358 



Abstract. -The biology and distri- 

 bution of arrowtooth, Atheresthes sto- 

 mias, and Kamchatka, A. evermanni, 

 flounder were examined in Alaskan 

 waters to determine whether there 

 were sufficient differences to justify 

 treating them as separate species in 

 resource assessment surveys conducted 

 by the National Marine Fisheries Ser- 

 vice. Geographic ranges of the two 

 flounder species overlap in Alaska wa- 

 ters; both occur in the eastern Bering 

 Sea and western Aleutian Islands re- 

 gion. However, only arrowtooth flounder 

 occur throughout the eastern Aleutian 

 Islands region and the Gulf of Alaska. 

 Arrowtooth flounder were abundant 

 over a wide range of depths ( 76-450 m i 

 and were more abundant than Kam- 

 chatka flounder in catches shallower 

 than 325 m. Kamchatka flounder were 

 abundant only in deep trawl hauls 

 (226-500 m) and were more abundant 

 than arrowtooth flounder in catches at 

 depths greater than 375 m. Arrowtooth 

 flounder were also abundant over a 

 wide range of bottom-water tempera- 

 tures (2. 1°-4.6°C ), whereas Kamchatka 

 flounder were abundant in a much nar- 

 rower range of bottom temperatures 

 (3 8° 4.2°C). By percentage, females 

 dominated the arrowtooth flounder 

 population in the eastern Bering Sea 

 (68.6^) and Aleutian Islands region 

 (59.6 r i ), whereas the Kamchatka floun- 

 der population was 55.9% and 47.59? 

 female, respectively. The females of 

 both species attained greater length at 

 age than did the males. The difference 

 in growth between the sexes was 

 greater among arrowtooth flounder and 

 may account for the preponderance of 

 females in the arrowtooth flounder 

 population 



Biology and distribution of 

 arrowtooth, Atheresthes stomias, 

 and Kamchatka, A. evermanni 

 flounders in Alaskan waters 



Mark Zimmermann 

 Pamela Goddard 



Alaska Fisheries Science Center 



National Marine Fisheries Service. NOAA 



7600 Sand Point Way NE, Seattle. Washington 981 1 5-0070 



Manuscript accepted 9 Januarj 1996 

 Fishery Bulletin 



Arrowtooth flounder, Atheresthes 

 stomias, and Kamchatka flounder, 

 A. evermanni, were not always 

 treated as separate species in re- 

 source assessment bottom trawl 

 surveys of the Alaska Fisheries Sci- 

 ence Center (AFSC) prior to 1991 

 because of their similarity in ap- 

 pearance, lack of commercial impor- 

 tance, and the limited abundance of 

 Kamchatka flounder in comparison 

 with arrowtooth flounder. They 

 were both grouped as arrowtooth 

 flounder and possible differences 

 between them were not thoroughly 

 documented. Most of the previous 

 research conducted on Atheresthes 

 spp. has treated them as a species 

 complex. The few comparative stud- 

 ies of Atheresthes spp., based on 

 morphometries (Norman, 1934; 

 Wilimovsky et al., 1967; Yang, 

 1988), genetics (Ranck et al., 1986), 

 diet (Yang and Livingston, 1986), 

 and geographic distribution (Shun- 

 tov, 1965; Wilimovsky et al., 1967; 

 Allen and Smith, 1988), have docu- 

 mented few differences between the 

 two species. 



Arrowtooth flounder accounts for 

 559? of the flatfish biomass in the 

 western Gulf of Alaska ( Brown 1 1; it 

 is the dominant flatfish of that area, 

 and yet it has not supported a large 

 fishery. Arrowtooth flounder have 

 been caught commercially in small 

 fisheries off the Pacific coast of 



Canada and off the Washington and 

 Oregon coasts for use in animal 

 feeds as well as for human con- 

 sumption (Kabata and Forrester, 

 1974). Softening of the flesh, prob- 

 ably caused by an enzyme released 

 from a myxosporean parasite 

 (Greene and Babbitt, 1990), has lim- 

 ited the marketability of arrowtooth 

 flounder as food. Recent work, how- 

 ever, has shown promise in produc- 

 ing marketable flounder products, 

 such as arrowtooth flounder fillets 

 (Greene and Babbitt, 1990), arrow- 

 tooth flounder surimi (Wasson et al., 

 1992; Porter et al., 1993; Reppond 

 et al., 1993), and Kamchatka floun- 

 der surimi (Haga et al. 2 ). Poten- 

 tially, a fishery targeting arrow- 

 tooth flounder in Alaskan waters 

 could have an effect on the Alaskan 

 population of Kamchatka flounder. 

 Knowledge of the biology of the two 

 species may provide crucial infor- 

 mation needed for their proper man- 

 agement and conservation. There- 

 fore, since 1991, these species have 

 been considered as two separate 



1 Brown. E S 1994. Alaska Fisheries 

 Science- ( lenter, Resource Assessment and 

 Conservation Engineering Division, 

 Sand Point Was NE, Seattle. WA 98115 

 Persona] commun 



J Haga. H . K Shigeoka, and T Yamauchi 

 1980. Method for proci ing fish con- 

 taminated with sporozoa U.S Patent 

 1,207,354, Jun. 10. 



