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Fishery Bulletin 92(3). 1994 



ratios (number recovered divided by 

 number released) for the two studies 

 were compared with a two-tailed test 

 of binomial proportions (Kalbfleisch, 

 1976). We used maturity ogives from 

 Tagart ( 1991) to infer the proportion 

 mature for specific lengths. He re- 

 ported 50% maturity at 39.6 cm and 

 45.4 cm for males and females, re- 

 spectively, for fish from northern 

 Washington. 



We conducted a linear regression 

 of the natural log of number recov- 

 ered against time (0.5 years— 9.5 

 years) for the Canadian releases to 

 derive a point estimate of the instan- 

 taneous annual rate of extinction. 



Results 



Canadian-tagged fish 



The Canadian program tagged and 

 released 4,895 fish off central Brit- 

 ish Columbia (B.C.) and 9,557 off 

 southern B.C. and northern Wash- 

 ington waters. Thirty-seven have 

 been recovered, all from commercial 

 catches from Oregon, Washington, 

 and B.C. waters (Figs. 2 and 3; Table 

 2 ). Of these, 36 were accompanied by 

 reliable information on recapture lo- 

 cation. Twenty-seven of the 36 (75% ), 

 moved less than or equal to 25 km from the release 

 location. However, among the nine fish that travelled 

 more than 25 km, three moved at least 100 km, three 

 others at least 125 km, and one at least 250 km. The 

 farthest displacements of Canadian-tagged fish were 

 one fish that moved from Queen Charlotte Sound to 

 the southwest coast of Vancouver Island (400 km) 

 and one that moved from southwest Vancouver Is- 

 land to southern Oregon (400 km). The most rapid 

 movements from original tagging sites were two re- 

 coveries of Canadian-tagged fish that moved from 

 the north coast of Washington to northern Oregon. 

 One travelled at least 100 km in 73 days (1.37 km/ 

 day) whereas the other travelled at least 125 km in 

 100 days (1.25 km/day). 



Average fork length of Canadian-tagged fish was 

 44.5 cm (23-58 cm). Recovered specimens averaged 

 45.9 cm (33-54 cm). Among the 21 recoveries for 

 which sex was known, only two were probably im- 

 mature at the time of release, based on their sex and 

 lengths. Among the nine individuals that travelled 

 further than 25 km, we know the sex of seven. Of 



Figure 2 



Number of releases (in hatched areas) and recoveries (in circles) of yel- 

 lowtail rockfish, Sebastes fiavidus, tagged in southeast Alaska and Queen 

 Charlotte Sound. 



these, only one, a 33-cm male, was likely to have been 

 immature at the time of release. 



The rate of recoveries from the Canadian study grad- 

 ually declined over time (Table 3). The point estimate 

 of the instantaneous annual rate of extinction was 0.2. 

 However, the 95% confidence range (0.099-0.307) was 

 wide, reflecting the low number of recoveries. 



Alaskan-tagged fish 



Of the 397 yellowtail rockfish tagged in Alaska, five 

 have been recovered. All five travelled south to B.C. 

 or to Washington waters over distances of 425-1400 

 km. The fish were tagged in 1982 but were not re- 

 covered until at least 1987. Time at liberty ranged 

 from 1,827 to 2,842 days. The opportunity for recov- 

 ery of yellowtail rockfish in southeastern Alaska com- 

 mercial fisheries was limited. The total reported com- 

 mercial catch in 1991 was three tons; the sport catch 

 was negligible. 5 However, the recovery ratio of Alas- 



5 O'Connell, V. Alaska Dept. Fish Game, Sitka, AK 99M:if, Per- 

 sonal commun., February 1991. 



