Food Habits of Larval Sablefish 

 Anoplopoma fimbria from 

 the Bering Sea 



Jill J. Grover 



College of Oceanography, Oregon State University 

 Hatfield Marine Science Center, Newport, Oregon 97365 



Bori L. Olla 



Cooperative Institute for Marine Resources Studies, Alaska Fisheries Science Center 

 National Marine Fisheries Service, NOAA, Hatfield Marine Science Center 

 Newport, Oregon 97365 



Sablefish Anoplopoma fimbria 

 spawn at depths exceeding 400 m 

 (Mason et al. 1983) and their larvae 

 ascend to surface waters soon after 

 hatching (Kendall and Matarese 

 1987). While in the neuston, they 

 are subjected to highly variable 

 oceanographic conditions. A com- 

 parison of the diet of sablefish lar- 

 vae collected off Oregon and Wash- 

 ington between years that differed 

 markedly in oceanographic condi- 

 tions (1980 and 1983) revealed a 

 difference in the size of copepods 

 that were ingested (Grover and 

 Olla 1987). Clearly diet can vary be- 

 tween years in one location in re- 



sponse to oceanographic conditions, 

 yet it is unclear how larval diet 

 might vary between distant geo- 

 graphical areas of differing ocean- 

 ographic conditions. 



The aim of the present work was 

 to examine the food habits of larval 

 sablefish that were collected in the 

 Bering Sea in 1979 and compare 

 these findings with those from an 

 earlier study of specimens collected 

 off Oregon and Washington (Grover 

 and Olla 1986, 1987). 



Methods 



Sablefish larvae were collected dur- 



60° N 



- 58° 



- 56° 



- 54° 



I76°W 



172° 



168° 



Figure 1 



Location of collec- 

 tion stations in the 

 I64°W eastern Bering Sea. 



ing 1979 as part of an ichthyoplank- 

 ton survey in the Eastern Bering 

 Sea (Walline 1981). Samples were 

 collected using a modified Sameoto 

 neuston sampler, 0.3 x 0.5 m with 

 0.505-mm mesh, towed at the sur- 

 face for 10 minutes at 2-3 knots. 

 Surfacewater temperatures ranged 

 from about 6°C to just over 8°C. 

 Collections were made from the RV 

 Miller Freeman between 17 June 

 and 10 July 1979. 



All specimens (A'^= 127) from 5 

 stations (Fig. 1) where larval den- 

 sities were at least 1/10 m- surface 

 area were examined. This repre- 

 sents more than 40% of the total 

 number of sablefish larvae that 

 were collected in 1979. 



Larvae were preserved in 10% 

 formalin and were switched into 5% 

 formalin after sorting. Standard 

 length (SL) of each larva was mea- 

 sured, the digestive tract was re- 

 moved, and contents from the en- 

 tire digestive tract were identified. 



Diet was analyzed in terms of 

 numerical percentage composition 

 (%A''), percent frequency of occur- 

 rence (%F0), and volumetric per- 

 centage composition (%VOL). Prey 

 volumes were calculated from prey 

 dimensions (Grover and Olla 1987). 

 An index of relative importance 

 (IRI = (%A^ + %VOL) X %F0) (Pin- 

 kas et al. 1971) was used for a more 

 comprehensive assessment of prey 

 importance. Data were examined by 

 larval size group (12-15 and 16-23 

 mm SL). 



Prey was categorized as diatoms, 

 copepod eggs, copepod nauplii, Oi- 

 thona similis, Pseudocalanus sp. 

 adults and copepodites, Acartia 

 longiremis, Acartia spp., unidenti- 

 fied copepods, amphipods, and all 

 other prey items. 



Prey widths that were used to ex- 

 amine prey-size selection were ob- 

 tained only from items that were 

 not badly broken or flattened. Over 

 2900 prey items were measured. 



Manuscript accepted 13 July 1990. 

 Fishery Bulletin. U.S. 88:8i 1-814. 



