ADFG Forecasts 2017 Sockeye Run

Photo by user "echoforsberg"/Wikimedia
Photo by user “echoforsberg”/Wikimedia
Photo by The Breach Film


The Alaska Department of Fish and Game has released its 2017 sockeye salmon forecast for the Bristol Bay watershed. You can view the entire report here. But let’s take a look at some of the numbers projected:

Listed in millions

Total Run 41.47

Forecast Range 31.20–51.73

Escapement 12.46

Commercial Common Property Harvest 29.01

Bristol Bay Harvest 27.47

South Peninsula Harvest 1.53

Inshore Run 39.93

From the report:

METHODS The 2017 Bristol Bay sockeye salmon forecast is the sum of individual predictions of nine river systems (Kvichak, Alagnak, Naknek, Egegik, Ugashik, Wood, Igushik, Nushagak, and Togiak rivers) and four age classes (ages 1.2, 1.3, 2.2, and 2.3, plus ages 0.3 and 1.4 for the Nushagak River). Adult escapement and return data from brood years 1972–2013 were used in the analyses. Predictions for each age class returning to a river system were calculated from models based on the relationship between adult returns and spawners or siblings from previous years.

Tested models included simple linear regression and recent year averages. In general, models chosen were those with statistically significant parameters having the greatest past reliability (accuracy and precision) based on mean absolute deviation, mean absolute percent error, and mean percent error between forecasts and actual returns for the most recent three year (2014–2016) and five year (2012–2016) windows.