Genetic stock identification of juvenile chinook and coho salmon in the Northern California Current
Stewart Grant and David J. Teel [NOAA, Northwest Fisheries Science Center, Seattle]
One of the core hypotheses of the Northeast Pacific GLOBEC project is that events in coastal regions during the early stages of migration and maturation largely influence the survivals of chinook and coho salmon. To test this hypothesis, juvenile salmon are being sampled at several nearshore localities in the Northern California Current in related GLOBEC projects to study feeding ecology and growth. Chinook and coho salmon express complex life history patterns, and this variability can influence the interactions between coastal variability and juvenile salmon survival. Collections of juveniles in coastal waters generally include individuals from a heterogeneous mix of populations with, often genetically influenced, life-history differences that affect growth and migration. An understanding of the vital features of juveniles in coastal waters requires the identification of the life-history types being studied. One approach is to use Genetic Stock Identification (GSI) to identify the populations of origin.
We propose to examine samples of juvenile chinook and coho (if available in sufficient numbers) salmon for allozyme variability and provide estimates of population origin with proven GSI methods. These samples will be collected in the Northern California Current as a part of other studies that have been designed to understand the temporal and spatial dynamics of juvenile salmon and to relate environmental and biological variability to juvenile abundance and survival. Allozyme methods were chosen for this study, because 1) allozyme data provide a level of resolution that is appropriate to delineate genetically discrete salmon populations, 2) an extensive coast-wide baseline of spawning population data is in place, and 3) statistical methods are available to provide accurate estimates of mixed-stock composition. Coded wire tags (inserted only into hatchery fish) recovered in the samples of juveniles will provide at least some corroboration of the GSI results. Observed patterns of migration will be used to understand the relationship between environmental variability and juvenile salmon abundance.
We will proceed with two tasks in the first year. One is to collect samples from the coastal waters of Washington and Oregon, chiefly in the Columbia River plume. To date, about 1,400 juvenile chinook salmon and about 600 coho salmon have been collected, and tissues from these samples are being held at -80°C for protein electrophoretic analysis of genetic variability. The second task it to survey these samples for genotypic variability at 33 polymorphic loci. Multilocus genotypes for each fish will then be used to assign the probable spawning-population origin of the various stock components in the sample. Initial results for June and September 1998 samples taken in the Columbia River Plume showed that the GSI results were consistent with 29 coded wire tags found in a sample of 393 chinook salmon. As expected, the June and September samples had contrasting stock compositions. The June sample was composed primarily of ocean-type chinook salmon originating in the Columbia and Snake rivers, including a substantial proportion of fish from the lower Columbia River. However, in the September sample the presence of Columbia River Basin populations decreased. The largest contribution was estimated to be fish from rivers along the mid and north Oregon coast as they migrated northward in their first year. Small proportions of chinook salmon from more southern populations, including fish from California's Central Valley, were also estimated in both the June and September samples.
This page was last updated on
March 15, 2007.
Maintained by:
Hal Batchelder
College of Oceanic and Atmospheric Sciences
Oregon State University
Corvallis, OR 97331-5503
phone: 541-737-4500; FAX 541-737-2064