Stories lead to educated guesses

I had to do a little checking, but if I figured correctly, this column marks the beginning of my 11th year writing about outdoor topics and politics for this newspaper. Trust me; I’m as surprised as you are that I’m still here. Back when I was first asked to write this column on a weekly basis, I almost passed on the offer because I didn’t think I could come up with a topic a week that would appeal to you, the readers.

Since then, I’ve found that there are a lot more things to write about than I have space or time to address. I have tried to present items that are either of significant importance or that I think are of interest for folks to read. My editors have been very supportive of my column ideas, as long as I tie the topic to life here in the Valley. For the most part, I think I’ve done that. The editors have also been great about not rewriting my material very much, so the screw-ups, when they have occurred, are mine and mine alone.

Now for the good stuff. We’ve been discussing the fisheries management situation in Cook Inlet the past couple of weeks and I promised to go into more detail on aspects of this fishery. The 2011 sockeye salmon run has been record-breaking for Cook Inlet. Fish and Game originally predicted a total return of 3.9 million reds to the Kenai River. The last I heard, the return was being estimated at between 6 million and 7 million fish.

This is noteworthy from several points of view. First, it demonstrates how widely inaccurate department return estimates can be. This 2011 sockeye return is 180 percent of the original estimate. And, no, I’m not picking on Fish and Game. It has publically stated that the accuracy of the preseason return estimates have varied over the years from within 5 percent of the actual return to as far off as 100 percent — either being double or half of the actual run.

This year’s forecast is close to the later. Since fish processors often gear up their operations based on preseason forecasts, an error of the magnitude seen here can have interesting consequences during the season. An example would be putting fishermen on quotas since the processors weren’t ready for the huge volumes of fish being caught. That happened in Cook Inlet this summer.

I hope the department attempts to refine and improve its preseason forecasting methodology. I know there are some predictive models in the private sector that at least equal, and usually best, the accuracy of the department models and methods. Maybe some discussions should begin between the two groups to come up with a method that will better serve everyone.

A second perspective on this huge return has to do with the term “over-escapement.” At the 2008 Board of Fisheries (BOF) Upper Cook Inlet meeting, the commercial fisheries industry folks ardently maintained that way too many fish had escaped up the Kenai for the previous few years. They stated, as fact, that the Kenai sockeye run was gravely endangered and that returns would start crashing if they were not allowed to harvest more of these “excess” fish. This 2011 record-setting return comes from brood parent years where the top end of the Kenai escapement range was significantly exceeded and the fish were “over-escaped.”

Perhaps a definition of that term “over-escapement” will shed some light on the different points of view here. The biological definition of over-escapement means that a brood year population of fish fails to replace itself by at least a 1:1 ratio. If, for example, 1 million fish escape up a river system to spawn and the returning adults from that brood year number less than 1 million when they return, then an over-escapement of the parent brood year has occurred. If 1 million or more fish spawned from that first generation returns, then biologically, no over-escapement has occurred.

From a fisheries management perspective, an ideal return of fish from a given brood year would be around 4:1, four fish returning for every spawner that escaped into the river. That would provide a large, harvestable surplus for all user groups as well as provide ample spawners for the next generation of fish. In the real world, the returns tend to fall more in the range of one-plus to as high as three fish returning per spawner. In an intensely managed system, such as the Kenai River, the term over-escapement is often used to refer to those fish exceeding the escapement goals established for that system. The term is being used in a management sense rather than in its true biological definition.

The problem here is that escapement goals are a best guess as to what would prove to be the optimal escapement for that system. Fish and Game and the BOF regularly review these escapement goals. Changes in number, both increased and decreased, are made on a routine basis as more information is analyzed in the number crunching procedures that established the goals to begin with. In other words, the absolute best optimal escapement goal range for any given system developed by Fish and Game is currently nothing more than an educated best guess.

Since the Kenai River has never experienced an over-escapement as biologically defined, the true biological upper limit of escapement is currently unknown. So calling fish in excess of the upper end of the escapement goal over-escapement is actually a misuse of the term; a foregone harvest opportunity, maybe, but not over-escapement.

Howard Delo is a retired fisheries biologist with the Alaska Department of Fish and Game. You can leave him a message by emailing sports@frontiersman.com.