VANC and LIVINGSTON: FOOD HABITS OF GREENLAND HALIBIT 



since the complexity of feeding and evacuation pat- 

 terns in field populations of fish makes it impossi- 

 ble to estimate the consumption and evacuation of 

 different food items ingested at different times. 



Bowering and Lilly (1985) estimated the consump- 

 tion rate of capelin, Mallotiis vUlosus, by Greenland 

 halibut in the northwestern Atlantic, using esti- 

 mates of gastric evacuation rate for Atlantic cod, 

 Gadus morhua, on capelin from Minet and Pero- 

 dou's (1978) study. Assuming a linear gastric evacu- 

 ation model, they found the time for Greenland 

 halibut to complete digestion of capelin at 2°-3°C 

 was 3-5 days. By using the gastric evacuation rate 

 calculated from this study, the time needed by large 

 Greenland halibut (^70 cm) to evacuate 99% of a 

 pollock meal at 3°C was 4.2 days, a value very 

 similar to Bowering and Lilly's (1985) estimate. 



Livingston and Dwyer (1986'^) calculated an aver- 

 age daily ration for arrowtooth flounder of 0.62% 

 of body weight per day. This value is close to the 

 daily ration values calculated from this study. Since 

 Greenland halibut and arrowtooth flounder are eco- 

 logically and morphologically similar species, it is 

 not surprising to find their daily ration needs are 

 similar. 



Huebner and Langton (1982) performed a gastric 

 evacuation study on winter flounder, Pseudopleuro- 

 nectes americanus. They used squid as food for fish 

 10-40 cm at 5.5°-7.0°C to get a gastric evacuation 

 rate of 0.079/h and calculated daily ration in the 

 range of 1.8-2.4% BWD. Compared to these values, 

 the daily ration of Greenland halibut calculated in 

 this study is low, possibly due to the lower temper- 

 atures in this study. 



Greenland halibut ^70 cm apparently ate a higher 

 daily ration (1.17% of body weight per day) than did 

 those <70 cm (0.66% and 0.64% BWD for size group 

 30-49 cm and 50-69 cm, respectively). Flowerdew 

 and Grove (1979) studied the effects of body weight 

 and meal size on gastric emptying time in the turbot, 

 Scophthalmus maximus. Their results showed that 

 large fish emptied a meal of a given size from the 

 stomach at a faster rate than small fish, and large 

 meals in a given fish were processed at faster rate 

 than small meals. Dwyer (1984) also found a higher 

 daily ration value for larger walleye pollock in the 



•'Livingston, P. A., and D. A. Dwyer. 1986. Food web inter- 

 actions of key predatory fish with northern fur seal, CallorhinMs 

 ursinus. in the eastern Bering Sea during summer 1985. In T. R. 

 Loughlin and P. A. Livingston (editors), Summan,' of joint research 

 on the diets of northern fur seals and fish in the Bering Sea dur- 

 ing 1985, p. 57-92. INTWAFC 86-19. Northwest and Alaska Fish- 

 eries Center, National Marine Fisheries Service, NOAA, 7600 Sand 

 Point Way N.E., Seattle, WA 98115. 



eastern Bering Sea. However, Windell (1978) stated 

 that small fish generally consume proportionately 

 more food per unit weight, and some studies showed 

 this trend; Daan (1973) used a prey size dependent 

 evacuation model and found that ration decreased 

 with increasing fish size for North Sea Atlantic cod. 

 Huebner and Langton (1982) calculated daily ration 

 of winter flounder and found the largest fish (>300 

 g) had the smallest ration. Other studies (Elliott 

 1972; Hofer et al. 1982) showed that predator size 

 and meal size have little or no effects on gastric 

 evacuation rate. Durbin and Durbin (1980) concluded 

 from an extensive review of daily ration studies that 

 particle size and meal size relationships on gastric 

 evacuation rates deserve further study. Since the 

 >70 cm Greenland halibut in this study, which had 

 the highest daily ration, also consumed much larger 

 walleye pollock than the other predator size groups, 

 a particle size interaction with gastric evacuation 

 rate seems a likely avenue for further research. 



ACKNOWLEDGMENTS 



We are grateful to Sandra Noel, Karen Conlan, 

 and Wendy Carlson for their excellent work on the 

 figures. Thanks also go to Doug Milward and Geoff 

 Lang for their assistance on the stomach content 

 analyses. We also want to thank the two reviewers 

 for their comments on the earlier manuscript. 



LITERATURE CITED 



Bakkala, R. G., and V. G. Wespestad. 



1983. Walleye pollock. In R. G. Bakkala and L. L. Low 



(editors), Condition of groundfish resources of the eastern 



Bering Sea and Aleutian Islands region in 1982, p. 1-27. 



U.S. Dep. Commer., NOAA Tech. Memo. NMFS F/N\VC-42. 



Bowering, W. R., and G. R. Lilly. 



1985. Diet of Greenland halibut off southern Labrador and 

 northeastern Newfoundland (Div. 2J-I-3K) in autumn of 

 1981-82, emphasizing predation on capelin. Northwest Atl. 

 Fish. Org. SCR Doc. 85/109, Ser. No. N1085, 16 p. 

 Chumakov, a. K. 



1969. The Greenland halibut Reinhardtius hippoglossoides 

 (Walbaimi) in the Iceland area— the halibut fisheries and tag- 

 ging. J. Ichthyol. 9:909-912. (Engl. Transl. Vopr. Ikhtiol.) 

 Daan, N. 



1973. A quantitative analysis of the food intake of North Sea 

 cod, Gadus morhua. Neth. J. Sea Res. 6:479-517. 

 Durbin, E. G.. and A. G. Durbin. 



1980. Some factors affecting gastric evacuation rates in 

 fishes. Int. Counc. Explor. Sea CM. 1980/L:59. 

 Durbin. E. G., A. G. Durbin, R. W. Langton. and R. E. 

 Bowman. 

 1983. Stomach contents of silver hake, Merltuccius bilinearis, 

 and Atlantic cod, Gadtis morhua, and estimation of their 

 daily rations. Fish. Bull., U.S. 81:437-454. 



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