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Rearing Methods and the Return of Fall‐Migrating Chinook Salmon
Author(s) -
Ellis C. H.
Publication year - 1958
Publication title -
transactions of the american fisheries society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.696
H-Index - 86
eISSN - 1548-8659
pISSN - 0002-8487
DOI - 10.1577/1548-8659(1957)87[132:rmatro]2.0.co;2
Subject(s) - fishery , hatchery , stocking , zoology , chinook wind , biology , fish <actinopterygii> , environmental science , oncorhynchus
Return of planted fin‐clipped juveniles of fall‐migrating chinook salmon (Oncorhyncus tshawytscha) as 3‐ and 4‐year‐old spawners is considered in relation to four different rearing methods. Four groups of salmon, of about 30,000 each, were first reared for 78 days in fresh‐water and all eventually planted in estuarial waters (salinity about 22 parts per 1,000) at the mouth of the Samish River. Highest return of spawners to the Samish River (0.75 percent) was from juveniles subjected to a 5‐day conversion to 75 percent sea water after fresh‐water rearing and prior to stocking. Second highest return (0.47 percent) was from fish planted directly after fresh‐water rearing. Third highest return (0.26 percent) was from fish subjected to an 8‐day conversion to 100 percent sea water followed by 25 days of rearing in sea water. Lowest return (0.19 percent) was from fish handled as the preceding but having a 60‐day rearing period in salt water. Sizes of fish in a planting were respectively 150, 150, 49, and 25 to the pound. Rearing in and conversion to salt water was carried out about 30 miles by water from the Samish Hatchery where the fresh‐water rearing was done. Migrational timing on return to the Samish River was similar for marked fish and unmarked fish in the run