Juvenile Salmon Migration Observations from the Hakai Institute Juvenile Salmon Program in the Discovery Islands in British Columbia, Canada in 2020

The Hakai Institute Juvenile Salmon Program has been monitoring juvenile salmon migrations in the Discovery Islands in British Columbia, Canada since 2015 with the specific purpose to understand how ocean conditions experienced by juvenile salmon during their early marine migration impact their growth, health, and ultimately survival. This report summarizes migration timing, purse-seine catch intensity and composition, fish length and weight, sea-louse loads, and ocean temperatures observed from six years of this research and monitoring program. Migration timing for sockeye, pink, and chum was not significantly different than respective time-series averages and occurred on May 23 for sockeye, June 17 for chum, and on June 20 for pink salmon. In order of highest to smallest catch proportion seines were dominated by juvenile pink, sockeye, and chum salmon. Catch intensity (our relative abundance measurement) for chum was the lowest on record in the time series, though sockeye and pink catch intensity were nearer their time-series averages. Mean annual fork length for sockeye, pink, and chum salmon were all within the time-series average range. The abundance of pre-adult and adult Caligus clemensi sea lice was relatively high on juvenile sockeye, pink, and chum salmon in 2020 compared to previous years. The salmonid-specialist sea louse, Lepeophtheirus salmonis, had relatively high abundance on pink and chum salmon but low abundance on sockeye. May–June 30 m depth integrated ocean temperature in the northern Strait of Georgia in 2020 was 0.79 °C warmer than average for the time series (2015–2020), and the warmest observed in this time series.