched. This farm progressed nicely until the beginning of the World War and the adoption of the eighteenth amendment to the Constitution. The cost of labor was more than trippled locally, the market value of terrapins dropped, owing to the general curtailment of the use of luxuries during the war, and it seems to have been believed by the manager that under prohibition terrapins never again would be in demand or command the fancy prices paid for them prior to prohibition and the war. In view of these seemingly adverse circumstances, the breeding terrapins as well as some of the young that had attained a marketable size were sold, and in 1918 the plant virtually was abandoned. The Beaufort 2 Because of the rather frequent changes in the scientific personnel, the experiments were planned by various individuals. The care of the terrapins and the actual work of carrying on the experiments, however, have always been in the hands of Charles Hatsel, the station’s able terrapin culturist and foreman. Mr. Hatsel also kept nearly all of the original records, and the success of the undertaking is due, in a very large measure, to his interest and painstaking work. DIAMOND-BACK TERRAPIN CULTURE 27 Terrapin Farm was patterned after the experimental plant of the Bureau of Fish- eries, and the success attained in raising terrapins compared very favorably with that of the Bureau of Fisheries. EXPLANATIONS Wherever the size of terrapins is mentioned in this paper it refers to the length along the median line of the plastron or lower shell, as this measurement has long been in use in classifying terrapins for the market. “Carolina terrapins,” when used in this paper to designate animals grown in captivity, refer to terrapins that actually are not of “pure blood,” because, as shown below, they are the result of a cross between the two closely related sub- species, Malaclemmys centrata centrata and M. centrata concentrata. This term is used for convenience in distinguishing the Atlantic-coast animals from the Texas- coast species, M. pileata littoraiis, as well as from certain hybrid lots also used in the experiments. DISTRIBUTION OF TERRAPINS Diamond-back terrapins occur on the coasts of the United States from Buzzards Bay, Mass., to Texas. Two species, divided into five subspecies, are recognized by Stejneger and Barbour (1923, pp. 131-132), as follows: The Carolina terrapin ( Malaclemmys centrata centrata), ranging from central North Carolina to Florida; the Chesapeake terrapin (M. centrata concentrata ), ranging from Buzzards Bay to North Carolina; the Florida terrapin (M. pileata macro spxlota) , on the Gulf coast of Florida; the Louisiana terrapin (M. pileata pileata), ranging from the mouth of the Mississippi River eastward on the Gulf coast to Florida; and the Texas terrapin {M. pileata littoraiis), which inhabits the coast of Texas and the shores of the out- lying islands. The differences between the Chesapeake terrapin and those from the Gulf coast are quite pronounced; that is, the Gulf-coast terrapins have evident tubercles (humps) on the median line of the back, which are obsolete or wanting in the Atlantic species, and generally there are also differences in color that aid in separating the species. The differences between the Atlantic (Chesapeake and Carolina) terrapins, however, are slight. In general, the Carolina terrapin has a larger head, a blunter snout, and the sides (lateral outlines) of the carapace are more nearly parallel and less flaring posteriorly than in the Chesapeake terrapin. These differences usually are evident and are recognized by dealers. However, North Carolina is the geographical meeting place of the Chesapeake and Carolina terra- pins. Therefore, it is not surprising that some animals are seen from time to time that are difficult to place in either variety. The Atlantic varieties (Chesapeake and Carolina) of terrapins have both been used from the very beginning of the experimental work at Beaufort, for the original brood stock (still on hand) was obtained in part from Chesapeake Bay and in part from the general vicinity of Beaufort, where both varieties occur. These terrapins have been confined together in a small pen for almost a score of years, and there is not the slightest doubt that interbreeding is occurring freely. It may be stated here that apparently no inferior stock has resulted from this “crossbreeding,” as the offspring raised to maturity in captivity are a fine race of animals and superior in appearance to their parents. 28 BULLETIN OF THE BUREAU OF FISHERIES The Chesapeake terrapin is generally preferred on the market, but the differ- ence between it and the Carolina terrapin is so slight that large, fat animals of the last-mentioned variety are accepted readily as “Chesapeakes.” EXPERIMENTS CONDUCTED AND SOURCES OF INFORMATION At the present time (January 14, 1928) 33 lots of terrapins are on hand at the station. The animals composing the various lots, exclusive of those that comprise the original brood stock, were hatched and grown in captivity and therefore are of known age. Every lot itself forms the basis for a separate experiment or is a part of an experiment. The following are some of the experiments for which the various lots of terrapins are being used: (a) Space requirements for young and adults; (b) size of egg beds required; (c) natural sex ratio; (d) sex ratio required for breeding purposes; (e) practicability for increasing growth, hastening maturity, and reducing the death rate by feeding young terrapins during the winter; (f) the control of disease among recently hatched animals (young terrapins only are mentioned in this connec- tion, as no disease has occurred during the course of the experiments among animals a year or more of age); (g) several experiments in selective breeding; (h) two experi- ments in crossbreeding the Carolina with the Texas terrapin. Some of the experi- ments have not been carried on long enough or far enough to yield results, and these will not be reported upon at this time. Others have yielded noteworthy results, however, and the information derived forms the basis for the present report. The latest previous report 3 made upon this investigation is entitled “Further Notes on the Natural History and Artificial Propagation of the Diamond-Back Terrapin,” by R. L. Barney (Bulletin, U. S. Bureau of Fisheries, Vol. XXXVIII, 1921-22 [1922], pp. 91 to 111). Although the present paper essentially is a progress report, nevertheless it is based upon the original data, all of which have been studied carefully. The data presented cover the entire period during which each experiment reported upon has been under way. In the interpretation of the data due considera- tion, however, was given to the published accounts. A different conclusion occa- sionally was arrived at, mainly on account of the much more extensive data now at hand and partly because of errors that were corrected and, no doubt, also in part because of a different personal viewpoint. PRODUCTION OF EGGS The production of eggs has varied from year to year within broods and even within lots of the same brood, as shown by tables presented herewith. Similar varia- tions have taken place among wild terrapins of unknown age confined for breeding purposes. For example, among a certain lot of wild breeders production has varied from about 7.6 to about 23.9 eggs 4 per female during the period 1915 to 1926, inclu- sive. It appears to be of interest to mention in this connection that wild terrapins have produced few eggs during the first two and three years of confinement. The 3U. S. Bureau of Fisheries Economic Circular No. 00, entitled “Diamond-Back Terrapin Culture at Beaufort, N. C.,’’ by- Samuel F. Hildebrand and Charles Hatsel, was issued in October, 192S. This short paper gives only the economic phases of the work and gives no specific account of the many experiments performed nor of the more scientific aspects of the work. A slightly larger number of eggs per female was produced than shown, as the terrapins themselves accidentally destroyed a few eggs from time to time and rats often destroyed an unknown number. Eggs thus destroyed are not taken into consideration in these data. DIAMOND-BACK TERRAPIN CULTURE 29 records for the original brood stock are rather obscure, but sufficient data are avail- able to show that only a small number of young was produced during the first years of confinement. Similar results (no definite figures are available) were obtained at a local terrapin farm and also for some wild terrapins purchased by the State of North Carolina and confined in 1925 for breeding purposes at the United States fisheries biological (Beaufort) station. The last-mentioned lot, consisting of 478 females and 108 males, laid only 0.8 egg per female in 1925, 1.2 eggs in 1926, and 4.2 in 1927. Another large increase was expected in 1928 but this, for reasons unknown, did not materialize, as the production of eggs remained the same as in 1927. The largest number of eggs laid per female by any group of terrapins that has been held in confinement during the course of the present experiments was produced by the first brood (1909) hatched and grown in captivity. In the first year few animals were hatched and only four females were grown to maturity. These four animals grew at a fairly uniform rate, and apparently all reached maturity at the same time. The rate of egg production was high and fairly constant, varying during the years 1915 to 1925, inclusive, from 22 to 34.3 eggs per female, with an average for the entire period of 29.4 eggs. The four females in this lot (used in certain dye feeding experiments in 1926, which proved fatal to two of them and sickened the others) appear to have been extremely fertile, and the rate of egg production far surpassed that of the later and larger broods. The broods of 1910 and 1911 prob- ably show to a far greater extent the rate of egg production that may be expected from terrapins grown in captivity. An increase in the average number of eggs laid per female for the lots is expected, as some of them have only recently reached sexual maturity. The tables show that a downward trend in egg production took place from 1919 to 1925 in the two lots of the 1910 brood and also for the winter-fed lot of the 1911 brood. A recovery is indicated for 1926 and a further one apparently will result for 1927, when all the young have been collected and counted. The general downward trend for these broods that took place, therefore, appears to have been only a “fluctuation,” which is shown also for the original wild brood stock. The data appear to indicate that certain years are not as productive of eggs as others. The tables show that egg production in 1921 and again in 1925 was lower than usual for nearly all the lots on hand. The causes for the “lean” years are not obvious. The care and the food received have not varied from year to year. In fact, the animals have remained in the immediate care of the same terrapin culturist throughout the course of the experiments. A study of the weather records kept at the station reveals nothing unusual during the lean years. On the other hand, the winters of 1917-18 and 1918-19 were both unusual, the first one having been extraor- dinarily cold and the second exceptionally mild, yet each of these winters was followed by a good laying season. The cause or causes of poor laying seasons remains for future investigation. The great variation in the number of eggs produced by individuals is referred to under the section of this report dealing with fertility, the range given for a single season being from 5 to 29 eggs. Experiments are under way whereby) it is hoped to determine whether certain females more or less constantly lay a small number of eggs while others produce a much larger number. These experiments have not been running long enough to yield definite results. The indications are, however, 30 BULLETIN OF THE BUREAU OF FISHERIES that among terrapins, as among chickens, certain females are “boarders.” If fur- ther observations confirm the results already obtained, it should be possible to elim- inate the boarders and to select animals of high fertility for breeding purposes. It appears to be of interest to call attention to the long period of time during which the original brood stock has produced eggs. Some of these animals were confined in 1909 and others in 1912. The early records of egg production by the old breeders are rather obscure, but there is on hand a fairly definite record dating from 1915 to 1926. Table 1 is based upon this record. It is evident from the table that the general trend in egg production over this period of years has been downward. Yet it has fluctuated from year to year, and the rather sharp recovery in 1926 is noteworthy. The age of these animals, as stated elsewhere, is not known, and the length of life of diamond-back terrapins, too, in unknown. Therefore, it is entirely impossible to state that the general decline in egg production is due to old age. Furthermore, the table shows an upward trend since 1921. An upward trend during recent years would scarcely be expected if the general decline were due to old age. For the same reason it does not seem logical to assume that the long confinement affected egg production. Neither can the decline readily be ascribed to food and care, for these have been uniform throughout the period. It seems very difficult, therefore, to find the cause or causes for the decline in egg production from 1915 to 1921, the partial recovery during recent years, and the annual fluctuations that have taken place. The number of eggs destro3red by rats has varied from time to time, but it is not believed that the loss was great enough to affect the results greatly. Table 1. — Average number of eggs produced by the wild brood stock, based on a, lot confined in a single pen from 1915 to 1927 Year Eggs Year Eggs Year Eggs 1915 23.9 1920 13.4 1925 9.8 1916 21.6 1921 7.6 1926 14.8 1917 20.8 1922.. 8.2 1927 10. 1 1918 18. 6 1923 9.2 1919 19.6 1924 11.6 Average. 14.5 The yearly egg production by the wild brood stock from 1915 to 1927, inclusive, has averaged 14.4 eggs per female. The average per year for all females 534 inches s and over in length, exclusive of two lots of wild animals recently confined, is 13 eggs per female. This, then, appears to be about the number of eggs per female that may be expected of acclimated animals. It is shown in another section of this report that a rate of fertility of the eggs of about 90 per cent usually prevails when sufficient males are present. These data, then, indicate that in general terrapin-cultural work about 12 young per female per annum may be expected. s The records show that no lot of terrapins grown in captivity has ever produced eggs until at least some of the females had reached a length (on the median line of the plastron) of 5J4 inches or more. Therefore, animals less than 5J4 inches long are consid- ered immature and are not considered in computing this average. DIAMOND-BACK TERRAPIN CULTURE 31 Table 2. — Average number of eggs produced per female of the brood of 1909 1 Year Eggs 2 Year Eggs 2 Year Eggs 2 1Q1 *» 24.0 1920- 35.0 1924... 22.0 IQIfi 29. 5 1921 32.3 1925 3 29.8 1917 24. 5 1922 29.4 1Q18 29.2 1923 . 33.0 Average 29. 4 1919 34.3 1 Those animals hibernated each winter. 2 All of the females in this lot were tpA inches in length or longer during the entire period. 3 Discontinued after 1925. Table 3. — Average number of eggs produced per female of the brood of 1910 Year Fed first winter Hibernated each winter Year Fed first winter Hibernated each winter Entire lot All bYi inches and over in length 1 Entire lot All 5J4 inches and over in length 2 Entire lot All 5^ inches and over in length 1 Entire lot aii sy2 inches and over in length 1 1915 0.3 5.7 8. 1 7.6 11. 1 9.5 6.6 8.1 1.4 13.4 1923 6.1 6.0 5. 1 6.5 9.2 4.0 3.5 3.2 3.2 3.6 1916 0.4 2.9 4.2 7.1 5. 1 2. 1 5.2 4.2 11.3 1924 1917 1925 5.9 4.4 1918 12.3 16.2 1926 1919 13. 2 1927 1920_ __ Average 2 6. 9 9.8 2 3.8 8.3 1921_ 1922 1 Female terrapins less than 5J4 inches long apparently do not lay eggs. Therefore, the rate of production shown in this column is the actual rate per sexually mature female. Measurements of the size of the terrapins are not available for every year and, there- fore, the rate of egg production per mature female can not always be given. 2 The first year of egg production is not considered in determining this average, as only a few eggs were produced and nearly all of the females were still immature. Table 4. — Average number of eggs produced per female of the brood of 1911 Year Fed first 3 winters Hibernated each winter Year Fed first 3 winters Hibernated each winter Entire lot All 5'A inches and over in length 1 Entire lot All 5A inches and over in length 2 Entire lot All 5 y2 inches and over in length 1 Entire lot All 5J4 inches and over in length 2 1915 0. 1 0.8 1923 7. 1 8. 7 11. 2 1916 0. 1 0.3 1924 6.8 8.0 1917 5.3 1925. .. 4.3 5. 5 7. 5 9.3 1918 7. 6 0. 7 1. 5 1926... 8.6 8.6 1919 11.9 18.0 2.3 4.8 1927 7.8 11.6 1990 8 1 5 6 1921 4.2 6. 9 Average 2 6. 0 6. 1 6. 7 6. 7 1922 6. 5 7.1 1 Female terrapins less than 5J4 inches long apparently do not lay eggs. Therefore, the rate of production shown in this column is the actual rate per sexually mature female. Measurements of the size of the terrapins are not available for every year and, there- fore, the rate of egg production per mature female can not always be given. 2 The first 2 years of egg production are not considered in determining this average, as only a few eggs were produced and nearly all the females were still immature. 35006—29 2 32 BULLETIN OF THE BUREAU OF FISHERIES Table 5. — Average number of eggs 'produced per female of the brood of 1912 Runts Selects Runts Selects Year Entire lot All 5H inches and over in length 1 Entire lot All 5J4 inches and over in length 1 Year Entire lot All hVi inches and over in length 1 Entire lot All 5 y2 inches and over in length > 1919 2.4 5.0 1.6 2. 5 1925 5. 1 9.0 1.7 8.9 1920 4. 5 21. 1 2. 5 31. 5 1926 8. 1 3. 7 1921 4. 1 1.9 1927 1 8.5 6.9 6.4 7.6 19.5 18.1 3.2 2. 1 41.0 14. 2 1923 Average 5.8 14.6 3.0 19. 6 1924 ... 6. 1 3.6 i Female terrapins less than inches long apparently do not lay eggs. Therefore the rate of production shown in this column is the actual rate per sexually mature female. Measurements of the size of the terrapins are not available for every year and, there- fore, the rate of egg production per mature female can not always be given. Table 6. — Average number of eggs produced per female of the brood of 1913 1 Year Entire lot All hYi inches and over in length 2 Year Entire lot All 5V2 inches and over in length2 1920 -- 0.4 1925__ 0.8 4. 1 1921 .4 1926- 1.5 1992 __ 1.8 18. 2 1927 3.1 1. 2 8. 9 1 924 1.4 Average. 1.3 10. 4 ■ These animals were fed the first winter. 2 Female terrapins less than 5H inches long apparently do not lay eggs. Therefore, the rate of production shown in this column is the actual rate per sexually mature female. Measurements of the size of the terrapins are not available for every year and, there- fore, the rate of egg production per mature female can not always be given. Table 7. — -Average number of eggs produced per female of the brood of 1914 1 Year Entire lot All 5^ inches and over in length Year Entire lot All 5J4 inches and over in length 0.4 .3 .8 1.4 1.6 17. 5 1925 0. 7 1. 7 4. 5 6.8 1926- 6.8 12.1 1927. 1923 -- -- - Average... ... 1.4 10.8 1 These animals were fed the first winter. FERTILITY OF EGGS The percentage of fertility of the eggs has fluctuated greatly from year to year and often within a single small lot. For example, in a lot of terrapins hatched in 1910 (fed the first winter), which consists of 13 males and 116 females, the percentage of fertile eggs has varied from 79.2 to 92.8 the average for the period 1915 (when the terrapins laid for the first time) to 1926, inclusive, being 85.2 per cent. In another lot hatched in the same year (1910), but which was allowed to hibernate each winter, now (1928) consisting of 5 males and 87 females, fertility has ranged from 57 to 91.9 per cent, with an average for the period 1917 6 to 1926, inclusive, of 71.8 per cent. « This lot laid for the first time in 1916, but the number of eggs produced was so small that the results for that year do not appear to be worthy of consideration. DIAMOND-BACK TERRAPIN CULTURE 33 Tables 8 to 15 show in detail the approximate number of eggs produced each year, the number of young hatched, and the percentage of fertility. It is difficult to account for the wide yearly fluctuations in the fertility of the eggs that have occurred in nearly all lots on hand. In general, the highest percentage of fertile eggs has been produced by those lots having the largest proportionate number of males. Examples of a high degree of fertility, as already shown, occurred in the wild brood stock (Table 8), in which the ratio of males to females has usually been about 1 to 2. A very high percentage of fertile eggs was laid from 1918 to 1925 by a small brood hatched in 1909, in which there also was one male to two females. During the first three years in which eggs were laid by this brood the percentage of fertile ones ran very low, and then, as shown by the table, fertility suddenly increased and thereafter remained fair to very high. The lowest percentage of fertility among the older broods, for which considerable data are at hand, occurred in a lot belonging to the brood of 1911 (Table 11), which was allowed to hibernate each winter. This lot now (1928) consists of 3 males and 35 females. Egg laying began in 1918. Since no males were penned with the females until the fall of 1919, the eggs for the first two summers were not fertile and have not been considered in these data. Fertility has varied from 23.6 to 89.7 per cent dur- ing the period 1920 to 1926, inclusive, with an average fertility for the whole period of 64.8 per cent. Another lot of the same brood (1911), consisting of 38 females (originally penned with the lot just discussed) and 3 old males taken from the original brood stock, has produced consistently a higher percentage of fertile eggs over the same period of years. Fertility in this lot was the lowest in 1921, when only 71.4 per cent of the eggs hatched, and it was highest in 1925, when 93.4 per cent of the eggs were fertile, the average fertility for the entire period being 81.5 per cent. It seems probable, although by no means certain, that the higher fertility in the last- mentioned lot may have been due to the old and fully matured males that were introduced, whereas it is not known that the young males of the other lot were all mature when eggs first were produced. It is a well-known fact that all females of one age do not become mature at the same time. Some females, in fact, require several years longer to reach sexual maturity than others. The same very probably is true of the males. This subject is discussed more fully in another section of this paper (see p. 56). The fact that the percentage of fertility in the lot penned with young males increased each year (Table 11) until 1925 lends support to the belief that the number of mature males present may have been insufficient. It will be seen, also, from Table 11 that the lot penned with young males each year produced a larger number of eggs than the other one, notwithstanding that there were three more females in the pen with the old males. This suggests earlier maturity for a larger proportion of the females penned with young males than for those penned with old males, and this, too, may have had a bearing upon fertility in relation to the number of males present. Owing to such great fluctuations in egg production, it can not be stated definitely that one of the two lots of the brood of 1911, compared in the preceding paragraphs, produced a greater number of eggs than the other because it contained a larger num- ber of mature females, for the difference in egg production, as just shown, may have 34 BULLETIN OF THE BUREAU OF FISHERIES been due to a difference in fecundity rather than to the number of mature females present. The highest degree of fertility for all broods on hand or used at one time or another in the many experiments conducted has almost consistently occurred among wild terrapins (Table 8) that have been confined for breeding purposes. The product of all wild animals is considered together here for convenience, although these terrapins have been separated into smaller lots at various times. To give a record of each lot separately would require much space. When last enumerated (1926) there were on hand 39 males and 72 females belonging to this “wild stock,” and this ratio has not varied greatly for several years. Fertility among the wild terrapins, or the “orignal brood stock,” during the period 1912 to 1926 was lowest in 1912, which was the first year of confinement for the majority of these animals, when 83.9 per cent of the eggs hatched. Two years later (1914) it was the highest that it has ever been, namely, 97.9 per cent. The average fertility for the entire period was 94.4 per cent. In the case of a few groups of animals the results with respect to fertility, as related to sex ratio, are contrary to the more general rule stated in a preceding paragraph, namely, that a large proportionate number of males tends to bring about a high percentage of fertile eggs. The 1910 brood (Table 10), for example, was divided into two lots. One lot was fed the first winter, the other being allowed to hibernate. The first-mentioned lot has one male to nine females and an average percentage of fertility for the entire period during which eggs have been produced (1915 to 1926) of 85.2 per cent; whereas in the hibernating lot, in which there is a ratio of one male to 7.8 females, the percentage of fertility during the period (1916 to 1926) in which eggs have been produced is only 71.8 per cent. It is evident from the foregoing discussion that the reason or reasons for the great fluctuations in fertility among the various lots and broods and even within a single lot and brood are not understood, and that sufficient data are not yet at hand from which specific recommendations relative to the proper sex ratio that should be maintained for breeding purposes may be made. This question is further complicated by the fact that females appear to produce a high percentage of fertile eggs for at least two years without recopulation. Thereafter, fertility apparently drops rapidly. This conclusion is based upon the results obtained from penning 10 old females without males. During the first season following separation from males these 10 females laid 124 eggs, and only 1 failed to hatch; during the second summer 116 eggs were produced and 14 failed to hatch; during the third summer 130 eggs were laid and 91 failed to hatch; and during the fourth summer 108 eggs were pro- duced and only 4 hatched. Thereupon, seven old males were introduced, and in the next season 145 eggs were laid, of which only 4 failed to hatch. The results of this experiment would indicate that annual copulations are not necessary, and that very few males would suffice for breeding purposes. The combined records for all adult terrapins on hand appear to show, however, that the highest rate of fertility is obtained when the males are fairly numerous. The indications are that for breeding purposes a ratio of about 1 male to 5 females should be maintained. DIAMOND-BACK TERRAPIN CULTURE 35 Table §. — Production and fertility of eggs of the original icild brood stock, most of which were confined between 1909 and 1912. Males, 39; females, 72 1 Year Eggs laid Young hatched Per cent fertile Year Eggs laid Young hatched Per cent fertile Year Eggs laid Young hatched Per cent fertile 1912 1, 337 1, 374 1,411 1,480 1,415 1, 275 1, 121 1, 289 1, 381 1,415 1, 335 1,215 83.9 93.9 97.9 95.7 94.4 95.3 1918 1,157 1,451 939 531 615 686 1, 113 1, 398 915 512 566 654 96.2 96.4 97.5 96.5 92. 1 95.4 1924 870 719 1, 065 733 829 680 985 626 95.3 94.6 92.5 92.2 1913 1919 1925 1914 1920 1926 1915 1921 1927 •___ 1916 1922 Total..- 17, 058 16, 084 94.2 1917 1923._ 1 The number of females in this brood stock was reduced from 123 in 1912 to 72 in 1927, which accounts in part for the smaller number of eggs produced during recent years. Table 9. — Production and fertility of eggs of the 1909 brood, which hibernated. Males, 2; females, 4 Year Eggs laid Young hatched Per cent fertile Year Eggs laid Young hatched Per cent feiiile Year Eggs laid Young hatched Per cent fertile 1915 96 17 17. 5 1920 140 126 90.0 1925 1 119 116 97.5 118 75 fi3 5 1Q21 129 120 9.3 1 1917 98 72 73! 5 1922 118 114 96. 6 Total 1,293 1,098 85.0 1918 117 112 95.8 1923 132 129 97.7 1919 137 129 94.2 1924 89 88 98.9 1 Discontinued after 1925. Table 10. — Production and fertility of eggs of the 1910 brood Year Fed first and in part in the second winter. Males, 13; females, 116 Hibernating each winter. Males, 5; females, 87 Year Fed first and in part in the second winter. Males, 13; females, 116 Hibernating each winter. Males, 5; females, 87 Eggs laid Young hatched Per cent fertile Eggs laid Young hatched Per cent fertile Eggs laid Young hatched Per cent fertile Eggs laid Y oung hatched Per cent fertile 1915 39 34 87.2 1923 710 648 91.3 360 233 64. 7 1916_ 754 587 77.9 38 37 97.3 1924. 697 606 87.0 304 218 71. 8 1917. 1,071 902 84.3 260 214 82.3 1925_ 592 549 92.8 283 223 78.8 1918 1,015 934 92.2 379 348 91.9 1926 757 652 86.2 281 203 72. 3 1919 1,428 1, 136 79.5 633 475 75. 1 1927. 1, 071 768 71.7 318 221 69.5 1920. - 1, in 932 83.9 456 263 57.7 1921 768 687 89.5 187 128 68.5 Total 10, 950 9, 228 84.2 3, 961 2,836 71.6 1922 937 793 84.7 462 273 59.1 Table 11 .-—-Production and fertility of eggs of the 1911 brood Year Fed first 3 winters. Males, 10 “old”; females, 78 > Hibernated each Males, 3; females, 35 yinter (2 lots) Males, 3 “old”; females, 38 * Eggs laid Young hatched Per cent fertile Eggs laid Young hatched Per cent fertile Eggs laid Young hatched Per cent fertile 1917 3__ 445 417 93. 3 1918--. 628 582 92.7 1919 973 821 84.4 1920 - 641 572 89.3 4 250 59 23.6 187 152 89. 1 1921 336 302 89.9 394 182 46.2 160 114 71. 4 1922- - 515 461 89.6 387 228 59.0 170 127 74.2 1923 561 529 94.3 452 305 67. 5 224 174 77.7 1924 529 471 89. 1 353 252 71.4 253 215 85.2 1925. 335 311 92.9 367 329 89.7 181 169 93.4 1926 673 532 79. 1 336 290 86.3 294 245 89.4 1927 613 463 75.5 454 288 61.2 393 320 81.4 Total 6,249 5, 461 87.3 2,993 1, 933 64.5 1,862 1, 516 81.4 1 This lot of terrapins upon maturity proved to be all females. 10 old males taken from the original brood stock of wild terrapins of unknown age were then added. 2 Three old males taken from the original brood stock were added in 1919. 3 In 1915 and 1916 a few eggs were produced but they are not considered in calculating fertility, as the number is too small to be of significance. 4 Eggs were produced for 2 years prior to this date but are not considered in calculating fertility as the females were penned without males. 36 BULLETIN OF THE BUREAU OF FISHERIES Table 12. — Production and fertility of eggs of the 1912 brood Year Smallest (runts) of the entire brood se- lected at 1 year of age, in part fed the first winter and all the second winter. Males, 10; females, 54 Largest selected from entire brood at 1 year of age, all fed first 2 winters. Males, 17; females, 67 Year Smallest (runts) of the entire brood se- lected at 1 year of age, in part fed the first winter and all the second winter. Males, 10; females, 54 Largest selected from entire brood at 1 year of age, all fed first two winters. Males, 17; females, 67 Eggs • laid Young hatched Per cent fertile Eggs laid Young hatched Per cent fertile Eggs laid Young hatched Per cent fertile Eggs laid Young hatched Per cent fertile 1919 135 102 75.5 124 113 91. 2 1925 _ 279 247 88.5 116 116 100.0 1920_ ... 255 226 88.7 189 161 85.2 1926 447 395 88.4 255 209 82.0 1921 _ 228 182 79.9 142 130 91.6 1927 . 461 396 85.9 459 392 85.3 1923 416 356 85.6 171 167 97! 7 Total 2, 907 2, 480 85.3 1,953 1, 750 89.6 1924 336 288 85.8 251 235 93.7 Table 13. — Production and fertility of eggs of the 1913 brood, which were fed first winter. Males, 4l females, 75 Year Eggs laid Young hatched Per cent fertile 1920 « 31 29 93.1 1921 42 35 83.3 1922 146 73 50.4 1923 101 88 87.1 1924 118 101 83.2 Year Eggs laid Young hatched Per cent fertile 1925 61 41 67.0 1926 115 60 49.0 1927. 234 157 67.0 Total 848 584 69.1 Table 14. — Production and fertility of eggs of the 1914 brood, which were fed first winter. Males, 2; females, 83 Year Eggs Young Per cent Year Eggs Young Per cent laid hatched fertile laid hatched fertile 1920 35 35 100.0 1925 61 61 100.0 1921.. 26 12 46.2 1926 140 99 71.0 1922 . 75 34 46.4 1927 371 241 64.9 1923 121 147 121 147 100.0 mo 1924... Total 976 750 76.8 Table 15. — -Production and fertility of eggs of the 1916 brood, which were fed first winter. Males, 40; females, 158 Year Eggs Young Per cent Year Eggs Young Per cent laid hatched fertile laid hatched fertile 1922 2 2 100.0 1926. 133 122 91.8 1923 34 34 100.0 1927.. 219 183 83.6 1924 63 52 61 44 96.9 84.6 1925 . Total 503 446 88.6 RECORDS OF SURVIVAL During the entire course of the experiments no evident diseases have occurred among the terrapins after they had attained an age of about 1 or 2 years, and there- after the loss from this source has been negligible. A very considerable death rate, apparently due to disease, has occurred among the young. Further remarks con- DIAMOND-BACK TERRAPIN CULTURE 37 cerning diseases are to be found in subsequent paragraphs. A definite record of the deaths that have occurred can not be given because several animals in nearly every lot are missing. Some of these animals may have died unnoticed (especially when they were small), others undoubtedly were carried away by rats, birds, or other enemies, or, again, they may have found an avenue for escape. It is definitely known that in a few instances a number of animals got away during storms, when the water nearly reached the top of the walls of the pens. On the other hand, not infrequently the missing animals simply were overlooked when a census was taken. It is very difficult, because of their very proficient hiding propensities, to find all the terrapins in an inclosure even though the pen be small. Therefore, the “missing” animals of one census sometimes reappeared in the next one. On account of the impracticability of getting and keeping definite records of deaths and escapes only the animals found when a census was taken were considered in many of the tables appearing in this report. From a practical standpoint, the animals that are missing, of course, are of no more significance (unless they can be found) than the dead ones, and the propor- tionate number of those hatched that may be grown to maturity is of chief importance. Many of the terrapins grown in captivity, as stated elsewhere, were selected, and the entire brood was kept only in 1910, 7 when only a small number was hatched. This brood originally consisted of 293 animals. It was divided into two lots. One lot, consisting of 120 individuals, was allowed to hibernate, and the other one, con- sisting of 173 animals, was kept warm and fed the first winter and part of the second winter. At the age of 1 year 93 per cent of the winter-fed terrapins and 85.8 per cent of the hibernating ones were alive. At 6 years of age, when at least some of the animals had become sexually mature and reproduction had begun, 83.2 per cent of the winter-fed lot and 78.3 per cent of the hibernating one still survived, and at 15 years of age 74 per cent of the former and 76.6 per cent of the latter lot were found. In two unselected lots of the brood of 1911, each originally consisting of 100 terra- pins, the percentage of survival at 1 year of age was 95 for the winter-fed lot and 89 for the hibernating one. At 6 years of age 82 per cent of the winter-fed animals were found and 78 per cent of the hibernating ones, and at 15 years 77 per cent of the former and 76 per cent of the latter were on hand. The four lots discussed in the preceding paragraphs are the only ones of those at hand that have reached maturity that were carried through as separate lots and without selection from the time of hatching to maturity. All the other lots of mature terrapins were selected at about 1 or 2 years of age from lots that had been fed the first winter, and therefore the records are not continuous and not directly comparable with those of the 1910 and 1911 broods. Winter feeding in an especially constructed brooder house 8 was begun with the 1913 brood. The object of winter feeding, of course, was mainly to increase the growth of the young animals. The results of this project, with respect to the rate of growth, are discussed in another section of this paper. Its results with respect to mortality or survival, however, appear to belong to the present section of this report. 7 In 1909 only a few terrapins were hatched, of which only 12 grew to maturity. This number is regarded as too small to be of much significance and is omitted in this discussion. 8 A description and photograph of the terrapin brooder house used in these experiments may be found in Bureau of Fisheries Economic Circular No. 60, 1920, pp. 17 and 18, fig. 8. 38 BULLETIN OF THE BUREAU OF FISHERIES Winter feeding, from the standpoint of survival, has resulted in varying degrees of success. The highest percentage of survival during the course of the experiments was obtained in the 1915 brood when 97.6 per cent of 1,306 animals placed in the brooder house in October, 1915, lived until May 15, 1916, at which time the surviving ones were removed from the house and placed in outdoor pens (Table 17). The results for the preceding brood (1914), however, were the most unsatisfactory, from the stand- point of survival, obtained to the present time (1928). Of 1,349 animals placed in the brooder house only 53.9 per cent lived until May 24, 1915, when the surviving ones were removed from the house. The best results under more crowded conditions, such as have prevailed during recent years in the nursery house, were obtained with the brood of 1921, of which 2,395 young were placed in the house in October, 1921. Of this number 87.7 per cent lived until May, 1922, when the surviving ones were removed from the house (Table 17), and this rate, under similar conditions, has not fallen below 68.6 per cent to the present time (July, 1928). Various methods of sanitation, several different kinds of food, fresh and salt water, and wooden and metal (galvanized-iron) tanks have been employed, but generally with indifferent success with respect to mortality. After an epidemic of a disease (elsewhere described and designated as “sores”) in the brood of 1914, the tanks were disinfected weekly with a solution containing potassium permangenate and so- dium bicarbonate. In 1922 this method of disinfecting the tanks was abandoned largely because it did not prevent the growth of algae. Food and excreta readily be- came lodged in the algae, fouling the tanks, and it was necessary to scrape the tanks to keep them clean. Thereafter an extra tank was provided, making it possible always to have an empty one, and the animals were shifted at about weekly intervals. Each trough was allowed to dry, and before replacing the animals it was scalded with hot water. This treatment prevented the growth of algae, and a considerable amount of work previously necessary to keep the tanks clean was saved. The results with respect to mortality, however, were quite indifferent (Table 16). It would appear from the rather unsatisfactory records that the death rate during the first winter among young terrapins subsisting on foods producing the greatest gain in growth (oysters and fresh fish) increased, whereas it decreased when food (salted fish) producing little growth was supplied. It does not necessarily follow, however, that a larger percentage of the slow-growing animals would reach maturity, for the larger and more robust ones appear to stand a much better chance of survival when liberated or placed in outside pens. Unfortunately, the data bearing upon this phase of the work are very meager. Animals kept in salt water had the appearance of being healthier, and generally the death rate appears to have been a little lower. It has been thought necessary, however, to supply such animals with fresh water once a day, which increases the amount of labor, and the slight advantage gained may not be suffi- cient, in practical terrapin culture, to offset the extra amount of work involved. A few galvanized-iron tanks have been in use for several years. Such tanks are kept clean somewhat more easily than wooden ones, but no advantage from the stand point of mortality is apparent. Different degrees of crowding of the animals have been tried in the brooder house with the view of determining the space requirements of the young animals. In this DIAMOND-BACK TERRAPIN CULTURE 39 series of experiments tanks 8 feet long and 20 inches wide, divided into four equal com- partments, have been used. Each compartment, therefore, had a floor space of about 20 by 24 inches. In some of the compartments 25 to 50 animals were held, 100 in others, and in still others 125 to 150 were placed. The experiment was carried through three seasons (October to May, 1923 to 1926) using each year an equal number of compartments for the different degrees of crowding. The rate of survival is very slightly in favor of the least crowding, for of 325 animals used, 80 per cent survived. Of 1,100 terrapins held 100 to a compartment, 79.5 per cent survived, whereas under the crowded condition of 125 to 150 animals to a compartment only 70.7 per cent of a total of 1,530 terrapins survived. The results with respect to the rate of growth for the different degrees of crowding are discussed elsewhere. It is sufficient to state here that they bear a relationship to each other somewhat similar to the rate of survival. It may be concluded, therefore, that it is practicable to confine as many as 100 young terrapins in a space having an area of 20 by 24 inches. The death rate among the young animals that are allowed to hibernate frequently is almost negligible during their first winter, as in the brood of 1926, of which 99.9 per cent of 1,627 animals survived (Table 17). However, in a few instances the death rate has run very high, as, for example, in the brood of 1922, in which only 44.7 per cent of 789 animals survived the winter. Records of survival of the hibernating animals, as well as the winter-fed ones, as far as data are available, are given in Table 17. The percentage of survival of the winter-fed and hibernating terrapins, given in the table are not directly comparable, as the hibernating ones usually emerged from hibernation and were counted during the latter part of March or early in April, whereas the winter-fed animals each year were counted from four to six weeks later; that is, at the time they were removed from the nursery house. During the first four to six weeks after emerging from hiberna- tion the death rate usually is quite heavy and generally much greater than in non- hibernating animals. Therefore, Table 17 does not contain directly comparable data, with respect to survival, of the advantages of one method over another. It does show, however, the yearly fluctuations in the rate of survival during the early months of life that has taken place during the course of the experiments, both for hibernating and winter-fed animals. The fluctuations in the death rate in the winter-fed animals can be accounted for, in part, by the prevalence of a cancerous disease (elsewhere referred to as “sores”) that as yet (1928) is of unknown origin and for which no preventive or cure has been found. This disease, which outwardly makes its appearance as sores chiefly on the tail or as discolored areas on the plastron, has always existed among winter-fed animals throughout the course of the experiments. However, it reached serious epidemic proportions only in the 1914 and 1927 broods, when the rate of survival, as shown in Table 17, was greatly reduced. Deaths have occurred from other causes, of course; principally of “soft shell” and a few of “limber neck” and miscellaneous causes. The deaths from these sources, too, have varied and are the cause of a part of the great fluctuations. The disease designated as “soft shell” is associated with a failure to eat, resulting, of course, in a failure to grow and in general emaciation. The majority of cases of soft shell occur among young that never have been induced to take food, although rather 35006—29 3 40 BULLETIN OF THE BUREAU OF FISHERIES rarely it occurs in animals that have fed and have gained some growth. Animals that fail to take food are inactive, and they seldom enter the water but seek the sun and heat. Many of these animals die, but others often suddenly begin to feed, and a rather rapid recovery (for a terrapin) takes place. For example, 200 soft-shell terrapins (the very poorest) were selected late in May, 1927, from 2,180 winter-fed terrapins of the 1926 brood. Of the 200 animals selected, 74 were living on August 15, 1927, when they were liberated. All had gained some growth, the shells had become hard, and, with the exception of 1 animal that had a tail lesion, all gave the appearance of being healthy and sound. Soft shell, except possibly during 1914, when a severe epidemic of sores existed, has caused the greatest loss among winter-fed terrapins. The loss from this source, combined with minor losses from limber neck, etc., for the several broods (1920 to 1927) for which fairly accurate data are available has ranged from 10.3 per cent (1921 brood) to 23 per cent (1924 brood). Table 16 shows in detail the percentage of deaths among winter-fed animals ascribed principally to soft shell and those due to sores. Soft shell, too, appears to be the chief cause, during their first summer, of the heavy mortality among terrapins that hibernated. Limber neck apparently is a form of paralysis, which most frequently causes the animal to lose the use of the muscles in the neck and fore limbs, but occasionally it affects only the hind limbs or the control of all muscles may be lost. Few recoveries have been noticed. No definite records of the death rate caused by this disease are available, but it quite certainly has never exceeded one-half of 1 per cent and, there- fore, is quite negligible. The cause or causes of the great fluctuations in the death rate of hibernating terrapins is much more difficult to find. Since the animals do not feed during the hibernation period, nor have fed previously, and since they do not expose themselves to light but lie buried underneath sand, sod, or debris, food and light appear to be eliminated as factors influencing survival. Weather conditions — that is, tempera- ture and precipitation — appear to be the most plausible influences to consider. Precipitation is of little importance, however, as the hibernating animals are pro- vided with covered quarters,9 into which little rain can enter, and moisture is provided artificially. Therefore, rainfall appears to be of little importance. A careful study of temperature records has revealed nothing. The greatest mortality that has occurred during the course of the experiments, as shown by Table 17, took place in the brood of 1922. In the 1926 brood it was negligible. In view of the contrast in the death rate of young hibernating terrapins, tem- perature records (kept at this station in cooperation with the United States Weather Bureau) were carefully compared for the months during which the 1922 and the 1926 broods were in hibernation. Comparing temperatures, month by month, for the two seasons, the greatest difference occurs in February, for the average maximum and minimum temperatures each were 9.5° F. higher in 1927 than in 1923. The highest temperature on any one day during February, 1927, was 74° and the lowest • A description of the winter quarters provided for hibernating terrapins is given in Bureau of Fisheries Economic Circular No. 60, 1926, p. 16. DIAMOND-BACK TERRAPIN CULTURE 41 was 28°. The highest temperature reached in 1923 was 66° and the lowest was 23°. None of these temperatures is regarded as unusual. The differences in the averages for the other months do not exceed 4°; nor are any of the daily temperatures regarded as excessively high or low. Certainly, if low temperatures were a detriment, the brood of 1917 would have perished, as the winter of 1917-18 was by far the coldest that has occurred during the course of the experiments (definite temperature records for this winter, unfortunately, are not at hand). The mortality records show, how- ever, that only 1 of 735 animals placed in hibernating boxes died that winter. The highest percentage of survival throughout the course of the experiments, then, appears to have occurred during an excessively cold winter and again (1926) during a moderate winter. Therefore, it is not evident that the fluctuations in winter tem- peratures as they have occurred at Beaufort in the years during which the present experiments have been under way have affected the death rate of young hibernating terrapins. The hibernating terrapins have been kept in winter quarters that have varied little, and the care has been about the same and in the hands of the same terrapin culturist from the beginning. It is evident, therefore, that the cause or causes for the pronounced differences in the death rate of various broods of young hibernating terrapins has not been found, and this subject remains for future investigation. Table 17 shows that in 9 of a total of 14 broods the percentage of terrapins that lived until they were removed from their winter quarters was greater among the hibernating terrapins than among winter-fed ones. However, the hibernating ones, as already stated, each year were taken from their winter quarters and counted four to six weeks earlier than the winter-fed lots. It has been pointed out elsewhere that the death rate usually has been quite heavy during the first several weeks after the terrapins emerge from hibernation and certainly much heaveir than in the winter- fed animals for the same period of time. Definite statistics are not available for comparison, but our terrapin culturist and the writer have not the slightest doubt, from their observations extending over several years, that by the middle of May, when the winter-fed terrapins usually were counted, the percentage of survival among them at that time, for all years combined, exceeded that of the hibernating animals. Furthermore, the winter-fed animals nearly all had gained some growth and thereafter had a much better chance to survive. A few comparatively large lots of terrapins have been retained at the laboratory during recent years, and although the records are marred by depredations wrought by rats, a far larger per- centage of the winter-fed lots than of the hibernating ones survived to reach an age of 1 and 2 years, and the deaths from natural causes certainly were much greater among the hibernating animals than among the winter-fed ones. The early broods (1910 and 1911) carried to maturity in captivity, as indicated in a preceding paragraph, appear to show that winter feeding, from the standpoint of survival, has a slight advantage. Later records (if they were not clouded with missing animals killed and frequently carried away by rats), it is confidently believed, would show a much greater advantage in winter feeding than the early ones. Our terrapin culturist and the writer are both firmly convinced (although they are unable to supply 42 BULLETIN OF THE BUREAU OF FISHERIES definite statistics) that a much larger percentage of winter-fed than of the hibernat- ing terrapins (if both were retained in equal numbers) would survive to reach an age of 2 or 3 years. Thereafter, as shown elsewhere (Table 19), the death rate is small. Winter feeding, even though considered only from the standpoint of sur- vival and entirely aside from the faster growth and earlier maturity, undoubtedly is advantageous. The percentages of survival of most of the lots of terrapins that were hatched and raised, or partly raised, in captivity are shown in Table 18. In this table “missing” terrapins are counted as dead, and the percentages are based upon the surviving ones only. In next to the last column is given (except in those lots in which the terrapin were carried through from hatching to maturity without selection and without remov- ing any of the original number) the percentage of the whole lot that probably would have survived had they been retained. In making the calculations it is assumed that equally as large a percentage of the entire broods or lots from which selections were made would have survived, had they been kept in captivity, as of the smaller lots selected. This appears to place the probable averages of survival a little too high, because in most instances the largest and finest animals were retained. The probable percentage of survival at 6 years of age (when at least some of the animals had reached sexual maturity) for all lots combined is 60.7. If depredations by rats could have been avoided, the average percentage of survival undoubtedly would have been considerably greater. It is quite certain, also, that in a plant built in the light of the knowledge gained from the experiments conducted and constructed especially for terrapin growing a somewhat better average could be attained. On the other hand, the average of 60.7 per cent of survival apparently compares favorably with results obtained in chicken farming. (See Hildebrand and Hatsel, 1926, p. 15, footnote.) It was stated in the first paragraph of this section that accurate records of deaths are not available. However, after a terrapin has reached an age of 3 years or more it is of a sufficiently large size that a dead one in a pen scarcely would be unnoticed. Table 19, giving the number of terrapins at 3 years of age in various lots held in con- finement, together with the deaths that were noticed during their third year and thereafter until disposed of or last counted, nevertheless appears to be of interest. It is evident at once that the death rate has been consistently low. Generally it was impossible to determine the cause or causes of the deaths that have occurred among the larger terrapins. The low death rate (see Table 19) that has occurred among the wild brood stock is noteworthy. Some of these animals were confined in 1909, others in 1911, and a few appear to have been held over from certain experiments conducted in 1902. Most of these animals were mature when confined, but not all of them, as stated by Barney (1922, p. 94) and Hildebrand and Hatsel (1926, p. 13). Measurements of the first lot of breeders, taken when purchased in Beaufort in 1909, have been found recently among the early records, and these show that 10 of 45 females obtained in this lot were less than 5 inches long and therefore almost certainly sexually imma- ture. The second lot of breeders, bought in 1910 and 1911, also appears to have con- tained at least 6 of a total of 43 females that were less than 5^ inches long. It seems to be incorrect, therefore, to say that all the wild terrapins were mature when DIAMOND-BACK TERRAPIN CULTURE 43 confined. On the other hand, some of them probably already were very old. The shells of some of these old animals have been worn smooth, leaving no trace of growth rings, which are prominent in younger terrapins. The writer does not care to venture to make an analysis of the age 10 of these terrapins. A conservative estimate, in the opinion of our terrapin culturist and the writer, is that the ages range from 25 to possibly 40 years or more. It is pointed out in the section of this report dealing with egg production that there is as yet no conclusive evidence indicating that these animals are declining in egg production because of old age ; nor is the death rate such (only two deaths having occurred during the past four years) as to suggest old age. The span of life of a diamond-back terrapin, therefore, remains undetermined. Table 16. — -Percentage of deaths caused by sores and other causes among winter-fed terrapins Brood Animals fed Per'cent of deaths due to sores Per cent of deaths due to other causes, prin- cipally soft shell 1920 2,502 1 4.9 14.7 1921 2,395 3.7 10.3 1922 2,787 3.7 21.4 1923 2,427 2.3 12.7 Brood Animals fed Per cent of deaths due to sores Per cent of deaths due to other causes, prin- cipally soft shell 1924_ 2,407 2, 391 2,936 3, 720 6.3 23.0 1925 2.0 13. 2 1926 2.4 20,8 15.0 1927... 13.4 1 The combined percentages of deaths due to sores and all other causes do not quite equal the percentages of loss shown in Table 17, because each year a small number of animals is missing and in the table showing survival such animals are counted as dead. Table 17. — Survival of young terrapin during their first winter ° Year Terra- pins fed in nursery house Per cent sur- vived Ani- mals hiber- nated Per cent sur- vived Year Terra- pins fed in nursery house Per cent sur- vived Ani- mals hiber- nated Per cent sur- vived Year Terra- pins fed in nursery house Per cent sur- vived Ani- mals hiber- nated Per cent sur- vived 1912 ».. 500 92.6 480 95.0 1917... 1, 481 82.5 735 99.9 1923... 2, 427 85.0 993 93.8 1913... 525 96.0 716 99.7 1919... 2, 937 82.0 1, 590 70. 6 1924... 2, 407 68.6 1, 163 99.0 1914. .. 1,349 53.9 254 82.2 1920... 2, 502 79.6 1, 404 99.5 1925... 2,391 85. 0 1, 066 81.3 1915... 1, 306 97.6 736 87.2 1921... 2,395 87.7 231 82.2 1926... 2, 936 74.2 1,627 99. y 1916... 1,906 89.7 636 90.2 1922... 2, 820 75.6 789 44.7 1927... 3, 720 69.4 3, 192 89.2 « The percentages of survival of the winter-fed and hibernating terrapins are not directly comparable because the hibernating terrapins were taken from the hibernating boxes and counted late in March or early in April, whereas the winter-fed terrapins were counted when removed from the nursery house at least 1 month later. The death rate among hibernating animals during the first month after emerging from hibernation usually is large and generally much greater than among winter-fed animals. i> It must not be assumed that the sum of tho winter-fed and the hibernating lots of each year equals the total hatch. All the young animals rarely are found in the autumn, and frequently there is a considerable addition in the spring. Such animals, of course, are not included in this table. 10 Barney (1922, pp. 93 and 94) has attempted to analyze the age of the wild brood stock on hand at this station. He estimated that their average age in 1921 was 28 years. If that be true, they would now (1928) be about 35 years old. 44 BULLETIN OF THE BUREAU OF FISHERIES Table 18. — Actual and probable percentage of survival of terrapins at 6 years of age Brood Terra- pins origi- nally in brood or lot Number surviv- ing when selec- tions were made (usually at 8 or 9 months of age) Number selected and retained Per cent of lots retained surviv- ing at 6 years of age Probable per cent of whole brood or lot surviv- ing at 6 years of age 1910 173 0 (>) 83.2 1910 120 78.3 1911 100 > 82.0 1911 100 (i) 78.0 1912 500 463 100 93.0 86.1 1912 500 463 100 69.0 63.9 1913 525 504 100 92.0 88.3 1914 1,349 661 100 91.0 49.0 1915 703 0 51. 1 1916 2,006 1, 710 200 97.5 83.1 1917. 1, 481 910 200 50.5 34.4 1918 1919. 2,433 1, 938 100 78.0 63.9 1919 . 214 0 61. 2 1919. 300 0 31.0 1920 2,503 1, 995 337 62.0 52.7 Average 2 60.7 Remarks All fed first winter and in part the second. Entire lot retained. Hibernating lot, all retained. Fed three winters. Hibernating each winter. Largest (best) selected from entire lot. Smallest (runts) selected from entire lot. Largest selected. Do. Missing, 84; probably escaped or carried away by rats or other enemies. This lot was liberated when 5 years of age. Largest selected. Largest selected; many missing. All liberated soon after hatching. Largest selected. Hybrids; Texas male, North Carolina female. Hybrids; North Carolina male, Texas female. Rats destroyed many during first year. Largest selected, three lots combined. 1 No selection. 2 In computing this average, the actual number of terrapins that survived in the unselected lots, as well as the number esti- mated that would have survived of the lots and broods from which selections were made, were taken into consideration. Table 19. — Deaths among adult and growing terrapins after an age of 3 years was attained Lot On hand 3 years old Last counted Deaths during inter- vening period Missing at end of period Lot On hand 3 years old Last counted Deaths during inter- vening period Missing at end of period 1910 — 157 1925 13 14 1917— Wide range 63 1927 3 21 1910— Hibernated 96 1925 5 0 1919 — Hybrids; Texas male, 1Q11 — Fftd 84 1926 6 0 Carolina female 54 1927 1 1 1911 — Hibernated. 81 1927 2 3 1919 — Hybrids; Texas fe- 96 1927 6 6 males, Carolina male 31 1927 0 0 79 1927 3 12 1919 — Domestic stock 87 1927 1 12 1913 — Selected 94 1927 9 6 1920— Hybrids; Carolina 96 1926 7 4 males, Texas females 64 1927 1 6 440 1920 20 82 1920 — Domestic stock 144 1927 6 24 1916— Selected ... 195 1927 6 0 Adults— Wild stock, age un- 1917— Close range 52 1927 1 0 known 1 154 1927 9 2 29 1 On handjn 1911. 5 Mostly sold. RATE OF GROWTH The average length of diamond-back terrapins at hatching is about 27 milli- meters (1X2 inches), the usual range in size being from 25 to 30 millimeters. Occa- sionally individuals are hatched that are only 22 to 24 millimeters long, and there is a record of one abnormally small one with a length of only 19 millimeters. The largest one of which we have a record was 31.5 millimeters long. Newly hatched terrapins do not feed immediately. Those that are left outdoors to hibernate, as in nature, do not take food until they are from 7 to 8 months old; that is, they do not feed in the autumn during which they are hatched. In fact, DIAMOND-BACK TERRAPIN CULTURE 45 some of them do not even leave the “nests.” They hibernate during cool and cold weather and generally do not emerge from the shelter in which they have spent the winter until the first warm days of the following spring. Even then they do not feed until the weather gets fairly warm. At Beaufort some of the terrapins generally emerge from hibernation during the latter part of March and others in 1310 1911 1912 1913 1914 19/S I9IG /9I7 1918 1919 1920 1921 1922 1925 1924 I9ZS Figure 1.— Rate of growth of two unselected lots of the brood of 1910. Line F represents a lot that was fed the first and in part the second winter, and line H represents a lot that hibernated each winter April. They do not feed regularly until about the latter part of May and do not make perceptible growth for a month or more after regular feeding takes place. GROWTH OF YOUNG TERRAPINS KEPT WARM AND FED DURING THE WINTER Winter feeding experiments were carried on at Beaufort almost from the begin- ning of the present investigation, and since 1912 a small house especially constructed for this purpose has been in use. This house, a frame structure with a natural sand floor, was provided with a long, gently sloping glass roof on the south side, which 46 BULLETIN OF THE BUREAU OF FISHERIES admitted direct sunshine to most of the floor space during the greater part of the day. The animals were held in water-tight wooden boxes or tanks (a few metal tanks also were used) from 8 to 10 feet long and 20 to 24 inches broad. These tanks were divided into four or five compartments. Each tank was tilted to one side, and enough water was supplied to cover about half of the bottom of each compartment. This arrangement made it possible for the animals to enter the water or to stay out, according to choice. The house was heated by a stove. i9ii m m m m m m m ms ipso 1921 1922 m3 1924 ms issg mi Figure 2. — Rate of growth of two unselected lots of the brood of 1911. Line F represents a lot that was fed the first three winters, and line H represents a lot that hibernated each winter. No males were present in either lot Generally, young animals were placed in the brooder house in October, ana an effort was made to keep the temperature at or above 80° F. in so far as possible with such an inefficient heating plant as a stove. Under these conditions terrapins remain active all winter. Recently hatched young, only, were winter fed, except a lot of the 1910 and another of the 1911 brood, which were fed, respectively, two and three winters. The gain in growth during the winter of terrapins that were over a year old was so small that winter feeding of all except the recently hatched young was abandoned because it appeared to be impracticable. DIAMOND-BACK TERRAPIN CULTURE 47 A small percentage of the terrapins placed in the brooder house begin to take food almost immediately, others will not eat for several weeks, and still others apparently never eat. Those that start to feed first also begin to grow earlier than the others. In general, very little growth is made, however, prior to the month of December. The animals that do not appear to feed at all for a long period of time become more and more sluggish, they become emaciated, and the shells gradually soften, causing what is described as “soft shell” under another section of this report. The death rate from this source, as shown elsewhere, has been heavy. It is remark - Figure 3. — Rate of growth of two lots of terrapins of the brood of 1912. Line S represents a lot that was selected at about 1 year of age as the largest, and line R represents a lot selected at the same time as the smallest (runtiest) in the whole brood able, however, that some of these animals that appear to have subsisted for months upon food stored within their bodies or, as it were, upon their own substance, until they are pitiful objects, may suddenly take food and thereafter make rapid growth and become strong and healthy animals. Elsewhere in this report (p. 40) it is shown that of 200 such animals selected during the latter part of May, 1927, which had never gained growth and which, so far as known, had never taken food although it had been supplied almost daily, 74 recovered without providing a change in food or in the environment in which they were living. Animals that have once fed occasionally 48 BULLETIN OF THE BUREAU OF FISHERIES cease feeding and in that event also become emaciated and gradually acquire a soft shell. The sudden change in the rate of growth of animals that have made little or no growth is further discussed in connection with the brood of 1912. Animals in hibernation, of course, make no growth, but subsist upon foods stored within the body. Such animals are poor when they emerge and generally have to feed for a month or more, as already stated, before perceptible growth is made. This is especially true of terrapins in their first year, and that is one of the reasons why winter feeding of recently hatched young appears to be profitable. 77? 7? ?. Figdre 4.— Rate of growth of a selected lot of the brood of 1913 The rate of growth of the winter-fed lots while in the nursery house — that is, until they are about 8 months old — has varied greatly, as shown by Table 20. The small lot of the brood of 1910, consisting of only 173 animals, the first one fed during the winter, was among the best produced to date (1928); for the average length of the terrapins was 39.7 millimeters (representing a gain of 11.6 millimeters) when they were removed from winter quarters on May 10, 1911 (Table 22). Small lots of 100 or so, held in separate compartments in the terrapin house, have done equally DIAMOND-BACK TERRAPIN CULTURE 49 as well or slightly better, but the greatest gain made by a large lot occurred in the 1916 brood, when 1,040 animals reached an average length of 39.2 millimeters on Figure 5.— Rate of growth of a selected lot of the brood of 1914 May 25, 1917, when they were removed from winter quarters. The least growth attained to date occurred in the broods of 1911 and 1923, the animals in each brood, upon removal from winter quarters, being found to have reached a length of only 30.9 millimeters. The average rate of growth of the 1923 brood, as in several other broods, quite probably was considerably reduced because of experimentation with different kinds of foods and various kinds of treat- ment. For example, some of the animals of the brood of 1923 were fed salted fish, which proved to be less acceptable to the terrapins than fresh fish or oysters and produced slower growth. Then, too, some of the animals, for the purpose of experi- mentation, were greatly crowded in the tanks in which they were held, and that appears to have retarded growth. The different kinds of foods used and their relative value, as well as the different conditions with respect to crowding, heat, water supplied, etc., are discussed elsewhere in this section. It appears to be suffi- cient to state at this point that a considerable number of experiments were run and that several of them actually retarded growth, which, however, was not unexpected. 19/S m 1917 1918 /S/9 /920 /9ZI Figure 6. — Rate of growth of a large lot of the brood of 1915. This lot was discarded in the spring of 1921 50 BULLETIN OF THE BUREAU OF FISHERIES If the sole aim had been to produce the greatest gain possible, a much better average rate of growth undoubtedly could have been produced. The excellent growth made by the winter-fed lot of the 1910 brood is noteworthy, especially because of the seemingly unfavorable conditions under which it was held. A special house, as already indicated, was not yet available. Therefore, the animals were placed in the pump house at the station. The tanks were so arranged with respect to the windows that they received the rays of the sun through the window glass during a part of the day. No special heating plant was provided. Some heat, however, was obtained from the steam boiler used for pumping water, but the boiler was used only intermittently and not every day. On especially cold days some Figure 7. — Rate of growth of two lots of selected terrapins of the brood of 1916. Line D represents offspring of domestic stock and line W that of wild stock extra heat was supplied from oil stoves that were run only on such occasions. It is quite remarkable, in the light of present knowledge, that such excellent results were obtained under these circumstances, and furthermore, as shown elsewhere, the death rate was extremely low. A part of the next brood (that of 1911) was kept under identical conditions, and although the death rate remained remarkably low, the rate of growth, as already indicated, was as low as it has been to date (1928) for any winter-fed lot. Somewhat similar fluctuations with respect to growth, as shown by Table 20, have taken place from year to year. They have occurred, also, within a brood among animals of the same parents and not infrequently among the small lots held in adjoining compartments of the same tank, receiving identical treatment. It is impossible, as yet, to explain the reason or reasons for all fluctuations. DIAMOND-BACK TERRAPIN CULTURE 51 In general, those animals that were nearest the stove where the temperature was the highest and probably somewhat more uniform than elsewhere made the greatest growth. On the other hand, those held in certain tanks rather far removed from the stove and placed in such a position that the animals received no direct sunshine invariably made the least growth. Various methods of sanitation (some of which are described in the section of this report dealing with the records of survival) have been employed, but apparently without appreciable effects upon the rate of growth. One metal (galvanized iron) tank has been used for several years. The animals in this tank, which was always placed near the stove, gained a fair to a good rate Figure 8.— Rate of growth of two lots of terrapins of the brood of 1917. Line Crepresents the lot under close “range” and line W the lot under a wild “range” of growth during certain years, and again the gain was quite small. The average rate of growth of the animals held in this tank during the period 1920 to 1926, com- pared with that of animals held in adjoining tanks during the same period of time, is just about equal; that is, the average size of 1,018 animals held in the metal tank during the period indicated was 32.5 millimeters, whereas it was 32.3 millimeters for 1,195 animals held in a wooden tank placed at one side of it, and 32.9 millimeters for 973 animals in another wooden tank on the opposite side. The metal tank, as indicated elsewhere, did not bring a lower death rate, for in this respect the results also are intermediate of those for the adjoining tanks. A metal tank is kept clean somewhat more easily, and this apparently is the only advantage it has over a wooden one. On the other hand, galvanized iron corrodes in a comparatively brief 52 BULLETIN OF THE BUREAU OF FISHERIES period of time in this climate and does not last so long as wood. Other metals and enamel are regarded as rather too expensive for economical use. Table 20. — Average size of terrapin fed during their first winter 1910. 1911. 1912. 1913. 1914. 1914. 1915. 1915. 1916. 1917. 1919. 1919. 1919. 1920. 1921. 1922. 1923. 1924. 1925. 1926. 1927. Brood When measured Average Number length in measured millime- Remarks ters ... May 10, 1911.... Apr. 23, 1912.... ... May 5, 1913 ... Apr. 29, 1914.... ... May 24, 1915.... ...do ... Mar. 15, 1916.... do ... May 17-25, 1917. ... May 15, 1918.... ... May 11, 1920.... do do ... May 13, 1921..., ... May 16, 1922.... ... May 23, 1923.... ... May 16, 1924.... ... May 11, 1925... ... May 13, 1926... ... May 12, 1927.... ... May 7, 1928 173 39.7 216 30.9 463 31.8 504 31.0 351 32.9 376 31.5 662 33.8 613 29.9 1,040 39.2 1,045 31. 1 290 33.7 169 34.9 158 36.0 1, 994 31.8 2,101 31.7 2,132 32.2 2,054 30.9 1,651 32.3 2,019 32.4 2,180 31.7 2,583 30.8 Average. 32.4 Fed fresh fish and oysters. Fed salted fish. Fed fresh fish and oysters. Fed salted fish. Hybrids, Texas and Carolina terrapins. Offspring domestic stock. Offspring wild stock. FOOD The following foods have been supplied: Fresh and salted fish, oysters, clams, and crabs. Vegetables have been offered at different times but were not eaten. A comparison of the utility of the various foods can not yet be given because of the unequal distribution of heat in the terrapin house. It is pointed out elsewhere that the greatest amount of growth almost invariably was made by the terrapins nearest the stove. This is true, in a measure, regardless of the food supplied or other treat- ment given. This factor, therefore, evidently is an important one, and a comparison of the rate of growth with respect to the foods supplied is not a fair one unless the animals were similarly situated with respect to the source of heat. As far as possible such comparisons have been made but are considered of only limited value, and only general discussions are given. It remains for future investigation to determine the actual value of the various foods that are available and that seem suitable, and that can be done only when a house becomes available in which uniform temperatures can be provided. Fresh fish was used much more extensively than the other foods that have been mentioned, because (next to salted fish) it was the most convenient and economical to use and the growth attained apparently was exceeded slightly only when oysters were fed. Salted fish (mullet) was not taken readily. In fact, terrapins that had been feeding on fresh food had to be starved for a week or two before they would take salted fish. It is not surprising that animals fed with this apparently distasteful food grew slowly. Crabs appear to be a good food and are taken readily, but they are so difficult to get during at least a part of the winter that it was found impracticable to feed them continuously. Clams are taken readily but have not been supplied over long periods of DIAMOND-BACK TEKRAPIN CULTURE 53 time and are regarded as too expensive to use in practical terrapin culture. Oysters, also, are regarded as too expensive to use extensively, even though they produce rapid growth in the young animals. Although definite data are not available, it would appear advantageous to supplement fresh fish from time to time with oysters, clams, and crabs. CROWDING Various degrees of crowding have been tried in the tanks in the brooder house with the view of determining the space requirements of the young animals. In this series of experiments, which extended over three seasons (October to May, 1923 to 1926), tanks 8 feet long and 20 inches broad, divided into four compartments, were used. Each compartment, therefore, had a floor space of about 20 by 24 inches. 1919 IXO 1921 IX 2 1923 1921 1925 1925 1927 Figure 9. — Rate of growth of two lots of terrapins of the brood of 1919. Line D represents offspring of domestic stock and line W offspring of wild stock Figure 10. — Rate of growth of two lots of hybrid terrapins of the brood of 1919. Line A represents a cross between Texas males and North Carolina females, and line B represents a cross between Carolina males and Texas females In some of the compartments 25 to 50 animals were confined, in others 100 were held, and in still others from 125 to 150 were placed. The rate of growth appears to be slightly in favor of the least crowding, for the average length of the 260 animals that survived was 34.8 millimeters. For the next degree of crowding, namely 100 animals to a compartment, the average size of 877 surviving animals was 33 milli- meters, and for 1,082 surviving animals crowded to the extent of 125 to 150 to a compartment the average length attained was 31.1 millimeters. It is shown else- where that a somewhat similar relationship with respect to the rate of survival existed for the different groups of crowding. It appears reasonable to conclude, therefore, that it is feasible and economically advantageous to hold as many as 100 young animals in a tank having a floor space of about 20 by 24 inches, but greater crowding appears to result in higher mortaility and slower growth. 54 BULLETIN OP THE BUREAU OP FISHERIES COMPARISON OF THE SIZE OF WINTER-FED AND HIBERNATING TERRAPINS AT ABOUT 1 YEAR OF AGE It has been shown that young terrapins were kept active and were induced to feed during the winter when they were placed in a warm house. Under such condi- tions the average gain in length per year over a period of 17 years ranged from about 4 to slightly over 11 millimeters, the average gain for all winter-fed terrapins (20,034) being 5.7 millimeters. During this time the hibernating terrapins, of course, are making no growth. Table 21 shows the difference in size of winter-fed and hiber- nating animals at about 1 year of age for six pairs of lots of six different broods. The winter-fed annuals of all lots combined (1,069 animals) had an average length of 44.1 millimeters, whereas the hibernating animals (780) had an average length of 37.5 millimeters. This advantage in growth appears to have been maintained fairty well in those lots that were grown to maturity in confinement. The gain in growth during their first winter of the animals that were fed repre- sents about a year’s growth. This lead in size over hibernating terrapins is important in terrapin farming, as it would hasten the turnover by just that length of time. Furthermore, sexual maturity was reached a year earlier and, as stated elsewhere, the death rate apparently was considerably lower. Winter feeding, when terrapin culture is engaged in for the purpose of reestablishing or augmenting the supply in nature, offers the advantage that most of the young will have gained considerable growth and will have passed through the most critical stages of life at about 8 months of age, when they may be liberated with the assurance that they stand a fair chance of survival. On the other hand, it has been considered advisable at Beaufort to retain the hibernating terrapins a year longer, involving extra care and work and a greater mortality. Table 21. — Comparison of size of winter-fed and hibernating terrapins at about 1 year of age Brood When measured Winter-fed Hibernating Number measured Total length Average length Number moasured Total length Average length 1910 Apr. 15, 1912 i 105 95 241 262 228 138 5, 614 4, 464 9, 424 11,074 9,097 7,531 53.4 47.0 39.1 42.2 39.4 54.4 ‘ 104 89 163 122 208 96 3, 954 3, 833 5, 350 3, 977 7, 469 4,686 38.0 43.0 32.8 32.5 36.2 48.7 1911 Sept. 9/ 1912 1923 Oct. 9, 1924 1924 Oct. 27, 1925— 1925 Oct. 5, 1926-.- 1926 Sept. 27, 1927- - 1, 069 47, 204 44. 1 780 29, 269 37.5 1 These animals were not measured at 1 year of age. However, the measurements were taken the following spring before the terrapins had started to make new growth, and the sizes here given of course, are the same as they would have been the preceding autumn, or at the age of 1 year. GROWTH OF TERRAPINS PAST 1 YEAR OF AGE It has been pointed out already that the rate of growth of terrapins during their first year is very irregular both among broods and within single broods. This irreg- ularity in size and rate of growth is equally pronounced in the older terrapins that are being grown in captivity. It does not follow, however, that those animals that grow slowly at first will continue their slow growth and always be “runts.” If that were the case, the runts would not constitute the serious problem they are to the terra- DIAMOND-BACK TERRAPIN CULTURE 55 pin culturist, for then they could be eliminated at an early age and before they had become much of a liability. It is not practicable to do this, however, for frequently the slow-growing animals suddenly begin to grow fast and in a comparatively brief time overtake those that grew fast earlier in life but discontinued their rapid growth. An excellent example of the changes in the rate of growth of terrapins is found in the brood of 1912 (Table 24). In this instance, from a total of about 800 yearling animals 100 of the largest were selected and placed in a separate pen; also 100 of the smallest and runtiest were selected and placed in an adjacent pen. Food and treat- ment and the general environment were made as nearly identical as possible. Meas- urements of the two lots at the time of selection (September 13, 1913) are not avail- able. The animals were measured in the following spring (April 29, 1914), however, m 1921 1922 1923 m 1925 7926 1927 Figure 11. — Rate of growth of two selected lots of the brood of 1920. Line D represents offspring of domestic stock and line W that of wild stock 1920 1921 1922 1929 I92f 1925 /92G 1927 Figure 12. — Rate of growth of an unselected lot of hybrid terrapins (Carolina males and Texas females) of the brood of 1920 and of course not much growth had taken place during the interval. The 100 “selects” all survived until spring and had an average length of 65 millimeters. The 100 “runts” had diminished to 89, and these animals had an average length of 32.3 millimeters. On October 6, 1917, the selects, which then numbered 89, consisted of 18 males and 72 females. The males had an average length of 88.7 millimeters and the average length of the females was 98 millimeters. On the same date the runts numbered 69 and were composed of 13 males and 56 females. The males averaged 87.2 millimeters in length and the females 109.5. The combined average length of male and female “runts,” therefore, was greater than that of the “selects.” The lead then secured by the “runts” has been maintained to the present time (1928). It is not known that identical results would be obtained if a similar experiment were to be undertaken. The selection experiment with the brood of 1912, together 56 BULLETIN OF THE BUREAU OF FISHERIES with others of much shorter duration, offer sufficient evidence, however, to show that it is not practicable to make selections of fast growing terrapins at 1 year or less of age. Furthermore, it seems very probable that such selections can not be made even at 2 or possibly at 3 years of age. The data on this last point still are quite meager. The fact that some animals (as is plainly shown by the accompanying tables) grow very slowly and require a much longer time than others to reach maturity and a size sufficiently large to make them valuable on the market, however, is well established, and these extremely slow growing individuals appear to furnish the chief obstacle to terrapin farming as an enterprise. Comparatively few females 11 (as shown by the tables presented herewith) reached sexual maturity and a length of 5% inches at the age of 5 years. A some- what larger percentage reached it at 6 years of age. However, 9.8 per cent of the females of the winter-fed lot of the 1910 brood were still under that size at the age of 15 years. Among the hibernating lot of the same brood, 19.5 per cent were under 5^2 inches in length at the same age. Although marketable at a smaller size, a terrapin is not considered a “count” and does not bring a fancy price until it has reached a length of 6 inches or more. According to this classification only 28.5 per cent of the winter-fed lot of the 1910 brood and 25.2 per cent of the hibernating lot of the same brood would have passed as counts at the age of 15 years. In the 1911 brood 12.9 per cent of the animals (no males included) of the winter- fed lot were less than inches in length at 14 years of age, and in the hibernating lot of the same brood 15.2 per cent were under this size at 14 years of age. The percentage of counts was somewhat greater than in the 1910 brood, for 41 per cent of the fed lot and 45.8 per cent of the hibernating lot could have been classed as counts at 14 years of age. Younger broods have made even slower growth. The growth curves presented herewith show that, in general, the average rate of growth is fairly rapid until the terrapins reach an age of 5 or 6 years. Thereafter it becomes much slower, and after the eighth to the tenth year it is extremely slow. The almost negligible growth of the older animals, as, for example, those of the 1910 brood, after attaining an age of about 8 years suggests that some of the animals will never reach a length of 6 inches. It seems improbable, even, that all of them will reach 5)^ inches. In the winter-fed lot of the 1910 brood, for example, 11 of the 102 females included were less than 5)^ inches long, the smallest one having a length of only 4 4/5 inches when last measured at the age of 15 years. In the hibernating lot of the same brood, at the same age, 17 of the 87 females included were less than 5}/£ inches long, and the 2 smallest ones were only 5 inches in length. The first-mentioned lot, according to our records, appears to have made an average gain in growth of only 2.5 millimeters, and the other lot only 4 millimeters during the six years prior to the last measurements, or between the ages of 9 and 15 years. In the winter-fed lot of the 1911 brood, 10 of the 78 females included were under B}/2 inches long, the smallest one having a length of 4 4/5 inches when last measured at the age of 14 years. Among the hibernating lot of the same brood at the same age 11 of the 72 females were less than 5^2 inches long, and the smallest one was 5 }z$ inches in length. The winter-fed lot had made an average gain of 3.4 millimeters " The males are not considered in this connection as none of them appear ever to reach as great a length as 5 Y> inches, and they reach sexual maturity at a much smaller size. DIAMOND-BACK TERRAPIN CULTURE 57 and the hibernating lot a gain of 8.9 millimeters during the 6 years prior to the last measurements, that is, between the ages of 8 and 14 years. The data presented in the foregoing paragraphs are illustrative of the extremely slow growth that is made by terrapins that are 8 to 10 years or more of age, and they suggest, as already indicated, that some females will never reach a length of 6 inches and that a small percentage may not even reach 5^ inches. It appears to be of interest to note that among the original wild brood stock confined, part since 1909 and part since 1911, and with few exceptions “adult” terrapins when secured, 17 females were under 6 inches in length when last measured (1925). It would seem almost certain that such animals will never reach a length of 6 inches. It is not surprising, therefore, that all females grown in captivity apparently do not reach a length as great as 6 inches. In commercial terrapin growing it probably would not be profitable to retain the animals after comparatively rapid growth ceases; that is, after an age of 8 to 10 Figure 13.— Rate of growth of a selected lot of the brood of 1921 Figure 14.— Rate of growth of the brood of 1922. Line D represents offspring of domestic and line W of wild stock years is reached. A considerable percentage of the terrapins at these ages, as shown by the accompanying tables, are 5 inches and over in length and would bring a fair price on the market, and it seems doubtful if the increment in size thereafter would justify the expense of food and labor involved to produce it. The largest size attained to date by any terrapin grown in captivity is 6% inches. It is well known, of course, that in nature individuals measuring 7 inches and over in length occasionally are taken. A single female occurs among the wild brood stock confined at this station having a length of slightly less than 1}{ inches (185 milli- meters). This animal probably approaches the maximum size attained by Carolina terrapins. The Texas terrapins, of course, grow somewhat larger and occasionally slightly exceed a length of 8 inches. Information relative to the rate of growth of terrapins in nature virtually is wanting. A few animals hatched at this station and liberated at about 1 year 58 BULLETIN OP THE BUREAU OF FISHERIES of age have been retaken. The recaptured animals had gained growth at about the same rate as the fastest growing ones of the same age that were raised in captivity. In the almost total absence of data on the rate of growth in nature, a comparison of the rate of growth of domestic and wild animals can not be given. Neither will it be known, until much more information is obtained, whether an equally large per- centage of wild animals are slow growers or runts as among domestic ones. There- fore, it is not yet known what influence, if any, domestication has on the rate of growth. Male terrapins have been omitted in the discussions on growth because they do not reach a large size and are of comparatively little value on the market. The sexes can not be distinguished in young terrapins until a length of about 3 inches or more is attained. For this reason the sexes are not listed separately in the accompany- ing tables until they have attained a considerable size. It is not evident that there is a difference in the rate of growth with respect to the sexes until they become dis- tinguishable. Thereafter the males appear to grow less rapidly, and consequently they are soon much smaller than the females. It is fortunate, from an economic point of view, as pointed out eleswhere, that the males appear to be greatly in the minority, for the largest one of which a record is on hand was 4 % inches long and the largest one among the domestic animals has a length of only 4% inches. The average size of adult males appears to be around 4 inches, and a considerable per- centage apparently never exceeds a length of 3% inches. CONCLUSIONS It is evident from the foregoing discussion and the data presented that the chief problem of the terrapin culturist is the elimination of the runty and slow- growing animals. It has been shown that this can not be done through selection at an early age. Therefore, the problem apparently must be solved, if in fact it can be solved, through selective breeding. Experiments along that line are under way, but owing to the slow growth and the long time it takes terrapins to mature no definite results have been obtained to the present time (1928). Slow growth, late maturity, and animals of comparatively small size may not be of importance in the case of terrapins that are liberated and attain their growth in nature, but they are of extremely great importance to the terrapin farmer, who would of necessity be interested in as quick a turnover as possible and in the production of large animals that would bring a fancy price on the market. It has been shown that little growth is gained after the animals reach an age of 8 to 10 years, and the writer believes that it would not be profitable in terrapin farming to retain the animals longer, but that they should be disposed of at about that age regardless of size. DIAMOND-BACK TERRAPIN ULTURE 59 Table 22. — Rate of growth of the brood of 1910 When measured Winter fed Hibernating Number Smallest Largest Females 125 mm. or more in length Average length Number Smallest Largest Females 125 mm. or more in length Average length Mm. Mm. Mm. Mm. Mm. Aim. October, 1910.. 171 25 31 i 28. 1 May 10, 1911 173 28 61 39.7 Feb. 9 to Apr. 22, 1912... 105 35 78 53.4 104 29 49 38.0 Sept. 9, 1912 161 41 98 78. 7 98 56. 5 July 2, 1913 94 38 90 68. 5 Sept. 10, 1913 157 52 122 88.4 97 62 105 84.4 Apr. 30, 1914 153 52 124 99.4 97 62 105 84.4 Apr. 12, 1915 94 83 118 101.8 Oct. 5, 1915 143 83 154 71 122. 1 95 89 137 19 117.6 Aug. 29, 1916: 1 2 Male 16 84 107 l Qt f 98. 0 5 90 96 \ 4, / 93.4 Female 127 100 154 1 130. 1 89 99 147 / 41 \ 121.4 Oct. 3, 1917: Male. . 5 91 97 } 55 r 94.2 Female 78 101 152 l 128.2 Sept. 13, 1918: Male.. 17 85 108 \ in / 98.8 5 91 97 / 94.2 Female 129 117 165 / 111 \ 140. 3 89 112 156 l 136. 7 Sept. 20, 1919: Male.. .. 18 85 3 109 / 3 97. 7 5 92 97 f 3 94. 8 Female 129 120 164 l 140. 1 89 114 158 \ 136. 4 Oct. 21, 1925: Male 11 88 112 f 102. 7 5 96 100 [ 97.8 Female 102 123 165 l 142. 6 87 127 163 I 87 \ 140. 4 1 The average size of newly hatched terrapins, according to more recent measurements, is about 27 millimeters. This difference between the early and more recent measurements very probably is the result of the methods used. The recent measurements were made with calipers, whereas the early ones were made with an ordinary rule and are therefore less accurate. 2 Some of the males, but not all, were distinguishable prior to this date. 3 The apparent slight decrease in size may be due in part to a closer measurement, but it is more probable that the terrapins measured in 1918 and 1919, in part, were not the same ones, as all the terrapins in any one pen seldom are found at one time. Table 23. — Rate of growth of brood of 1911 1 When measured Winter fed Hibernating Number Smallest Largest Females 125 mm. or more in length Average length Number Smallest Largest Females 125 mm. or more in length Average length Aim. Aim. Aim. Aim. Mm. Aim. Sept. 10, 1911 100 25 30 2 28.1 100 25 30 2 28. 1 Apr. 23, 1912 98 25 38 30.9 98 24 31 27.9 Se'pt. 9, 1912 95 29 68 47.0 89 30 59 43. 1 May 21, 1913.. 86 41 79 58.8 86 31 63 46.8 Sept. 12, 1913 83 47 102 79. 1 84 42 88 64.6 Apr. 29,' 1914 82 49 105 79.5 81 51 89 71.8 Mar. 23, 1915- 78 65 120 97.7 77 64 110 90.5 Oct. 5, 1915 81 96 145 33 115.0 78 83 131 5 105.8 Sept. — , 1916... 82 94 155 49 129. 8 78 85 141 19 112.4 Sept. 26, 1919 82 110 162 82 141.2 78 107 159 70 135.7 Oct. 16, 1923 74 116 162 38 140.7 Oct. 29, 1925— 78 120 165 107 144.6 72 110 164 35 143.6 Oct. 21, 1927 72 129 164 35 145.6 1 The two lots of the 1911 brood contain no males. 2 The average size of newly hatched terrapins, as shown, is about 28.1 millimeters (1J4 inches). 60 BULLETIN OF THE BUREAU OF FISHERIES Table 24. — Rate of growth of the brood of 1912 When measured Selects 1 Runts s Number Smallest Largest Females 125 mm. or more in length Average length Number Smallest Largest Females 125 mm. or more in length Average length Atm. Aim. Atm. Aim. Aim. Aim. Apr. 29, 1914. . 100 51 83 65.0 89 27 42 32. 3 94 76 110 92.0 82 30 82 53. 2 Sept. 7, 1910: » 19 81 98 87.2 77 77 119 97. 6 Oct. 11, 1917: 18 82 98 88.7 13 80 95 / 87 2 72 82 130 98.0 56 77 136 / 9 1 109. 5 Sept. 30, 1918: Male..- 18 85 100 / 90.0 13 83 94 1 17 / 88.3 Female. 73 88 131 / 6 \ 109. 7 56 100 145 / 17 \ 117.0 Oct. 1, 1919: Male 18 « 83 ‘ 99 / 91.8 12 83 95 1 34 / 89.7 Female 75 * 87 139 / 19 \ 115. 1 56 < 95 149 / 34 1 123. 0 Oct. 5, 1920: Male 17 83 100 / <91.6 13 83 95 1 nn f « 89. 6 Female..- - 75 89 143 i 11 \ 119.0 55 108 151 1 127. 1 Dec. 12, 1922: Male,.- . 18 83 100 / 92.3 12 84 97 1 48 / 91.0 Female -. < 73 97 145 \ 123. 7 55 118 153 ) 48 \ 134. 0 Oct. 10, 1923: Male.. - -. 18 85 101 f 93.4 12 85 98 1 5n / 91.7 Female 70 111 146 \ 127. 1 55 122 155 \ 135. 9 Oct. 21, 1925: Male 17 85 * 100 f 93.8 12 87 102 \ 55 / 93.9 Female 69 * 100 148 I 48 \ 128. 0 55 125 155 \ 138. 2 Oct. 15, 1927: Male - 17 86 102 f 94.0 11 90 < 101 / 97.7 Female 67 115 151 \ 130. 7 54 126 158 \ 141. 1 i “Selects”; 100 best selected from entire brood, Sept. 13, 1913. i “Runts”; 100 poorest selected from entire brood, Sept. 13, 1913. 3 The sexes could not be distinguished definitely prior to this date. < The apparent decrease in size may be due to a somewhat closer measurement, or it may be that the same terrapins were not measured, for all the terrapins in 1 pen often are not found. Table 25. — Rate of growth of the brood of 1913 When measured Number Smallest Largest Females 125 mm. or more in length Average length Remarks Apr 29, 1914 686 Aim. 22 Aim. 32 Aim. 27.6 Hibernated. Do 504 23 48 31. 1 Fed first winter. Do 100 34 48 37.5 Selected best from preceding lot; measurements based on 100 largest. 96 69 104 81.1 Sept 20, 1916 94 73 112 88. 6 Oct. 11, 1917: 4 77 95 } 4 / 84.5 Prior to this date the sexes could not be separated definitely. 90 76 125 l 96.0 Oct. 1, 1918: 4 80 ‘ 89 \ 3 f 86.0 90 83 134 J 3 \ 103. 7 Oct. 1, 1919: 4 80 100 } 10 / 88.0 Female. 88 86 138 \ 108.3 Oct. 13, 1920: 4 81 101 } 11 / 89.2 86 88 140 l 110. 7 Dec. 12, 1922: 4 82 1 100 } 29 f 90.2 85 95 144 \ 121. 2 Oct. 10, 1923: 4 85 101 } 59 f 92.2 79 102 148 \ 125. 6 Oct. 21, 1925: 4 85 103 J 56 J 94.0 75 105 150 \ 128. 1 i All the terrapins in a pen seldom are found at one time. The decrease in size probably is due to missing one of the smallest animals the preceding year. DIAMOND-BACK TERRAPIN CULTURE 61 Table 26. — Rate of growth of the brood of 1914 When measured Number Smallest Largest Females 125 mm. or more in length Average length Remarks Aim. Mm. Mm. May 24, 1915 351 25 48 32.9 Fed fresh fish. Do-_ 376 24 45 31.5 Fed salt fish first winter. Aug. 25, 1915... 284 27 67 42.2 Fed fresh fish. Do 303 28 69 41.6 Fed salt fish first winter. Do 100 49 69 54.2 Selected 100 best from preceding lots. Sept. 20, 1916 97 58 93 70.3 Oct. 11, 1917 88 63 115 81.6 Oct. 3, 1918 91 75 126 1 93.2 Two males present in lot but they were not kept separate in measurements and therefore their size can not be shown. Oct. 2, 1919 91 76 133 2 96. 1 Oet. 13, 1920 91 76 138 9 101.3 Dec. 12, 1922 92 79 144 19 114.0 Oct. 10, 1923 97 87 146 27 116.6 Oct. 21, 1925 85 84 149 34 121.3 Table 27.— Rate of growth of the brood of 1915 When measured Num- ber Small- est Larg- est Females 125 mm. or more in length Aver- age length When measured Num- ber Small- est Females Larg- I2Sm PQt6 or more esl i in length Aver- age length Mm. Mm. Mm. Mm. Mm. 1 Mm. Mar. 15, 1916 i 613 24 40 29.9 Oct. 15, 1918. 435 35 112 60 3 Mar. 16^ 1916 3 662 25 51 33.8 Oct. 8, 1919 395 38 122 65 6 Aug. 24,’ 1916. 586 29 76 44.8 Oct. 8, 1920..- 338 41 134 2 6Q 4 Oet. 13,' 1917 475 32 94 50.8 June 23, 1921 303 47 127 : l 69.9 1 This lot was fed on salted fish during the winter of 1915-16. After these measurements were taken it was discarded. 2 This lot was fed on fresh fish during the winter of 1915-16. All subsequent measurements are based on this lot. It was discarded after the last measurements listed in the table were taken. Table 28. — Rate of growth of the brood of 1916 When measured Offspring of wild brood stock Offspring of domestic stock Number Smallest Largest Females 125 mm. or more in length Average length Number Smallest Largest Females 125 mm. or more in length Average length Aim. Aim. Mm. Aim. Mm. Aim. May 25, 1917 1, 040 23 80 39.2 670 24 62 82 6 Oct. 4, 1918 i 120 47 104 70.6 1 81 47 83 62 2 Oct. 9, 1919 99 2 45 116 74.4 96 3 45 85 Oct. 8, 1920 99 2 42 123 75.5 95 47 92 66 8 Sept. 24, 1921.... 99 56 133 1 82.6 88 53 103 73 7 Sept. 13, 1922 103 69 136 4 91.4 92 69 120 85 2 Oct. 5, 1923 100 74 138 4 97.2 91 71 135 2 93.0 Sept. 12, 1924 100 77 139 6 101.9 95 73 2 130 2 95.5 Oct. 20, 1925. 93 78 140 7 103.3 95 74 132 5 98.0 Oct. 1, 1927: 3 Male.. 18 81 102 f 89.3 22 78 101 1 f 90.7 Female 82 92 141 \ 119. 4 76 83 141 > 33 { 116. 4 1 This lot was selected at 1 year of age from the lot listed above. 2 The apparent decrease in size probably is due to closer measurements or to the probability that the same terrapins were not measured each year, for all the animals in a pen often are not found. 3 The measurements of the sexes were not definitely kept separate prior to this date. 62 BULLETIN OP THE BUREAU OF FISHERIES Table 29. — Rate of growth of the brood of 1917 When measured Close confinement Wide range Number Smallest Largest Females 125 mm. or more in length Average length Number Smallest Largest Females 125 mm. or more in length Average length Aim. Mm. Mm. Aim. Aim. Aim. May 19, 1919 100 50 84 60. 1 100 46 72 52. 5 Oct 23,' 1919 98 51 101 66.7 81 50 81 60. 9 Oct. 5, 1920 1 50 58 109 74.8 i 63 57 96 70. 6 Sept. 24, 1921 _ 50 68 127 1 89. 5 58 61 109 81. 1 Sept. IS, 1922 77 135 3 97.8 51 81 121 96. 3 Oct. 5, 1923 53 84 141 10 107.9 48 82 135 1 100.4 Sept. 11, 1924 50 86 141 15 112. 1 44 83 139 1 101.7 Oct. 20, 1925 53 2 82 144 19 117.0 41 85 2 130 2 102/3 Sept. 30, 1926 50 91 152 32 123.8 39 85 147 13 118.0 Oct. 15, 1927 3 50 89 154 37 134.8 4 39 87 150 31 126.4 1 Rats destroyed many of the animals in this lot. Others probably were not found when measurements were taken. 2 The apparent decrease in size probably is brought about measuring different terrapins, as all the animals in any 1 pen seldom are found. 3 This lot contained 10 males, but the measurements for them were not kept separate and can not be given. 4 This lot contained 7 males, but the measurements for them were not kept separate and can not be given. Table 30. — Rate of growth of the offspring of the wild and domestic brood stock of the 1919 brood When measured Offspring of wild brood stock Offspring of domestic brood stock Number Smallest Largest Females 125 mm. or more in length Average length Number Smallest Largest Females 125 mm. or more in length Average length Aim. Aim. Aim. Aim. Aim. Aim. May 11, 1920 4 73 30 55 38.2 i 85 23 48 35.7 Do' 2 85 26 46 34. 1 2 84 26 54 34. 2 May 13, 1920. __ a 100 37 55 38.4 4 100 33 48 40. 2 Sept. 30, 1921... 54 36 71 51.8 90 41 82 62. 0 Sept. 19, 1922 . . 47 49 96 70. 7 87 46 110 77. 4 Oct. 10, 1923 81 53 117 87. 6 Oct. 8, 1924 46 75 114 91.3 78 69 123 90. 2 Oct. 27, 1925 44 78 123 96.0 78 75 132 4 95. 3 Oct. 8, 1926 41 83 135 101.0 78 75 139 14 104. 7 Sept. 28, 1927: 22 74 98 / 90. 4 Females _ 52 87 144 1 26 l 119.3 1 This lot, which originally consisted of 100 terrapins, was fed on oysters during the winter of 1919-20. 2 This lot, which originally consisted of 100 terrapins, was fed on fresh fish during the winter of 1919-20. 3 This lot was selected on May 13, 1920, from the 2 lots listed above, and it originally consisted of 100 terrapins, some of which were destroyed by rats. All subsequent measurements were based upon the surviving ones of this lot. * This lot was selected from the 2 lots listed under the preceding date. All subsequent measurements were based upon the surviving ones of this lot. Table 31. — Rate of growth of hybrid terrapins of the brood of 1919 When measured Texas males and Carolina females Carolina males and Texas females Number Smallest Largest Females 125 mm. or more in length Average length Number Smallest Largest Females 125 mm. or more in length Average length Aim. Aim. Aim. Aim. Aim. . Aim. May 11, 1920 - i 48 25 52 35.6 1 96 26 47 33. 4 Do __ 2 50 26 48 34.0 2 96 27 49 32.9 May 12, 1920 3 80 28 52 35.7 3 100 29 49 35. 5 Sept. 24, 1921 4 54 33 90 63.0 4 30 43 93 58.3 Sept. 14, 1922 53 42 107 78.0 31 5 41 « 92 62.3 Oct. 10, 1923 54 55 120 86. 1 31 65 119 83.1 Oct. 9, 1924_ 53 3 52 124 89.2 31 74 127 2 92.8 Oct. 22, 1925 49 61 135 3 95.5 30 J 72 130 i 94.2 Oct. 2, 1926- 51 72 144 7 98.3 30 72 143 4 102.6 Sept. 28, 1927 : Males 33 86 104 / 98.3 18 81 108 \ o / 91.8 Females. 19 81 148 / 10 \ 125. 3 13 92 150 / 8 \ 127. 0 1 This lot was fed on oysters during the winter of 1919-20. 2 This lot was fed on fish during the winter of 1919-20. 3 This lot was selected on May 12, 1920, from the 2 lots listed under the preceding date. All subsequent measurements were based upon the surviving ones of this date. 4 Many terrapins were destroyed by rats. 3 The apparent decrease in size may be accounted for by closer measurements or by the fact that the same terrapins are not measured each year, as all the terrapins in a pen often are not found. DIAMOND-BACK TERRAPIN CULTURE 63 Table 32. — Rate of growth of the Carolina terrapins of the brood of 1920 When measured Number Smallest Largest Females 125 mm. or more in length Average length Number Smallest Largest Females 125 mm. or more in length Average length May 13, 1921.. i 1, 994 2 200 Mm. 22 Mm. 54 Mm. 31.8 Aim. Mm. Mm. 32 47 38.5 3 50 33 37.5 Sept. 24, 1921... . 165 35 57 43.8 50 46 83 59.6 Sept. 14^ 1922 163 35 73 50.3 Oct. 10, 1923... 144 40 87 61.3 39 68 105 83.2 Oct. 11, 1924 145 45 110 63.0 4 31 76 108 91. 1 Oct. 22’ 1925 122 52 111 75.7 Oct. 1, 1926— 121 56 126 1 84.7 26 76 130 4 108.0 Sept. 28, 1927: Males 23 72 97 \ 9 f 84.0 } 25 98 138 116.9 Females 89 61 132 / 2 \ 98.1 1 This lot contains ail the winter-fed animals of the brood. The 2 lots listed under the next date were taken from this one. 2 Offspring of domestic stock. 3 Offspring of wild stock. 4 13 males, for which no measurements are available, were removed from this lot. Table 33. — Rate of growth of hybrids of the 1920 brood produced by crossing Carolina 7nales with Texas females When measured Num- ber Small- est Largest Females 125 mm. or more in length Aver- age length When measured Num- ber Small- est Largest Females 125 mm. or more in length Aver- age length Mm. Mm. Mm. Mm. Aim. Aim. .Tunc 13, 1921 87 28 50 38.5 Oct. 20, 1925 63 66 121 96. 1 Oct. 3, 1921 65 31 68 48.4 Sept. 30, 1926 60 82 135 9 105. 1 Sept. 14, 1922 67 41 86 63.6 Oct. 1, 1927: Oct. 5, 1923 64 51 115 79. 1 Males 40 85 109 / 94. 4 Sept. 12, 1924. 64 55 115 86.6 Females.. .. . 20 108 146 I 10 1 128.2 Table 34. — Rate of growth of the brood of 1921 When measured Number Smallest Largest Average length When measured Number Smallest Largest Average length Aim. Aim. Aim. Aim. Aim. Aim. May 18, 1922 2, 101 25 50 31.8 Oct. 27, 1925. 45 51 106 78 8 i 100 29 42 34.4 Oct. 6, 1926 41 79 120 86.0 Sept.. 19, 1922.. 72 29 48 38.5 Oct. 21, 1927: Oct. 5, 1923 __ 40 69 55.3 Males 2 86 92 89 5 Oct. 7, 1924 50 46 94 64.4 Females 31 93 124 108.3 1 This lot was selected from the one listed under the preceding date. Table 35. — Rate of growth of the brood of 1922 When measured Offspring of domestic stock Offspring of wild stock Number Smallest Largest Average length Number Smallest Largest Average length Aim. Aim. Mm. Aim. Aim. Mm. May 23, 1923 2, 051 23 47 31.9 454 25 51 33.3 June 3, 1923 200 36 47 37. 0 200 36 51 37.2 Oct. 24, 1924 1 130 36 70 43. 1 > 142 36 72 47. 5 Oct. 27, 1925. 105 41 84 53.4 99 41 92 58.0 Oct. 7, 1926... 94 42 91 62.3 93 44 95 65. 2 Sept. 27, 1927.. 93 46 106 78.7 93 51 130 80. 6 > This lot was selected from the one listed under the preceding date. 64 BULLETIN OF THE BUREAU OF FISHERIES PERIOD OF ACTIVITY The length of the period of activity of diamond-back terrapins, of course, varies from year to year according to temperatures. At Beaufort some of the animals begin to move about on warm days in March, but generally they do not become active and take food until about the latter part of April or early in May, and the period of activity may be said to end again sometime during October or, rarely, as late as early in November. They feed regularly only from about the latter part of May until early in October. On cool days they cease to feed and even mild days in midsummer cut down their capacity for food. FOOD, FEEDING, AND COST OF FOOD The food of terrapins in nature is reported to consist of small mollusks and crus- taceans. In captivity, as already indicated, they readily take fish cut in pieces of suitable size, crabs, shucked oysters, and clams. At Beaufort, however, fish and some blue crabs chiefly are fed. Fiddler crabs enter the pens, and some small mollusks, too, are available. The animals appear to thrive on these foods. The fish used during the summer are purchased directly from commercial fisher- men, and they generally consist of menhaden and other unsalable fish or of small food fishes that would bring little on the market. Frequently quite a few blue crabs are included with the “scrap” fish. During the winter months, when only about 1 ]/2 pounds of food a day is used, small and cheap grades of fish are purchased from local fish dealers; or when oysters were fed they either were collected by the terrapin culturist or purchased in the shell and opened at the laboratory. During 1927 the fish and crabs delivered by the fishermen were purchased at 2 cents per pound. During the winter, when the fish were bought from dealers, the price ranged from 6 to 7 % cents per pound. The total cost of food for the calendar year 1927 was $236.52. With this amount, about 2,936 recently hatched young terrapins were fed during the winter and 3,707 animals of various ages (mostly adults) were fed during the summer. The cost of food for the young winter-fed animals for a seven-months period was 7% mills per head. The cost for all the animals held in outdoor pens for the year 1927 averaged nearly 6 cents per head. It is evident, therefore, that the cost of food at Beaufort is not great. For the small terrapins, a year or less of age, the fish are scaled, the large bones are removed, and then they are put through a food chopper. For larger terrapins, the fish and crabs together, as received from the fishermen, are put through a feed cutter of the type used by farmers, which cuts the food into pieces small enough to be managed by the terrapins. The food is thrown on the ground in a clean, solid place near the edge of the water. The animals emerge, take a piece of food, and generally return to the water to eat it. Care is exercised to supply sufficient food and not too much. Food placed on the ground at the edge of the water can be removed readily if it is not all consumed, for it is highly essential to prevent putre- faction, and less is wasted by the animals than if it were thrown into the water. DIAMOND-BACK TERRAPIN CULTURE 65 COPULATION, LAYING SEASON, AND INCUBATION PERIOD Copulation seldom has been observed. Males frequently persist in following certain females, however, and it is supposed that this indicates a desire to copulate and that copulation probably follows. If that be true, copulation may take place at any time during the period of activity. This sex activity is greatest in the spring, very soon after the animals emerge from hibernation, and it is probable that that is the chief “mating” season. The laying season begins in May, generally about the middle of the month, and it ends about the first of August. A female may lay only once during a season, or she may lay as many as four and, rarely, five times. The earliest date of hatching that has been noticed at Beaufort was July 28, but generally hatching does not occur before the middle of August, and the last eggs hatch during the first half of October. The length of the incubation period, of course, varies somewhat with the prevailing temperatures, being shortened by high tempera- tures and lengthened by low ones. Using the earliest dates (generally around May 15) when laying was observed and the first dates (generally around August 15) when young terrapins emerged from the nests as a basis, the incubation period would appear to extend over about 90 days. Since newly hatched terrapins generally do not emerge from the nests immediately upon hatching, it may be assumed that the incubation period is somewhat short of 90 days. SPACE REQUIREMENTS It has been shown elsewhere (p. 53) that it seems practicable to confine as many as 100 recently hatched terrapins for winter feeding in a brooder house in a tank having a floor space of about 20 by 24 inches. To this statement there is little to add, except the caution that a high degree of cleanliness must be maintained. The tanks in which the animals were held at Beaufort under such crowded conditions were washed twice a day and scrubbed whenever it appeared necessary, and after each washing and scrubbing new and clean water was supplied. Care must be taken particularly to prevent the decay in the tanks of uneaten foods. The extent of crowding that terrapins can stand in outdoor pens is not well known. None of the experiments performed to date indicate that the different degrees of crowding that have been tried were deleterious. Certainly, much depends upon cleanliness and the free exchange of water; that is, much greater crowding will be possible when the pens are fairly free of decaying organic matter and when the tides and conditions are such that an almost complete exchange of water takes place twice daily and clean water is brought by each flood tide. The greatest crowding of growing and fairly large terrapins among the experiments under way at Beaufort is 198 in a pen 5 feet wide and 36 feet long. The length of the pen probably has little significance as the animals stay in the water, or at least very close to it nearly all of the time. Therefore, only about one to three fourths, depending upon the stage of the tide, of this particular pen generally is occupied by the animals. The rate of growth of the animals in this pen compares favorably with other less crowded lots, and from the standpoint of survival this lot is ahead of all others grown in captivity. 66 BULLETIN OF THE BUREAU OF FISHERIES In 1919, 100 animals of the 1917 brood were placed in a small pen measuring about 5 feet wide by 36 feet deep and 100 in a much larger pen, similarly situated, having a width of about 24 feet and a depth of about 36 feet. Owing to depreda- tions by rats the numbers were greatly reduced. In 1927 only 50 animals were left in the small pen, and these (including 10 males) had an average length of about inches (134.8 millimeters), whereas only 39 were found (more animals probably were present, but they were difficult to find due to the large size of the pen) in the larger pen, which (including 7 males) had an average length of slightly over 5 inches (126.4 millimeters). If this experiment could be used as a criterion, “close range” would seem to be better than a wider one. The animals are sluggish, and it is not believed that a large pen is necessary for the purpose of providing space for exercise. The main consideration is the provision of sufficient room to furnish the necessary sanitation. It seems reasonable to conclude from the experiments described and from the results obtained with several other lots that under the conditions existing at Beaufort certainly as many as 100 animals may be held and grown to maturity in pens having an area of 5 by 32 feet. Space requirements, as already suggested, undoubtedly would vary in different localities according to the cleanness of the water brought by flood tides and other local conditions. SEX RATIO The sexes of terrapins can not be distinguished from external characters until a length of 3 to 4 inches is attained. When this size is reached the males may be recognized by the much larger and heavier tail. There are other differences, such as the smaller head and the more wedge-shaped posterior outline of the carapace in the male, but the most evident character is the tail. Because it is impossible to distinguish the sexes in young animals from external characters, and because dissec- tions of such animals have not been attempted, information concerning sex ratio is still quite incomplete. It may be stated, however, that the males are greatly in the minority among the total number of terrapins grown to maturity in captivity. This becomes evident from the fact that in 1927 among a total of 1,300 such animals in which the sexes could be distinguished positively there were only 242 males, thus giving a ratio of 1 male to 4.4 females. Omitting certain hybrid lots, in which the males are numerous, and using only pure stock of Carolina terrapins, the ratio becomes 1 male to 6.4 females. Most of the lots from which the foregoing data were derived consist of animals selected (usually at about 1 year of age) from a year’s brood (which usually con- sisted of a few hundred to a thousand or more individuals) because of the rapid growth they had made, while the rest were liberated. One lot was selected for the opposite reason, however; that is, the “runts” were retained; and still other lots were unse- lected. It is not evident from the results that the selections affected the sex ratio constantly in any one direction. The large variation in sex ratio among the small lots on hand suggests, however, that the element of chance selection as well as chance survival may have been important. The extremes in sex ratio are represented in two lots of the brood of 1911 of Carolina terrapins, and in a lot of hybrid terrapins (Carolina males crossed with DIAMOND-BACK TERRAPIN CULTURE 67 Texas females) hatched in 1920. The two lots of the 1911 brood originally consisted of two groups of 100 each of unselected animals. When last counted (1927), 163 of these terrapins were found, all of them being females; nor has a male ever been noticed among these animals. The lot of hybrid terrapins to which reference was made in the preceding para- graph originally consisted of 100 animals selected at 8 months of age. This lot, when last counted (1927), consisted of 60 terrapins, of which 40 were males. It appears to be of interest to note further that a somewhat similar abundance of males prevails among the only other two lots of hybrid terrapins (both hatched in 1919) on hand- One of these is the product of Texas males crossed with Carolina females, and it originally consisted of 80 unselected animals. When last counted (1927), 52 of these terrapins were found, and 33 of them were males. The other lot at first contained 100 selected animals, the offspring of Carolina males crossed with Texas females. This lot, due largely to depredations by rats when the terrapins were small, has been reduced to 31, and of these 18 are males. The greatest abundance of males in pure stock occurs in a selected lot originally consisting of 100 young, now (1927) reduced to 74, of Carolina terrapins hatched in 1919, in which there are 22 males. In all other lots of pure stock the males are in an even smaller minority. These data would appear to indicate that cross-breeding Carolina and Texas terrapins tended to increase the proportionate number of males. However, the lots are too small to justify that conclusion, and until more information is obtained it may be assumed that the present results are a mere coincidence. Table No. 36 shows in detail the sex ratio existing among the several lots of terrapins grown in captivity. The lots appear to be sufficiently large and numerous to justify the conclusion that a considerably larger number of females than males may be expected to reach maturity in terrapin farming. This is important from a practical viewpoint, as the females reach a relatively much larger size than males and have a correspondingly greater value on the market. As stated elsewhere, no definite information relative to the natural sex ratio in terrapins has been gained. A few lots of young animals are on hand, however, which may help to cast some light on this problem when they reach a sufficiently large size to admit of the recog- nition of the sexes. If it were assumed that the usual 1 to 1 ratio prevails among young terrapins, then it would follow that the males simply fail to reach maturity. The selection of the larger and stronger animals at about 1 year of age, as was often done, does not appear to have resulted in constantly choosing females in preference to males. If it had, then it might be reasonable to expect the males to be in the majority among those terrapins that were chosen because they were small and undersized. This does not appear to be the case, however, for a lot of 100 terrapins of the 1912 brood was selected at 1 year of age as the very poorest and smallest among several hundred animals. When last counted (1927), 64 animals were found and among them were only 10 males. In unselected groups of Carolina terrapins the males, too, are greatly in the minority. The supposition that the males failed to mature is complicated by the fact that the number of males present at maturity in some of the unselected lots as well as selected ones, added to the total number of animals that died (assuming that the loss consisted wholly of males), still would not make a sex ratio of 1 to 1. 68 BULLETIN OF THE BUREAU OF FISHERIES Table 36. — Sex ratio in several lots of diamond-back terrapins hatched and grown to maturity in confinement 1 Year of hatching Number origi- nally in lot Number on hand, 1927 2 Ratio of males to females Remarks Males Females 1910 171 13 116 1:8.9 All fed first winter, some the second winter; unselected. 1910 119 5 87 1:17.4 Hibernated each winter; unselected. 1911 100 0 78 Fed first three winters; unselected. 1911 100 0 73 Hibernated each winter; unselected. 1912 100 10 54 1:5.4 Some fed first winter, all fed the second winter. Selected at the age of 1 year, the smallest of the entire brood, consisting of 1,221 animals. Majority fed first winter, all fed the second winter. Selected at the age of 1 year, the largest from the entire brood, consisting of 1,221 animals. 1912 100 17 64 1:3.8 1913 100 4 75 1:18.8 Fed first winter; selected at 1 year of age, the largest from lot consisting of 504 animals. 1914 100 2 83 1:41.5 Fed first winter; selected at age of 1 year, the largest from a lot consisting of 587 animals. 1916 200 40 158 1:4.0 Fed first winter; selected at age of 1 year, the largest from a lot consisting of 1,710 animals. 1917 200 17 73 1:4.3 Fed first winter; selected at 9 months of age, the largest from a brood consisting of 961 animals. 1919 100 22 52 1:2.4 Fed first winter; selected at 8 months of age, the largest from a lot com- posed of 169 animals. 1919 80 33 18 1:0. 5 Hybrids (Texas males and Carolina females). Fed first winter; un- selected. Number reduced through depredations by rats when the terrapins were small. 1919 100 13 18 1:1.4 Hybrids (Carolina males and Texas females) . Fed first winter; selected at 8 months of age, the largest from a lot consisting of 192 terrapins. Original number much reduced through depredations by rats when the terrapins were small. 1920 200 23 89 1:3.9 Fed first winter; selected at 8 months of age, the largest from several hundred animals. 1920 87 40 20 1:0.5 Hybrids (Carolina males and Texas females). Fed first winter; un- selected. Total 1,857 239 1,058 Ratio for all lots combined, 1 male to 4.4 females. 1 The animals are Carolina terrapins unless otherwise stated under remarks. 2 The difference between the number originally in a lot and the number on hand in 1927 does not indicate the natural death rate that has occurred in each group. In a few instances several animals were taken away and used for other purposes; in a few cases some terrapins were lost in a storm; and in several lots rats killed some of the animals while small. Furthermore, the census varies from year to year; for it is extremely difficult to capture all of the animals at one time, because of their highly developed hiding propensities; and therefore the census for any one lot may vary from one to several from one year to the next, even though no deaths have occurred and no animals have been removed. SUMMARY The present series of experiments in diamond-back terrapin culture was started in 1909. Two subspecies (Chesapeake and Carolina) of terrapins are used in the experiments. Texas terrapins, too, were used at one time but have been discarded, except as represented in certain hybrid lots. Some of the experiments that have been undertaken have not been carried on long enough to yield results, and upon those no report is given. The discussion is confined to the experiments from which noteworthy results have been secured. Egg production has fluctuated greatly from year to year within lots and within broods. The number of eggs produced by individual females of the same age is known to vary from 5 to 29 during a single season. Within a single lot, egg production has varied from 7.6 to 23.9 eggs per female. It is concluded that in general terrapin culture an average annual production of 12 eggs per female may be expected. The degree of fertility of the eggs, too, has fluctuated greatly, for which often no good reasons can be given. In general, the highest percentage of fertility has resulted in the lots having the largest proportionate number of males, although exceptions to this rule are noted. Data are presented that would indicate that with DIAMOND-BACK TERRAPIN CULTURE 69 the proper sex ratio present, which appears to be about one male to five females, at least 90 per cent of the eggs laid should be fertile. Great fluctuations in the death rate have taken place among the young animals, both among the ones that were kept warm and fed during the winter as well as among the hibernating lots. The cause of the deaths in the hibernating lots is not known, but in the winter-fed lots the mortality has been due principally to two causes, namely, a disease causing sores and to “soft shell.” The disease causing sores, which may be of bacterial origin, was not equally severe from year to year, and it, more than anything else, has caused fluctuations in the death rate of winter-fed animals. Soft shell is associated with a failure to eat, causing general emaciation and gradually the softening of the shell, frequently, although not always, followed by death. Soft shell also causes many deaths among terrapins after they emerge from hibernation, and it results in more deaths than all other losses combined in both groups of animals. The percentage of terrapins that were grown to maturity has been reduced materially in some of the lots on hand through depredations by rats while the animals were small, losses during storms, and apparently by escapes made by the terrapins because of their well-developed climbing propensities. Evidence is produced that would tend to show that about 60.7 per cent of the animals hatched may be grown to maturity and that winter feeding increases the rate of survival. Terrapins have an average length of about 27 millimeters at hatching. Young animals, when kept warm — that is, if placed in a brooder house — remain active during the winter, and the majority of them will begin to take food within a month or two after hatching. If the young are left out doors, they do not feed until they are 7 to 8 months old; that is, they go into hibernation soon after hatching or they remain in the nests in which they are hatched to hibernate, and they do not feed until the weather gets warm the following spring. Generally about 1 year’s growth was gained during their first winter by the recently hatched young when placed in the brooder house, in which the temperature was kept as far as possible at 80° F. or higher; that is, an average gain of growth (for all lots that had been fed the first winter) of 4.7 millimeters was made. The advantage in growth attained through winter feeding usually was retained and, furthermore, the winter-fed animals produced eggs a year earlier than the hibernating lots. Winter feeding, aside from its advantages with respect to earlier maturity when animals are grown in captivity, has the advantage of carrying the animals through the critical stages of life at an earlier age. When terrapin culture is engaged in for the purpose of rebuilding or augmenting the supply in nature, the winter-fed animals apparently are able to take care of themselves and stand just as good a chance of survival at an age of about 8 months as the hibernating ones do a year later. The earlier liberation reduces the amount of care necessary and presumably hastens returns. Some females reach a length of about 5 ){ inches and sexual maturity in 5 years; others require a much longer time to reach this size and stage in life. Evidence is produced that tends to show that some females never reach a length as great as 6 inches. Males rarely exceed a length of 4% inches. Data are presented that show 70 BULLETIN OF THE BUREAU OF FISHERIES that in general terrapins grow rather rapidly during the first 5 or 6 years, followed by a much slower growth, and after an age of 8 to 10 years is attained growth is so slow that it is almost negligible. The males in all broods of Carolina terrapins grown to maturity have been greatly in the minority. This disproportionate sex ratio has existed in unselected lots as well as in selected ones. A ratio of 1 male to 6.4 females exists among the Carolina terrapins grown in captivity. In certain hybrid lots (crosses between Carolina and Texas terrapins) the males are much more numerous. Since the lots are small ones, this greater proportion of males may have no significance. If the usual 1-to-l sex ratio exists in young terrapins (which has not been determined), then it apparently would have to be assumed that the males are less resistant to life in captivity than the females, and they simply fail to reach maturity. This supposition does not appear to be tenable, however, because the number of deaths in some of the lots was too few, even if males only had died, to make a ratio of 1 to 1. BIBLIOGRAPHY Barney, R. L. 1922. Further notes on the natural history and artificial propagation of the diamond-back terrapin. Bulletin, U. S. Bureau of Fisheries, Vol. XXXVIII, 1921-1922 (1923), pp. 91-111, figs. 76-84. Bureau of Fisheries Document No. 917. Washington. Coker, R. E. 1906. The natural history and cultivation of the diamond-back terrapin, with notes on other forms of turtles. North Carolina Geological Survey, Bulletin No. 14, 1906, 69 pp., XXIII Pis. Raleigh. Hay, William Perry. 1905. A revision of Malaclemmys, a genus of turtles. Bulletin, U. S. Bureau of Fisheries, Vol. XXIV, 1904 (1905), pp. 1-20, Pis. I-XII. Washington. 1917. Artificial propagation of the diamond-back terrapin. U. S. Bureau of Fisheries Economic Circular No. 5, revised, 1917, 21 pp., 5 figs. Washington. Hay, W. P., and H. D. Aller. 1913. Artificial propagation of the diamond-back terrapin. U. S. Bureau of Fisheries Economic Circular No. 5, 1913, 14 pp., 3 figs. Washington. Hildebrand, Samuel F., and Charles Hatsel. 1926. Diamond-back terrapin culture at Beaufort, N. C. U. S. Bureau of Fisheries Economic Circular No. 60, 1926, 20 pp., 8 figs. Washington. Stejeneger, Leonhard, and Thomas Barbour. 1923. Check list of North American amphibians and reptiles. Ed. II, 1923, 171 pp. Harvard Univ. Press, Cambridge. [Malaclemmys, pp. 131-132.) REVIEW OF THE WEAKFISHES (CYNOSCION) OF THE ATLANTIC AND GULF COASTS OF THE UNITED STATES, WITH A DESCRIPTION OF A NEW SPECIES 1 By ISAAC GINSBURG Assistant Aquatic Biologist, U. S. Bureau of Fisheries The relation of the sand squeteague or, as it is locally called in Texas, sand trout of the Gulf coast to the gray squeteague of the Atlantic coast has been a perplexing- problem. Welsh and Breder, who were the first authors of record to examine critically a large series of specimens and who recognized but a single species of sand trout from the Gulf coast, which they identified with Cynoscion nothus, state in regard to their species as follows: Examination of a large series of specimens taken by the Fisheries schooner Grampus in Gulf waters indicates that the species is very close to Cynoscion regalis, and that its claim to specific rank is at least doubtful. Although an apparently well-marked variety, further study may show complete intergradation of characters with the latter species. R. J. Coles (1916)2 considers it simply a color variation of C. regalis. (Bulletin, U. S. Bureau of Fisheries, Vol. XXXIX, 1923-1924, p. 169.) Commercially, the gray trout is a very important species in the fisheries of the Atlantic coast from Cape Cod to the coast of North Carolina. In any study of its migrations and localized races it becomes evident that it is important, first of all, to determine definitely its interrelationship with closely related species. It is especially important to know the exact morphological limits of the species in determining such problems as the age of the fish or its rate of growth. In general, it is axiomatic that in a study of the life history of any species all conclusions must be based on an examination of individuals of the same species, but this has not been the universal rule in the case of the squeteagues. Workers with these fishes, including myself, have not always properly separated their material and frequently have based their identifi- cations on geographical lines. That this is true becomes evident from a study of the published records of these fishes as well as some of the material on which the records are based, after one becomes familiar with the real specific characters, as outlined below. Hitherto young individuals, especially, have been confused because they are almost inseparable in general appearance. The present study was undertaken for the purpose of finding, if possible, usable characters by which the individual fishes may be distinguished and recognized at all stages of growth. The status of the species of Cynoscion on the Atlantic and Gulf coasts of the United States, as they are generally understood at the present time, may be reviewed and summarized as follows: First of all, we have the spotted squeteague, Cynoscion nebvlosus. This species is fairly common on the Atlantic and Gulf coasts, and be- cause of its distinctive color and scaleless dorsal and anal fins it is easily recognized and distinguished from the paler weakfishes. It is now generally agreed that there is but one species of spotted weakfish common to the Atlantic and Gulf coasts. This species is not considered in the present paper. • Submitted for publication Apr. 22, 1929. • Russell J. Coles: Is Cynoscion nothus an abnormal regalis? Copeia, No. 30, Apr. 24, 1916, pp. 30-31. New York. 71 66401—29 72 BULLETIN OF THE BUREAU OF FISHERIES The gray weakfish or, as it is commonly called in more southern localities, the gray trout ( Cynoscion regalis ) is the common commercial fish of the Atlantic coast. The individuals comprising the commercial catch, or the vast majority of them, seem to belong to one species; at least now they are generally so regarded. As to the geographic distribution of this species, it is significant that authors generally have failed to record it from the Gulf coast, especially those who reported on ex- tensive collections from that coast. Jordan and Eigenmann (Report, U. S. Fish Commission, 1886, p. 367) record it from Mobile based on material (the number of specimens not stated) in the Museum of Comparative Zoology at Harvard University. This is the only direct record of regalis from the Gulf that is known to me. In the literature Cuvier and Valenciennes generally are quoted as authority for including the Gulf coast in the range of regalis, but the statement on which this supposed record is based is as follows (Histoire Naturelle des Poissons, Tome 5, quarto ed., 1830, p. 53): “Les colons francais de la Nouvelle-Orleans le possedent aussi, et lui ont transfere le nom de truite, a cause de ses taches.” This statement obviously refers to the spotted weakfish, since this is the only species of Cynoscion on the Gulf coast having well-defined spots. A third form that is at present recognized is Cynoscion nothus. This was described originally from the coast of South Carolina and has since been recorded from Chesa- peake Bay to the southwestern coast of Texas. There is difference of opinion as to the status of this species. Welsh and Breder, as quoted above, doubt the real dis- tinctiveness of this form from regalis. On the other hand, Hildebrand and Schroeder (Bulletin, U. S. Bureau of Fisheries, Vol. XLIII, Pt. I, p. 300), who had two speci- mens of this species from Chesapeake Bay, state: “ * * * the differences between a true nothus, such as we believe to have in hand now, and a regalis are so evident and so numerous * * *.” Jordan and Gilbert (Proceedings, U. S. National Museum, Vol. V, 1882, p. 607) are the only authors known to me who record this species as being common on the Atlantic coast — namely, at Charleston, S. C. Inci- dentally, it may be stated that the description of the species given by these authors is probably the best extant, because it is evidently based on abundant material com- prising specimens of this species only and not a mixture of individuals of different species. As to the occurrence of this form on the Gulf coast, nearly all authors who have worked over the fishes from that coast, especially those who have studied the fisheries and hence have dealt with masses of individuals, have referred the pale weakfish of the Gulf to nothus. Finally, a fourth species has been described under the name of thalassinus. This species was first described by Holbrook (Ichthyology of South Carolina, 1855, p. 132, pi. 18, fig. 2) from a “few specimens” taken off the coast of South Carolina. Gunther (Catalogue of Fishes of the British Museum, vol. 2, 1860, p. 308), who had a single specimen of the pale weakfish from the Gulf coast, doubtfully referred it to thalassinus. Jordan and Eigenmann (op. cit.) have picked out three specimens from those studied by them — two from the Gulf and one from the Atlantic coast — and referred them to thalassinus. These authors state: “As C. regalis is subject to considerable variation, we have regarded C. thalassinus as an extreme form or variety rather than a distinct species. It may, perhaps, be found to inhabit a different depth of water than that which the common weakfish frequents.” Jordan and Gil- bert (Bulletin, U. S. National Museum, No. 16, 1882, p. 582) call it “a doubtful species.” Welsh and Breder (op. cit., p. 148) state that “Cynoscion thalassinus WEAKFISHES 73 (Holbrook), which has not been recognized since the describer’s time, seems to be merely nominal, as the description is close to C. regalis and C. nothus.” Briefly, then, the consensus of opinion at the present time may be stated as follows: Omitting the spotted squeteague, there are two species of squeteagues com- mon enough to enter into the commercial catch; one, the gray squeteague ( Cynoscion regalis), is the common market fish of the Atlantic coast, while the other, the bastard trout or sand trout ( Cynoscion nothus), is the common market fish of the Gulf coast. C. regalis does not occur or is very rare on the Gulf coast, and C. nothus usually is taken rather sparingly on the Atlantic coast. C. thalassinus is a very doubtful species. I had these ideas in mind when I began the study of the sand trout of the Gulf. It soon became evident, however, that such ideas do not fit the actual facts, and a study of considerable available material was undertaken in order to throw more light, if possible, on the subject. The present study has shown that instead of one there are two very distinct and easily separable species of sand trout on the Gulf coast. Both are common, although the relative abundance of the two must be left for future determination. One of these species is smaller than the other and, so far as the material at hand discloses, apparently does not enter to any great extent into the commercial catch; the other species is the common market fish. This larger and common species is not nothus. It is very close to regalis, but evidently is sufficiently distinct to require a separate designation and is here named Cynoscion arenarius. The name thalassinus is definitely based on specimens from the Atlantic coast and is not applicable to this species, which is confined to the Gulf coast. The smaller Gulf species evidently is the same as that described by Holbrook under the name of Otolithus nothus and is here recognized under that name. Many specimens of this species from both the Atlantic and Gulf coast have been examined. Some of this material has been previously identified by me or by other workers either as nothus or regalis, depending on whether it came from the Gulf or the Atlantic coast, respectively. This is easily explained by the fact that nearly all of the material consists of small specimens of less than 7 inches, and when of that size the appearance of the fish is such that the species can not be distinguished by a mere visual com- parison, even when such comparison is made by an experienced ichthyologist. How- ever, when the distinguishing characters outlined below are examined no trouble will be experienced in identifying even the smallest specimens. When identification is thus definitely made, our material shows that Cynoscion nothus is really more common on the Atlantic coast, from North Carolina southward, than most of the discussions in current literature would seem to indicate. The present study has failed to confirm the distinctness of the form that has been named thalassinus. Of the many specimens of gray trout examined from Chesapeake Bay, from the coasts of North and South Carolina, and from the east coast of Florida, I have failed to distinguish more than one species and am therefore forced to the conclusion that thalassinus is untenable. It was evidently based on some slender individuals of regalis, which manifestly show considerable variation in that character. The coloration shown by Holbrook is essentially that of regalis. The number of fin rays is used by the author as one of the chief distinguishing marks, but his counts are obviously unreliable; as, for instance, when he states that regalis has only 9 dorsal spines, whereas it nearly always has 10. Besides this, the number of soft dorsal rays given in the original description falls within the range of variation of 74 BULLETIN OF THE BUREAU OF FISHERIES regalis, as noted below. The other characters given by him are apparently of no significance. Instead of being hard to distinguish, as has been asserted, Cynoscion nothus is, in fact, readily separable. The present extensive study has revealed three striking characters that prove conclusively that this species is distinct, and by means of which a single individual may be identified readily; namely, (1) the number of vertebrae, (2) the correlation of the numbers of soft dorsal and anal rays, and (3) the absolute number of anal rays. Counting the vertebrae of many individuals has shown that their number furnishes a valuable and positive character for differentiating this species from the other two. In the specimens of Cynoscion nothus counted there were always 27 vertebrae, except in one, which had 26. This was a small specimen from off the coast of North Carolina. Altogether 114 specimens of this species from the Gulf and Atlantic coasts were counted. Cynoscion regalis and C. arenarius invariably were found to have 25 vertebrae. Fifty-five specimens of these two forms were counted and recorded. The counts were made after the mass of muscles had been removed from one side. The first vertebra, which articulates with the skull and has a different shape than the succeeding vertebrae, and also the hypural were included in the count. A study of the correlation of the numbers of dorsal and anal soft rays is what first led me to suspect that two distinct species were being confused under the name sand trout on the Texas coast. Table 1 shows this correlation in specimens from various localities on the Gulf coast. A mere glance at the table is sufficient to show that we are dealing here with two distinct forms, one having a shorter anal in combination with a longer dorsal than the other. Table 2 shows the same correlation for specimens from various localities on the Atlantic coast. Those specimens having the short anal in conjunction with a long dorsal also have 27 vertebrae and consequently are Cynoscion nothus. Comparing Tables 1 and 2 for Cynoscion nothus it may be seen that there is a tendency to an increase in the number of fin rays on the Atlantic coast. However, an increase in the number of rays in northern localities is a common phenomenon occurring among fishes having a wide latitudinal distribution. It may be noted that the increase occurs both in the anal as well as the dorsal, and the differ- ences are not marked enough to be of specific significance. For practical purposes merely counting the anal rays is sufficient to determine nothus. From an examination of Table 1 it will be seen that there is virtually a break in the series of 217 specimens enumerated, as far as the number of anal rays is concerned, except for 12 individuals. Every one of these 12 specimens was dissected and found to have 25 vertebrae, which placed them definitely with arenarius. The number of specimens examined is sufficient, for practical purposes, to enable us to make the statement that in Gulf waters nothus has 8 or 9 soft anal rays, while arenarius has 10 to 12. Similarly, Table 2 shows that for Atlantic coast fish there is a virtual break in the number of anal rays even more pronounced than in Gulf specimens, there being only 5 of 259 Atlantic fish examined that may be said to be intermediate. Of these 5 specimens 4 were found to have 27 vertebrae, which places them unquestionaly with nothus, and 1 had 26. This is the only individual of all those examined for vertebrae (169 in all) that had 26, all the others having either 25 or 27. It is a small specimen, having a standard length of 49 millimeters, taken at Beaufort, N. C., on September 29, 1926. Since on the same trip many others of similar size and presumably in company with it were taken, which WEAKFISHES 75 unquestionably were nothus, it may safely be assumed that this single individual is a nothus showing a rare individual variation. On the basis of the material examined, which was manifestly sufficient for all practical purposes in so far as distinguishing species is concerned, it may be stated that on the Atlantic coast nothus has 8 to 10 anal rays and regalis 11 to 13. Table 1. — Correlation of the number of articulate rays of the dorsal and anal fins of Cynoscion arenarius and C. nothus from the coast of the Gulf of Mexico [The first short ray of the soft dorsal, which is about one-fourth as long as the anterior fully developed rays and apparently remains unjointed even in the largest specimens, has not been included in the count. The second ray, which is about one-half to two-thirds as long as the anterior fully developed rays and becomes more or less jointed, has been included. The last two rays of both the dorsal and the anal, which apparently are joined at their base, have been counted as one. All specimens having 10 anal rays have been checked by the vertebral count and found to belong to arenarius. The numbers in the body of the table represent frequencies] Table 2. — Correlation of the number of dorsal and anal articulate rays of Cynoscion regalis and C. nothus from the Atlantic coast. ( All specimens having 10 anal rays belong to nothus, as shown by the vertebral count) Anal rays Dorsal rays 24 25 26 27 28 29 30 31 Cynoscion nothus: 8 _ 1 3 19 1 16 44 3 9 34 2 1 9 1 5 1 3 10 1 21 62 1 C. regalis: 11 5 14 12 12 13 It is not deemed necessary for the purpose of the present study to expend more time in working out in detail other structural marks that differentiate nothus, since the three characters outlined above convincingly prove its distinctness and con- stitute usable marks for identifying individual fish. Indeed, according to the stand- ards that some authors use in creating genera, the single character of the vertebral count may be considered to be of generic importance. Having thus definitely delimited and separated out the smaller Cynoscion nothus, ihere are left the two larger common commercial species — of the Atlantic and Gulf coasts, respectively — and the next matter to settle is the relation between the two. The common commercial fish of the Gulf coast is not nothus, as has been generally supposed ; it is either regalis or something else. In considering the differences between the Gulf fish and the regalis of the Atlantic coast it is well to take note of the fact that nearly all previous authors have regarded the common sand trout of the Gulf as differ- ent from the gray trout of the Atlantic. The fact that it was generally referred to nothus is beside the question. The important fact to remember is that the commercial Gulf fish is apparently of such a different appearance from the Atlantic fish that it was 76 BULLETIN OF THE BUREAU OF FISHERIES generally referred to a different species, even by investigators who dealt with the large numbers of individuals handled by fishermen. The Atlantic and Gulf forms, then, apparently are separable when taken in bulk, but when we consider each character separately the matter is not so simple because usually there is considerable inter- gradation. However, when all the characters are considered together it becomes evident that the two fish are sufficiently different to be regarded as distinct species. The more striking differentiating characters are as follows: Color. — Apparently color was the chief character on which the distinction rested heretofore. The difference in adult fish is quite striking. The Atlantic coast fish usually has small spots arranged in rather indefinite and irregular streaks, while TOTAL NUMBER OF GILL RAKERS Figxjrp; 1.— Frequency distribution of the total number of gill rakers on the first gill arch of Cynoscion arenarius and C. regalis. The solid columns represent specimens from the Gulf of Mexico ( arenarius ) and the blank columns species from the Atlantic coast (regalis), in this as well as in the subsequent figures. The numbers at the top of the columns represent the actual number of specimens studied the Gulf fish is usually pale. There is considerable variation in color. Occasionally there are Atlantic specimens that have the typical coloration faintly developed, while in some Gulf fish there may be faint development of pigmentation. However, taken as a whole, the adults of these two species may be separated nearly always by color alone, especially when in fresh condition. The young of both species are pale and hence can not be separated by color. Form of the caudal fin. — As in many other scisenids, the caudal fin of the young of Cynoscion is very pointed, the middle rays being considerably prolonged As the fish grow older the decided prolongation 6f the middle rays diminishes and the caudal fin becomes somewhat double concave. In regalis the transformation of the caudal fin is carried farther, and it becomes distinctly emarginate in large individuals. As may be expected in a case of this kind, there is considerable individual difference WEAKFISHES 77 uo i •< o OcC in the size at which this change takes place. An examination of a number of regalis from Chesapeake Bay showed that the change to an emarginate condition takes place when the fish reaches a total length between 250 and 300 millimeters. All those below 250 millimeters have the middle rays of the caudal longest, in all those over 300 it is distinctly emarginate, while in those between these lengths both condi- tions may be found, and some of them have a caudal fin that can best be described as truncate. In arenarius, on the other hand, the middle rays of the fin are longest, even in specimens over 300 millimeters long. It may be remarked that the fins of these fishes are rather brittle, and in preserved material they are more or less frayed. This probably explains why this character is not mentioned more often in discussions of the dif- ferences between the two forms. However, judging from the condi- tion of our specimens, it is apparent that the difference in the form of the caudal is substantially as described. Number of gill rakers. — This character has been mentioned by previous writers as differentiating the Gulf and Atlantic forms, and the present study has shown it to be usable, but there is considerable overlapping. The modal number for regalis in specimens of over 70 millimeters, standard length, is 5 + 12, while in arenarius it is 3 + 10 or 4 + 10. In the study of this character the size of the fish must be taken into consideration, since it has been found that the number varies with the size, especially in arenarius. In the young fish the gill rakers are comparatively longer and more slender. As the fish grow older they become shorter and stouter, and the foremost one on the lower limb of the first arch and one or two uppermost ones on the upper limb tend to become absorbed and disappear. Moreover, this disappearance is more marked in arenarius, and consequently when larger specimens are compared the difference is more pronounced. For the purposes of the present study all specimens have been divided into two groups, those of 70 millimeters or less and those over 70 millimeters standard length, and like groups have been compared. It might have been desirable to make a finer division of groups, but thcre^was not enough material of all sizes in both forms. However, this division seems sufficient to bring out the essential facts. Figures, 1 and 56401—29 2 10 II IZ 13 NUMBER OF GILL RAKERS ON LOWER LIMB OF FIRST ARCH. Figure 2. — Frequency distribution of the number of gill rakers on the lower limb of the first arch of Cynoscion arenarius and C. regalis. The one gill raker that stands at the angle of the arch and has one root on the lower limb and one on the upper limb has been included uniformly in this count 78 BULLETIN OF THE BUREAU OF FISHERIES 2 are graphic representations of the frequency distribution of the gill rakers in the group of larger specimens. In 69 smaller specimens of arenarius of 30 to 60 milli- meters the mode for the total number of gill rakers falls at 15, with the class 16 a very close second. Comparing these smaller specimens of arenarius with the larger regalis, it may be seen that the modes are even then distinct, although the overlapping is quite considerable. I do not have a sufficient number of smaller regalis to estab- lish the frequency distribution, but from the few specimens counted it seems evident that the difference between the larger and smaller members of this species is not so marked as it is in arenarius. A precaution to be taken when the number of gill rakers is used as a distinguishing character may be mentioned. As may be conjectured, it is sometimes difficult to NUMBER OF DORSAL RAYS. Figuee 3. — Frequency distribution of soft articulate dorsal fin rays of Cynoscion arenarius and C. regalis. The first short ray, which remains unjointed in the largest specimens, was not in- cluded in the count, and the last two rays, which are apparently united at their base, have been counted as one decide as to what constitutes a gill raker and what is a mere tubercle at each end of the gill arch. It is hard to describe in so many words where a line may be drawn. The number counted will vary somewhat with the observer, but when the same investigator makes the counts in both species the numbers are comparable. In the present study all gill rakers were included that were big enough to be manipulated with a dissecting needle, or about 1 millimeter long as a rough estimate. If the gill rakers on the lower limb only are counted, the number of doubtful cases will be surprisingly small. When the total number of gill rakers is enumerated, the diver- gence in the two species is emphasized because there is usually a difference of one or two gill rakers also on the upper limb. However, there is greater Affiance for error WEAKFISHES 79 due to the personal equation of the observer, because it is harder to draw a line between gill rakers and tubercles at the uppermost part of the gill arch. In the present study, therefore, the number of gill rakers on the lower limb (fig. 2) and also the total number (fig. 1) have been enumerated separately, the first because of the greater accuracy possible and the second because of the greater divergence shown. Number of Jin rays. — Figures 3 and 4 represent the number of articulate fin rays in the dorsal and anal, respectively. It may be seen at a glance that while there is considerable overlapping, each form shows a strongly marked mode. Furthermore, the mode is markedly conspicuous in both characters. While, because of the large number of overlapping individuals, these characters by themselves do not prove the distinctness of the two species very con- vincingly, yet they furnish additional proof when considered in conjunction with the other characters. The advantage in the use of the fin rays lies in that their numbers can be determined accurately in terms of exact figures and are not subject to varia- tion with the personal idiosyncracies of the observer or with the size of the fish. Using the following standard formulae: Standard deviation =