New study raises concerns about proposed mitigation strategy for marine bycatch

Jun 18, 2008

Huge numbers of fish, seabirds, and other marine animals are routinely killed and discarded after being inadvertently caught during fishing operations. Known as marine bycatch, this problem is an ongoing challenge to the fishing industry, regulatory agencies, and conservationists. One recent proposal would compensate for bycatch by reducing other impacts on affected species, but a new analysis suggests that this strategy could end up doing more harm than good.

A paper published last year in Frontiers in Ecology and the Environment made the case for "compensatory mitigation" of fisheries bycatch, using seabird deaths caused by a longline fishery as an example. The authors suggested that eradicating rats from an island with seabird nesting colonies could have more benefits for a population of shearwaters than efforts to reduce bycatch in the longline fishery.

A number of seabird experts, however, were skeptical of the paper's findings. Given its potential influence on fishery policies, they decided the proposal warranted a careful evaluation.

"There are so many complexities involved in fisheries bycatch, we felt compelled to thoroughly examine the strengths and weaknesses of this approach and establish the criteria that would have to be met for it to work," said Myra Finkelstein, a postdoctoral fellow in ecology and evolutionary biology at the University of California, Santa Cruz.

Finkelstein is the lead author of a paper published June 18 in the journal PLoS ONE that evaluates the potential effectiveness of compensatory mitigation for marine bycatch. She worked with a dozen coauthors whose areas of expertise include seabird conservation and ecology, marine bycatch, and mathematical modeling of wildlife populations. The researchers concluded that compensatory mitigation could only rarely succeed in reducing or offsetting the effects of marine bycatch.

"It's very difficult to make this work," Finkelstein said. "Most of the species threatened by bycatch evolved to live long and reproduce slowly. When bycatch kills adults, these populations just aren't capable of making up for it through increased reproduction. It really is about the bycatch."

Another major stumbling block is that bycatch typically involves a large variety of nontarget species, whereas compensatory mitigation actions are likely to affect only one or a few of those species.

"Marine bycatch is not a single-species problem," Finkelstein said. "So many nontarget species are caught in a given fishery that mitigating the effects on one species could lead to a bigger impact on other species."

The researchers also found flaws in the case study of flesh-footed shearwaters used to support the compensatory mitigation strategy in the original paper. But the bulk of the new paper is devoted to a set of five criteria for evaluating any proposals to implement such strategies. The researchers found that compensatory mitigation for marine bycatch is likely to be successful only in a limited number of situations. In many cases, they said, it has the potential to accelerate declines of marine species currently threatened by fisheries bycatch.

"These are complicated situations. We have to be very cautious, especially with critically endangered species, before we adopt a policy that allows continued mortality from bycatch," Finkelstein said.

Source: University of California - Santa Cruz

Explore further: Sheep flock to Eiffel Tower as French farmers cry wolf

add to favorites email to friend print save as pdf

Related Stories

A major study of all penguin populations

Aug 06, 2014

A major study of all penguin species suggests the birds are at continuing risk from habitat degradation. Writing in the journal, Conservation Biology, a group of internationally renowned scientists recomm ...

Recommended for you

Genomes of malaria-carrying mosquitoes sequenced

12 hours ago

Nora Besansky, O'Hara Professor of Biological Sciences at the University of Notre Dame and a member of the University's Eck Institute for Global Health, has led an international team of scientists in sequencing ...

Bitter food but good medicine from cucumber genetics

12 hours ago

High-tech genomics and traditional Chinese medicine come together as researchers identify the genes responsible for the intense bitter taste of wild cucumbers. Taming this bitterness made cucumber, pumpkin ...

New button mushroom varieties need better protection

16 hours ago

A working group has recently been formed to work on a better protection of button mushroom varieties. It's activities are firstly directed to generate consensus among the spawn/breeding companies to consider ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.