There’s an old adage in fisheries allocation issues that numbers don’t lie but that you can lie with numbers. 

The interpretation of scientific data by opposing parties – the National Marine Fisheries Service, and that of a scientist hired by the Wild Fish Conservancy – moves front and center in the latest round of litigation, after a federal district court judge ruled on May 2 that NMFS needs to re-assess the biological opinion underpinning harvest limits in the troll fishery. 

The premise of lawsuit filed by the Wild Fish Conservancy in 2020 argues that when NMFS rendered its biological opinion in the formation of the Pacific Salmon Treaty it did not consider a portion of the commingling stocks as forage fish for a pod of 73 killer whales in Puget Sound. The WFC suit rides on the contention that the agency acted out of compliance with the Endangered Species Act.

In a 2021 ruling the same court agreed that NMFS was out of compliance. Since then, the agency had been working on language corrections in hopes of satisfying mandates within the ESA. But apparently that didn’t fly, and the latest court ruling requires NMFS to go back to the drawing board.

The heart of the argument rides on differing calculations as the nation’s top fishery scientists weigh in how the troll fishery and its annual allocation and harvest of treaty chinooks could affect the killer whales. On the WFC side of the equation, killer whale survival rate projections have been rendered through the services of Dr. Robert Lacy.  WFC hired Lacy to conduct studies that show where the current NMFS biological opinion fails in protecting the pod of Puget Sound whales.

Since 2020, Lacy has submitted three scientific declarations to the court, the latest of which (Sept. 7, 2022), takes into account that three of the whales have died since the original submission of his model. Plugging in the deaths and noting no recent births of the whales into his model, a total closure of the Southeast troll fishery would net an extra 6 percent of chinooks as killer whale forage.

From the third declaration, Lacy states: “I was asked by the Wild Fish Conservancy to calculate the expected effect on Southern Resident Killer Whale population stability and growth if the commercial troll component of the SEAK Chinook fishery was removed from the current levels of harvest of Chinook. As in the First and Second Lacy Declarations, based on data provided in the NMFS 2019 Biological Opinion (“2019 SEAK BiOp”), we can estimate that there is about a 6 percent reduction in prey available to the Southern Resident Killer Whales caused by the Southeast Alaska fishery as a whole (the 6 percent being an approximate middle value from the many estimates made in the 2019 SEAK BiOp), but with considerable uncertainty around this number.

"The Pacific Salmon Commission Annual Report of Catch and Escapement for 2020 provides data showing that 80.8 percent of the overall PST Treaty catch of Chinook from 2009 to 2020 was taken by the commercial troll fishery. Thus, we can estimate that closing of the SEAK commercial troll fishery would result in an increase of 80.8 percent x 6 percent = 4.848 percent in Chinook availability to the Southern Resident Killer Whales.

“Applying the above estimates to the current population model results in a projection that closing the SEAK commercial troll fishery of Chinook would provide just enough benefit to the Southern Resident Killer Whales to allow the population to stabilize – that is, the projected long-term mean population growth rate would be 0.00 percent.

“Given the uncertainty in the impact of the current SEAK fisheries on the availability of Chinook to the Southern Resident Killer Whales, I tested also the benefit if the Chinook availability were only half or were double the 6% estimate. If the SEAK fisheries currently reduce Chinook availability by 3 percent, then I estimate that the decline of the Southern Resident Killer Whale population would be slowed to -0.3 percent per year if the commercial troll was closed. If the SEAK fisheries currently reduce Chinook availability by 12 percent, then I estimate that the Southern Resident Killer Whale population could start to recover at a mean rate of +0.4 percent per year following a closure of the commercial troll fishery.”

Under the current biological opinion and management plan Lacy estimates the killer whale population would decline by 0.5 percent per year.

A point of contention from the Alaska trollers, the State of Alaska and others supporting the fishing industry is the assumption that trollers have taken 80.8 percent of the PST chinooks from 2009 to 2020. Estimates from the Alaska Department of Fish and Game each year have ranged between 30 percent and 80 percent of PST fish. The Puget Sound Chinook Salmon Harvest Analysis, an analytical document prepared by ADF&G, found that an even smaller percentage of the harvest is comprised of fish destined for Puget Sound. 

“In terms of percentage contribution, Puget Sound origin Chinook salmon comprised 1.13% of the Early Winter fishery whereas the Summer fishery only comprised 0.10% of it. Puget Sound Chinook salmon comprise 0.19% and 0.14% of the total Late Winter and Spring fisheries.” 

Data from the harvest analysis estimates the total take of Puget Sound chinooks during the period from 2009 to 2018 at between 1,348 and 3,784 fish.

At the same time other studies published in Nature, Ecology and Evolution in March  point toward inbreeding as the possible cause of the decline in the Southern Resident Killer Whales.

“We find that the ‘Southern Residents’, which are currently endangered despite nearly 50 years of conservation efforts, exhibit strong inbreeding depression for survival,” reported an international team of researchers, including experts from the NMFS Northwest Fisheries Science Center, other U.S. scientists and genetic specialists in China. “Our population models suggest that this inbreeding depression limits population growth and predict further decline if the population remains genetically isolated and typical environmental conditions continue. 

“The Southern Residents also had more inferred homozygous deleterious alleles than three other, growing, populations, further suggesting that inbreeding depression affects population fitness. These results demonstrate that inbreeding depression can substantially limit the recovery of endangered populations.”

The paper also points out that the Northern Resident Killer Whale population is recovering and that it and another transient pod feed on seals and sea lions.

Meanwhile, the response from NMFS posted on its website as of May 5 states: “NOAA Fisheries is aware of the U.S. District Court decision to remand the 2019 Biological Opinion that evaluates the effects of the Southeast Alaska salmon fisheries on threatened and endangered species, and to vacate the Incidental Take Statement for the Chinook summer and winter commercial troll fishery.

"The 2019 Incidental Take Statement that applies to the rest of the Southeast salmon fisheries remains in place. NOAA Fisheries knows these issues are of utmost importance to the communities that rely on the SEAK troll fishery. We are working expeditiously to address the court's order.”

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Charlie Ess is the North Pacific Bureau Chief for National Fisherman.

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