ABSTRACT 



The setting of oysters in Broad Creek and Tred 

 Avon River, on the eastern shore of Chesapeake Bay, 

 was monitored during 1961 and 1962. Setting was 

 substantially greater both years in Broad Creek, 

 and the highest number of spat were found on shells 

 suspended from 0.3 to 9 meters below the surface. 

 Three times more spat were caught on shells in 

 bags than on shells broadcast on the bottom. 



In Tred Avon River setting was very light in 

 1961 and light in 1962, except during the week of 

 30 July to 6 August. In Broad Creek setting was 

 heaviest during the week of 17 to 24 July 1961 and 

 during each week from 25 June to 13 August 1962. 



First-season survival rates were 1 to 27 percent. 

 There was some indication, especially in Broad 

 Creek during 1962, that the greater the setting rates 

 the lower the first-season survival rates. 



568. The Japanese Atlantic longline fishery, 

 1964, and the status of the yellowfin tuna 

 stocks, by John P. Wise. August 1968, 5 pp., 

 1 fig., 5 tables. 



ABSTRACT 

 The Japanese Atlantic longline fishery increased 

 in 1964 to nearly 85 million hooks. Catches of yel- 

 lowfin tuna decreased slightly, while catches of al- 

 bacore increased markedly. Even though fishing 

 has decreased since 1964, the effort is still greater 

 than necessan,- for optimum yield in numbers of 

 yellowfin tuna. 



569. Oyster mortalities, with particular refer- 

 ence to Chesapeake Bay and the Atlantic coast, 

 of North America, by Carl J. Sindermann. 

 July 1968, iii + 10 pp., 7 figs. 



ABSTRACT 

 A number of recent mass mortalities of oysters 

 of the Middle Atlantic States and elsewhere in the 

 world have been attributed to the efl'ects of disease. 

 Oyster production in Delaware Bay and lower 

 Chesapeake Bay has been seriously reduced during 

 the past decade by an epizootic of a protozoan path- 

 ogen, Mhichinia nelsoni. Other recent disease-as- 

 sociated mortalities of oysters have occurred in the 

 Gulf of Saint Lawrence and the Gulf of Me.xico. 

 Man may have aided spread of diseases by transfers 

 and overcrowding of beds. Reduction of this threat 

 to oyster production could be effected by quaran- 

 tines, development of disease-resistant strains of 

 oysters, and use of environmental barriers (such 

 as low salinity) to the pathogens involved. 



570. Fishes taken during shrimp trawling 

 along the south Atlantic coast of the United 

 States, 1931-35, by William W. Anderson. 

 July 1968, iv -f 60 pp., 9 figs., 13 tables. 



ABSTRACT 

 Fish of numerous families and species are taken 



with shrimp on the shrimping grounds. Records 

 of the fish taken during a study of the white shrimp 

 by the U.S. Bureau of Fisheries, are provided. These 

 records cover the coast from Cape Romain, S.C., to 

 Cape Kennedy, Fla., and are organized under four 

 basic areas: South Carolina Outside, Georgia Out- 

 side, Georgia Inside, and Florida Outside. The en- 

 tire region is treated also as a unit. Yearly and 

 monthly average numbers of fish taken per hour of 

 trawling and percentages of the catch are provided 

 for all species for the region and for the several 

 basic areas. 



Seasonal variation in the numbers of fish on the 

 shrimp fishing grounds is large; numbers are low- 

 est during the late winter and spring, build up rap- 

 idly in the summer and early fall, and are highest 

 in the late fall and early winter. 



The croaker family (Sciaenidae) was the most 

 abundant and important found on the shrimp fish- 

 ing grounds. Croakers were captured in greater 

 numbers than all other families of fish combined 

 in every month of the year. 



Four families of fish — The Sciaenidae (croakers), 

 Carangidae (jacks), Ariidae (sea catfish), and 

 Bothidae (flounders) — were taken in greatest num- 

 bers per hour of trawling and together contributed 

 almost 87 percent of the yearly average catch in 

 the region. 



Seven species of fish — Stellifer lanceolatus (star 

 drum), Micropagon undulatxis (Atlantic croaker), 

 Leiostorrms xanthurus (spot), Menticirrhus spp. 

 (king whiting), Chloroscombrus chrysurus (bump- 

 er), Cynoscion regalis (gray seatrout), and Etropiis 

 crossotvs (fringed flounder) — each contributed 3 

 percent or more of the yearly average catch for the 

 region, and together represented over 76 percent 

 of the yearly average catch in the region. 



571. Spawning areas and abundance of chinook 

 salmon {Oncorhynchus tshatvytscha) in the 

 Columbia River Basin — past and present, by 

 Leonard A. Fulton. October 1968, iii -h 26 pp., 

 5 figs., 8 tables. 



ABSTRACT 

 Chinook salmon, the most abundant species of 

 salmon in the Columbia Basin, formerly spawned 

 in nearly all tributaries of the Columbia River and 

 in many areas of the main river. Over the past 60 

 years, the construction of dams has inundated, im- 

 peded, or blocked access to spawning areas. 



Despite these heavy losses, large areas of spawn- 

 ing grounds in the middle and lower portions of 

 the drainage are still available to chinook salmon. 

 Stream improvements by State and Federal fishery 

 agencies have rehabilitated some areas and have 

 brought others into production for the first time. 



Important spawning areas are listed and charted 

 in this report according to their past use (before 

 1965) and present use (1966). Estimates of recent 

 spawning populations in major tributaries and in 

 segments of the main stem are also given. Former 



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