How to Save Sharks off Cuba s Coast and in the Gulf of Mexico [Slide Show]

Is it possible to create a sustainable fishery for sharks before the ocean's top predators are gone?

By Melissa Gaskill

SHARK SHACK: A typical Cuban fishing boat that targets sharks in the country's coastal waters. Image: ROBERT HUETER, MOTE MARINE LABORATORY

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Throughout 2011 researchers from the University of Havana prowled fishing docks in Caba?as and Cojimar on Cuba?s northwestern coast. The teams met returning fishing boats, noted the type and number of fish caught, and asked crews where they had fished, how long and what effort was involved. Oceanic whitetip sharks regularly appeared in catches, and fishermen reported hauling in smaller ones and using them as bait. Researchers say this could indicate the presence of a whitetip nursery area nearby.

So far, that is the only piece of good news from a widespread, collaborative effort by scientists and policy makers to fill in gaps in our knowledge of sharks in Cuban waters. That knowledge is needed to determine how to save these apex predators in the Gulf of Mexico as a whole. The regional population of Oceanic whitetips and other shark species may have declined by as much as 99 percent since the 1950s, according to Doug Rader, chief oceans scientist with the nonprofit advocacy group Environmental Defense Fund (EDF). Populations have plummeted in part because sharks are often swept up as incidental by-catch.

>> View the slide show here.

Researchers have documented at least 54 species of sharks in Cuban waters, many of them important to low-tech, small-scale fisheries. But shark fishermen are reporting decreases in their catches, likely due to the accidental capturing of sharks by boats targeting other species of fishes. Little historical data exist for Cuban fisheries, making it hard to compare targeted and untargeted shark catches over the long term. "We have to go on discussions with fishermen, which is helpful but not truly quantitative," says Robert Hueter, a shark researcher at Florida's Mote Marine Laboratory.

There also is little data about the presence of shark nurseries and the frequency of the species?s migration in Cuban waters.

This lack of dataspurred U.S., Cuban and Mexican scientists to launch the Trinational Initiative for Marine Science and Conservation in 2007. The group set six research priorities, including expanding knowledge of sharks in Cuban waters in order to support conservation decisions for the Gulf of Mexico and Caribbean. The ambitious effort currently involves scientists from the EDF, Mote Marine Laboratory, Mexico's El Colegio de la Frontera Sur, and the University of Havana's Center for Marine Research.

The port surveys are one part of their work. During a nine-day research cruise in February 2013 a multinational group of scientists aboard the Felipe Poey collected water, plankton and sediment samples on the south side of Cuba around Golfo de Batabano and Isla de Juventud. They also interviewed fishermen harvesting finfish, tuna, and lobster in the area (pdf). A key objective of the cruise was tagging sharks, but although researchers had estimated five to 10 sharks per 100 hooks cast, Hueter says, ?We caught three sharks total, or 1.44 per 100 hooks set.? The low numbers as well as discussions with fishermen suggest that overfishing in the area has affected shark populations.

Port surveys planned later this year for Batabano and Jucaro Bay on the south coast may confirm these suspicions. Scientists will also look for evidence of another whitetip nursery?a possibility given the location?s ecological similarity to the nursery area on the north side of the island.

A cruise planned for the fall will explore the Jardines de la Reina archipelago and Golfo de Ana Maria, two popular ecotourism areas where researchers expect to tag higher numbers of sharks. The group will eventually compile tagging, observational data and port surveys to create a formal habitat classification system. The system will describe the distribution and abundance of sharks in Cuban waters to help determine their habitat needs, Rader says, an important first step toward protecting them. "Most scientists believe sharks are critical to the resilience and robustness of marine systems, and that one of the best ways to maintain a warming and acidifying marine environment is to rebuild robust shark populations," he adds.

Source: http://rss.sciam.com/~r/sciam/biology/~3/EfAzqHIPWf4/article.cfm

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