Deeply Flawed Population Survey Fuels False Claims
April 5, 2018 — BUELLTON, Calif. — The following was released by the California Wetfish Producers Association:
This Sunday, April 8, the Pacific Fishery Management Council is meeting in Portland to debate the fate of the West Coast sardine fishery, after the 2018 sardine stock assessment estimated the biomass has declined by 97 percent since 2006. The only problem with that finding is it belies reality.
“Fishermen are seeing more sardines, not less, especially in nearshore waters. And they’ve been seeing this population spike for several years now,” said Diane Pleschner-Steele, executive director of the California Wetfish Producers Association (CWPA). “This stock assessment was an update that was not allowed to include any new methods and was based primarily on a single acoustic survey that reached only as far south as Morro Bay and totally missed the nearshore coastwide.”
The 2018 update assessment of 52,000 tons, down from 86,586 tons in 2017 and 106,100 tons the year before, is based on a change in methods and assumptions in estimating population size developed during an independent stock assessment review in 2017. Scientists acknowledged that assuming the acoustic survey ‘sees’ all the fish leads to lower biomass estimates. But it’s obvious to fishermen that the survey missed a lot of fish. In fact, with different assumptions, the 2017 biomass estimate would have increased from 86,586 tons to 153,020 tons.
The thorny problem the Council faces in April is what to do with a flawed assessment that is perilously close to the 50,000-ton minimum stock size threshold that would trigger an “overfished” condition and curtail virtually all sardine fishing. (The directed fishery has been closed since 2015, but incidental harvest in other fisheries, as well as Tribal take and live bait fishing have been allowed under a precautionary annual catch limit of 8,000 tons for all uses.) The extremist group Oceana has already signaled its intent to lobby for the Council to declare sardines “overfished.”
“Despite ample evidence to the contrary – most scientists agree that environmental factors play the primary role in sardine populations swings – Oceana claims that overfishing is the cause of the sardine fishery decline,” said Pleschner-Steele. “But the absolute opposite is true: fishing is a non-issue and more importantly, the sardine stock is not declining.”
The NOAA acoustic survey was based mainly on the 2017 summer acoustic trawl cruise that ran from British Columbia to Morro Bay, CA, but did not include the area south to Pt. Conception and Southern California where fishermen have reported large schools of sardines for the past three years. What’s more, this stock assessment update was based on a model that the chair of the 2017 Stock Assessment Review panel termed the “least worst” option. In part, the problem is that acoustic trawl surveys conducted by large research vessels cannot gather data in nearshore waters inside about 50 meters depth – 27 fathoms. But 70 to 80 percent of California’s sardine catch comes from nearshore waters inside the 20-fathom curve.
Acoustic trawl survey methods also underwent review in January 2018, and independent scientists criticized current survey methods and assumptions, noting that the current ATM trawl procedure seems to focus on precision at the expense of accuracy, and the protocol is repeatable but not necessarily objective.
To document the missing fish, the California Department of Fish and Wildlife and CWPA conducted a cooperative aerial survey in the Monterey / Half Moon Bay area last summer – at the same time the acoustic trawl cruise was surveying outside waters – and saw a significant body of both sardine and anchovy inside the acoustic survey nearshore limit.
Here is the map illustrating the thousands of tons of sardine that the NOAA acoustic survey missed, an estimated 18,118 mt of sardine and 67,684 mt of anchovy.
And here is a video from fisherman Corbin Hanson who was out fishing for squid last November and saw large schools of sardines in Southern CA. He commented that, “…this is just one school. Last week we drove by the biggest school of sardines I have ever witnessed in my career driving boats. It was out in front of Ventura Harbor and we saw countless other schools along with it.”
The problem is this evidence has not yet been qualified for use in stock assessments. However, at the upcoming meeting, the Department of Fish and Wildlife will present the data from our nearshore aerial surveys in 2016-17. CWPA will also request that the Council approve our experimental fishery permit to help us qualify our aerial surveys as an index of nearshore abundance for future assessments.
“The bottom line is it’s vital for proper management of our fisheries that we use all available scientific data. That’s why the Council needs to take into consideration these nearshore findings when recommending sardine management measures in 2018,” said Pleschner-Steele. “CWPA along with sardine fishermen contest the 52,000-ton stock assessment and will request a new stock assessment review as soon as possible, including other indices of abundance in addition to acoustic trawl. If the Council closes the sardine fishery entirely, California’s historic wetfish industry – which until recent years produced 80 percent or more of the volume of seafood landed statewide – will suffer unnecessarily, along with the state’s entire fishing economy.”
About the California Wetfish Producers Association
The California Wetfish Producers Association is a nonprofit dedicated to research and to promote sustainable Wetfish resources. More info at www.californiawetfish.org.