For six of the past seven years, king salmon returns to the Chilkat River have failed to meet the Alaska Department of Fish and Game’s minimum escapement goal of 1,750 fish. On a bar graph measuring escapement over time, it looks like a ramp going down.
The slope began its decline at 1,723 large spawning kings in 2012 and ended this year at 900 fish. That slope leads to a question—what is the point of no return?
The short answer for Chilkat kings? There is not enough data to know, said Fish and Game area biologist Brian Elliott.
But the department does have a policy for using such a number, as described in Alaska Administrative Code. When managing fisheries to protect salmon stocks, Fish and Game uses different types of escapement goals. One that might help to understand that point of no return has yet to be used, or defined, in Alaska. It’s called the sustained escapement threshold or SET.
The SET is the lowest possible number of spawning salmon that can sustain a population. If escapement falls below that number, the stock is jeopardized. That threshold plays a crucial role when determining at what level a salmon stock is considered a stock of concern—a designation Fish and Game gave to Chilkat, King Salmon and Unuk River kings last winter that resulted in unprecedented subsistence, sport and commercial fishing restrictions in Southeast Alaska.
There are three tiers within the stock of concern designation: yield, management and conservation. Chilkat kings are at the level of “management concern,” a concern arising from a continuing or anticipated inability to meet escapement thresholds over a four to five-year period, despite use of specific management measures.
Chilkat kings won’t be elevated to a conservation concern, the most severe category within the stock of concern designation, until they fall below the SET—a threshold below the low end of Fish and Game’s 1,750 escapement goal. But biologists haven’t officially defined a SET for the Chilkat River, or any other river in the state.
“SET is difficult to estimate, because for many of these [Southeast king] systems we are observing escapements outside the range of historical levels,” Fish and Game biologist Brian Elliott said. “We simply have not had the opportunity to assess production from an escapement of 900 large spawners in the case of the Chilkat.”
Elliott said once biologists see how many salmon make it back after poor brood years, they’ll be able to better determine SET thresholds. “I would say starting with 2016 we’re getting into levels that call into question how quickly this population could rebound,” Elliott said. “In 2016 we definitely missed. Last year we missed it by a lot. The Chilkat stock is not doing well at all.”
Still, biologists won’t know how many salmon will return from the 900 that came back this summer for another five years. And the latest SET modeling isn’t necessarily accurate, either. In 2010, Fish and Game biologist Bob Clark came up with a model that estimated the Chilkat SET using data from 1991 to 2005—a number that landed within the ideal escapement range currently used by Fish and Game. Returning salmon that fell below that theoretical SET produced stocks that approached the high end of the escapement range.
“The 1991-2005 time period saw consistent escapements either within or above the escapement goal range,” Elliott said. “At that time there simply was not the contrast in the data set to assess production from varying escapement levels. Since 2005, we now have that contrast through low escapement estimates, unfortunately.”
2012 and 2013 kings fell just short of the lower end of the escapement range. Those parent years produced the returning five-year old spawners in 2017 and 2018, the two lowest returns on record. “I think that if the department or the state wants to go in this [SET] direction, that we’re going to need about four or five more years of data to see how many fish are produced from these low escapement years,” Elliott said.
But will it be too late by then? Will an accurate SET be nothing more than a data point describing a threshold on a river void of kings?
When asked if determining a SET is a catch-22, that biologists can only know the threshold below which a salmon stock can’t sustain itself after it has stopped sustaining itself, former Haines Fish and Game biologist Randy Ericksen said, “Yeah. Unfortunately, I think it is.” When determining SET, Ericksen said finding such a threshold is purely theoretical. “It would probably be worth trying to look at different models and to play with the numbers to see if there’s a range in there that you basically don’t have enough recruitment to sustain the population,” Ericksen said. “I don’t think there’s any real good studies of population that are that low to really measure what that level would be.”
Anecdotally, king populations in the Chilkat have declined in the past, although biologists are unsure at what levels. Ericksen worked in the area for 22 years. He said local residents complained about poor king runs in the 1950s. But Fish and Game only has data going back to 1991.
Fish and Game currently uses a “maximum sustained yield” approach to management, Elliott said. That model is designed to provide the largest average annual yield. That happens when escapement is maintained within a specific range on an annual basis, regardless of annual run strength.
“This escapement goal strategy was designed to never approach the jeopardy level of escapement, so fishery-related issues would never cause biological problems,” Elliott said. “In this case fisheries would be closed long before fishery impacts and other factors, such as habitat loss and climate change, would impact the stock in question.”
There are 18 salmon stocks across the state designated as stocks of concern, all that fall within the management or yield levels. This year, out of the 11 systems biologists monitor in Southeast, seven failed to meet escapement goals.