The Salish Sea Marine Survival Project: Canadian Program Summaries summarizes findings from the Pacific Salmon Foundation’s five year study on salmon declines in the Strait of Georgia.
Issue link: http://digital.canadawide.com/i/1354465
70 COHO SURVIVAL CHINOOK SURVIVAL SITE RELEASE STRATEGY BY 2013 BY 2014 BY 2015 BY 2016 BY 2014 BY 2015 Big Qualicum River Traditional - 1.54% 2.53% - 0.54% 0.16% Delayed - 2.88% 6.48% - 1.10% 1.11% Quinsam River Traditional - 0.95% 1.63% 1.96% 0.32% 0.40% Delayed - 2.67% 5.01% 2.82% 0.63% 0.64% Inch Creek Traditional 3.28% 4.08% 5.94% 4.51% Delayed 4.10% 3.54% 6.25% - Chilliwack River Traditional - 3.20% * * Delayed - 2.60% * * Seymour River Delayed 6.70% * * * * Results not yet available STUDIES OF HATCHERY SALMON BACKGROUND PSF supported a number of projects that were designed to assess hatchery-wild interactions in the Salish Sea, as well as to improve understanding of the behaviour, marine distribution, habitat use and survival of hatch- ery-produced salmon. Some of these studies also investigated how to produce hatchery fish that survive at higher rates in the marine environment, which may then allow for reductions in hatchery production while at the same time sustaining or improving adult salmon production. PROJECTS 1. Delayed Release of Hatchery Coho and Chinook Salmon in the Strait of Georgia Past studies on the influence of time and size at release of juvenile Coho and Chinook Salmon on their juvenile survival and subsequent return as mature fish indicated that a later sea entry and larger body size increased marine survival. Large late releases of Coho may also result in a greater proportion of Coho residing in the Strait of Georgia (i.e., 'inside' distribution) during their second summer at sea where they may be more available to the local fisheries. Trials on late releases of large hatchery Coho and Chinook Salmon, funded by the SSMSP, were conducted for three years (2014-2016) at Quinsam and Big Qualicum hatcheries on the East Coast of Vancouver Island. Funding supported the extended rearing, feeding and coded wire tagging of smolts at these facilities, as well as the coded wire tagging of a late large release of Coho at the Seymour River Hatchery in the lower mainland. Similar trials on late releases of large hatchery Coho at Chilliwack and Inch Creek were conducted concurrently by the DFO Salmon Enhancement Program (SEP). At these hatcheries, Coho and Chinook juveniles were reared and released at a later date, typically late June, along with a traditional production group which were released in May for comparisons. Seymour Hatchery released all of their Coho smolts in June. Although later releases of Coho and Chinook were at a larger size than the traditional May releases, their growth during the extended rearing period was controlled such that the target size at release would be representative of their estimated size in the marine environ- ment had they been released in the traditional May period. Results to date suggest Big Qualicum and Quinsam Coho and Chinook stocks may be benefiting from later/larger releases with up to a three-fold increase in survival over traditional releases for Coho, and as much as 6 times greater survival for Big Qualicum BY 2015 Chinook. In contrast, mainland populations of Coho from Inch Creek did not show any change in survival between the two strategies but data have yet to be compiled for Chilliwack Hatchery Coho in 2015-2016. Returns beyond 2019 will allow for more detailed evaluations, providing more clarity on the potential benefits of large late Coho and Chinook release strategies. Table 1. Survival of Brood Year (BY) 2013-2016 Coho and BY2014 and 2015 Chinook from traditional and delayed juvenile releases.