AGE-LENGTH- WEIGHT AND DISTRIBUTION 



OF ALASKA PLAICE, ROCK SOLE, AND 



YELLOWFIN SOLE COLLECTED FROM 



THE SOUTHEASTERN BERING SEA IN 1961 



Japanese fishing companies explored the trawl fish 

 resources of the eastern Bering Sea in 1929 and 

 1931. They began commercial fish meal production 

 in 1933 and continued until 1937; a frozen fish 

 operation was initiated in 1940 but was interrupt- 

 ed by World War II (Bourgois 1951).' In 1954, 

 Japan resumed trawling in the eastern Bering 

 Sea, again producing fish meal and frozen fish. The 

 Soviet Union began sending bottom trawl fleets to 

 the eastern Bering Sea in 1959, and combined an- 

 nual catches of flatfishes (excluding Pacific 

 halibut, HippoglossKf^ stoiolepsif^) by Japan-USSR 

 rose to a peak in 1961 when it exceeded 600,000 

 metric tons (Fadeev 1965). In the years following 

 1961, eastern Bering Sea flatfish catches by Japan 

 decreased and in the period 1963-1970 have 

 averaged less than 20% of the 456,890 metric tons 

 caught in 1961 (International North Pacific 

 Fisheries Commission 1973). Comparable Soviet 

 data are not available. 



Prior to intensive exploitation of eastern Bering 

 Sea resources, there were two groups of surveys in 

 which samples of flatfish were taken to assess the 

 age-length structure of the population. One such 

 series was conducted by the U.S. Fish and Wildlife 

 Service in 1947-49 (King 1949; Ellson et al. 1950; 

 Wigutoff and Carlson 1950). The other surveys 

 were made 10 yr later by the Soviet Union (sum- 

 marized by Moiseev 1965). Age-length determina- 

 tions from flatfish samples collected in 1949 were 

 reported by Mosher (1954); the Soviet collections of 

 1957-60 were studied by Fadeev (1963), Mineva 

 (1964), and Shubnikov and Lisovenko (1964). 



In July-August 1961, personnel of the Bureau of 

 Commercial Fisheries (now National Marine 

 Fisheries Service) conducted a trawl survey of the 

 southeastern Bering Sea. This survey, although 

 conducted principally to estimate the abundance 

 of Alaska king crab, Paralithodes spp., provided an 

 opportunity to sample several flatfish species. The 

 purpose of the present report is to present 

 biological information on the distribution, age. 



'Bourgois reported that Alaska pollock was the principal 

 species taken by these Japanese fisheries. However, Alverson et 

 al. (1964) pointed out that the areas of the eastern Bering Sea 

 fished by Japanese trawlers from 1933 to 1941 were the same 

 locations as post-World War II flounder fisheries, so there is 

 reason to doubt the complete accuracy of Bourgois' information 

 as to species. 



length, and weight by sex for three commercially 

 important species of Bering Sea flatfish: yellowfin 

 sole, Limanda a^tpera (Pallas); rock sole, Lepidop- 

 setfa bilineata (Ayres); and Alaska plaice, 

 Pleuronectes quadritiiberculatus Pallas. 



Methods and Materials 

 Sample Collection 



Otter trawl hauls of 1-h duration were made at 

 51 predesignated stations 20 nautical miles (37 

 km) apart (Figure 1). The trawling speed of the 

 vessel was about 2.5 knots (4.6 km/h). The trawl 

 was a 400-mesh, Eastern type, as described by 

 Greenwood (1958). A 1.5-inch (3.8 cm) mesh liner 

 was laced into the cod end to retain small 

 specimens which might otherwise pass through 

 the 3-inch (7.6 cm) meshes in that part of the trawl. 

 At the completion of each haul, the catch was 

 examined, and the weight of each major com- 

 ponent was estimated. At five of the stations 

 where one or more of the target species was 

 abundant, samples of yellowfin sole, rock sole, and 

 Alaska plaice was selected for length-weight-age 

 determination. Specimens were measured to the 

 nearest centimeter to obtain a representation of 

 individuals throughout the available length range. 

 Each fish to be retained was then frozen in- 

 dividually in a plastic bag which was sealed to 

 prevent shrinkage and weight loss through 

 dehydration. 



At the laboratory, 3 mo after collection, the 

 specimens were thawed, the total length (snout to 

 longest rays of the tail fin) was measured, the 

 weight recorded to the nearest gram, and sex de- 

 termined from an examination of the gonads. 



BERING SE« 



=8> 



Figure 1.— Sampling station pattern and location of sample 

 collections for 7 July-4 August 1961 survey. 



919 



