Fishery Collapse in Gulf Greatly Overestimated

A new analysis of fish in the Gulf of Mexico suggests that previous estimates of fishery collapse were vastly overestimated.

In particular, a study from 2006 provoked widespread concern after concluding that between 1950 and 2001, nearly 80 percent of all fisheries in the Gulf of Mexico, from the Northern red snapper to the Atlantic croaker, collapsed. The new analysis suggests the accurate figure for collapsed fisheries is closer to 20 percent.

"We all recognize the threat of overfishing to sustainability, but we have to be very careful when we generate these doom-and-gloom prophecies," said James Cowan Jr., a coastal fisheries expert at Louisiana State University and co-author of the new study.

"If we keep saying those kinds of things, and it turns out they’re not true, then people are going to get numb to those kinds of calls, and they’re going to ignore severe threats to the environment."

The new study, published this week in the journal Proceedings of the National Academy of Sciences, concludes that previous methods of estimating fish populations relied too heavily on so-called "landings data" from the catches of fishermen, which may not adequately reflect the overall numbers of fish.

Problems remain Despite the seemingly rosier picture, however, problems remain in the Gulf, said Roger Zimmerman, director of a Galveston-based lab within the National Oceanic and Atmospheric Administration Fisheries Service.

Certain species such as the red snapper have definitely been overfished, and the loss of wetlands could have a serious long-term impact on Gulf fisheries, Zimmerman said.

"Although we’re not severely overfished, there are problems, and certainly we need to address those problems," he said.

The 2006 study, led by Boris Worm at Halifax, Nova Scotia-based Dalhousie University, sparked much attention among the public and in the marine biology community as it found that fish populations around the world were in decline.

The new work led by Cowan and LSU’s Kim de Mutsert does not undermine the conclusion that, globally, fisheries are severely threatened, Worm said.

"The Gulf of Mexico is, of course, a cherry-picked example, as this is one of the few regions in the world where there are strong legal instruments to stop overfishing, and many stocks are under heavy regulation that are limiting catches," Worm said. "Global fisheries are in bad shape and getting worse."

Worm’s study was based upon "landings" data, which is the primary means used by regulators and scientists to assess fish stocks primarily because it provides the only widely available data.

But there are clear flaws in the landing data, as a decline in a catch can be explained by other factors beyond its overall population. Its value in the marketplace could drop, so fishermen look to other species, or new regulations could limit total catches.

‘False positives’ For the new study, Cowan, de Mutsert and their colleagues supplemented landings data with sampling data taken in Louisiana estuaries and along the coast by that state’s Department of Wildlife and Fisheries.

Comparing the two sets of data turned up a lot of "false positives," Cowan said, which led his team to conclude that the Gulf’s fisheries outlook was not so bleak.

The new work nicely highlights the overall difficulty of accurately knowing the overall fish populations, even in a frequently studied body of water like the Gulf, said Jay Rooker, a marine biologist at Texas A&M University at Galveston.

"I don’t think anyone would argue that there’s overfishing, and therefore some threats to long-term sustainability," he said.

"It’s pretty clear, for something like red snapper, there’s definitely an issue. But is it severe? Is it pretty bad? Or is it just marginally overfished? We just don’t know."