searun
Well-Known Member
Here you go, latest forecast for Area 23 WCVI:
WCVI Area
2014 WCVI CHINOOK PRE-SEASON FORECAST - AMENDED
Overall, the total production of WCVI chinook stocks for 2014 is expected to increase by about 25% relative to 2013 observations. However, due to the large Abundance Index (AI) for the Southeast Alaska (SEAK) AABM fishery, the resulting SEAK TAC, and the predicted stock composition of SEAK catch, fishery impacts in the SEAK AABM are also modelled to increase relative to 2013 by over 50%.
Return to Canada
The forecast return of adult Somass (Robertson Creek Hatchery + Somass River) chinook to Canada in 2014 is about 34,400 (Table 1). In 2013, Somass chinook accounted for 18% of WCVI chinook salmon production. In 2014, Somass origin chinook are expected to account for about 15.5% of WCVI chinook salmon production (Figure 2). Therefore, about 221,600 WCVI origin chinook are forecast to return to Canada (34,400/0.155). Allowable mortality in the Northern BC Troll fishery is 3.2% of the return to Canada. Based on pre-season expectations, this level amounts to approximately 7100 interceptions (221,600*0.032).
Somass chinook pre-season forecast (Area 23 Terminal Return)
The forecast terminal return of adult Somass chinook to Barkley Sound and Alberni Inlet for 2014 is approximately 30,000, similar to the level observed in 2013 (Table 1, Table 1). The predicted adult age composition is 8%, 85% and 7% of 3, 4 and 5-year old fish, respectively. This forecast is a low return of Somass chinook given the 25 year average of approximately 100,000 (90,000 adults) fish returning to the terminal area.
At a forecast terminal return of 30,000 adults, limited directed chinook fisheries are anticipated in the terminal Alberni Inlet area (Area 23-1).
While lower hatchery production in the recent period relative to the historic is a factor in the 2014 forecast, the key driver is lower than the lower than average marine survival rate of two of the three contributing brood years. CWT data for both the 2009 brood year and 2011 brood years (2010 and 2012 sea entry years, respectively) suggest marine survival rates forthose broods were extremely low. To date, the marine survival rate observed for 2009 and 2011 brood years are estimated at 0.34% and 0.17%, respectively; some of the lowest observations on record.
Forecast performance / Uncertainty
The performance of pre-season forecasts is evaluated according to the deviation of observed return from forecast return. Expressed as a mean absolute percentage error (MAPE), over the long term the terminal Somass chinook forecast performs with a MAPE of 25%. That is, the actual return is typically 25% higher or lower than the pre-season forecast. In the 3 most recent years, the tendency has been to underforecast return (Figure 1).
The forecast models predict the return of older age classes with progressively more accuracy as more information is available regarding brood survival rate as the cohort matures (i.e. the 5-year old forecast is more accurate than the 3-year old forecast). For 2014, the majority of the forecast terminal return is 4 and 5 year old adults.
Other WCVI chinook populations:
The trend in brood survival and harvest impacts for other WCVI chinook populations are assumed similar to the Robertson Creek Hatchery Indicator Stock. Therefore, it is possible to use brood survival and exploitation rate information from Robertson Creek to forecast returns for other WCVI terminal areas or populations. When detailed age data information is available for contributing brood years from these other stocks (i.e. sibling performance of earlier age classes that have already returned), this information is used to adjust expecations for these stocks.
Overall, forecast returns of the entire WCVI chinook unit (hatchery and wild) are expected to increase relative to 2013 (Table 3). The major contribution is expected from terminal abundances in Nootka (Conuma Hatchery) and Nitinat; which are foreast to return at record abundances unlike the Somass/RCH forecast which remains low.
The main reason for the divergence of Somass/RCH from other WCVI stocks is a relative increase in the marine survival rate of these stocks. Although not directly measured through CWTs, recent marine survival rates for the other major hatcheries and some other WCVI stocks appears to be significantly higher than the survival of stocks originating from Area 23. This observeration is particulary apparent for the 2009 brood year that returns as 5 year olds in 2014.
Overall, returns of other WCVI stocks (wild and enhanced) are expected to be somewhat lower than 2013 (Table 4). In 2013, escapements to Clayoquot Sound (Area 24) and Nootka Sound (Area 25) were generally improved relative to the 10-year average. In other WCVI areas, observed escapement levels remained relatively low at about the 10 year average. Some enhanced stocks, such as the Burman River (Area 25) and Cypre River (Area 24) observed record returns.
WCVI Area
2014 WCVI CHINOOK PRE-SEASON FORECAST - AMENDED
Overall, the total production of WCVI chinook stocks for 2014 is expected to increase by about 25% relative to 2013 observations. However, due to the large Abundance Index (AI) for the Southeast Alaska (SEAK) AABM fishery, the resulting SEAK TAC, and the predicted stock composition of SEAK catch, fishery impacts in the SEAK AABM are also modelled to increase relative to 2013 by over 50%.
Return to Canada
The forecast return of adult Somass (Robertson Creek Hatchery + Somass River) chinook to Canada in 2014 is about 34,400 (Table 1). In 2013, Somass chinook accounted for 18% of WCVI chinook salmon production. In 2014, Somass origin chinook are expected to account for about 15.5% of WCVI chinook salmon production (Figure 2). Therefore, about 221,600 WCVI origin chinook are forecast to return to Canada (34,400/0.155). Allowable mortality in the Northern BC Troll fishery is 3.2% of the return to Canada. Based on pre-season expectations, this level amounts to approximately 7100 interceptions (221,600*0.032).
Somass chinook pre-season forecast (Area 23 Terminal Return)
The forecast terminal return of adult Somass chinook to Barkley Sound and Alberni Inlet for 2014 is approximately 30,000, similar to the level observed in 2013 (Table 1, Table 1). The predicted adult age composition is 8%, 85% and 7% of 3, 4 and 5-year old fish, respectively. This forecast is a low return of Somass chinook given the 25 year average of approximately 100,000 (90,000 adults) fish returning to the terminal area.
At a forecast terminal return of 30,000 adults, limited directed chinook fisheries are anticipated in the terminal Alberni Inlet area (Area 23-1).
While lower hatchery production in the recent period relative to the historic is a factor in the 2014 forecast, the key driver is lower than the lower than average marine survival rate of two of the three contributing brood years. CWT data for both the 2009 brood year and 2011 brood years (2010 and 2012 sea entry years, respectively) suggest marine survival rates forthose broods were extremely low. To date, the marine survival rate observed for 2009 and 2011 brood years are estimated at 0.34% and 0.17%, respectively; some of the lowest observations on record.
Forecast performance / Uncertainty
The performance of pre-season forecasts is evaluated according to the deviation of observed return from forecast return. Expressed as a mean absolute percentage error (MAPE), over the long term the terminal Somass chinook forecast performs with a MAPE of 25%. That is, the actual return is typically 25% higher or lower than the pre-season forecast. In the 3 most recent years, the tendency has been to underforecast return (Figure 1).
The forecast models predict the return of older age classes with progressively more accuracy as more information is available regarding brood survival rate as the cohort matures (i.e. the 5-year old forecast is more accurate than the 3-year old forecast). For 2014, the majority of the forecast terminal return is 4 and 5 year old adults.
Other WCVI chinook populations:
The trend in brood survival and harvest impacts for other WCVI chinook populations are assumed similar to the Robertson Creek Hatchery Indicator Stock. Therefore, it is possible to use brood survival and exploitation rate information from Robertson Creek to forecast returns for other WCVI terminal areas or populations. When detailed age data information is available for contributing brood years from these other stocks (i.e. sibling performance of earlier age classes that have already returned), this information is used to adjust expecations for these stocks.
Overall, forecast returns of the entire WCVI chinook unit (hatchery and wild) are expected to increase relative to 2013 (Table 3). The major contribution is expected from terminal abundances in Nootka (Conuma Hatchery) and Nitinat; which are foreast to return at record abundances unlike the Somass/RCH forecast which remains low.
The main reason for the divergence of Somass/RCH from other WCVI stocks is a relative increase in the marine survival rate of these stocks. Although not directly measured through CWTs, recent marine survival rates for the other major hatcheries and some other WCVI stocks appears to be significantly higher than the survival of stocks originating from Area 23. This observeration is particulary apparent for the 2009 brood year that returns as 5 year olds in 2014.
Overall, returns of other WCVI stocks (wild and enhanced) are expected to be somewhat lower than 2013 (Table 4). In 2013, escapements to Clayoquot Sound (Area 24) and Nootka Sound (Area 25) were generally improved relative to the 10-year average. In other WCVI areas, observed escapement levels remained relatively low at about the 10 year average. Some enhanced stocks, such as the Burman River (Area 25) and Cypre River (Area 24) observed record returns.
