EXPLORATORY TUNA FISHING IN INDONESIAN WATERS Marine Biological U"-- WOODS HOLE, MASS. :"] SPECIAL SCIENTIFIC REPORT: FISHERIES No. 45 UNITED STATES DEPARTMENT OF THE INTERIOR FISH AND WILDLIFE SERVICE EXPLANATORY NOTE Tho series embodies results of investigations, usually of . ^.H^codI int-'nded to aid or direct management or '!'■'■ tlorac'tiiesond as auides for administrative or °;i'iSed w'or «cno4 ond ."^o o^oid de^,:n publicCicn. Vashingtcn, D. C. January 1951 United States Department of the Interior Oscar L„ Chapman, Secretary- Fish and "Stldlife Service Albert Mc, Da/j, Director Special Scientific Report - Fisheries Noo Kb EXPLORATORY TUNA FISHING IN INDONESIAN WATERS Translated from the Japanese language by SOAP translators and W^ G„ Van Campen Edited by- Bo Mo Shimada and W„ Go Van Campen Pacific Oceanic Fishery Investigations CONTENTS A survey of tuna grounds in Eq-aatorial waterSy By Assistant Technician Tokuzc Uehara l/oo„o„, Page loooooooooc'oooeooo 2o Report of tuna investigations by the Wakayama Prefect-ore research vessel, Kiyo J/Iarup in the Timor, Arafura, and Banda Sea„ By Kenzc Ikebe, South Seas Government-General Fisheries Experiment Station 2/„ « . „ o » o ., o » « = o « o o o o » o c « o o » . . . <, . » . o . <, « o o , . . » o 5 1/ South Sea Fishery News /"Nanyo Suisan JohF_7, Vol„ 5, No. 3, pp„ 13-17o June 25i, 1941 o 2/ South Sea Fisheries /"Nanyo Sui3an_7j No. 80, (Vol. 8), No. 1, January 25, 1942^ pp. 29='4lo A Suirvey of Tuna Grounds in Equatorial 'teters 1„ FNirpose. Good results were obtained from the previous survey of tuna fishing grounds in the waters south of Palau, however, further attention must be paid to the equatorial waters, which are considered as a continuation of these fishing grounds, since they have been fished recently by tuna fishing vessels from Japan and since they must be considered as future fishing ground So For this reasonj an extensive area was siarveyed to determine Ti^iether or not it has any value as a fishing groundo The findings are submitted herein as reference data for the planning of commercial operations.. (Note) The first fishing test was planned in accordance with the northward shift of the Equatorial Counter^current at this seasono 2„ Particulars of the survey, a„ Survey period=May 9 to May 24>, 194-1=16 days bo Area sarvey6d=From 6'^ N latitude to 1^ S latitude and from 129° to 134o E longitude o Co Survey shlp„ Zuiho Kara, 133 tons, 360 HP do Fishing gear used in the survey=Tuna longlines (50 baskets^ 6 hooks per basket),, Brief description of one basket of tuna longline fishing gear. Main line - cotton line 10- strand, 4-5 gr per £" 5-foot_J fathom; total length 175 fathoms (length of one section is 25 fathoms) » Branch lines^lO-strand cotton line, 37,5 gr per fathom, length 12,5 fathoms. 6 pieces Float lines=10=strand cotton line, 4-5 gr per fathom, length 12o 5 fathoms, 1 piece _ Cotton=covered wire=3 strands of 3 wires each, (eyes / ?_7 both ends) , length 4 fathoms, 6 pieces Wire leader=length 1,5 fathoms, 6 pieces 3o Resv.ltSc (l) Jesuit of each operation. First fishing test, May 10 This fishing ground is located about 100 -iiiles south of Palau (5°40°N, 134°31'E) and due to the seasonal north/irard shift of the Equatorial Counter-current, is believed to be in the Counter-current area, Detaxls of the current, however, were not known. Lines were set in a southwesterly direction from 50 baskets. Since the catch amounted to only 3 yellowfin and 1 blg^eyed tuna, it was believed to be too early for the fishing season. Second fishing test, May 12 This fishing ground is located about 300 miles south of the first fishing ground at 0°35" N latitude and 134-^26" E longitude near the Equator. Lines from 50 baskets were set in a southerly direction. The current flowed 'H^ at 1„6 knots^ The water temp^ratares of 29,6 degrees at the surface, 28,6 degrees at the 50-meter layer and 24.,^ degrees at the 100- meter layer were satisfactoryo Since '.ve were close to the ftopia IslandSj young tunas were seeno The catch consisted of 25 yellowfin (5 shark-eaten) and i spear'"ish„ Third fishing test, May 13 This fishing ground is located near the Equator at 0°35' N latitude and 13/V^26' ?, longitudeo Of the fishing grounds surveyed, this ground showed the best results (catch ratio of L4cO)» / i,e„ lAoO fish per 100 hooks fi3hed_7„ Lines from 50 baskets were set in a southerly direction. The current flowing '.V / N 3/4- N at 1„5 knots ^iras roughly the same as that of the second fishing station and clearfy indicated that this ground lies wii,hin the Southern Equatorial Current „ The water temperatures were 30,5 degrees at the surface, 28„5 degrees at the 50"meter layer and 25oO degrees at the 100=!neter layer„ The catch consisted of 37 yellowfin (5 sharks eaten) and 1 skipjack. The fish in general were small in size. Fourth fishing test^ May 14 This ground is located at 0°11' N latitude and 131^44" E longitude in the equatorial waters west of the third fishing groundo Lines from 50 baskets were set in a southeasterly direction. The current velocity was W / N at 1„3 knots (in the Southern Equatorial current). The water temperatiires were 29<>7 degrees at the surface, 26o5 degrees at the 50- meter layer, and 24... 8 degrees at the lOO-meter layer „ The catch con- sisted of 25 yelloWfin and 2 sailfisho Fifth fishing test. May 15 This fishing ground is located about 1 degree north of the Equator at i®!!" N latitude and 131° 50 « E longitude^ Lines from 50 baskets were set in a v/esterly direction. The current flow was NW at 2.0 knots. The water temperatures were 29.3 degrees at the surface, 260^^ degrees at the 50"meter layer, and 24.8 degrees at the 100-meter layer. About one-half of the yellowfin catch consisted of young tuna (15 large yellowfin and 12 young yellowfin) which weighed from 2 to 3 kan //l kan ^ 8,27 Ibs^^/" From two or three floating logs seen in the area this school is believed to have been associated with birds and driftwood. Sixth fishing test, My 17 For the first time we entered the southern latitudes. This ground is ioca-.ed U' south of the Equator at O'^U" S latitude and 129°25' E longituaeo Lines from 50 baskets were set out to the NNW„ This ground is located between the northwest shores of New Guinea and Halmahera Island. Numerous islands are found in the area and the flow of tidal currents is very complex. Numerous sharks infest the area and about one-half of the catch was shark-bitteno (The catch comprised IL yellowfin, 13 of them shark-bitten, and 7 sharks,) The fish were generally large. The water temperatures were 29.5 degrees at the surface, 28,8 degrees at the 50-meter layer, and 23»0 degrees at the 100-meter layer. Seventh fishing test, May 18 This fishing ground is located about 30 miles south of the sixth ground at 0°44c5' S latitude and 129'^3.5" E Icngitnde, Since the fish hold was full, only 30 baskets were used. Lines were set in a southerly direction. The flow of the current was similar to that of the sixth fishing ground. The catch consisted of 5 yellowfin and 1 sailfish. (2) Investigation of the vertical distribution of the tuna (yellowfin) (Note) Float lines 12^5 fathoms long and branch lines 12.5 fathoKS long (also cotton-covered wire 4 fathoms long and wire leaders 1,5 fathoms long) were used. (3) Handling of the catchy After capture, the viscera were removed and the fish were washedo The washed fish were immediately vsrapped in paper, covered with crushed ice 5 and stored in a refrigerator » Due to mechanical trouble, the refrigerator cculd not be operated during this trlpo Although sufficient care was taken in icingj the fish deteriorated to a certain extent due to the length cf time which elapsed before returning to Palau„ (4) The peculiar phenomena of the catch ratio and water temperat'ore (at the 100-meter layer) The catch ratios ranged from, a minimum of IcO to a maximum of I4.0O0 The second^ thirdj, fourthj and fifth fishing grounds showed catch ratios of 10,0 and overo An interesting phenomenon is presented when these catch ratios a^e considered in connection with the water tempera- tures of the 100-meter layere FISHING CATCH WATER TEMPERATURE GROUND RATIO AT 100 "METER LAYER loO 22„6° 2 10 oO 2Ac3'5 3 UoO 25„0° 4 10 .,0 24e80 5 lloO 2^08° 6 9o0 23„0° 7 2„0 22„0" As seen in the above tables^ fishing grounds having catch ratios of lOoO or more^ all showed water tenperatures higher than 24 degrees at the 100-meter layer ^ 5fe can deduce therefore, that yellowfin prefer a water temperature of over 24.o0 degrees to that of less than 24o0 degrees^ FISHING GROUND DATE POSITION BASKETS USED HOOKS USED CATCH BY HOOK NUMBERS CATCH RATIO (INCLUDING FISH EATEN BY SHARKS) 1 2 '2 .4 5 6 T_ 10 Mav 5°40"N 134-4l"E 50 300 1 1 1,0 2 12 May 0=^35 'N 134^26 «E 50 300 3 6 ■"' 8 U 2 lOoO 3 13 May 0^13 -N r33'^27«E 50 300 u 10 9 8 8 3 UoO 14 May O^^l?'!} 13i'^4'v'E 50 300 L 4 5 s ,. 6 10,0 5 15 May 1011 'N 131^50 «E 50 300 7. 3 9 3 8 5 lloO 6 17 Mav 0'^L4''S 129°2o5'E 50 300 3 4 5 3 8 U 9,0 7 18 May 0"4^„5'S 129° 3„5'E 30 180 3 ^ <. 1 2oO TOTALS 16 32 38 32 35 21 Gk.a^rc- of Tana Grounds ir. Equatnxial '^t^iis, 3u?.hc' Maru May *♦ Report of Tuna Investigations by the Wakayama Prefecture Research Vessel, Kiyo Maru, in the Timor, Arafura^ and Banda Seas 1„ Introduction With the recent grant of subsidy funds from the Colonial Office to the Nanko Fishing Company for the purpose of investigating the fisheries of the Outer South Seas area 5, the Company employed the Wakayaraa Prefecture research vesselj Kiyo Maru, to carry out a survey in the Timor, Arafura, and Banda seas,, areas which are under foreign domina- tiono I was aboard the vessel during that investigation and will publish herewith the information which was contained in the report submitted to the Colonial Office „ 2o Outline of the Investigation Period of the survey - From June 29., 194lp to July 25, 19A1 - 27 days Area surveyed - Timor Sea, Arafura Sea, Banda Sea Surveying vessel - Kiyo Maru, research vessel of Wakayama Prefecture, a steel vessel of 127„23 gross tons and 220 horsepower. Personnel of the sur-vey - Technician Saburo Kawabe^ the captain of the Kiyo Maru and 24 men Fishing gear used in the s-jrvey = tuna longlines, 230 baskets Construction of one basket of gear - trunk line of cotton^ 8 ffiomme to the fathom^ / 1 momme ~ cl32 ozo_/ 189 fathoms overall length (7 pieces joinedj each piece 29 fathoms long) o Branch lines of cottonj 9 momme to the fathomp 2 lines 10 fathoms long; 2 lines 7 fathoms long;, 2 lines 6 fathoms longo Sekiyama of 3x3 strands of wire with eyes in both ends, 4 fathoms long„ Wire leader, 2 fathoms long, HookSy 4„86 inches and 3o2 inches long., Float lines, cotton, 3 momme to the fathomj, 15 fathoms long. However^ about half of the float lines and trunk lines were made of Manila hemp,, / TN; The "fathoms" mentioned above are Japanese fathoms, about 5 feet longo Hook sizes are the total length from eye to point around the curve of the hook. The -5-= Also of the Nanko Fislaing Company- Captain Chief Engineer Radi'''rnan Fishing Captain Deckhand -Fisherman Oiler Sakuraij Dsiikichi TsucKiij Tatsuhiko Iwamoto, Soemon Kasajimaj Shuji Yapura. Otomatsu Shima, Hidetaro Higashi, Sadahachi Ctanij Fusao Ilatashimo, Koichiro liamamoto, Iwazo Ido, I'iiasao Okachi, Shoichiro Kawachi, Hikotaro Tanimoto, Tadao Iziuni, Kiichi Kakanura, Juichiro ShiochXj iSanpei Ilatashimo, Sadami Matsubara, Skiichi Ivawabata, Ilisao Ibuki, Yoshio LTatsushita, Suzuo Matsubara. Sadaichi 3. Progress of the investigations fi ^ "..--, irt-vnon-(-= and Sailing track 0900 - Departed Palauo noon - Passed vrest of Merir !» - 0600 - Passed Tokoba I. to starboardo - 1100 - Passed through Djailolo Passage , - 0200 - Passed .'through I&nibar Strait, - Fished first station off Tetar I., sez 50 baskets. (4 yellowfin, 1 black marlin, 1 broadbill, 2 skipjack) - 0800 - Entered Dilli Harbor, Timor o - At anchor at Dilli c - D900 - Departed Dilli. - Fished second station off south side of Timor, set 200 baskets . July 10 - 0200 - Finished o . ' ellowfin, 10 albacore. .-overaents June 29 June July July July- July 30 1 - 2 4 r: July 6 July 7 July 3 July 9 3 big-eved, 13 shark-oa^. in, 16 shark. July 11 - Fished third station off south side of Babar I„j, set 120 bask'?ts„ (14 yellowfin, 2 big-eyed, 1 albacore, 1 broedbill, 47 fish bitten by sharks and killer whales )„ July 12 - Fished fourth station west of Tanimbar I„j, set 120 baskets „ (80 yellov/fin, 1 true marlinj, 1 sailfish, 1 bir-eyed, 18 fish shrrk-bitten, 4 sharks) July 13 - Fished fifth station at saine positinrij set 185 baskets, (52 yellov;-fin, 1 big-eyed, 1 black marliHj 1 true marlin, 5 sharks, 10 fish shcrk-bitten) July 15 - Fished sixth station west cf Kei 1,, set 100 baskets o (78 yellowfin, 2 big-eyed, 6 sharks , 16 sherk»bitten fish) July 16 - Fished seventh station at same position, set 100 baskets o (47 yellowfir.j, 3 big-eyed^ 2 v/hite marlin^ 8 fish shark-bitten) July 17 - Fished eighth station east of Banda I,, set 120 baskets. (42 yellov/fin, 11 big-eyed, S sharks„ 21 fish shark- bitten) July IS - Fished ninth station at =;ane positio-, 130 baskets o (116 yellowfins 6 big-eyed, 17 sharks, 33 fish shark= bitten) July 19 - Fished tenth station east of Ceram I„, set 20 baskets « (4 yellovrfin, 2 sharks, 2 fish shark-bitten) July 20 - 1700 - Passed western end of J.'issol I„ July 21 - TToon - Passed through Sagewin Strait„ July 22 .» Noon position 1° 51 'II. 132° 10» £„ July 23 - Noon position 4° 17»N, 133° 20 'Eo July 24 - lOOO - Passed east of Angaur 1„ July 24 - 1530 - Entered Palsu Harbor, (2) iveather and sea conditions The T.eather and sea oonditicns will be outlined for the areas in the order in which the research vessel passed through them after its departure froTTi Palau on ' ""^ liSter leaving Palau the vessel follov;ed a generally southwest course, ontil Angaur was passed at noon on the 29th the wind v/as northeast with forces of around 2 to 3 and the sea v/as calm, .but on the follov/ing day, the 30th, the wind shifted to southwest and from 1100, when the vessel passed the '/icinity of Merir I„, to its entrance into Djailolo Passage on Julj)- 2 the wind force was from 5 to 7 and the waves v/ere higho Because of the headwind the vessel took the seas on its bov;- and pitched violently „ In the vicinity of irarir I., that is at 4'^ IS'N, 132° 17«E, the direction of the curr-^nt was SSE with a velocity of 1^3 knots o Somewhat farther south at 3° 43 'N, 132° 2»S the current was ESE with a velocity of 3.2 knotn. At 3° 42 'IT, 131° 57 'E the current v/as ESE with a high velocity of 3oO knotsc Still farther south at 2° 55'N, 131° 14'E, that is in the vicinity of Tokobe I,, the current was SE with a velocity of 1„8 knots. From the directiins of these currents it is clear that this sea area is bathed by the Equatorial Countercurrento After passing Tokobe I„, hovrever, there v/as an area in which during this period almost no current drift was -7= perceived while steaming. It is not hard to deduce that this area corresponds to the boundary between the Equatorial Countercurrent and the southern Equa"&orial Current, Farther south at the northern end of Djailolo Passage;, V-' 12"Nj, 129° 36"E, the current was Nx7/ wxzh a velocity of 0„5 knots.. This area appears to be where the tip of the southern Equatorial Current which flows west along northern New Guinea strikes the islands of Haimahera and Morotal and turns northward o After we passed through Djailolo Passage on July 3 the wind shifted to the south, hat its force did not decrease, remaining at 5 to 6j and the seas were rather high„ Thereafter until we passed Ceram I„ the wind frequently shifted to southwest or sovith, but after we passed Ceram and entered the Banda Sea until we arrived at Timor the wind blew steadily from the southeast vith forces of 4 to 5.. This was the so- called easterly monsoon of the Banda Seaj, a seasonal wind which continues until Augijisto It is said that the strength of this wind gradually declines m September and Octobero The color of the sea water every^/vhere between Tobalai I„ and the west side of Ceram was notably poor as compared with that of the waters of the South Sea Islands, E-ven beyond Ceram in the Banda Sea the water color appeared generally to be unfavorable, however p farther south near Timor where the first station was fished off Ifetar I, the water color seemed rather good. Observations made during the first fishing trial showed a transparency of 4-0 meters. The vertical changes in water temperature at that position were 27,9^ at the surface, 27,4-^ at 25 meters, 27,3° at 50 meters^ 23,4^ at iOO metersy 14,3° at 200 meters, 12,1° at 300 meters. On July 8 the vessel sailed from Dilli on Timor lo, proceeded east around the north coastj rounded the eastern tip of the island, and headed into the Timor Sea, At this time the wind was from the north= east and the force remained unchanged at 4 to 5, The air temperature at noon vias as low as 26.5^' and as a result we felt quite cold. While anchored at Dilli we made inquiries concerning the weather there and -found that generally fey, June, July, and August are the dry season while January and February are the rainy season, the two sensons thus being just opposite to those of the Inner South Seas, D-jring the so=called northeast monsoonj, which is the dry season^, dry cool winds bloWc, and although it is in the tropics one feels cool and refreshed. During the day in the Dilli region the seasonal wind begins to blow around 10s 00 a,m„ and ceases around 3300 pom,, the morning and evening being usually completely windlesSc During the rainy season the wind blows from the northwest,, Observations taken at the second fishing station in the Timor Sea showed a transparency of 27 meters. The sea water seemed somewhat turbid compared to the previous stationj and the vertical changes in water temperature were 26, 8o at the surface^ 2.6,8° at 25 meters, 26,7° at 50 meters, 23,.^.'^' at 100 meters, 13, 2^^' at 200 meters, and 10,2° at 300 meters. The positlor: of the third station was soiithv/sst of Tanirabar 2o in the westei-n part of the Arafura Soao The current at this position flowed southwest and a lew Telocity of 0-33 knot was detected o It is thought that the current which flows west in the northern part of th© Arafura Sea strikes Tanimbar I ,. and. turns southwssto The transparency was £7 meters and the ?@rties4l ehangea in water temperature were 26o2° at th© surfac©, 26cl^ at 25 meters j, 26cO° at 50 meters j, 19o8^ at 100 meters, 14^9^ at 200 meters^, and 10o9° at 300 met^rgo The temperature at the 100=-iaetsr level was lower than that in the Tiseor Seao fhts was the ©niy groaad we fished in the .irat^wra iie&c fhere-afii-er we sioresd north into the Banda flea and ran fishing stations at six places around th& islands in the eastern part of that body of waters. Daring these opera-clons in the Banda Sea we eonstantly encountered the southeast monsoons To be more exact, the wind was from th© ESE and it blew steadily with forees generally from S to 5o The air temperature was around 25 cr ?6 degrees ^ and those of us who were aecustomed to the h©at of the Inner South Seas ssouM feel the coolness soaking into Ota* bodieso To sunrniariKa the results of the oceanographie ob= sarvations mad© in the eastern cart of the F?-rada .^ea,, the transparen= ciefc ranged from a masrimura ol -.iaijama of :c;? meters p and the water eolar appsarec^ ,0 ds arcuti:-. « ;c. 4 on the standard w&ter color gauge. Considering only the Banda Sea,, it seemed that the water color was generally mere fa-srorable ia the eastern than in the western parte As for the vertical changes in water temperature, whereas In the Inner South Seais th© difference between the surfaee and the SO^meter level is only Ocl° = Oo2*' or almost negliglbles, in this area it is 1° = 3** 0 Th© temp-? rata res at th© 100=3iieter levsl had & minimum of 18c3° and a maxlm-ura of SloS'^j far lower than the 24=25° of the waters of our South Sea islands o After eompleting fishing tests at four places in th© Banda Sea wa made our last station at the eastern end of Cer&n lo la this area all there is to record of oeeanographic conditions is that the eurrent was north= westerly with a velocity of OoS knots o In other respects the situation was the same as in the Band* Soa^ with nothing worthy of special note „ On July 21 we traversed Dampier Strait and set a coiurse for Palauo I will conclude with some remarks on th® currents and oceanographie conditions which were observed along the wayo On July 22 at the noon position of 1** 51°Mp 132° ICE th© current flowed A'S;7 at the low velocity of 0o36 knot. It is thought that this area may be the northern limit of th© southern Equatorial Current o The water color improved notably from this area on, and while steaming we (saught one small yellowfin (76 em long) on a trolling line. On July ^ at th© noon position of 4° IT'N^ 133° 28 "E th© current flowed ESE with a velocity of lc38 knots, indi-sating that w© were in the Kiuatorial Colsnter-gurreato On th© following day, the 24thp at ^he noon position of 6° If.'N, 154® 0°E tha current was SSE with a veiooity of 0o97 knotj. froia which w© could se© th© northward movement of the E^uatorial Countereurrento .9= ff (3) Fishing situation First Trial MorEin^ and evening arej, of couraej, eonsldsred the raost suitable times for eondueting experimental fishing far t\m& with longliaeSj, horteveTg because the -yessel was scheduled to put in at Dilli in Timerj a trial was made on the preceding day-j, July 5p at ISBO about S mile» off the west side of Wetar Ic. using 50 baskets of lin® set in a westerly direetiono From the time the vessel passed Ceram lo and entered the Banda Sea the color of the sea water had generally appeared unfavorable, but as we moved gradually south into the vicinity of Wetar lo it improvedo Obs©rva= tions on the station showed a transparency of 40 meters ^ and flocks of birds were seen flying in the vieinityc Although good tuna fishing was antiuipatedp only 4 yeiiowfiUj, 1 bli?.ek marlinj, and 2 iskipjaek were taken and the catch rate was less than 2 fish per 100 hookSo None of the fish were shark=bitteno It was felt that the transparency of the water was to© great o geoond '^rlal After leaving Dilli we rounded th© ©astern tip of Timor and entered the Tinor Sea<, The second station was fished about 30 miles off shoreo At 0605 July 9^, 200 baskets were set in a SS direetiono The baitj, as in the previous trial p was a mixture of frozen saury and salted sardine which we had brought from Japano Three hours and 40 minutes were required to set the 200 basket® of linSo W© began patrolling the line immediately after it was set, and w© saw numerous schools of skipjack while doing soo These skipjack appeared to be small fish of about 1 k^ ^^o^T poundsT' weight . Vlhile patrolling the linsSp we took in one inarlin (blaek7 of about 40 kan;, one yellowfin, and one blue sharko We began hauling in the lines at 1500o Because the weight of the fish on the lines was too great for the buoyaney of the floats^ the gear sank av'id the lines broke four times while we ware hauling themo As a result 11 hours were recuired to haul in the 200 baskets of gear^ and the work was not finished until 0E£0 the following day^ July lOo The catch was 18 yeliowfinp 10 albacorej, 3 big^eyedj, 1 white marlinj, 2 black marlin^ and IS sharks „ and 13 fish (10 yeliowfinp 3 raarlin) were damaged by shark-bite o The catch rate at this location j, if th© shark=bitt©n fish are not counted, v/as ZoS, and with the shark^bitten fish it was 3o9o Furthermore g because of the difficulty of getting materials, the gear used in this test was made with rather fine line and wire in some of its branch lines ^ and for this reason 50 of the branch lines or hooka were broken off the gear by the fisho If thes® were added in to the total J the catch rate would be considerably increasedo Third Trie-l The position of this fishing ground v/as 8^ 53«i>p 129® bb'E, south«= =10= west of Taninibar lo On July 11 at 0505 120 baskets of gear were set in an ESE directiono It required 2 hours and 10 minutes to set the lines, and the total ler-gth of the lines was lOoS miles ^ Tffhil® patrolling the lines we boated § yellowfin and 1 big^eyedo Eight hours were spent in hauling the lines j, and the total cateh was 14 yellowfinj, 2 big=eyed„ 1 albacorCj and 1 broadbillg 47 fish were damaged by sharks and killer whales « Most of the yellowfin taken were large ones over 130 cm in lengtho The catch rate was 2^5 without the shark-bitten fish,, or 9oO including themo In addition 31 hooks were broken off the lines sOp if this is taken into consideration, the cateh rate should be further increased in -view of fchi; amount of fish occurring in the ar^a.- A peciiliar phenomena whieh should be noted in connection vnth this trial is the fact thatj aside from the fish damaged by 8te.rkSf there were 40 fith eaten by killer whales o The remains of fish eaten by killers differ from those damaged by sharks o In the ease of the killers only th® head of a hooked tuna is left^ and ths distinction is clear at a glaneeo Fourth Trial The position of this fishing ground was 7® 05«Sp 130° SO'E., to the west of Tanimbar lo On July 12 at noon 120 baskets were ^»% in an BSE directiono About sight hours were required for setting the lines g and the catch was 80 yellowfing 1 true oarlinp 1 sailfishp 1 big=eyed, and 4 sharkSj, with 18 fish damaged by sharks o In addition 17 hooks were broken off th® lines „ The catch rate was llo5 without the shark^bitten fish,, or 14o0 with themo Measurements of th« yellowfin taken showed that th® greatest number fell within the rang© of 130 em long (assumed to b© fish in their ninth yti&r), Th© big-eyed tuna was about 153 cm longo Tllhen the yellowfin wer® gutted, the gonads were examined, but all of them were found to b® insmatur© with no distinguishable ova, Fifsh Trial Tha position of the fishing ground was 6^ 58 "S, 130® 38 «E, off the w3st side of Tanimbar lo On July 13 at 0600 we set 185 baskets of line in a NW directiono The ©xcessiT© weight of th© fish on the lines sank the gear and it could not be hauled in with th© line=haul©r. The attempt was made to haul it by manpower^ but in the end th© lines parted and 50 baskets of gear was unavoidably losto A long time was required to haul th© lines in^ the operation beginning at llbO and being completed at 2350o It actually took 12 hours o Th© catch was 52 yellcwfin, 1 big=eyed/ 1 black marlin, 1 true marlin„ and 5 sharkSj, with 10 more fish 8hark=-damaged and 10 hooks torn off the llneo The catch rat© was 6o8 without th® shark-bitten fishp and 8oO if they are includedo Sine*! it can be presumed that there were many tuna hooked on th© 50 baskets which were lost, th© catch rate should b© considered even higher o 41= The iacid©ace of sharks all orer this area is fery higho Sixth trial fhe positdon ©f the fishing grevmd ms 5® IS'Sp 131° 18»Es ©ff to th© west of Kei lo On July 15 at 0540 100 baskets of gear wer© set in an ESE direstioa for a total length of 8o5 miles o Eauliag in th€i lines was b©g\m at 122S mid eompleted at 1850o Daring th© hauling=-ln 7 baskets of line sankj, biat th© line did not break and w© were able to recover this gearo The csat^sh wag 78 yellowfins 2 big= eyed J, and 6 sharks, with 16 fish sh&rk^bitten and nine branch lines broken off o The catch rate was 13 o3 net couating the shark=-bitt®n fish^ ©r i6oO if these are includedo Measuring the yellcwfin showed that the smallest was just under 1 meter and raost of them were 110 ■= 120 em in lengtho An examination of the stoasach eontents mad® wh®n. gutting th© fish showed that they had been eating saostly sqiiido S®Ten-'5h frial ■fh© position of this fishisig grotmd was 5° Ib^B^ 131° 15°E- off Kei lo On July 16 at 0510 100 baskets war® sat in sua ESE direetiono In order to prsveiat the weight of th® hooksd fish from sinking th© gear w@ began from this day on to attach two glass floats and two paulownia wood floats to eaeh of th© float lines o While patrolling th® lines we boated 7 yellowfino Th® tc't©l catsh was 47 yellowfirip 3 big^eysdj, 2 white marl in, and is addition 8 shark^bitten fish and 4 brok^an branch lines o The cat«3h rats was 8o7 if th© shark^bittan fish are ©seepteds or lOoO if they are in 6r« sn m isn © ■«* ^ ifn @ o 0 o 0 o o o o 0 o •*^ f ifV cv w (i=-« vO iC^ a iC» M\ ll«^ ^ ^1 H H (H bH a o :f3 H G 13 o 0^ ^:- vr\ isA o f^ P ■*3 c o o O O O 0 u o o CO M o gj ♦ rv m * Ov. vO O ■© O 4^ U O E o iH H! 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0 iH. "^ ^ Rj oa c% ffi as o -H ^ M « .--^ «5 0 1 a) fl a flg 1 n» «| 0 fi '^ V 0 m 0 ^ ^ X) +> trt +» J ^ m %^ crt ^ ^ Xi 4* rt HP O m vi o «n e-i sO to * n-l «i CV 0 i °° ■IP ^ 0 t*, W. <7» CA, C^, ' o^ o»^ Oti fK i^-i 6 «w a, oijO «>-. S ^ ^ ffi «M N. »1 U ® 1^ to +s ^ t»»^ S>s "S ^ *° S>»-P • !>% ^ J>» «H CO g^ i^ >» =Q *s j f-J SO ^ 43 to a ^ eo «V iH «fc r- «v c^ f-S eo =p ®3 so ■^ iH (HSiH H M> r~ •^ -^ HI =* •S «6 bo 0 o a? ^ O 0 0 0 ^ »A «e "d 'd Jp «n o o OS CV M\ cv •«n cv CV •-* s ^ H «s w o IIA «»^ J^ r-« 3 ir-t 0"* cv to A o •'^ pl 4h w ® cv n-i (T-* iH iH iH If* «H H o X o 50 O O fQ ^ U CO •P pH ® I o iH ■^ ■ - - * * ^ «8 C O «0 545 Eh ® o o $< ^ o its vO . O a «& lA o ^©Q a o SA ® «B so or\ -<* I-! jH rt iT^ 1,^ «A O o x> Ou ■^ S «H vO 150 r- "4 o , & ?r' c- to t- Xi B «~i r-( a5 n iH O O oH 8=^ o o- iH m ^ «S S^ »X1 o «} ® ^ ma « -O O 03 ® O srn US ^ if ■'5 o u\ o Wi Wl «n o O o. •^\ M^ vO 0 =rl ^1 CD (H o o - o O O O o HI Xi O 0 0 o o ^ lu ^ o m O O cc -p O m a? ffl •P W S SB R 9) 80 o o o mn. O o o o o oH ,0 X^ ^5 (H ?l (i<^. iiT^ vO E^ to OS +» H (H |e ^ Wi o iH (H Hi iH F-i (H H CO !-» »H 0) CO 0 11 0 0 C 0 a o C 0 ^ 0) 9} H wH a l~- £- C^ 1> r- !D^ c~ J>- r- C^ +5 >» «o c o O 0 ' ® ® r-< « 0 o ■P H CO o o O p »H O sH CV sn -* isA SO ?^- «D a-- o ^ ^ S « ^.a eH * ^* w -'^ &-I -16= 10^ TRACK CEART OF TOTA FISHING GROUND SURVEl' KIYO MARU (Wakayaraa Prefecture Fisheries Experiment Station) June-July., 19^1 — — sailing track Q fishing stations, numbers show order s— = direction of current, nnmbers show Telocity in knctf- Palau 10^ 1?.2 17 l11?M,„)iy,':tP',.l-""^'y ■ Serials 5 WHSE 0 026