Science Advisory Report  2012/032

Assessment of west coast Vancouver Island Chinook and 2010 Forecast

Summary

• The status of wild WCVI Chinook remains poor.  Over the last 15 years wild populations in south-west Vancouver Island have continued to decline despite management actions. Wild populations from north-west Vancouver Island are more stable; however they are only stable at low levels and show no signs of rebuilding.
• Many of the other index systems, which have not declined, are dependent on hatchery supplementation to maintain current spawner levels.  Sampling of escapement for hatchery marks indicates that a high proportion of spawners in some systems in some years are hatchery origin fish.
• Of particular concern, are wild populations originating from the south-west area of Vancouver Island. Wild spawner populations in Area 24 (Clayoquot Sound) have declined an average of 53% over the last three generations despite relatively pristine freshwater habitat and harvest reductions.
• Currently, a few productive (or enhanced) systems and hatcheries contribute to the bulk of WCVI Chinook production (i.e 90%). A consequence of the current management system is the mass production from WCVI hatcheries increases the allowable harvest rate in PST-regulated AABM fisheries where hatchery and wild stocks are treated similarly.
• From 1995 to 2009, the average estimated annual fishing mortality was 18% in US AABM (Southeast Alaska) fisheries; 11.5% in Canadian ocean (AABM) fisheries and the average terminal (ISBM) exploitation rate was 22%, based on an analysis of coded wire tags (CWTs). From 1997 to 2007, the management objective for WCVI Chinook was a 10% to 15% maximum mortality in Canadian AABM fisheries. From 2008, the management objective has been a 10% maximum mortality in Canadian AABM fisheries.
• With the exception of terminal fisheries targeting hatchery surpluses (e.g. Alberni Inlet, Barkely Sound, Tlupana Inlet and Nitinat Lake) ISBM fishing mortality is assumed low (i.e. <5%) because fishing opportunities in areas where wild WCVI Chinook are vulnerable are severely restricted.
• Stakeholders are concerned about the potential impact of near-shore activities (e.g. aquaculture) on WCVI Chinook populations, particularly in Nootka Sound (Area 25) and Clayoquot Sound (Area 24). However, there is uncertainty in level of harvest in some areas and the role additional harvest among other factors, such as marine mammal predation, may play in the decline of populations there.
• The 2009 terminal return to the Stamp River/RCH indicator stock was estimated at about 43,200 adults and 5000 jacks (age-2 males), approximately 8% less than forecast.
• The 2010 forecast total return of Stamp River/RCH Chinook to Canada is 48,700. After Canadian ocean fisheries, the forecast return of adult Stamp/RCH Chinook to the terminal area of Barkley Sound and Alberni Inlet is 42,900, similar to levels observed in 2009.
• In 2010, the age-4 component is forecast to comprise 41% of the terminal run (27% age-3, 41% age-4, and 31% age-5), with an expected sex ratio of 46% female.
• For 2010, expectations for WCVI natural stocks are similar to the 2009 observed return.  However, the outlook for SWVI populations is below recent average abundance whereas the outlook for NWVI is about recent average levels.

This Science Advisory Report is from the May 26 & 27, 2010 Cultus Lake Sockeye Stock Status, 2010 Barkley Sound Sockeye Forecast, 2010 West Coast Vancouver Island Chinook Abundance Forecast, and Fraser River Sockeye Spawning Initiative Meeting. Additional publications from this process will be posted as they become available on the Fisheries and Oceans Canada Science Advisory Schedule.

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