Some results of monitoring for the pink salmon hatchery stocks from the Aniva Bay (Sakhalin Island)

Several population parameters (length and dynamics of spawning run, size-sex composition, variability of morphological and physiological characteristics) are determined and indices of survival are calculated for the pink salmon hatchery stocks from the Aniva Bay of the 2008-2011 generations on the base of the cultured pink salmon differentiation by thermal marks on otoliths. The hatchery pink salmon begin their migration to the bay rivers in late July, together with the wild fish. Size-weight parameters of the fish and their variability are similar for the hatchery and wild stocks in this period, obviously because of low impact of hatcheries on natural reproduction and high portion of wild fish among the spawners used in the hatcheries (> 50 %). Mean portion of the hatchery-reared pink salmon on spawning grounds of the main rivers was 17.9 % in the 2010-2013, the coefficients of their return varied from 1.0 % to 6.4 % that was lower than for the wild fish.

Advances in Fish Tagging and Marking Technology

<i>Abstract</i>.—We investigated the marine migratory behavior and survival of Sakinaw Lake sockeye salmon <i>Oncorhynchus nerka </i>during their outbound migration as juveniles and return migration as adults two or more years later by tracking individuals that had been implanted with Vemco acoustic tags programmed to have two periods of active transmission. We tracked both hatchery-reared anadromous sockeye salmon (‘hatchery sockeye’) and wild nonanadromous ‘kokanee,’ two genetically-distinct, sympatric ecotypes inhabiting Sakinaw Lake, British Columbia. Tagged kokanee were distinguished from wild sockeye by haplotype frequencies at two mitochondrial DNA genes. Migrations were inferred from detections by the Pacific Ocean Shelf Tracking (POST) receivers, and supplemental tracking near the release site and in Sakinaw Lake. We found no significant differences between the ecotypes in the proportion of ‘migratory’ fish (those detected migrating seaward by POST telemetry in the year of release, 42% of all 254 fish released) or in the proportion of ocean-going fish (those detected at receivers near the open ocean, 20% of all fish released). Seaward migration in both ecotypes was primarily northward through Johnstone Strait in 2 of the 3 years studied (92% of migratory fish in 2004 and 84% in 2006). A significantly higher proportion of fish moved southward in 2005 (45% of migratory fish) than in 2004 or 2006, but this difference could not be attributed to ecotype, body size, or release date. One significant difference observed between the ecotypes was that 6 kokanee but no sockeye migrated back into Sakinaw Lake within 2 weeks of release in 2006. The number of tagged fish detected as returning adults with operational tags was low (3 sockeye at the release site and 2 kokanee at Sakinaw Creek), but none of these fish had been detected crossing seaward POST lines as juveniles and thus appeared to be nonmigratory. The adult return rate of these nonmigratory tagged fish (3.4% in sockeye, 4.3% in kokanee) was higher than for migratory tagged fish (0% for both ecotypes). This discrepancy suggests that factors outside the Strait of Georgia have caused the poor marine survival that is preventing recovery of the endangered Sakinaw sockeye population (mean <0.2% since 2003).