GROOT and QUINN: HOMING MIGRATION OF SOCKEYE SALMON 



high seas tagging locations of the recovered fish 

 give information on the distribution of Fraser 

 River sockeye in the ocean. Southern British Co- 

 lumbia sockeye (of which at least 90% are Fraser 

 River fish) were distributed in the Gulf of Alaska 

 southward to lat. 45°N and westward to long. 

 178°E, a distance of 6,600 km from the Fraser 

 River. The monthly changes in distribution of 

 tagged fish from April to August and recovered in 

 the year of tagging suggest that during spring 

 and summer there is first a shift northeastward 

 in May and June and then southeastward in July 

 and August along southeast Alaska and the 

 Queen Charlotte Islands towards Vancouver Is- 

 land (Fig. 2). The findings are in accordance with 

 the migration model for southeast British Colum- 

 bia sockeye salmon presented by French et al. 

 (1976). 



Further indications of the coastal approach 

 routes of Fraser River sockeye salmon can be 

 derived from the rate of travel and the assumed 



direction of movement. From the positions and 

 the dates of tagging and recovery, the rate of 

 travel along the shortest route can be calculated 

 for each fish. The rates ranged up to 98 km/day 

 (4.1 km/hour or about 2 body lengths/second). 

 Sonic tracking studies by Madison et al. (1972), 

 Stasko et al. (1976), and Quinn and terHart (in 

 press) showed that sockeye salmon travel at aver- 

 age speeds of 1.8 to 2.2 km/hour (about 1 body 

 length/second) when migrating, which approxi- 

 mates the optimum sustained swimming speed 

 for mature sockeye in endurance tests (Brett 

 1983). 



For 373 sockeye salmon that were tagged 1,000 

 km or more away from the Fraser River and re- 

 covered around Vancouver Island, 86 (or 23%) 

 travelled at speeds greater than 45 km/day (1.9 

 km/hour or about 1 body length/second) (Fig. 3). 

 These estimates of swimming speed discount any 

 effect of currents. Current direction and speed 

 vary considerably in the regions through which 



64°N 



I30°W 



Figure 2. — Distributions in the Gulf of Alaska of releases of sockeye salmon from April through August that were recovered during 



the year of tagging around Vancouver Island, 1953-85. 



457 



