|Document Type:||Technical Memorandum|
|Title:||Beach and purse seine sampling of juvenile salmonids in the Columbia River estuary and ocean plume, 1977-1983. Volume II: data on marked fish recoveries|
|Author/Editor:||Earl M. Dawley, Richard D. Ledgerwood, Alvin L. Jensen|
|Tech Memo Number:||NMFS F/NWC-75|
Data for marked fish collected from 1977 through 1983 in beach and purse seine sampling of juvenile salmon, Oncorhynchus spp., and steelhead, Salmo gairdneri, in the Columbia River estuary and ocean plume are listed and summarized. Included are release information for marked fish, catch adjustments for sampling effort, weekly mean fork lengths, dates of recovery, average movement rates calculated for migration to the estuary, and fork lengths of fish recovered.
We conducted extensive beach and purse seine sampling of juvenile salmon, Oncorhynchus spp., and steelhead, Salmo gairdneri , at the upstream entrance of the Columbia River estuary, from 1977 through 1983. Limited sampling was also conducted at other locations in the estuary and the ocean plume within 24 km of the river mouth from 1978 through 1980. The sampling program provided recovery data for marked fish within a few weeks of release from hatcheries and thereby provided an early evaluation of cultural techniques which would require several years using adult data. In addition, variables that influenced survival during migration to the estuary were isolated from variables that influenced survival in the ocean. The objectives of the sampling were to:
1) define the migrational characteristics of juvenile salmonids to and through the estuary,
2) make various biological observations of migrants,
3) monitor the relative survival of marked fish migrating through the Columbia River, and
4) correlate juvenile catch data with adult recovery information to assist in evaluation of hatchery production techniques and procedures.
This report, the second of two volumes, lists and summarizes data obtained from marked juvenile salmonids. Volume I provides details of sampling methods plus effort and catch data. Analyses of the data relating to the above objectives are contained in a report entitled: Migrational characteristics, biological observations, and relative survival of juvenile salmonids entering the Columbia River estuary, 1977¿1983.