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Fishery Bulletin 94(2). 1996 



dominant species on the northwestern side of the 

 Pacific Ocean, and arrowtooth flounder the dominant 

 species on the northeastern side of the Pacific Ocean 

 (Wilimovskyetal., 1967). 



Kamchatka flounder occurs along the eastern 

 shores of Japan from as far south as 38"N (Moiseev, 

 1953), in the Sea of Japan (Allen and Smith, 1988), 

 along the eastern and western shores of the 

 Kamchatka Peninsula, and along the eastern coast 

 of Siberia north to Cape Navarin (Shuntov, 1965). 

 Shuntov ( 1965) also reported that Kamchatka floun- 

 der occurs in the eastern Bering Sea, Commander 

 Islands region, throughout the Aleutian Islands, and 

 into the Gulf of Alaska as far east as Shelikof Strait. 



On the western side of the Pacific Ocean, arrow- 

 tooth flounder occurs along the eastern shore of the 

 Kamchatka Peninsula north to Cape Navarin ( Shun- 

 tov, 1965). It occurs in the Commander Islands re- 

 gion ( Shuntov, 1965 ), the eastern Bering Sea, through- 

 out waters off the Aleutian Islands chain, in the Gulf of 

 Alaska, and down the West Coast of North America to 

 San Simeon, California, 40°N (Allen and Smith, 1988). 



The geographic distribution and overlap of 

 Atheresthes species in Alaskan waters were more 

 clearly defined than had been previously reported 

 (Shuntov, 1965; Wilimovsky et al., 1967; Allen and 

 Smith, 1988). The arrowtooth flounder population 

 was less abundant in the Aleutian Islands than in 

 the southern Bering Sea area. The absence of 

 arrowtooth flounder from the northwest tip of the 

 eastern Bering Sea shelf perhaps also indicates the 

 decreasing abundance of arrowtooth flounder from 

 east to west in the eastern Bering Sea. The waters 

 around the easternmost Aleutian Islands marked the 

 general southeastern border of the Kamchatka floun- 

 der population. Our bottom trawl survey data show 

 a smaller geographic range for Kamchatka flounder 

 than that reported by Shuntov ( 1965). Data collected 

 by the Fishery Observer Program of the AFSC were 

 supported by the findings of Shuntov (1965), indi- 

 cating that the Kamchatka flounder distribution also 

 extends into the Gulf of Alaska, but only in limited 

 numbers and in deep water. Future bottom trawl 

 hauls in deeper waters (>500 m) during AFSC Gulf 

 of Alaska surveys may extend the Kamchatka 

 flounder's known range farther east. 



Although large-size Kamchatka flounder were re- 

 ported from deep waters in the Gulf of Alaska 

 (Conrad'), the lack of any Kamchatka flounder in 

 our Gulf of Alaska survey may indicate that this is 

 not a self-sustaining population. These large-size 

 Kamchatka flounder may have ventured into the Gulf 

 of Alaska from the Aleutian Islands or eastern Bering 

 Sea areas. The westerly flowing currents in the Gulf 

 of Alaska do not foster retention of larvae in this area 



(Schumacher 6 ), which might make it more difficult 

 for larval Kamchatka flounder spawned in the Gulf 

 to remain there. 



The observed high percentage of females in the 

 arrowtooth flounder population clearly distinguishes 

 this species from Kamchatka flounder. The overabun- 

 dance of females in the arrowtooth flounder popula- 

 tion is an unusual occurrence among the major fiat- 

 fish species in the eastern Bering Sea. The possibil- 

 ity that the sampling gear undersampled males, ei- 

 ther by not catching them or by not retaining them 

 as well as it did females, remains a possible expla- 

 nation that was not examined. Many other possible 

 sources of error were explored to determine whether 

 the number of arrowtooth flounder females was over- 

 estimated. There was no indication that areas high 

 in percentages of males were excluded from the trawl 

 surveys. The possibility that fishery biologists con- 

 ducting the surveys might have consistently made 

 incorrect sex determinations seems highly unlikely 

 because females are determined by the presence of 

 ovarian tissue, whereas males are often designated 

 males simply because no gonadal tissues were found. 

 Any error made because of improper sex determina- 

 tion should have overestimated the number of males 

 in the population. An explanation for the overabun- 

 dance of female arrowtooth flounder in our observa- 

 tions may come from the length-at-age results. 



The difference in length at age between male and 

 female arrowtooth flounders was significant and in- 

 dicated that for fish over 5 years old, female arrow- 

 tooth flounder were larger than male arrowtooth 

 flounder. Our results were supported by earlier AFSC 

 surveys for the eastern Bering Sea (Smith and 

 Bakkala, 1982; Bakkala et al., 1985; Sample et al., 

 1985; Walters et al., 1988) and Aleutian Islands 

 (Ronholtetal., 1994). These studies show that growth 

 curves for arrowtooth flounder males and females 

 diverge as early as three to five years of age and that 

 females are larger than males. It is doubtful, how- 

 ever, that in past surveys arrowtooth and Kamchatka 

 flounder were regularly separated for otolith collec- 

 tions, because they were not consistently separated 

 for other purposes. Our results differ from the length- 

 at-age data collected from arrowtooth flounder in 

 British Columbian waters, which showed no separa- 

 tion in growth curves between sexes until age 9 

 (Kabata and Forrester, 1974). 



Our findings that female arrowtooth flounder at- 

 tain a greater size at age than do male arrowtooth 

 founder was supported by sexual maturity studies. 

 Fifty-percent maturity occurs at a larger size in fe- 

 male arrowtooth flounder than in males off both the 

 Washington (37 cm vs. 28 cm, respectively, Rickey, 

 1995) and Oregon coasts (44 cm vs. 29 cm, Hosie and 



