Research / Sea Grant News

New grant to “fill gap” in sardine stock assessment

Spotter pilot Devin Reed (right) flies a transect while the passenger takes photos of sardine schools. Credit: Kirk Lynn/CDFW

California Department of Fish and Wildlife pilot Tom Evans (left) flies transects while spotter Devin Reed (right) identifies sardine schools, which are then photographed. Credit: K. Lynn/CDFW

New aerial surveys of sardines off Southern California will address fishermen’s concerns that sardine abundance estimates are effectively “missing California fish.”

Collaborative Fisheries Research West has awarded a $16,000 grant to a California sardine industry group to help pay for two spotter-pilot surveys. The first survey is being flown this summer and the second will occur in the spring of 2014.

The project’s leaders hope to use digitally enhanced photos of fish schools taken during the flights to develop a scientifically rigorous method for calculating sardine abundances. If this can be done, they will ask the Pacific Fishery Management Council, which manages the Pacific sardine fishery with NOAA Fisheries, to consider including California aerial survey data into its future stock assessments, from which harvesting limits are set.

Grant recipient Diane Pleschner-Steele, executive director of the California Wetfish Producers Association, which represents California’s sardine industry, said that “fishermen have been concerned that sardine stock assessments have been under-representing the number of fish.”

An untouched aerial photo of sardine schools off Southern California. The photos will be digitally enhanced to document relative abundance estimates. Credit: K. Lynn/CFW

An untouched aerial photo of sardine schools off Southern California. The photos will be digitally enhanced to document relative abundance estimates. Credit: K. Lynn/CDFW

“Our fish do not behave like fish in the Pacific Northwest,” Pleschner-Steele said. They don’t form the same large, feeding aggregations over shelf waters. Instead they tend to stay inshore.

These fish, she said, may be missed by other survey methods, notably acoustic surveys, which are conducted farther offshore.

“A better stock assessment helps everyone,” she said.

California Department of Fish and Wildlife environmental scientist Kirk Lynn, the grant’s co-recipient, agreed that the surveys would “fill gaps in what is known about sardines in nearshore areas of California.”

“We would like to know where the sardines are, where they go and how they use habitats,” he said.

In addition to the aerial surveys, Lynn and staff will be conducting some “chaser boat” sampling of fish schools spotted by plane – to verify that the species they think they have spotted has been correctly identified. Besides looking at sardines, the group has a secondary interest in documenting anchovy abundances.

Pacific sardines are small fish, found from southeastern Alaska to the Gulf of California, Mexico. Credit: NOAA Fisheries Southwest Fisheries Science Center

Pacific sardines are small fish, found from southeastern Alaska to the Gulf of California, Mexico. Credit: NOAA Fisheries Southwest Fisheries Science Center

Paul Crone, a research fishery scientist at NOAA Southwest Fisheries Science Center, said that the qualitative information on anchovy could be valuable.

“I am skeptical of aerial surveys as quantitative tools because of the expanse [range] of the animal,” said Crone, who is a co-author of the federal 2012 Pacific sardine stock assessment. “The problem is we are caught between a rock and a hard place in gathering information on these animals. We know we need rigorous data but they are a far ranging species.”

Spotter pilots have historically been used by fishermen to help them locate schools of fish. Since 2008, the Pacific Northwest sardine industry has been funding spotter-pilot sardine surveys off the coasts of Oregon and Washington to provide another method for estimating relative sardine abundances.

The 2012 sardine stock assessment, which directs the management of the U.S. fishery in 2013, included sardine biomass estimates from aerial surveys, acoustic surveys and an egg-production model, based on egg survey data. The core objective of the collaborative fisheries research project is to piggyback – adapt and expand – the existing aerial survey program to California.

California fishermen landed about 51-million pounds of the iconic fish in 2012, worth an estimated $5.1-million dockside, making it the state’s seventh most valuable fishery and its second largest by weight, according to Fish and Wildlife.  “The sardine fishery is important to the state of California,” Lynn said.

California Sea Grant administers this research project on behalf of Collaborative Fisheries Research West, which is funded through the California Ocean Protection Council.

For more information on the project, contact: Diane Pleschner-Steele, California Wetfish Producers Association, diane@californiawetfish.org.

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Written by Christina S. Johnson, csjohnson@ucsd.edu

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