FISHERY BULLETIN: VOL. 86, NO. 2 



frey (1965) and French et al. (1975), but by far the 

 most comprehensive data were provided by Hartt 

 (1980) and Hartt and Dell (1986). All of these 

 studies, however, were based on recovery of ma- 

 ture or maturing coho in the year following tag- 

 ging and on tagging in northern waters from the 

 Strait of Juan de Fuca to the Alaska Peninsula. 

 The only other studies of juvenile salmon in the 

 ocean off Washington and Oregon have been re- 

 stricted to within 24 km of the Columbia River 

 (Dawley et al. 1981) or to coastal waters during 

 1980 (Miller et al. 1983). Our 1979-85 research, 

 covering large areas along the coast, provides ex- 

 tensive and unique data on the movements of ju- 

 venile coho salmon during their first summer in 

 the ocean. 



METHODS 



Purse seines, our primary sampling method, 

 were used to sample juvenile salmonids during 

 1979-85 (Table 1). Cruises were in coastal waters 

 off Oregon in 1979-80, off Oregon and southern 

 Washington in 1981, and off Oregon and the en- 

 tire Washington coast during the summers of 

 1982-85 (Fig. 1). During July 1984, sets were also 

 made from northern California (lat. 40°32'N) to 

 northern Vancouver Island (50°26'N). Except for 

 the exploratory cruises off Oregon in 1979 and 

 1980, purse seine sets were usually made along 

 east-west transect lines (Fig. 1). Sets started at 

 the 37 m (20-fathom) contour, and continued at 

 9.3 km (5-mi) intervals farther offshore, usually 

 until no salmonids were captured. Repeat sets 



were sometimes made when fish with missing 

 adipose fins were common, indicating the pres- 

 ence of coded wire tagged (CWT) fish. In 1985, 

 special sets were made in the vicinity of the Co- 

 lumbia River plume. Detailed sampling data are 

 provided in Pearcy (1984) and our cruise reports 

 (Wakefield et al. 1981; Fisher et al. 1982, 1983; 

 Fisher and Pearcy 1984, 1985). 



The mesh size of the seines were the same dur- 

 ing all years, 32 mm (stretch), with 32 mm or 

 smaller mesh in the bunts of the seines. The seine 

 was 495 m long except in 1981 (457 m). Depths 

 that seines fished, sometimes measured with a 

 depth gauge on the lead line, varied among years 

 from about 20 m to 65 m (Table 1). 



Generally, purse seine sets were "round hauls", 

 where the seiner and the skiff made a circle with 

 the net. The seine was fully pursed after about 

 one-half its length was aboard (half-purse sets). 

 All sets were "blind". We attempted to use sonar 

 on some cruises to locate concentrations of sal- 

 monids but were unsuccessful. Radar was some- 

 times used to determine the distance between the 

 seiner and the skiff when a semicircle was made 

 with the net. Each round haul encompassed about 

 17,000 m2 (1981) or 19,000 m2 (1979-85). To de- 

 termine the direction of movement of fish, eight 

 "half-round" hauls, or "semicircular" sets, were 

 made in 1979, where the entire net formed an 

 open semicircle. Paired sets were made in close 

 succession, with sets open in a northern and a 

 southern direction, at four locations. The seine 

 was open for the same duration (15-45 minutes, 

 depending on location) in each paired set while 



Table 1. — Summary of number of purse seine sets and latitudinal range of sampling, 1979-85. 



^Quantitative sets. 

 ^Measured with depth guage. 



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