Fraser River Sockeye Fisheries and Fisheries Management - Cohen ...

each district. A variety of methods have been tried/used for system-specific pre-seasonforecasting in Bristol Bay, but can be generalized into four types: (1) means models, (2)spawner-recruit models combined with assumed age composition, (3) sibling models, and(4) smolt models combined with assumed age composition. Beginning in 2001, allmodels were tried, but only the top performing model over the previous three years isused for the upcoming forecast. Forecasts are less reliable for individual stocks than allstocks combined. The high and low errors for individual stocks tend to cancel each other;as a result, total run forecasts for half of the years (i.e., the median) were within 15% oftheir corresponding observed returns and did not consistently over- or underestimate byan appreciable amount (MPE= -3%; 1990-2010).In-season forecasting – In-season forecasts of returns to either the Bay as a whole or tospecific fishing districts are not reported by ADF&G and done on an ad hoc basis byresearch staff and AMBs. Two sources of data are used for in-season forecasting: (1) thePort Moller test fishery, which intercepts the run 6-8 days prior to arrival in the Bay, and(2) catch and escapement (C+E) to date. The manager’s use of the Port Mollerinformation depends on how well the test fishery tracts the C+E estimates during the firstpart of the season. Given that subtle changes in run timing can affect the in-seasonforecasts, these forecasts are not particularly precise until later in the season when about60% of the run has returned. The performance of both forecasts improves as the seasonprogresses, and during the peak of the run (around July 4) MAPE for the C+E method isabout 5% on average, but about 30% for the test fishery forecast.Management – Ultimate management authority for salmon fisheries in Alaska rests withthe Commissioner of the Alaska Department of Fish and Game (ADF&G). Regulationsand regulatory management plans are established through a public process via the AlaskaBoard of Fisheries (BOF). Salmon fisheries in Alaska, including Bristol Bay, aresomewhat unique compared to other jurisdictions in that the Commissioner of ADF&Gdelegates full management authority to open the fishery to local Area ManagementBiologists (AMBs). ADF&G’s research biologists develop biological escapement goalsfor individual river systems based on sustained yield and/or maximum sustained yield(MSY) principles using relationships between escapement levels and subsequent returns(termed stock-recruit analyses). The primary duty of all AMBs is to hit these goals anddistribute the escapements across the season based on historical run timing schedules.The tools available to AMBs in more or less chronological order are: (1) pre-seasonforecasts, (2) offshore test fishing at Port Moller, (3) district test fishing, (4) commercialfishery performance with catch and age sampling, (5) inside test fishing, (6) aerialsurveys, (7) escapement monitoring. Historically, AMBs have been very adept at hittingescapement goal targets for several reasons: (1) catch and escapement estimates are very126