% ^?^^%'%^. .f UNITED STATES DEPARTMENT OF THE INTERIOR U.S. FISH AND WILDLIFE SERVICE BUREAU OF COMMERCIAL FISHERIES VERTICAL SECTIONS OF TEMPERATURE AND SALINITY IN THE TRADE WIND ZONE OF THE • ;:;:r: i CENTRAL " "?- -L J NORTH PACIFIC, ^ FEBRUARY 1964 TO JUNE 1965 Circular 323 October 1969 UNITED STATES DEPARTMENT OF THE INTERIOR Walter J. Hickel, Secretary Paissell E. Train, Under Secretary Leslie L. Glasgow, Assiatant Secretary for Fish and Wildlife, Parks, and Marine Resources Charles H. Meacham, Commissioner, U.S. FISH AND WILDLIFE SERVICE H. E. Crowther, Director, Bureau of Commercial Fisheries VERTICAL SECTIONS OF TEMPERATURE AND SALINITY IN THE TRADE WIND ZONE OF THE CENTRAL NORTH PACIFIC, FEBRUARY 1964 TO JUNE 1965 Gunter R. Seckel Oceanographer Bureau of Commercial Fisheries Biological Laboratory Honolulu, Hawaii 96812 Circular 323 Washington, D.C. October 1969 CONTENTS Introduction 1 Descri|)tion of sections 2 The meridional temperature distribution 4 Tlie meridional salinity distribution 5 Gross features in the meridional dissolved oxygen distri)jution 7 Conclusion 9 Literature cited 9 Appendix figures 11 ABSTRACT Temperature and salinity data obtained between lai. 10'^ and 26' N.. along the four meridians long. 148°, 151°, 154°, and 157' W. are presented in vertical sections tor 16 monthly cruises ot the Trade Wind Zone Oceanography Pilot Study. Tht sections can be used in planning applied oceanography experiments, exploratory cruises in marine biology and fish- eries, or in fishery extension work. The text will aid those who are not familiar with the central North Pacific oi who are not specialists in oceanography. VERTICAL SECTIONS OF TEMPERATURE AND SALINITY IN THE TRADE WIND ZONE OF THE CENTRAL NORTH PACIFIC, FEBRUARY 1964 TO JUNE 1965 Gunter R. Seckel Oceonographer Bureau of Commercial Fisheries Biological Laboratory Honolulu, Hawaii 96812 INTRODUCTION This circular contains sections of the vertical temperature and salinity distributions between lat. 10° and 26° N., along the four meridians long. 148°, 151°, 154°, and 157° W. for each month from February 1964 to June 1965, except August 1964. The sections are based on data collected by the R/V Town- send Cromwell as part of the TWZO (Trade Wind Zone Ocea- nography) Pilot Study. A fixed grid of oceanographic stations (fig. 1) was occupied on a series of 16 cruises. The TWZO Pilot Study was described by Seckel (1968) and the observations were published by Charnell, Au. and Seckel (1967a, 1967b. 1967c. 1967d, 1967e. 1967f). .Mtliough these sections were obtained to study the mechanism of change in the distribution of temperature and salinity, they can. at the same time, serve the needs of applied oceanography. .\ main purpose of the vertical sections presented here is to serve these needs. For example, the sections can be used in planning experiments or exploratory cruises in marine biology and fisheries, and may also become of use in "fishery exten- sion'' work, where the results of research in fishery oceanog- raphy are interpreted to the fishermen. N. 26' 156° 154° V2C>"^"' 0 ^■-.. Figure 1. --Cruise track and station pattern of the Trade Wind Zone Oceanography Pilot Study. Open dots represent oceanographic stations, crosses represent bathythermograph stations. The general distribution of temperature and salinity in the trade wind zone region of the central North Pacific based on historic data is well known. (See, for example, recent publi- cations by Barkley, 1968; Reid, 1965; and Tsuchiya, 1968.) The sections of this circular, however, provide, in addition to more detail, the month-to-month changes in the distribution of temperature, salinity, and water masses that occurred from February 1964 to June 1965. Although predictions for any given month cannot be made, the sections show the month-to-month variability and limits of occurrence that can be expected of the properties presented. Not all of those who may use this circular are familiar with the central North Pacific or are specialists in oceanography. For this reason some basic features of the vertical tempera- ture and salinity distributions are described below and pos- sible applications are indicated. Finally, since the oxygen concentration was not determined regularly during the TWZO cruises, I show how the gross dis- tribution of the dissolved oxygen concentration can be inferred from salinity sections. DESCRIPTION OF SECTIONS The temperature and salinity sections are presented in sets of four each per cruise and are identified by cruise number, month, and year when the cruise began. The temperature dis- tribution in ° C. from the surface to 240 m. is based on bathy- thermograph observations made at 30-nautical mile intervals. The salinity distribution in parts per thousand (grams of salt per kilogram of water) from the surface to 600 m. is based on oceanographic stations occupied at 90-nautical m ile intervals (see fig. 1). At these stations samples were obtained at 25-m. depth intervals in tlie upper 300 m., and at 100-ni. intervals from 300 m. to 600 m. In the North Pacific trade wind zone the salinity distribution can be used to identify water masses (Seckel, 1968). Those of concern in this circular are the North Pacific Central, the North Pacific Equatorial, the North Pacific Intermediate, and the Pacific Equatorial Intermediate Waters. In the salinity sections each water mass is shaded differently. The transi- tion waters between water masses have been left unshaded. The North Pacific Central Water occurs at the surface in the northern portion of the sections and protrudes southward in a tongue below the surface layer. It has a salinity ol more than 34.8°/oo and in the charts of this circular is warmer than 16.5° C. The North Pacific Equatorial Water occurs as a shallow surface layer in the southern portion of the sections. It is generally found in the eastern Pacific centered about lat. 10° N., but may extend into the region shown here, as in sum- mer and fall of 1964, when it has a salinity oi less than 34.2Voo and a temperature of more than 15° C. The North Pacific Intermediate Water, with a salinity ot less than 34.4°/oo and a temperature of less than 15° C., occurs below the North Pacific Central Water in the northern jjortion of the sections. It markedly decreases in thickness southward of lat. 18° N. The Pacific Equatorial Intermediate Water, with salinity of more than 34.6°/oo and temperature of less than 16° C.. occurs below the North Pacific Equatorial Water in the southern por- tion of the sections. It is found at intermediate depths in a band across the equatorial Pacific. THE MERIDIONAL TEMPERATURE DISTRIBUTION 0 \ 1 1 1 \ 1 1 1 1 1 1 I 1 40 H - 80 ^^ V ^ 120 ^\ 20» - 200 ?40 I \ 1 ; \ i 1 '. 1 — ^ 1 i 1. . ■ . ■Ui:::!!-.j 1 18° 20° NORTH LATITUDE Figure 2 .--Schematic presentation of the meridional thermocline structure in the trade wind zone based on the temperature section at long. 148° W., February 1964. W indicates a geostrophic flow setting west- ward . In the trade wind zone of the North Pacific, the meridional temperature distribution is basically defined by the charac- teristic thermocline structure. The thermocline structure is illustrated schematically in figure 2 by the 15° and 20° C. iso- therms, which lie within the thermocline. Isotherms slope up- ward towards lat. 10° N. where the minimum depth occurs in this schematic example at lat. 10° N. Maximum depths of iso- therms below 20° C. are north of lat. 20° N. In addition to the upward sloping of the isotherms, the vertical distance between isotherms becomes smaller toward lat. 10° N. Thus, as one progresses southward from lat. 20° to 10° N., at a depth of 150 m. for example, the temperature decreases. This meridional temperature gradient at 150 m. is not obvious from the surface temperature, which increases toward the lower latitude. Also, the temperature decrease with increas- ing depth (the vertical temperature gradient) is greater at lat. 10° N. than at 20° N. This information can be usefully applied when longlining for fish. Assume, for example, a fish which prefers a range of 15° to 18° C. In fishing at lat. 20° N., fishermen must place the hooks at greater depth than when fishing at 10° N. Also at lat. 20° N. the depth range within which hooks must be placed is larger than at 10° N. where 15° and 18° C. water may be found in depths which are less than 20 m. apart. The thermocline structure, which is evident from the tem- perature sections, can also be used to estimate qualitatively the east-west component of the ocean current. This use is demonstrated in figure 3, showing schematically the thermo- cline fluctuations at long. 157° W., in March 1964 and the re- lated current directions. When the thermocline slopes upward toward the south, there is a component of flow to the west, and when it slopes downward toward the south, the component of flow is to the east. The steeper the slope, the faster the cur- rent. Thus (in fig. 3), the westward flow between lat. 19° and 20° N. is faster than that between lat. 14° and 18° N.. which in turn, is faster than the flow between lat. 10° and 20° N. in fig- ure 2. When the thermocline slope is small, the flow direction is indeterminate. The convention for the direction of flow shown in these figure applies to the Northern Hemisphere. THE MERIDIONAL SALINITY DISTRIBUTION The definition of water masses and their distribution in the trade wind zone which was given above is principally based on the salinity distribution. Thus, lateral or vertical changes in the position of salinity isopleths (lines of equal salinity) also may indicate changes in the lateral distribution and thickness of water masses. This relation holds particularly for those isopleths that are associated with water mass boundaries. Consider, for example, the salinity sections tor May and October 1964 at long. 148° W. At the sea surface one finds the boundary of the North Pacific Central Water in May at lat. 22° N. and in October at lat. 18' N. The North Pacific Equatorial Water is not present during May but is found at 17° N. in Octo- ber. Displacement distances of the subsurface boundary of the North I'acilic Central Water (at or just below 100-ni. depth) are similar. This boundary is at lat. 12° N. in May and at lat. 17° N. in October. The thickness ol the North Pacific Central Watei- and North Pacific Intermediate Water masses is greater in the northern portion of the sections than in the southern portion. In the northern portion the North Pacific Central Water extends Ironi NORTH LATITUDE Figure 3. --Schematic presentation of the meridional thermocline structure and east or west direction of the ocean current in the trade wind zone based on the temperature section at long. 157° W. , March 1964. I.L'UO SKIPJACK LANDINGS OAHU 1 , ll ,,lli II ll 0 ^iilulU II ■III II Figure 4. --Weekly skipjack tuna landings at Oahu, March to September 1965 (upper panel), and salinities at Koko Mead, Oahu (lower panel) . the surface to about 200 m. The North Pacific Intermediate Water occurs below about 250 ni . At any fixed location, changes in thickness also occur due to varying depths of water masses or lateral displacement of boundaries. Compare for example the distribution of the North Pacific Central Water for the sections of May and October 1964 at long. 148° W. The sections showing the distribution of salinity and water masses can again be of aid to longline fishing. Evidence of an association between the availability of skipjack tuna to the Ha- waiian fishery and the type of water surrounding the islands, was presented by Seckel and Waldron (1960), Murphy, Waldron, and Seckel (1960), and Seckel (1963). The association indi- cates that availability of skipjack tuna during spring and sum- mer is poorer than normal when North Pacific Central Water is in the fishing area and better than normal when the lower salinity transition water is in the area. An outstanding exam- ple of this association occurred in the spring of 1965 and is illustrated in figure 4, which shows the salinity of the water at Koko Head, Oahu, and the weekly catches of the skipjack tuna fishery. The rapid increase in weekly landings coincided with the drop of the salinity below 34.8°/oo at Oahu. The concur- rent changes mean that as the North Pacific Central Water moved out of the island region and was replaced by transition water of lower salinity, skipjack tuna became abundant. (Also see location of the boundary at the sea surface of the North Pacific Central Water along long. 157° W. during April, May, and June 1965.) The association between skipjack tuna and the water mass distribution at the sea surface implies that such associations may also exist between longline-caught fishes and the subsurface distribution of water masses. The salinity section can therefore be used to place longline hooks in the desired water mass or orient them relative to desired vertical or horizontal water mass boundaries. GROSS FEATURES IN THE MERIDIONAL DISSOLVED OXYGEN DISTRIBUTION Finally, the salinity sections can be used to make gross estimates of the concentration of dissolved oxygen in the dif- ferent water masses. To illustrate, figure 5 shows the salin- ity and dissolved oxygen concentration in a vertical section along long. 148" W. for September 1964. In the North Pacific Central and the North Paciiic Equa- torial Waters the oxygen concentration is greater than 4 ml. /Ji- lt declines in the transition to the intermediate water masses. The decline in oxygen concentration is most rapid in the tran- sition to the Pacific Equatorial Intermediate Water where it is less than 0.5 ml./ a. In the southern portion of the sections the Pacific Equatorial Intermediate Water with the low oxygen concentration may be found within 100 m. of the surface. Again this condition is of in- terest in longline fishing since hooks may fish deeper than 100 m. It is unlikely that active species of fish with a high oxygen demand are found in water with an oxygen concentration as low as that in the Pacific Equatorial Intermediate Water. Interesting features in the vertical distribution ot oxygen are relatively thin layers of higher oxygen concentration in the upper portion ot the thermocline. Two such layers are apparent in figure 5. A thin layer with an oxygen concentra- tion of more than 5 ml./t. occurs at 30 to 40 m. between lat. 10" and 13° N., and another layer occurs at 50 to 100 m. Ije- tween lat. 16° and 23° N. These layers are common in the region where the salinity increases with depth in the upper portion of the thermocline. Although the continuity or season- ality of these layers of higher oxygen concentration is not known, they are probably of biological significance. 100 200 s I 300 CL UJ ° 400 500 600 100 „ 200 I 300 a. u o 400 500 600 10' 16° 18"" 20° NORTH LATITUDE Figure 5. --Upper panel: Meridional salinity (°/„o) distribution, lat. 10° to 25° N., long. 148° W., September 1964. Lower panel: Meridi- ional oxygen (ml. /•£<.) distribution, lat. 10° to 25° N., long. 148° W. , September 1964. SALINITY SECTION I I NORTH PACIFIC EQUATORIAL [ j NORTH PACIFIC CENTRAL ^J PACIFIC EQUATORIAL INTERMEDIATE [ j NORTH PACIFIC INTERMEDIATE OXYGEN SECTION '^^\ OXYGEN CONCENTRATION > 5 ml. /I. I I OXYGEN CONCENTRATION < I ml./ 1. CONCLUSION In the trade wind zone the seasonal and year-to-yeai- changes in temperature and salinity are of the same order of magni- tude. It cannot, therefore, be inferred that a distribution found during any one of the months shown in this circular will be the same as during the same month of other years. The sections are, however, a reference to the characteristic distribution of the temperature, salinity, and water masses in the trade wind zone of the central North Pacific and give an indication of the limits of occurrence and month-to-month variability of these properties. If more detailed information is desired, the read- er is referred to the tabulations of the original data (Charnell, Au, and Seckel, 1967a-f). LITERATURE CITED Barkley. Richard A. 1968. Oceanographic atlas of the Pacific Ocean. Univ. Hawaii Press, Honolulu. 20 pp., 156 figs. Charnell. Robert L., David W. K. Au, and Gunter R. Seckel. 1967a. The Trade Wind Zone Oceanography Pilot Study. Part I: Town- send Cromwell cruises 1, 2, and 3. February to April 1964. U.S. Fish Wildl. Serv., Spec. Sci. Rep. Fish. 552, v + 75 pp. 1967b. The Trade Wind Zone Oceanography Pilot Study. Part II: Townsend Cromwell cruises 4. 5, and 6. May to July 1964. U.S. Fish Wildl. Serv., Spec. Sci. Rep. Fish. 553. v + 78 pp. 1967c. The Trade Wind Zone Oceanography Pilot Study. Part III: Townsend Cromwell cruises 8. 9, and 10, September to November 1964. U.S. Fish Wildl. Serv., Spec. Sci. Rep. Fish. 554, v + 78 pp. 1967d. The Trade Wind Zone Oceanography Pilot Study. Part IV: Townsend Cromwell cruises 11, 12, and 13, December 1964 to February 1965. U.S. Fish Wildl. Serv.. Spec. Sci. Rep. Fish. 555, V + 78 pp. 19678. The Trade Wind Zone Oceanography Pilot Study. Part V: Townsend Cromwell cruises 14 and 15. March and April 1965. U.S. Fish Wildl. Serv., Spec. Sci. Rep. Fish. 556, iv + 54 pp. 19671. The Trade Wind Zone Oceanography Pilot Study. Part VI: Townsend Cromwell cruises 16, 17, and 21, May and June 1965 and January 1966. U.S. Fish Wildl. Serv., Spec. Sci. Rep. Fish. 557, iv + 59 pp. Murphy, Garth I., Kenneth D. Waldron. and Gunter R. Seckel. 1960. The oceanographic situation in the vicinity o( the Hawaiian Islands during 1957 with comparisons with other years. Calif. Coop. Oceanic Fish. Invest. Rep. 7: 56-59. Reid, Joseph L., Jr. 1965. Intermediate waters of the Pacific Ocean. Johns Hopkins Oceanogr. Stud. 2, 85 pp. Seckel. Gunter R. 1963. Climatic parameters and the Hawaiian skipjack fishery. In H. Rosa, Jr. (editor). Proc. World Sci. Meet. Biol. Tunas Related Species. "fAO Fish. Rep. 6, 3: 1201-1208. 1968. A time-sequence oceanographic investigation in the North Pa- cific trade wind zone. Trans. Amer. Geophys. Union 49:377-387. Seckel, Gunter R., and Kenneth D. Waldron. 1960. Oceanography and the Hawaiian skipjack fishery. Pac. Fish. 58: 11-13. Tsuchiya, Mizuki. 1968. Upper waters of the intertropical Pacific Ocean. Johns Hopkins Oceanogr. Stud. 4, 50 pp. MS #1929 10 APPENDIX FIGURES Vertical sections ot temperature and salinity in the trade wind zone of the central North Pacific, Townsend C rem well cruises 1-6, February to July 1964. and cruises 8-17, September 1964 to June 1965. 12° 14° 16° 18° 20° 22° NORTH LATITUDE 24' 10° 12° 16° 18° 20° NORTH LATITUDE m PACIFIC EQUATORIAL INTERMEDIATE '.:'■:':':'■;' NORTH PACIFIC EQUATORIAL NORTH PACIFIC CENTRAL NORTH PACIFIC INTERMEDIATE 14° 16° 18° 20° NORTH LATITUDE 22° 24° 16° 18° 20° 22° 24° 26° NORTH LATITUDE TOWNSEND CROMWELL CRUISE . FEBRUARY 1964 14° 16° 18° 20° NORTH LATITUDE 22° 24" 10° 12° 16° 18° 20° 22° 24° 26° NORTH LATITUDE |H PACIFIC EQUATORIAL INTERMEDIATE NORTH PACIFIC EQUATORIAL NORTH PACIFIC CENTRAL NORTH PACIFIC INTERMEDIATE 16° 18° 20° NORTH LATITUDE 22° 24 10° 12° 16° 18° 20° NORTH LATITUDE TOWNSEND CROMWELL CRUISE 2, MARCH 1964 12° 14° 16° 18° 20' NORTH LATITUDE 16° 18° 20° NORTH LATITUDE 22° Pli PACIFIC EQUATORIAL INTERMEDIATE ' NORTH PACIFIC EQUATORIAL NORTH PACIFIC CENTRAL NORTH PACIFIC INTERMEDIATE 12° 14° 16° 18° 20° 22° NORTH LATITUDE 24 10° 12° 14° 16° 18° 20° NORTH LATITUDE TOWNSEND CROMWELL CRUISE 3, APRIL 1964 12° 14° 16° 18° 20° NORTH LATITUDE 22° 24' 10° 16° 18° 20° NORTH LATITUDE PACIFIC EQUATORIAL INTERMEDIATE NORTH PACIFIC EQUATORIAL NORTH PACIFIC CENTRAL NORTH PACIFIC INTERMEDIATE 16° 18° 20° NORTH LATITUDE TOWNSEND CROMWELL CRUISE 4, MAY 1964 12° 14° 16° 18° 20° NORTH LATITUDE 22° 24* 10° 12° 14° 16° 18° 20° NORTH LATITUDE PACIFIC EQUATORIAL INTERMEDIATE T >:"! NORTH PACIFIC EQUATORIAL NORTH PACIFIC CENTRAL ,,,,, NORTH PACIFIC INTERMEDIATE 16° 18° 20° NORTH LATITUDE TOWNSEND CROMWELL CRUISE 5, JUNE 1964 12° 14° 16° 18° 20° 22° NORTH LATITUDE 24' 10° 16° 18° 20° NORTH LATITUDE ^ PACIFIC EQUATORIAL INTERMEDIATE i'li'i ;■; ■ iiM NORTH PACIFIC EQUATORIAL -.;:;■■ NORTH PACIFIC CENTRAL NORTH PACIFIC INTERMEDIATE ^ 348 35 2- —_-— 350- :::;-- 344 \ -■~-~*__" ,„_^\^^^ 34 2 - T I 46 ) I54» W. , ^ >- < If) 16° 18° 20° 22° NORTH LATITUDE 24° 10° 12° 14° 16° 18° 20° NORTH LATITUDE TOWNSEND CROMWELL CRUISE 6, JULY 1964 12° 14' 16° 18° 20 NORTH LATITUDE 22° 24 0° 12° 16° 18° 20° NORTH LATITUDE 22° 24° 26 PACIFIC EQUATORIAL INTERMEDIATE NORTH PACIFIC EQUATORIAL NORTH PACIFIC CENTRAL □ NORTH PACIFIC INTERMEDIATE 16° !8° 20° NORTH LATITUDE 22° 24° 10° 12° 16° 18° 20° NORTH LATITUDE 22° 24° 26° TOWNSEND CROMWELL CRUISE 8, SEPTEMBER 1964 12° 14 16° 18° 20' NORTH LATITUDE 22° 24° 10° 12° 14' 16° 18° 20° 22° 24° 26° NORTH LATITUDE TOWNSEND CROMWELL CRUISE 9, OCTOBER 1964 12° 14° 16° 18° 20° 22° 24 NORTH LATITUDE 10° 12° 16° 18° 20° NORTH LATITUDE 'SS PACIFIC EQUATORIAL INTERMEDI/VTE Kjis NORTH PACIFIC EQUATORIAL NORTH PACIFIC CENTRAL NORTH PACIFIC INTERMEDIATE 16° 18° 20' NORTH LATITUDE go I go 20° NORTH LATITUDE TOWNSEND CROMWELL CRUISE 10, NOVEMBER 1964 16° 18° 20° NORTH LATITUDE 22° 24' 10° 12° 16° 18° 20° NORTH LATITUDE ^M PACIFIC EQUATORIAL INTERMEDIATE NORTH PACIFIC EQUATORIAL ill NORTH PACIFIC CENTRAL NORTH PACIFIC INTERMEDIATE 12° 14' 16° 18° 20° NORTH LATITUDE 22° 24 14° 16° 18° 20° NORTH LATITUDE 22° 24° 26° TOWNSEND CROMWELL CRUISE II, DECEMBER 1964 12° 14° 16° 18° 20° 22° 24 NORTH LATITUDE 10° 12° 14° 16° 18° 20° NORTH LATITUDE PACIFIC EQUATORIAL INTERMEDIATE NORTH PACIFIC EQUATORIAL n NORTH PACIFIC CENTRAL NORTH PACIFIC INTERMEDIATE 16° 18° 20° 22° 24° 26° NORTH LATITUDE TOWNSEND CROMWELL CRUISE 12, JANUARY 1965 16° 18° 20° NORTH LATITUDE 22° 24 10° 12° 16° 18° 20° NORTH LATITUDE ..« PACIFIC EQUATORIAL INTERMEDIATE '■;■:■::•■,•;■: NORTH PACIFIC EQUATORIAL NORTH PACIFIC CENTRAL NORTH PACIFIC INTERMEDIATE 14° 16° 18° 20° 22° 24' NORTH LATITUDE 10° 12° 14° 16° 18° 20° NORTH LATITUDE 22° 24° 26° TOWNSEND CROMWELL CRUISE 13, FEBRUARY 1965 Q. UJ Q 200 240 X I- 0. UJ o 200 240'- 12° 14° 16° 18° 20° NORTH LATITUDE 22° 24' 10° 12° 14° 16° 18° 20° NORTH LATITUDE 1 J PACIFIC EQUATORIAL INTERMEDIATE | | NORTH PACIFIC EQUATORIAL | j NORTH PACIFIC CENTRAL [ ^ j NORTH PACIFIC INTERMEDIATE 12° 14° 16° 18° 20' NORTH LATITUDE 22° 24° 10° 12° 14' 16° 18° 20° NORTH LATITUDE 22° 24° 26° TOWNSEND CROMWELL CRUISE 14, MARCH 1965 12° 14° 16° 18° 20° 22° NORTH LATITUDE 24- 10° 12° 16° 18° 20° 22° NORTH LATITUDE PACIFIC EQUATORIAL INTERMEDIATE NORTH PACIFIC EQUATORIAL NORTH PACIFIC CENTRAL NORTH PACIFIC INTERMEDIATE 16° 18° 20' NORTH LATITUDE 16° 18° 20° 22° 24° NORTH LATITUDE TOWNSEND CROMWELL CRUISE 15, APRIL 1965 12° 14' 16° 18° 20' NORTH LATITUDE 22° 24 10° 12° 14° 16° 18° 20° 22° 24° 26° NORTH LATITUDE PACIFIC EQUATORIAL INTERMEDIATE NORTH PACIFIC EQUATORIAL NORTH PACIFIC CENTRAL „ NORTH PACIFIC INTERMEDIATE 500 600 L 16° 18° 20° 22 NORTH LATITUDE TOWNSEND CROMWELL CRUISE 16. MAY 1965 16° \e° 20° 22° NORTH LATITUDE 2-a \C' 12° 14° 16° 18° 20° NORTH LATITUDE 22° 24° 26° R&CIFIC EQUWORIAL INTERMEDIATE Wi^:: NORTH PACIFIC EQUATORIAL lli i NORTH PACIFIC CENTRAL €M NORTH PACIFIC INTERMEDIATE liVi.'i'i'i'i'J 1..-.V.-..-J Y//////A TOWNSEND CROMWELL CRUISE 17, JUNE 1965 MBL WHO! Ltbrai WHSE 00484 ^e« 5, UNITED STATES DEPARTMENT OF THE INTERIOR U.S^ FISH AND WILDLIFE SERVICE BUREAU OF COMMERCIAL FISHERIES WASHINGTON, D.C. 20240 4 -* POSTAGE AND FEES PAID U.S. DEPARTMENT OF THE INTERIOR OFFICIAL BUSINESS Return this sheet to above address, if you do NOT wish to receive this material | | , otif change of address is needed | ] (indicate change including ZIP Code). A Librarian I.:arine Biological Lab., Voods l!n1o M^^.-, ooc^ S L C Woods Hole, li3.3s. 02543 ^i