PEARCY and FISHER: MIGRATIONS OF COHO SALMON 



salmon from the Rogue River in the troll fishery 

 off California (R. Garrison'^) is further evidence 

 for a southern distribution of this stock. Marked 

 juvenile coho salmon from California hatcheries 

 were reported from the sports fishery off southern 

 Oregon, however, as will be shown later. 



Washington Coastal Hatcheries 



Juvenile coho salmon from Washington public 

 hatcheries demonstrated southerly movements, 

 sometimes into Oregon waters, during May 1981 

 and 1982 (Figs. 4, 5). During June 1982, 1984, 

 and 1985, Washington coastal fish were found 

 both north and south of ocean entry. Except for 

 one fish that moved north in September 1984, no 

 Washington coastal fish were taken in August or 

 September of other years, suggesting that most 

 Washington fish may have migrated out of our 

 sampling area by late summer. 



Oregon Private Hatcheries 



All marked juvenile coho salmon originating 

 from Yaquina and Coos Bays that we captured at 

 sea were from private hatcheries. Those from 

 Yaquina Bay were mainly age 0.0 smolts from 

 OAF, those from Coos Bay were either age 1.0 

 smolts from Anadromous, Inc. or age 0.0 smolts 

 from OAF. Forty-one recoveries of marked OAF 

 fish released from Yaquina Bay were caught to 

 the north while only 4 were to the south of 

 Yaquina Bay. In general, more juvenile coho 

 salmon from Yaquina Bay were captured in late 

 than early summer, and distances traveled to the 

 north were largest (up to 413 km) for fish caught 

 in later summer (Figs. 4-8). All recoveries of 

 marked Anadromous, Inc. and OAF fish released 

 into Coos Bay were to the north in all years. 

 Large northerly movements were demonstrated 

 by some of these fish (Figs. 4, 6, 8). Since our 

 sampling in the ocean usually did not extend 

 south of Coos Bay, recoveries of these fish are 

 biased to the north; however, strong northward 

 movements of these stocks were indicated. 



Rates of Movement 



Recoveries of marked juvenile coho salmon in 

 the ocean provided information on the minimum 

 rates of movement from hatchery release to cap- 



3R. Garrison, Oregon Department of Fish and Wildlife, Cor- 

 vallis, OR 97330, pers. commun. December 1983. 



ture in the ocean. Some fish moved rapidly 

 through estuaries into the ocean. We captured 

 some tag-groups in the ocean only a few days after 

 the median date of capture at Jones Beach (75 km 

 from the ocean) as reported by Dawley et al. 

 (1985): 5 fish after 2 days in 1981, 6 fish after 

 3-11 days in 1981, 8 fish after 1-14 days in 1982, 

 and 5 fish after 3-8 days in 1983. Dawley et al. 

 (1986) found average rates of movement of 14-23 

 km d"^ for marked groups of coho smolts from 

 areas of release on the Columbia River to river 

 km 75, and rates of movement that were 40% 

 faster from river km 75 to the lower Columbia 

 River estuary and to the ocean plume. These re- 

 coveries and those reported by Miller et al. (1983) 

 for yearling chinook salmon and steelhead trout 

 indicate rapid movements of juvenile salmonids 

 of over 20 km d^^ through the Columbia River 

 estuary. 



Some juvenile coho salmon released from 

 Yaquina Bay and Coos Bay also demonstrated 

 rapid movements into and in the ocean, e.g., 17 

 Anadromous, Inc. fish were captured 11 km north 

 of Coos Bay only two days after release in June 

 1983 (Table 5). Myers (1980) described an expo- 

 nential decrease in the catches of juvenile coho 

 salmon released from the OAF facility into 

 Yaquina Bay; about one-half the fish from 

 marked groups remaining in the bay after 1.7-9.0 

 days. Juvenile coho salmon apparently emigrate 

 rapidly from estuaries into the ocean. 



Some of the marked fish recovered within 10 

 days of release demonstrated rapid movements 

 down-rivers or in the ocean. Twenty-four fish 

 traversed 10 km d~^ or more largely in the ocean, 

 in both north and south directions (Table 5). Four 

 fish released in bays or in the ocean moved over 

 18.8 km d~^ Two of these swam to the north, 

 presumably against coastal currents. These 

 speeds are equivalent to 1.7 body lengths (BL) per 

 second or more and suggest that some fish must 

 be traveling nearly straight courses during 

 24-h days, since 1-3 BL s"^ are thought to be 

 optimal cruising speeds for small (<20 cm) 

 pelagic fishes (Weihs 1973; Ware 1978). These 

 maximum rates of movement for purse seine 

 caught juvenile coho salmon are similar to 

 those estimated by Hartt (1980) and Hartt and 

 Dell (1986) for tagged sockeye salmon during 

 their first summer in the ocean: 14-27 km d"^ 

 for 11 Fraser River fish and 6-14 km d"^ for 

 10 Skeena River fish that were between about 

 8 and 23 cm in length during the migration 

 period. 



187 



