Salish Sea Marine Survival Project

76 FINAL SUMMARY The primary objective of the Salish Sea Marine Survival Project was to: DETERMINE THE PRINCIPAL FACTORS AFFECTING THE SURVIVAL OF JUVENILE SALMON AND STEELHEAD IN THE SALISH SEA. In Canada the objectives of these studies were intended to: 1. Re-build production of wild Pacific Salmon and steelhead through a program that is ecosystem- based, considers hatchery effectiveness, and engages communities; 2. Promote sustainable fisheries and increase their value to BC communities; and 3. Provide a foundation for long-term monitoring of the Salish Sea and salmon health. The Salish Sea Marine Survival Project has made a significant contribution to our understanding of wild Pacific Salmon, and our findings will allow for implementation of a number of management actions which will benefit Chinook and Coho production. Ultimately, we believe that the research results and subsequent management actions may also benefit other marine life in the Salish Sea, such as the southern resident killer whales. Key findings from our SSMSP studies are summarized in Table 1. RESEARCH TOPIC OUTCOMES Biological Oceanography Studies examined water quality, temperature, turbidity, oxygen levels, salinity, ocean acidity, nutrients and chlorophyll levels — and how variations affect marine life from phytoplankton up to forage fishes. Data were derived from moorings, buoys, satellite imagery, the PSF Citizen Science Oceanography Program, and DFO research cruises for zooplankton and herring. Changing oceanographic conditions directly alter plankton community structure, abundance and distribution, and the changes to the phytoplankton community have direct effects on higher trophic levels, such as changes in composition and abundance of zooplankton and larval fish assemblages; changes to zooplankton prey quality; impacts on harmful algal blooms; and abundance of forage fish such as herring. Warming waters and impacts of the North Pacific "Blob" in the Strait of Georgia over the course of SSMSP were conditions that are completely out of our experience, and which created a mixture of positive and negative outcomes for salmon. There were negative impacts to kelp populations, but at the same time, increased abundance of Northern anchovy in the Strait, and increased growth of juvenile Coho and Chinook. This study has informed us on the drivers of spring bloom in the Strait of Georgia. The amount of Chlorophyll 'a' in the Northern Strait is strongly linked with large-scale ocean climate indices (e.g. Pacific Decadal Oscillation) whereas in the Central Strait it is more strongly influenced by localized factors (e.g. Fraser River discharge) and thus indirectly related to climate indices. Certain areas of the Strait of Georgia are production 'hotspots" for phytoplankton and zooplankton. Temperatures below 17° C are best for juvenile salmon early rearing; given that surface waters were warmer than this in July and August for 2015-2017, it appeared that waters as deep as 10 m in the summer in most regions of the Strait were not good habitat for juvenile salmon. However, there were regional variations, with favorable water temperatures in highly mixed areas of the Strait (e.g. Campbell River and the Gulf Islands). Harmful algal blooms (both toxic and mechanically harmful species) are common in the Strait and they affect wild juvenile salmon with impacts similar to those previously confirmed in BC salmon farms e.g. reduced feeding, changes in diet, histopathological changes showing damage in the liver, brain, gills etc., and signs of starvation. Table 1: SSMSP Findings in a Nutshell

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