Yano and Dahlheim: Depredation of bottomfish on longline catches by Orcmus orca 



369 



f A 



n= 999) 



301 401 



501 601 701 801 901 



401 501 601 701 801 901 



n= 110 



301 401 501 601 701 801 901 



Fork length (mm) 



Figure 9 



Length-frequency distribution of arrowtooth flounder, Atheresthes 

 stomias. (A) All areas (see Fig. 1): (B) all stations fished where 

 depredation occurred; (C) calculated length (head length and 

 maxillary length) of partially consumed fish. 



Dahlheim 2 estimated that the U.S. domestic 

 longline fishery in the Bering Sea incurred an aver- 

 age loss of $2,300 per day during the winter of 1988, 

 similar to the values ($928.90 in RNT and $3,373.50 

 in REA per operation [per day]) reported for this 

 study. However, losses reported for this study may 

 be underestimated. For example, monetary losses 

 would be greater if the time spent by fishermen trav- 

 eling from one area to another to escape whales was 

 considered. Also the price per kilogram of sablefish 

 is greater than that for larger fish. Since whales were 

 shown to prefer larger fish, the actual monetary losses 

 per operation may be greater than those reported (val- 

 ues based on an average cost/kg). Matkin et al. 20 esti- 



20 Matkin, C. O., G. Ellis, O. von Ziegesar, and R. Steiner. 1987. 

 Killer whales and longline fisheries in Prince William Sound, 

 Alaska 1986. Alaska Fisheries Science Center, National 



mated sablefish losses of $34,300 to $55,500 over the 

 entire season for the 1986 Prince William Sound 

 sablefish longline industry. During the 4-month re- 

 search survey, a minimum value (calculated from RNT) 

 of $2,982.00 and a maximum value (calculated from 

 REA) of $34,571.00 was estimated. 



Acknowledgments 



We express our sincere appreciation to T. Sasaki (Na- 

 tional Research Institute of Far Seas Fisheries) and 

 M. Kuroiwa (Japan Marine Fishery Resources Re- 



20 (continued) Marine Mammal Laboratory, Seattle, Washington, 

 National Marine Mammal Laboratory, 7600 Sand Point Way 

 N.E., Seattle, WA 98115-0070. Unpubl. manuscr., contract 

 40ABNF6 2262, 18 p. 



