SUTHERLAND: DISTRIBUTION OF STEELHEAD TROUT 



Table 6. — Age, length, and weight of steelhead trout caught by research vessels of the National 

 Marine Fisheries Service, 1955-61. The data are grouped by the number of winters spent in salt 

 water. 



' Freshwater age precedes dot; saltwater age follows dot. 



and two winters in the ocean is now a 3 yr-old 

 fish. 



Ages of steelhead trout caught at sea ranged 

 from 2 to 8 yr with 20 different life history 

 categories represented. Those categories in- 

 cluded various combinations of freshwater 

 ages of 1 to 5 yr and saltwater ages of to 6 

 yr. The majority, however, belonged to three 

 categories: 2.1 (22% ), 3.1 (30% ), and 3.2 (12% ) 

 and were 3, 4, or 5 yr old. Most of the steel- 

 head trout sampled spent 2 or 3 yr in fresh 

 water before migrating to the sea. None were 

 age 0. and less than 1% were age 1. A large 

 percentage had migrated to sea at age 2. (33% ) 

 or at age 3. (47% ). A substantial number of the 

 fish had remained in fresh water to age 4. (17% ) 

 and some to age 5. (3% ) before first entering 

 salt water. The ages of those fish at initial entry 

 into salt water differed markedly from those 



returning to Waddell Creek, Calif., as observed 

 by Shapovalov and Taft (1954). Of 383 adult 

 first spawners examined from Waddell Creek, 

 3% had migrated to sea; at age 1., 79%^ at age 

 2., 14% at age 3., and 4% at age 4. The age 

 composition of the high-seas catches did not 

 differ appreciably from that of steelhead trout 

 taken from the Chilliwack River, British 

 Columbia. A majority of steelhead trout taken 

 from that stream had migrated to sea at age 2. 

 or 3. (Maher and Larkin, 1955). 



The number of years steelhead trout caught 

 by NMFS spent at sea ranged from .0 to .6. 

 Because of a minimum gill net mesh size of 51 

 mm, steelhead trout in their first year at sea 

 were not caught by the sampling gear in pro- 

 portion to their theoretical abundance; it is 

 unlikely, however, that age .0 fish were avail- 

 able in much of the area sampled, since it is 



I 



795 



