ABSTRACT 



Six hundred forty-two tuna, including 438 yellow- 

 fin tuna {Thunnus (tllmcares) , 102 bigeye tuna {T. 

 obe.ius) , 51 albacore (T. alahinga) , and 51 skipjack 

 tuna {Katsiiivonus pelamis) , were caught by long- 

 line fishing on three cruises across the Equator on 

 long. 132° and 150° W. and around the Marquesas 

 Islands (ca. long. 140° W.) between August 195fi 

 and May 1958. These cruises were part of an in- 

 vestigation of fishery resources of the Marquesan 

 area by the Bureau of Commercial Fisheries Bio- 

 logical Laboratory at Honolulu. 



The distribution and abundance of yellowfin tuna 

 are considered in greatest detail in this report, be- 

 cause this species dominated the catches. Yellow- 

 fin tuna were more abundant during the Southern 

 Hemisphere summer than winter and on long. 132° 

 W. than on long. 150° W.; also, they were more 

 numerous in the "inshore," <148 kilometers (80 

 nautical miles) from land, waters of the Marquesas 

 than in the adjacent "oceanic" (>148 kilometers 

 from land) waters. Their abundance differed sea- 

 sonally in the insular waters of the Marquesas. 



Although bigeye tuna were not as abundant nor 

 as widely distributed, their distribution was some- 

 what similar to that of yellowfin tuna. 



No albacore were caught north of lat. 7° S. on 

 long. 132° and 150° W. This distribution appeared 

 to be associated with a discontinuity of the oceanic 

 structure extending east-west around lat. 10° S. 



547. Response of migratino: adult salmonids to 

 vertical and horizontal rectangular orifices at 

 two depths. By Clark S. Thompson, William 

 Spencer Davis, and Emil Slatick. June 1967, 

 iii + 8 pp., 7 figs., 5 tables. 

 ABSTRACT 

 The response of migrating adult salmonids to var- 

 ious placements of rectangular fishway orifices was 

 studied at the Fisheries-Engineering Research Lab- 

 oratory, on the Washington end of Bonneville Dam. 

 Chinook salmon (Oncorhynchus tshatvytscha) , steel- 

 head trout {Salmo gairdneri) , and coho salmon (O. 

 kisutch) approaching a vertical wall had the alter- 

 natives of entering rectangular orifices positioned 

 either horizontally or vertically and either shallow 

 (3 feet) or deep (9 feet). The respon.ses of the 

 three species to the various orifice conditions are 

 analyzed. More migrants passed through shallow 

 orifices than deep orifices, and more salmonids en- 

 tered vertical orifices than horizontal orifices. 



584. Expendable bathythermograph data on 



subsurface thermal structure in the eastern 



North Pacific Ocean. By J. F. T. Saur and 



Dorothy D. Stewart. August 1967, iii + 70 



pp., 9 figs., 13 tables, 50 charts. 



ABSTRACT 



This report contains reproductions of original 



temperature-depth traces, two temperature sections, 



and synoptic weather observations taken between 

 San Francisco and Honolulu in November-December 

 1965, using an expendable bathythermograph system 

 aboard a merchant ship. A third temperature sec- 

 tion derived from closely spaced observations shows 

 the complicated temperature structure with temper- 

 ature maximums and minimums over a distance of 

 about 45 nautical miles (85 km.) across the outer 

 boundary of the California Current. 



549. Atlas of July oceanographic conditions in 

 the Northeast Pacific Ocean, 1961-64. By R. 

 W. Owen, Jr. January 1967, vi -f 85 pp., 82 

 figs. 



ABSTRACT 

 An atlas of July oceanographic conditions in 1961- 

 64 is presented for the region bounded by the coast 

 of Oregon-Washington and long. 132° W. The atlas 

 consists of charts that show distributions of tem- 

 perature, salinity, density, oxygen concentration, 

 thickness of mixed layer, dynamic height, chloro- 

 phyll a concentration, and catch of albacore, Thun- 

 nus alaliinga ( Bonnaterre) , at the time of year when 

 albacore first become available to the commercial 

 fishery of the region. Some remarks on the albacore 

 catch and the environment are included. 



550. Biology and management of the American 

 shad and status of the fisheries, Atlantic Coast 

 of the United States, 1960. By Charles H. 

 Walburg and Paul R. Nichols. August 1967, 

 iv -1- 105 pp., 33 figs., 55 tables. 



ABSTRACT 



This paper summarizes current information on 

 the American shad, Alosa sapidissima, and describes 

 the species and its fishery. Emphasis is placed on 

 (1) life history of the fish, (2) condition of the fish- 

 ery by State and water area in 1960 compared to 

 1896 when the last comprehensive description was 

 made, (3) factors responsible for decline in abun- 

 dance, and (4) management measures. 



The shad fishery has changed little over the past 

 three-quarters of a century, except in magnitude of 

 yield. Types of shad-fishing gear have remained 

 relatively unchanged, but many improvements have 

 been made in fishing techniques, mostly to achieve 

 economy. 



In 1896 the estimated catch w-as more than 50 

 million pounds. New Jersey ranked first in produc- 

 tion with about 14 million pounds, and Virginia sec- 

 ond with 11 million pounds. In 1960 the estimated 

 catch was slightly more than 8 million pounds. Mar- 

 yland ranked first in production with slightly more 

 than 1.5 million pounds, Virginia second with slightly 

 less than 1.4 million pounds, and North Carolina 

 third with about 1.3 million pounds. 



Biological and economic factors blamed for the 

 decline in shad abundance, such as physical changes 

 in the environment, construction of dams, pollution, 

 overfishing, and natural cycles of abundance, are 

 discussed. Also discussed are methods used for 



