Advanced Sonar Technology Helps NOAA Count Anchovy

Fishery managers should use data to review, revise catch limits for vital species

Advanced Sonar Technology Helps NOAA Count Anchovy
Reuben Lasker
The Reuben Lasker can work with wind-powered drones to gather fish data in shallower, nearshore areas.
NOAA

One of the hallmarks of American fishery management is the requirement that it be based on the best available science. Another is that it be adaptable: The plans that guide federal management of fish stocks are frequently updated in response to new information. These two themes will figure prominently when the Pacific Fishery Management Council meets in San Diego on June 21 to discuss potential changes to West Coast anchovy management.

Anchovies are one of the most important forage fish in the Pacific Ocean, a vital source of food for more than 50 species of marine wildlife. Unfortunately, they are also managed using fixed catch limits that can remain in place indefinitely. This “set it and forget it” approach doesn’t work for a species that experiences wide, natural population fluctuations.

When their numbers are low, static, multiyear catch limits can leave anchovies at risk of overfishing and harm whales, seabirds, and other wildlife that depend on the prey. This is no way to run a fishery, especially for a species as crucial to Pacific ecosystems as anchovies. It’s time for the council to amend its anchovy plan and start managing this forage fish with science-based catch limits that are updated annually.

Making such a change means measuring the West Coast anchovy population on a regular basis. Thanks to some of the most advanced fish-counting technology in the world, federal scientists are already conducting up to two surveys a year using the NOAA Fisheries-operated ship Reuben Lasker.

The NOAA fishery research vessel Reuben Lasker is equipped with multibeam sonar and echo sounders that use underwater sound waves to: 1) Detect and track fish schools up to several hundred meters in every direction. 2) Create 3-dimensional images of schools beneath the ship and estimate their densities. 3) Help measure the size, shape, and behavior of fish directly beneath the ship. 4) Characterize fish behavior and estimate densities of schools to the side of the ship.

The most technologically advanced ship in the National Oceanic and Atmospheric Administration’s survey fleet, the Reuben Lasker has logged more than 30,000 miles counting forage fish since coming to the West Coast in 2014. It is equipped with four sonar systems that can look for anchovy in virtually any direction. And its specially designed propeller, bow, and engines make it as quiet as a gray whale, NOAA says, which is important for getting close to the fish.

Scientists aboard the vessel don’t just rely on high-tech echo sounders to determine the health of the anchovy population. After searching for fish with sonar during the day, the ship returns to hot spots in the evening to sample schools of anchovy or sardines with a net. It also continuously counts and identifies fish eggs in the water. And scientists who sail with the Reuben Lasker are constantly refining their analyses to improve the accuracy.

Rather than setting multiyear fixed catch limits that don’t always reflect the size of the anchovy population, the council and NOAA Fisheries should use the data that the Reuben Lasker and other NOAA survey ships are gathering every year to inform anchovy management. This should lead to catch limits that correspond to the amount of fish in the water and help meet the obligations of our nation’s signature fishing law, the Magnuson-Stevens Fishery Conservation and Management Act, which calls for using the best available science when setting regulations.

The only thing standing in the way of this sensible, science-based approach is outdated language in the council’s management plan. When the body meets in June, it should initiate an amendment to its Coastal Pelagic Species Fishery Management Plan allowing the council to review anchovy catch limits every year and update them in response to significant population changes.

The Reuben Lasker and its team of scientists are already hard at work for healthy, sustainable West Coast fisheries. To help meet that goal, the council should set sensible policies for anchovy management.

Paul Shively directs The Pew Charitable Trusts’ efforts to protect ocean life and coastal habitats on the U.S. West Coast.