ABSTRACT 

 Pelagic fur seal research as required by the In- 

 terim Convention on Conservation of North Pacific 

 Fur Seals was conducted off Washing-ton (2-24 

 April) and off California (11 April to 23 June). 

 One hundred forty-seven fur seals {Callorhinus 

 ursiniui) were taken off Washington and 269 off 



California. Off Wa.shington, seals were mest nu- 

 merous near Grays Harbor in mid-April. Off Cal- 

 ifornia, seals were concentrated off Monterey from 

 late April to early June and near Cordell Bank west 

 of Pt. Reyes in .■Xpril and early May. Observation 

 or transect lines extending from 10 to 80 miles off- 

 shore were established between Bodega Head and 

 Pt. Sur, Calif., at 20-mile intervals, to study distri- 

 bution and migration. Seals were most abundant 

 from 30 to 40 miles offshore. Of the 387 female seals 

 taken, 44 percent were pregnant; the youngest preg- 

 nant females were 5 years old. A squid, Moroteuthis 

 robusta, is reported for the first time as fur seal 

 food. By volume, the principal species of fish eaten 

 by seals off California was Merluccius productus and 

 off Washington was Engraulis mordax. 



538-542. Published in 1966. 



543. Inventory of U.S. exploratory longline 

 fishing effort and catch rates for tunas and 

 swordfish in the Northwestern Atlantic, 1957- 

 65. By Peter C. Wilson and Martin R. Bart- 

 lett. February 1967, v -i- 52 pp., 81 figs., 13 

 tables. 



ABSTRACT 

 This report summarizes the results of longline ex- 

 plorations for tunas and swordfish by the Bureau of 

 Commercial Fisheries and the Woods Hole Oceano- 

 graphic Institution in the Northwestern Atlantic 

 from March lO.'jT to June 1965. Fishing log data 

 from 31 exploratory cruises are summarized in 12 

 monthly tables that give the date, time, position, 

 number of hooks fished and catch for each longline 

 set. The total and monthly fishing effort (number 

 of longline sets and hooks fished within each 1° lat- 

 itude and longitude square) is shown by 13 figures. 

 Similar figures show the total and monthly average 

 and maximum number of bluefin, yellowfin, albarore, 

 and bigpye tunas, and swordfish caught per 100 

 hooks within each 1° square. Two figures show 

 the monthly catch rates for blackfin and skipjack 

 tunas by 1° squares. 



544. Abundance and distribution of zooplank- 

 ton in Hawaiian waters, 1955-56. By Eugene 

 L. Nakamura. May 1967, v + 37 pp., 18 figs., 

 15 tables, 17 apn. tables. 



ABSTRACT 

 Methods and results of a study of zooplankton are 

 described. Sampling was conducted on eight cruises 

 by vessels of the Bureau of Commercial Fisheries 



Biological Laboratory, Honolulu, and on nine cruises 

 by the motor vessel Mnkua of the Hawaii Division 

 of Fish and Game. Sampling included oblique hauls 

 with a single open net at to 60 m. and to 200 m., 

 and three nets towed simultaneously at three levels: 

 an open net at to 60 m. and closing nets at 70 to 

 130 and at 140 to 200 m. (estimated depths). 



The catches from the three-net hauls revealed 

 a greater abundance of zooplankton in the uppermost 

 layer than in deeper water regardless of the time 

 of sampling. Differences existed between windward 

 and leeward areas of the island of Oahu at certain 

 times, but one area did not have consistently greater 

 volumes of zooplankton than the other area through- 

 out the seasons. The significance of seasonal dif- 

 ferences was masked by the possibility of annual 

 fluctuations. 



Composition of plankton varied by depth, sea.son, 

 and area. Relative abundance was comparatively 

 stable with depth and season. Decapod crustaceans 

 were consistently more abundant in the windward 

 than in the leeward area. Halosphaera viridis, a 

 planktonic alga, was sometimes very numerous. 

 Various groups of zooplankton exhibited conspic- 

 uous diel movement. 



545. Evaluation of a pump and reeled hose 

 system for studving the vertical distribution 

 of small plankton. By Roderick Leong, Jan- 

 uary 1967, iii + 9 pp.. 6 figs., 2 tables. 



ABSTRACT 



The system consists of a submerged pump that de- 

 livers water from sampling depth to inboard filters 

 through a long hose. It features a special winch 

 that can store more than 120 m. of collapsible, large- 

 diameter hose. Sources of error due to fragmenta- 

 tion and dispersion of organisms during passage 

 through the system, and escapement through the 

 strainers, were examined. Fragmentation may be 

 excessive if animals are fragile or longer than 5 mm. 

 Organisms that enter the system simultaneously may 

 become widely dispersed but most remain together. 

 Strainers of lOO/i mesh (bar measure) retain or- 

 ganisms as narrow as lOO/i. 



The capabilities of the pump were illustrated by 

 its use in obtaining vertical profiles of abundance 

 of eggs and larvae of sardines (Siardinops caerulea) 

 and of chaetognaths and doliolids at one station. The 

 eggs and larvae were clearly restricted to the upper 

 mixed layer and upper part of the thermocline. 

 Numbers of chaetognaths increased and numbers of 

 doliolids decreased with increasing depth. The ad- 

 vantages and limitations of the pump for studying 

 vertical distribution are discussed. 



546. Longline fishing for deep-swimming tunas 

 in the Marquesas Islands and adjacent areas. 

 By Howard 0. Yoshida. April 1967, iii -f 

 10 pp., 10 figs., 3 tables. 



