SEVENSEAS Marine Conservation & Travel Issue 16, September 2016 - Page 38

pounds versus 3.2 million pounds, a trend that repeated in 2014, though to a lesser extent. While these statistics do not account for unwanted species caught by commercial vessels and dumped at sea (though most are landed), it suggests that a many people with a single hook can in fact have an impact akin to one person with many hooks.

The targeting of large sharks by recreational fishermen hoping to break world records may also exacerbate these effects. As in other species of fish, larger sharks have a greater reproductive potential, showing an ability to carry more young and reproduce more often. Females also tend to be larger than males, meaning the largest individuals in a population are often pregnant females. Therefore, removing a single large shark could have a disproportionately negative impact on the population, which is of special concern for species with already declining numbers. Currently, 15 species of sharks with world records issued by the International Game Fishing Association are also listed as “Threatened with Extinction” by the International Union for the Conservation of Nature.

Even if a shark is released alive, the stress caused by its capture could result in its death, even days or weeks later. Research shows that certain species are more susceptible to capture stress than others, with hammerheads named as particularly vulnerable. Dr. Austin Gallagher, who studies sharks’ behavioral and physiological response to capture, says his work implies that hammerheads’ elevated stress response is associated with its hard-fighting nature and tendency to “pull line,” the same quality that makes them a highly sought target for recreational anglers.

Many fishermen are aware of hammerheads’ vulnerability, and try to increase their chances by minimizing fight times and keeping them submerged while removing gear. While Dr. Gallagher appreciates these efforts, he says given hammerheads’ high stress response even at low fight times, they are not enough to stop the plummeting of their populations. In one of his studies, a great hammerhead died minutes after being released while being fought for under half an hour, even when using lower-stress fishing techniques. Given this outcome, Dr. Gallagher says hammerheads are better off risking the hazards of retained gear left by an angler cutting the line immediately than fighting being reeled into the boat or shore. Although, the best practice, he says, would be for fishermen to stop targeting fragile species altogether. “I love recreational anglers, they are great people and most of them really care about the resource,” he says, “but they have to listen to the data.” He also stresses the responsibility of scientists to effectively communicate this data and actively engaging with anglers, the importance of which “cannot be overstated.”

particularly vulnerable. Dr. Austin Gallagher, who studies sharks’ behavioral and physiological response to capture, says his work implies that hammerheads’ elevated stress response is associated with its hard-fighting nature and tendency to “pull line,” the same quality that makes them a highly sought target for recreational anglers.

Many fishermen are aware of hammerheads’ vulnerability, and try to increase their chances by minimizing fight times and keeping them submerged while removing gear. While Dr. Gallagher appreciates these efforts, he says given hammerheads’ high stress response even at low fight times, they are not enough to stop the plummeting of their populations. In one of his studies, a great hammerhead died minutes after being released while being fought for under half an hour, even when using lower-stress fishing techniques. Given this outcome, Dr. Gallagher says hammerheads are better off risking the hazards of retained gear left by an angler cutting the line immediately than fighting being reeled into the boat or shore. Although, the best practice, he says, would be for fishermen to stop targeting fragile species altogether. “I love recreational anglers, they are great people and most of them really care about the resource,” he says, “but they have to listen to the data.” He also stresses the responsibility of scientists to effectively communicate this data and actively engaging with anglers, the importance of which “cannot be overstated.”

Hammerheads are already protected in certain states, such as Florida, but Gallagher says given their fragility they should also be given greater federal protections, though petitions to do so were rejected for two of the three species. A recent study by Gallagher’s colleague from the University of Miami, Dr. Neil Hammerschlag, could help bolster this argument. It showed that only 17 percent of hammerheads’ core range on the Atlantic seaboard—the places where they spend most of their time—are protected, but covering hammerheads under federal law would cover this range entirely. “One of the big arguments is that sharks are highly mobile and will end up in international waters where there’s no protection in place, so why should we lose the economic opportunity if it will be exploited elsewhere?” Dr. Hammerschlag states, “But if you protect them in key areas where they are doing important things like feeding and reproducing, you don’t necessarily have to protect them everywhere they go,” adding that in the past, such policies have brought other migratory species, such as birds, back from the brink of extinction.

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