BioEd Online

A growing trend towards fancier fish tanks threatens the future of Florida's invertebrate fishery, researchers warned this week.

While some question the scientists' bleak conclusion, data on crabs, anemones, starfish, snails and the like collected off the coasts of the Sunshine State, show a huge increase in catches for aquaria since 1994.

"The invertebrate ornamental fishery in the State of Florida, with increasing catches over a more diverse array of species, is poised for collapse," warns a paper in PLoS ONE¹.

The problem, says lead author of the paper Andrew Rhyne, is a trend away from simple fish-only display tanks towards having entire coral ecosystems in your living room. To create these miniature reefs, invertebrates are harvested from the wild, either to adorn a tank or to provide a useful role, such as keeping algae under control.

Florida hosts the world's third largest ornamental fishery, behind only Indonesia and the Philippines. Rhyne, a marine biologist at the New England Aquarium in Boston, Massachusetts, and Roger Williams University in Bristol, Rhode Island, and his colleagues looked at how fishing in the state has changed. For this, they used the Florida Marine Life Fishery (FMLF) database, which records details of fisheries products caught in the state.

They found that, each year between 1994 and 2007, the number of invertebrates taken from Florida waters increased by 13.3%, or half a million individual animals. Nine million individuals were collected in 2007, with the most popular including the blue-legged hermit crab (Clibanarius tricolor), the five-holed keyhole sand dollar (Mellita tenuis) and the star snail (Lithopoma americanum).

Worryingly, there has also been a shift towards collecting grazing species. These are prized by aquarium keepers as they keep algae under control. But they perform a similar function in the wild, and their removal may hasten what some researchers have dubbed the "slippery slope to slime", in which coral is killed off by algae.

The FMLF fishery, Rhyne et al write, "appears to be crawling to collapse".

"We're not saying the system is totally destroyed or that this is a terrible fishery that shouldn't be occurring," Rhyne told Nature. "We're saying there should be a different management system."

Downturn hopes

The difficulty, says Rhyne, is that there are no real baseline data for many of these species. Simply put, no one knows what a sustainable level of take for many of these animals might be.

With the aquarium industry quick to respond to new trends, Rhyne worries that some animals might become imperilled under the current management system if demand suddenly increases.

At present, most of the invertebrates in question are caught under 'multi-species' licences that allow collectors to take any species except some corals and endangered animals.

In their paper, the researchers suggest that a predicted — although probably temporary — decline in demand for relatively exotic aquarium species owing to the current economic downturn presents a real opportunity to change the management of these animals. Rhyne suggests individually managing the most popular species or reducing the number of licences granted.

The researchers also note that there is legislation under discussion in the US that could ban trade in non-native wildlife. If laws are enacted banning the import of species from outside the US this could "dramatically increase" the pressure on Florida.

Sherry Larkin, a researcher in marine resource management at the University of Florida, says there is a lot of good work in the paper, including information about types of species gathered and exploration of the potential implications of a trade ban.

"I'm less thrilled about the general categorization of the worldwide problem and how the Florida data supports statements that the fishery is headed for collapse," says Larkin. "The regulations for the Florida commercial industry are extensive but the article gives the impression that the effort by the current restricted fishermen is a run-away train that will be solely responsible for a collapse."

Lee Schlesinger, a spokesman for the Florida Fish and Wildlife Conservation Commission in Tallahassee, denied that there was a problem with the management of Florida's marine resources.

"Our fisheries are well managed and have been for years. The resources are considered to be fairly healthy and abundant," he says. "Five hundred-plus species are collected for the aquarium trade. It is a highly regulated fishery here in Florida."