A brief history of Susitna salmon

A brief history of Susitna salmon management begins when the first escapement goal was set for Susitna sockeye in 1979.

A Bendix sonar counter was placed into service about that time to measure the escapement. In the late 1980s, the goal was revised based on a study of 24 sockeye-producing lakes in the Susitna drainage.

The purpose of an escapement goal is to ensure sustainability and maximize yield (harvest). State policy requires that escapements goals must be scientifically defensible.

For over 25 years there was a perception that the sockeye returning to the Susitna River were not meeting the escapement goals. This was driven by the assumption that the Bendix sonar counter was accurately counting the sockeye escapements. The perception led to numerous time and area restrictions on the Central District drift fleet and Northern District setnets.

The escapement counts in the Susitna were periodically called into question, particularly after the 1989 season when the Exxon Valdez oil spill caused drift gillnetting to be closed in Cook Inlet. The closure resulted in a large over-escapement in the Kenai River but had no apparent effect on the Susitna escapement sonar count. Increasing uncertainty with the Susitna escapement assessment prompted ADF&G to initiate a 3-year study in 2006. The study utilized a DIDSON system, weir counts and a mark-recapture program to compare with the Bendix sonar counts.

In 2009 ADF&G released a special report because the study determined that the errors with the sonar counts were so significant. (ADF&G, FMS 09-01) The report documented that both the Bendix and DIDSON were grossly underestimating the number of sockeye salmon returning to the Susitna system.

The study results indicated that the Bendix sonar count (dating back to 1981) was biased low by more than 100 percent. From 1981 through 2008 escapement goals were being exceeded by an average of more than 100 percent, some years the goals were exceeded by 300-400 percent or more. More recent data indicates that trend continued until at least 2011. A reasonable person would think that, once this error was discovered, both ADF&G and the Board of Fisheries would revise the management plans that were based on this faulty data, but they did not and still have not.

During the decades that time and area restrictions were placed on the drift fleet to conserve northern sockeye stocks, no studies were ever done and no evidence or data was ever generated to show that the restrictions had any effect on escapements. What we have learned from the use of mandatory restrictions is that they prevent fishery managers from reacting to real-time information during the season and interfere with their ability to manage the whole fishery. Harvest opportunity has been lost due to the restrictions; not only the millions of sockeye that exceeded escapement goals in the Susitna, but also millions of sockeye that exceeded escapement goals in other Cook Inlet systems due to mandatory restrictions that were based on the faulty sonar data and flawed assumptions.

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