McFarlane and King: Migration patterns of Squalus acanthias 



365 



earlier studies. Ketchen ( 1986) concluded that populations 

 in inside waters (i.e. Strait of Geor^a and Puget Sound) 

 are largely independent of those off the open coast. Our 

 study supports the idea that the majority of spiny dogfish 

 in the Strait of Georgia remain in the Strait of Georgia. 

 However, the low proportion of standardized recoveries in 

 Puget Sound suggests very little movement between these 

 two areas. In fact, a higher proportion of standardized re- 

 coveries of spiny dogfish from the Strait of Georgia were 

 reported for coastal waters of Washington State than for 

 Puget Sound. 



Until this present study, little tagging had been con- 

 ducted in open waters off the west coast of North America 

 (Bonham et al., 1949; Holland, 1957; Ketchen, 1986). 

 Holland (1957) observed a tendency for fish tagged off 

 Washington and Vancouver Island to move south in the 

 fall and winter, and north in spring and summer. The 

 distance travelled (with a few exceptions) was generally 

 small. Ketchen (1986) reported a similar pattern (based 

 on seasonal fishery catches during the liver fishery of the 

 1940s) but noted that fishing did occur year round from 

 northern British Columbia to Oregon. He concluded that 

 some individuals may traverse the full commercial range 

 of the species (Oregon to northern British Columbia) be- 

 tween summer and winter, but these instances are more 

 the exception than the rule. 



Seasonal movement aside, it is clear from our study that 

 male and female spiny dogfish of all size categories in open 

 coastal areas migrate considerably farther than previous 

 studies suggest. For example, in the recapture areas where 

 abundance estimates are similar and standardization to 



catch is possible (Strait of Georgia, Puget Sound, west 

 coast Vancouver Island, Washington State coastal waters), 

 the percentage of recaptures for west coast Vancouver 

 Island releases indicates substantial movement south to 

 Washington State coastal waters. This movement is greatly 

 underestimated with nonstandardized data. Unfortunately 

 it is not possible to standardize recapture data for all re- 

 leases because of the paucity of fishing data or abundance 

 estimates. Outside of Canadian waters, excluding Washing- 

 ton State (Puget Sound and coastal waters), there are no 

 targeted spiny dogfish fisheries (i.e. landings are typically 

 less than 10 t) and therefore the proportion of recaptured 

 spiny dogfish in these areas would be expected to be small. 

 However, it is possible to comment on the long-range move- 

 ments (up to 7000 km) of these open coastal dogfish. 



Tagged spiny dogfish released between 1980 and 1987 

 in open coastal waters (west coast of Vancouver Island 

 and northern British Columbia) underwent extensive mi- 

 grations and approximately 16'7( of recaptured fish came 

 from outside Canada waters. From earlier studies, a few 

 recaptured fish indicated that some spiny dogfish at least 

 are highly mobile. In the early 1940s a large male dogfish 

 tagged in northern British Columbia waters was recovered 

 off California 171 days later (Manzer, 1946). Holland ( 1957) 

 reported that a fish tagged off the west coast of Vancouver 

 Island was recaptured off Baja California. One trans-Pacif- 

 ic migration (Washington State to Japan) was reported by 

 Kauffman ( 1955). In our study, the 30 fish captured off Ja- 

 pan were all (with one exception) tagged in outside waters. 

 These recaptures represented 6% of the recaptures from 

 these release areas. Similarly, nine fish were captured off 



