Salish Sea Marine Survival Project

4 EXECUTIVE SUMMARY The Salish Sea Marine Survival Project (SSMSP) was designed as an intensive, short-term study of the Salish Sea to simultaneously examine the major components of the salmon ecosystem; evaluate the marine survival of Chinook, Coho and steelhead; and identify the primary determinants of survival/production of these species. In a nutshell, our findings are as follows: BIOLOGICAL OCEANOGRAPHY: Changes in environmental variables (sea surface temperature, salinity, winds, and light/cloud cover) and zooplankton relate to changes in Chinook and Coho marine survival rates; confirming that annual variation in weather translates into food availability; this subsequently affects the survival and growth of juvenile salmon, and ultimately becomes a major determinant of adult returns/ abundance for Chinook and Coho Salmon in the Salish Sea. These studies also introduced a new Citizen Science Oceanography program in the Strait of Georgia that involves local citizens in monitoring of their local marine waters. We recommend on-going monitoring in the Strait in order to forecast change in salmon production, particularly under climate change. BOTTLENECKS TO SALMON SURVIVAL: Chinook salmon in the Cowichan River were intensively studied as a proxy for other systems surrounding the Strait of Georgia, and included a comparison of wild and hatchery-produced juveniles. Minimum water flows, 1 the condition of riparian and estuary habitats and hatchery release locations were critically important to juvenile salmon survival in the river; low flows of water resulted in higher losses of juvenile salmon by predators; and wild-produced juveniles survived at twice the rate of the hatchery fish. A surprising finding was the high level of predation by herons, particularly on hatchery fish. A novel tagging program identified that the early marine entry period and then the first winter at sea appear to limit production (i.e. are bottlenecks to survival). We recommend a broader application of such studies throughout the Strait, further study of the first winter at-sea, and a study of the effectiveness of salmon production from hatcheries. NEARSHORE HABITAT RESTORATION AND RESEARCH: Healthy estuaries 2 and nearshore habitats serve as nursery areas essential for sustaining production and biodiversity of forage fishes and Pacific Salmon. Coastal development and climate impacts have resulted in degraded estuaries and loss of connectivity of nearshore habitats (including marsh, kelp and eelgrass). Under climate change, warming waters and storm surge will pose increasing risks to these habitats. Our work under- scores the need for increased protection and restoration of these vital habitats including reduction of shore-line hardening, marine debris clean-up, and improvements to connectivity of nearshore habitats. These activities can engage many people in community stewardship. JUVENILE SALMON IN THE SALISH SEA: The survival and growth of juvenile Chinook and Coho Salmon through their first summer in the Salish Sea is a strong indicator of adult returns to be expected in subsequent years (1 year for Coho, and 1-3 years for Chinook). Genetic analyses of juvenile Chinook and Coho Salmon within the Strait revealed that groups of juvenile Chinook Salmon consistently rear in specific areas but that Coho were widely mixed throughout during their first summer at sea, and that location of rearing was related to patterns of survival. These studies reinforce the importance of oceanographic processes in their survival and growth. Changes in abundance and diversity of Pacific Herring in the Strait of Georgia (in particular age-0 herring, a major prey item), is likely a major determinant of the growth and survival of Chinook and Coho Salmon. We recommend actions to protect and maintain diversity in herring populations.

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