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Supplement to the pre-season abundance forecasts for Fraser River Sockeye Salmon returns in 2016

Regional Science Response Process – Pacific Region

January 21-22, 2016
Vancouver, BC

Chairperson: Sue Grant

Context

The factors that drive Fraser Sockeye population dynamics (i.e. declining trend in survival through the 1990’s versus improved survival in recent years for most stocks) are currently poorly understood. As a result, Fraser Sockeye pre-season return forecasts are associated with high uncertainty (i.e. broad prediction intervals). Return forecasts are required annually for fisheries management, and improvements in forecast precision would assist planning processes.

In order to improve our understanding of Fraser Sockeye population dynamics, related research will be synthesized by the experts in Fisheries and Oceans Canada (DFO) and the Pacific Salmon Commission working on Fraser Sockeye. This will also include experts on lake limnology in areas where Fraser Sockeye spend their first few years of life, and experts on ocean conditions in the Northeast Pacific Ocean where Fraser Sockeye spend their last few years of life.

The first component of this process will be to evaluate the 2015 Fraser Sockeye supplement and forecast against preliminary 2015 in-season returns. This evaluation will broadly assist with improving our understanding of Fraser Sockeye population dynamics. It will also assist with informing the group of the expected survival of five year olds returning in 2016. For a number of stocks, five year olds are expected to contribute a higher proportion to total returns than usual, due to the negligible four year old brood year escapements (i.e. poor 2012 escapements for a number of stocks).

The second component of this process will be to summarize information on Fraser Sockeye from the 2012 brood year that will return as four year olds in 2016. Information to be synthesized includes: brood year adult return migration and fish health; spawning ground assessments on sockeye numbers and condition; nursery lakes’ limnology and carrying capacity; abundance and condition of juvenile fish in lake rearing habitats; abundance and size of outmigrating smolts at their lake outlets; and relative abundance and condition of migrating juveniles sampled in the Mission juvenile monitoring program, and in the Strait of Georgia and Johnstone Strait. DFO expertise on ocean conditions will also be synthesized in the context of Fraser Sockeye health and survival. Stocks expected to contribute the most to the total 2016 return include the following: Chilko (~40% of the total predicted return), Stellako (~11%), and Chilliwack, Quesnel and Late Stuart (each at ~8%).

Science Branch has requested this information to support and supplement the 2016 pre-season abundance forecasts for Fraser River Sockeye Salmon. Pre-season abundance forecasts are used for planning fisheries and are a Canadian obligation under the Pacific Salmon Treaty. DFO, the Pacific Salmon Commission, and the Canada-US bilateral Fraser River Panel will be the primary users of this Science Response (SR).

Results will be reported via a Science Response (SR) and will serve as background information for subsequent advisory processes on this issue.

Objectives

Specific objectives for this SR process are as follows:

  1. Evaluate the 2015 Fraser Sockeye supplement and forecast against preliminary 2015 in-season returns.
  2. Review returns, adult migration conditions, escapement and fish condition, and environmental conditions in 2012.
  3. Review juvenile abundance and condition in the freshwater environment in 2012, including density-dependent mechanisms for particular stocks (i.e. Shuswap and Chilko).
  4. Review juvenile abundance and condition in the marine environment.
  5. Review Northeast Pacific Ocean conditions from 2014 through to time of publication.
  6. Review three year old sibling models (jacks and 3sub1 fish for Harrison).
  7. Review relationships with other stocks as indicators of Fraser Sockeye survival.
  8. Explore uncertainty in the information presented.

The results of this SR process will inform the 2015 return forecasts for Fraser River Sockeye Salmon following the methods of Grant and MacDonald (2012), MacDonald and Grant (2012), Grant and MacDonald (2011), and Grant et al. (2010).

Expected Publication

 Expected Participation

References

DFO. 2014a. Pre-season run size forecasts for Fraser River Sockeye (Oncorhynchus nerka) Salmon in 2014. DFO Can. Sci. Advis. Sec. Sci. Resp. 2014/040.

DFO. 2014b. Supplement to the pre-season return forecasts for Fraser River Sockeye Salmon in 2014. DFO Can. Sci. Advis. Sec. Sci. Resp. 2014/041. 57 p.

Grant, S.C.H. and MacDonald, B.L. 2011. Pre-season run size forecasts for Fraser River Sockeye and Pink Salmon in 2011. DFO Can. Sci. Advis. Sec. Res. Doc. 2011/134. vi + 48 p.

Grant, S.C.H. and MacDonald, B.L. 2012. Pre-season run size forecasts for Fraser River Sockeye (Oncorhynchus nerka) and Pink (O. gorbuscha) salmon in 2013. DFO Can. Sci. Advis. Sec. Res. Doc. 2012/145. vi + 42 p.

Grant, S.C.H., Michielsens, C.G.J., Porszt, E.J. and Cass, A. 2010. Pre-season run size forecasts for Fraser River Sockeye salmon (Oncorhynchus nerka) in 2010. DFO Can. Sci. Advis. Sec. Res. Doc. 2010/042. vi + 125 p.

MacDonald, B.L. and Grant, S.C.H. 2012. Pre-season run size forecasts for Fraser River Sockeye salmon (Oncorhynchus nerka) in 2012. DFO Can. Sci. Advis. Sec. Res. Doc. 2012/011. v + 64 p.

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