Trawl gear rarely produces a one-species catch. The haul in this checker is dominated by Atlantic croaker, but it also includes a large sand tiger shark, several hogchokers, and a few spot (a bottom feeder related to croaker). This catch was from as single tow during a September, 2002 survey in the Delaware Bay area. NOAA NEFSC photo by fishery biologist Pete Chase aboard the R/V Albatross IV.

Observer Gioia Blix weathers a cold day aboard F/V Michael Brandon, a gillnet vessel steaming back to Scituate, Massachusetts, after a December fishing trip. On-board observers like Blix monitor the catch and provide the most reliable data on fisheries bycatch. NOAA Photo by NEFSC fishery biologist Eric Matzen.

Observer Bill Lewis, working in Cape Cod Bay aboard the F/V Zachary Nicholas in September. Lewis is determining the sex of a yellowtail flounder. Observers not only identify the types and number of bycaught animals, they also gather biological data that fisheries scientists need for stock assessments. NOAA Photo by NEFSC fishery biologist Eric Matzen.

by George Liles

It’s hard to keep track of what commercial fishermen land, and it’s even harder to track what they toss back. For the past three years, fishery scientists around the country have redoubled the effort to figure out how much and what kind of fish, turtles, mammals, and birds are caught unintentionally and/or discarded every year.

The FAO estimates that eight percent of the world’s marine fisheries catch is discarded, which means 7.3 million tons of fish or protected species are thrown back every year. Some types of fishing are much more likely to result in discards, with tropical shrimp trawl fisheries having the highest discard rate and small-scale fisheries having the lowest rate, at 3.7 percent of their catch.

“You have to monitor bycatch to know the full impact of fishing on the stocks,” said Michael Fogarty, an NEFSC biologist who served on a working group that won a 2005 DOC Bronze Medal for its study on monitoring bycatch. “You get an incomplete picture if you only know about the animals that are retained.”

Bycatch covers a lot of territory, but it’s essentially any marine life that’s caught or killed in fishing gear but isn’t really a target of the fishery. Fish that are too small, noncommercial, or are illegal to possess are examples of bycatch - as are seals, whales, sea birds, and other marine wildlife. Bycatch is an issue in virtually all commercial fisheries in the nation – from pot fisheries to hook fisheries, from trawls to gillnets. Even abandoned or lost gear contributes to bycatch, when animals become caught in the ghost gear and may die, often unobserved.

Scientists have explored a variety of methods to monitor bycatch, including surveys, logbooks, and at-sea observations, either by trained observers or using digital video cameras mounted on the vessels. The current effort to find the most reliable ways to monitor bycatch was sparked in part by the Sustainable Fisheries Act of 1996 and in part by subsequent litigation over how much monitoring is needed and how it should be done.

In 2003, NOAA Fisheries Services formed a National Working Group on Bycatch to help develop a national strategy for bycatch monitoring and reduction.

“We put our heads together to look at our experiences in different regions, and to craft a bycatch monitoring strategy for the country as a whole,” said Fogarty, who represented the Northeast on the working group.

The working group labored nearly two years, and in October 2004 produced a report detailing their findings: “Evaluating Bycatch: A National Approach to Standardized Bycatch Monitoring Programs.” The bycatch omnibus has everything scientists, managers, and fisheries stakeholders might want to know about monitoring bycatch: legal requirements, bycatch issues region by region, alternate methods for monitoring bycatch, notes on estimating bycatch, identification of fisheries that have significant bycatch problems, and strategies to address bycatch.

The report notes that deploying observers on fishing vessels is the best method for getting reliable information about what is being discarded in most fisheries. But the report cautioned that selecting a random sample of vessels to monitor is crucial to obtaining useful results.

What’s Your Acronym Agility? The acronyms here are used in the 2004 NOAA Technical Memorandum “Evaluating Bycatch: A National Approach to Standardized Bycatch Monitoring Programs.” In that report, what do these acronyms mean? Answers at the bottom. 1. MSE a. minimum sustainable equilibrium b. mean square error c. marine standard electronics 2. OY a. out year b. oh yes c. optimum yield 3. GLM a. global limit method b. generalized linear modeling c. Globec landing modules 4. ABC a. acceptable biological catch b. all but completed c. actual bycatch calculation 5. RPA a. revised plan of action b. Redfish Protection Act c. reasonable and prudent alternative 6. SBRM a. shark bycatch reduction method b. standardized bycatch reporting methodology c. significant biological research modules 7. ETP a. estimated time of payment b. estimated total performance c. Eastern Tropical Pacific Ocean 8. MUS a. management unit species b. management under stress c. marine umbrella stocks 9. BRD a. bycatch reduction device b. bias review designation c. basic research design 10. CV a. cost over value b. catch variation c. coefficient of variation (scroll down for answers)

Fogarty said that this aspect is one of the most important. “We have to minimize unrepresentative sampling,” he said, “and move from ad hoc vessel selection to something more statistically defensible.”

Another key element in the report is the question of precision: how precise do bycatch estimates have to be to be useful to fishery managers?

“To a certain extent,” Fogarty said, “you can increase precision by having more complete coverage.” But when it costs more than $1000 to gather and process one sea-day’s worth of observer data, as it does in the Northeast, managers have to decide how much precision they need to manage each fishery.

The working group’s other major contributions, according to Fogarty, are the analysis of strengths and weakness of different methods for measuring bycatch, and the region-by-region, fishery-by-fishery, evaluation of bycatch issues.

The report finds, for instance, that 26 U.S. fisheries are rated as highly vulnerable for bycatch of fish or protected species such as marine mammals. The working group identified those fisheries as candidates for additional funding and improved at-sea observer programs. Six of those highly vulnerable fisheries are Northeast fisheries that often take marine mammals or sea turtles.

The results of the two-year project did not surprise Fogarty, but he notes that some of the findings run counter to assumptions people sometimes make about bycatch monitoring.

On the question of how much observer coverage is needed to get a good picture of bycatch in any one fishery, some have argued that the minimum standard should be a certain percentage – i.e., a certain percentage of the fishing trips should be observed. The working group found that the key is not the percentage of trips but the number of trips. For instance, if observers covered two percent of the trips in a particular fishery but vessels in that fishery made 4,000 trips, 80 trips would be observed - which might give a reliable picture of the whole fishery. On the other hand, 20 percent coverage of a fishery that involves 30 trips might provide a less reliable picture.

While the national working group won a Bronze medal in 2005 for their efforts, the work on bycatch continues in each of NOAA Fisheries’ six regions. In the Northeast, Fogarty is still working on the issue, along with a team that includes analyst Susan Wigley and biologist Paul Rago, chief of the NEFSC’s Population Dynamics Branch.

Wigley serves on a team working to develop a standardized bycatch reporting methodology (SBRM). “The team is analyzing observer data, identifying gaps in coverage, and identifying the precision of the discard rate for each fishery,” Wigley said. The SBRM analysis will go to the New England and Mid-Atlantic Fishery Management Councils where it will become the basis for an omnibus amendment to every fishing management plan (FMP) developed by the two Councils.

A key piece of SBRM groundwork is already in place – in August 2005 the NEFSC team of Rago, Wigley and Fogarty published a reference document that includes a tool for translating precision decisions into observer days-at-sea. Fishery managers can use the tool to determine how many days observers should be deployed at sea to gather enough data to provide the level of precision managers need for each fishery. The tool was developed for groundfish fisheries in the Northeast, and similar tools may be built for each of the 84 marine fisheries managed in U.S. waters.

Various workshops are being held around the country to tackle other issues identified in the working group’s report. In January, 2006, the Northeast Region Bycatch Committee held a workshop in Portsmouth, NH, to produce a step-by-step guide to developing cooperative research projects evaluating methods to reduce bycatch.

This month (May) a workshop will be held at the NEFSC Technology Park campus in Falmouth to discuss methods for selecting vessels to provide a representative picture of a entire fishery. In July, Rago will lead a team of NEFSC scientists to Seattle for a national workshop that will focus on procedures for estimating bycatch.

Posted May 10, 2006