Science Advisory Report  2012/026

Pacific sardine 2011 seasonal biomass and migration in British Columbia and harvest advice for 2012

Summary

• Marine waters off the west coast of Vancouver Island serve as a migratory corridor as well as preferred foraging habitat for large aggregations of Pacific sardines between June and October.
• Sardines in British Columbia waters are forage for many pelagic and migratory marine predator species.
• Population and WCVI seasonal abundance trends both show increases in sardine biomass from 2010 to 2011. The 2009 year class had above average recruitment and likely contributed to the population increase.
• In 2011, the total sardine catch from B.C. waters was 20,621 tonnes, approximately 95% of the total allowable catch of 21,917 tonnes.  All harvesting occurred in waters off the WCVI, with the majority of catch coming from Pacific Fishery Management Areas 23, 25 and 123.
• Fishery Management Framework harvest control rules for setting the annual maximum available commercial harvest are based on the product of three factors: 1) current sardine biomass estimates of the Northeast Pacific population (e.g. from Ensenada Mexico to British Columbia) from a U.S. led stock assessment, 2) an estimated running average seasonal migration rate into B.C. waters, and, 3) an annual harvest rate (ranging from 5-15%) approximating what is applied in the U.S. (15% since 2002).
• Changes to the population assessment model resulted in some re-scaling of biomass estimates in the time series, which resulted in reducing 2006-2010 migration rates (and harvest rates) from previously reported estimates.
• The estimated 2011 adult (age 1 year and older) sardine biomass (and 95% confidence interval) representing the northeast Pacific California Current population as of July 2011 (from a U.S. led stock assessment) is 988,385 (619,322 – 1,357,448) tonnes. 
• The estimated 2011 sardine biomass (and 95% confidence interval) for the WCVI survey region is 151,162 (82,361 – 230,051) tonnes. The extrapolated 2011 biomass estimate for mainland inshore areas is 21,822 tonnes. The extrapolated 2011 biomass estimate for WCVI inlets is 9,451 tonnes.
• The estimated three-year average sardine migration rate into B.C. waters is 18.4% and the forecasted average sardine biomass for the season starting in 2012 is 181,863 tonnes. 
• Due to high levels of uncertainty associated with inshore area biomass extrapolation methods, especially in the absence of sardine observations from some inshore PFMAs, it is recommended that the methods and rules associated with estimating sardine biomass in un-surveyed areas be re-evaluated.
• Given uncertainty associated with B.C. sardine biomass forecasts under the current harvest guideline control rules, additional consideration of alternative harvest control rules and/or alternative biomass forecasting is recommended.
• Fishery Managers are advised to consider uncertainty associated with biomass forecasting for the fishing season starting in 2012 and risks of exceeding the maximum harvest rate (e.g. 15%) if there is an inter-annual decline in biomass.  They are also advised to consider uncertainty associated with localized ecosystem attributes, such as incidental harvest of other species and possibly important forage habitat of sardine predators.

This Science Advisory Report has resulted from a Fisheries and Oceans Canada, Canadian Science Advisory Secretariat Pacific Regional Advisory Meeting of January 10, 2012 on Pacific sardine 2011 seasonal abundance and migration in British Columbia and harvest advice for 2012. Additional publications from this process will be posted as they become available on the DFO Science Advisory Schedule.

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