West Coast Pacific Ocean Perch Stock Assessment Results Shows Dramatic Improvement

SEAFOODNEWS.COM [Seafood News] by Susan Chambers – July 6, 2017

Nobody saw it coming: Pacific ocean perch rockfish (POP), a West Coast species of rockfish listed as overfished and one that has constrained fisheries for decades, is likely rebuilt.

Or rather, it was probably never overfished to begin with, according to a new stock assessment.

The estimated depletion (relative spawning output) is 75 percent in the pre-review stock assessement draft, which is above the target of 40 percent, the authors wrote. At a 95 percent confidence interval, the estimated depletion has been above 40 percent since at least 2008 and possibly before.

The final base model coming out of a recent Stock Assessment Review panel (STAR Panel) was even more optimistic. Those results will be in the final panel report prior to the September Pacific Fishery Management Council meeting.

“The spawning output of Pacific ocean perch reached a low in 1994,” the authors wrote in the pre-STAR panel draft assessment. “Landings for Pacific Ocean perch decreased significantly in 2000 compared to previous years. The estimated relative depletion was possibly below the overfished level in the early 2000s, but has likely remained above that level otherwise and is currently significantly greater than the 40 percent unfished spawning output target.”

“The stock showed increases in stock size following the year 2000 due to a combination of strong recruitment and low catches,” the authors wrote in the draft assessment.

Also, the 2008 year class of POP was enormous.

“In recent years, a recruitment of unprecedented size is estimated to have occurred in 2008,” the authors said. “Additionally, there is early evidence of a strong recruitment in 2013.”

The STAR Panel met last week to review the draft stock assessment recently completed by Chantel R. Wetzel and Lee Cronin-Fine. The panel includes scientists, independent reviewers and an industry member.

POP has been a main ingredient in the groundfish trawl fisheries for years. Foreign fleets decimated the stock in the 1960s and 1970s off of Washington and Oregon with estimated removals of 18,883 metric tons in 1966. Domestic trawling also contributed to the stock’s decline, but harvested a fraction of POP that Russia and Japanese fleets did. The highest domestic fishery landings were 5,627 mt in Oregon in 1965 and 2,501 mt in Washington in 1968 until the stock was listed as overfished in 1999.

The PFMC and NMFS implemented a management strategy in 1981, with a goal to rebuild POP within 20 years. Landings continued to drop since 1994 due to more restrictive management. A subsequent rebuilding plan was put in place in 2001 with even greater management restrictions. In 2016, landings from all sources were roughly 65 mt. Given that POP off the West Coast is the tail end of the stock that is distributed primarily all the way from northern California through Alaskan waters, the industry lost hope in ever rebuilding the POP.

In the Gulf of Alaska and the Bering Sea, POP stock assessments determined neither stock is overfished and suggest acceptable biological catches of 23,918 mt and 423, 273 mt, respectively, for 2017, the authors said. Similarly, in Canada, POP is the largest single-species quota and account for 25 percent of all rockfish landings by weight in the bottom trawl fleet.

At the same time trawlers targeting rockfish were held to restrictive limits, in the past few decades, allowances for bycatch in the at-sea whiting fisheries — both catcher-processors and motherships — resulted in a cessation of fishing or radical fishing behavior changes to the prosecution of the whiting fishery to avoid POP.

For example, in April, the at-sea fleets requested a release of POP the Pacific Fishery Management Council set aside specifically for an instance in which the whiting fleets encountered more POP — which happened this year. In an attempt to fish further north to avoid Klamath River fall Chinook, the at-sea fleets said in April it was likely they would encounter more POP. They did. In June, the Council and NMFS released more POP to the catcher-vessels and motherships so bycatch of POP wouldn’t shut down the whiting fisheries.

The last POP assessment was done in 2011. The authors re-evaluated all of the aspects of the model, including landings, data and modelling assumptions.

One of the key changes to this stock assessment was to discard data from the triennial shelf survey and instead depend on the Northwest Fisheries Science Center’s surveys. The triennial survey was stopped several years ago and the NWFSC survey data are more robust.

Previous assessments showed POP struggling. The 1998 assessment estimated the stock was at 13 percent of the unfished level, which led to the declaration that it was overfished. The 2011 assessment showed the stock was improving, at 19 percent, but still below the 40 percent target.

The 2011 assessment, which used 2010 data, would not have captured the strong 2008 year class, PFMC groundfish staff officer John DeVore said. POP tend to recruit into the NWFSC at age 3 or above and into the fishery at about age 6, so this is the first full assessment that would have captured the monster 2008 year class.

The STAR Panel must finish a report for the September PFMC meeting, at which the Scientific and Statistical Committee and the Council must adopt the assessment. After that, NMFS must accept the assessment as the best scientific information available.

Thanks to Seafood News for their generous reprint policy.