176 



Fishery Bulletin 102(1) 



0.8 H 



0.6 



0.4- 

 0.2- 







t* 



000000 



2 



-e- 



311 2 12 



000 000 



P mat = 1/(1+e3"'»-"'M 



00 i 



30 35 40 45 50 55 60 65 70 75 80 85 90 



Length (cm) 



10 15 



Age (years) 



20 



25 



Figure 7 



Proportion of female prowfish mature (P mat ) as logistic functions of length (L) and age 

 it). Data points based on 39 maturity-at-length and 27 maturity-at-age observations are 

 shown by diamonds, and numbers of females of each cm-length and year-age class are 

 shown next to the corresponding symbol. The fitted logistic models are shown by solid 

 lines. The length and age at which P mat = 0.5 with 95^ confidence limits are 57.0 ±0.4 cm 

 and 5.1 ±0.7 years. 



Discussion 



Geographic distribution 



Historically occurring in the catch in AFSC bottom trawl 

 surveys in areas of the eastern Bering Sea, Aleutian 

 Islands, and Gulf of Alaska regions, prowfish were also 

 observed more rarely farther south along the West Coast 

 as far as the vicinity of San Miguel Island, California. 

 This is the apparent southern limit of their range in the 

 northeastern Pacific (Allen and Smith, 1988). They were 

 most often encountered in the vicinity of the edge of the 

 continental slope near 200 m depth (Fig. 2), although our 

 data increase the maximum known depth of occurrence 

 from 675 m (Allen and Smith, 1988) to 801 m. As indicated 

 by survey CPUE, prowfish density was greatest between 

 the depths of 100 m and 240 m (Fig. 3). Our distribution 

 data show similarities with those of Tokranov ( 1999), who 



studied >300 bottom trawls executed in 1995-97 on the 

 shelf and slope off the southern Kamchatka Peninsula and 

 northern Kuril Islands, in which adult prowfish were taken 

 at 100-480 m. Tokranov often found fish concentrated in 

 areas of high-relief, rocky bottom — a common feature of 

 the shelf edge in the Gulf of Alaska and Aleutian Islands 

 regions. Such areas near the shelf break may be important 

 prowfish habitat. Underwater videos taken in the north- 

 east Gulf of Alaska by the Alaska Department of Fish and 

 Game (Brylinsky 5 ) show numerous adult fish resting on or 

 just above this type of substrate. 



Density was greater in the AI than in the GOA, over all 

 bottom depths combined and in most cases by individual 

 depth interval (Fig. 3). One reason may be that preferred 

 habitat comprises a larger proportion of the Aleutian Is- 



5 Brylinsky, C. 2000. Pers. commun. Alaska Department of 

 Fish and Game, 304 Lake Street, Sitka, AK 99835. 



