The Alaska Department of Fish and Game is reevaluating many of the sustainable escapement goals it has set around the state using a new method designed to correct the faults of an old one.
Fish and Game sets two kinds of goals for escapement into rivers: biological escapement goals and sustainable escapement goals. Biological escapement goal are set on stream systems for which the department has enough data to determine the best number of fish in the system to produce the maximum sustainable yield. Sustainable escapement goals were established for streams on which the department has less information and determine the best chance for sustained yields over a five- to 10-year period.
Since 2001, the department has set many sustainable escapement goals using a methodology called the Percentile Approach, which uses a four-tiered mathematical calculation to determine the ranges for escapement based on the number of spawners a system can take without going over carrying capacity for the habitat over time. The approach was never published, but the department used it in response to the Board of Fisheries’ instructions to set sustainable escapement goals. By 2012, the Percentile Approach was used to calculate about half of the sustainable escapement goals in Alaska.
In 2012, Fish and Game reevaluated the Percentile Approach and determined that a flaw in the method had set many goals too high and “likely exceeded carrying capacity” for many of the stocks, according to the final paper, published in 2014. The department is now using the updated approach to reevaluate escapement goals. During a presentation to the Board of Fisheries in Homer during the first day of the board’s Lower Cook Inlet cycle meeting on Wednesday, Lower Cook Inlet fisheries biologist Ted Otis presented the board with the new numbers.
The department maintains goals on 41 streams in Lower Cook Inlet, a management area that stretches from central Cook Inlet southward to include Kamishak Bay and Kachemak Bay and wraps around the southern coast of the Kenai Peninsula eastward up to Cape Fairfield, about 15 miles east of Seward. All of them are sustainable escapement goals rather than biological escapement goals.
“With few exceptions, streams in Lower Cook Inlet are monitored by foot and aerial surveys,” Otis said in his presentation. “As such, most of our escapement data represent relative abundance indices rather than absolute abundance guidelines. We also lack key data to build production models to calculate the number of spawners that are needed to achieve (maximum sustainable yield).”
The department recommended adjustments on 38 of the 41 escapement goals. A few remained unaltered for a variety of reasons, depending on the stock. Most of the others had their escapements reduced because the department used the updated Percentile Approach to evaluate them. The new recommended escapement goals were between 5 and 35 percent lower than the escapement goals the former approach recommended, Otis said, though they vary by system.
One of the questions that arose during the discussion about the changes to the Percentile Approach was about peer review. Because the original approach was never published, it did not have to go through the regular peer review process that published papers do. Jack Erickson, the Southcentral regional coordinator for research for Fish and Game, told the Board of Fisheries that the approach had been developed very quickly and did not get the regular review.
He said the department usually keeps peer review in-house rather than requesting third-party review from universities because it publishes so many papers that are mostly used for department functions.
“We’re the ones who are really using these, actually using these tools,” he said. “They’re going to look at us quite often and say, ‘You guys know better than we do.’”
Fish and Game made a formal recommendation to the Board of Fisheries on Wednesday to designate the McNeil River chum salmon a stock of concern, which would trigger additional management actions to conserve the stock.
It seems to be at least partially because of bears.
The McNeil River State Game Sanctuary and Refuge, an area designated by the Legislature in 1967 for the protection of bears, occupies a space on the west side of Cook Inlet along the river. Over the years, the bear population has grown significantly, and they crowd around the McNeil River falls to feed on the chum salmon returning there. Some estimates have the bears harvesting as much as 59 percent of the chum salmon run there, about 10,000 fish.
“Certainly the density of bears at the falls itself does play a role,” Otis said.
Fish and Game maintains a sustainable escapement goal of about 28,000 to 48,000 fish on that river, but has only made the goal twice since 2008. The fish face the challenge of both heavy predation by bears and several sets of stepped falls low on the river that make it difficult for them to get above the falls to the good spawning habitat. Fish and Game tagging studies have shown that almost 90 percent of the fish die below the falls, with only 10 percent making it upriver to spawn.
There’s also a commercial fishery authorized in the area, but it’s been closed in the McNeil River subdistrict as well as a neighboring area, the Paint River subdistrict, every year since 1994. Most of the fish the commercial fishermen harvest in the area are headed for the Big Kamishak and Little Kamishak rivers, Otis said.
The department recommended several potential actions on the stock. The options the department could use to limit harvest, a traditional method Fish and Game uses to help restore a fish stock, would have limited benefits because of the major factor of bear predation.
However, it would be hard to interfere with the bears. The sanctuary prohibits hunting, and the department would have to haze the bears to get them away from the falls to protect the stock. That would interfere with the extremely popular bear-viewing program the state runs, which allows a limited number of people to fly to the sanctuary and observe and photograph the bears there.
The department could build a fish ladder or other system to allow the fish to get around the falls, but that would be prohibitively expensive and take years, he said. The last option would be to let the stock naturally recover or fluctuate. The stock has recovered from periods of low productivity in the past, according to Fish and Game data.
Reach Elizabeth Earl at email@example.com.