Hammerheads Dwindle, Agency Blames Finning
WASHINGTON (CN) - Due to sharp population declines from finning, four distinct population segments (DPSs) of scalloped hammerhead sharks now have federal protection. The National Marine Fisheries Service has listed two DPSs as endangered and two DPSs as threatened under the Endangered Species Act. The agency's action is in response to a 2011 petition jointly filed by the WildEarth Guardians and Friends of Animals environmental groups.
The NMFS uses genetic testing, geographical habitat and observed behavior to group the sharks into the DPS designations. For scalloped hammerhead sharks, six DPSs have been identified world-wide. The agency determined that two of the DPSs do not warrant listing protection at this time.
Scalloped hammerheads, named for the wavy front edge of their heads, are highly mobile within their range, but tend to have "site fidelity" and "limited distance movements." The known ranges correlate with the genetic differences noted between populations, which allows the agency to determine the "discreteness" of each population, the action said.
Of the four DPSs that have now been listed, the Central and Southwest Atlantic DPS and the Indo-West Pacific DPS are listed as threatened, and the Eastern Atlantic DPS and Eastern Pacific DPS are listed as endangered.
"Shark species worldwide are dwindling in the face of heavy fishing pressures; sharks are killed for their meat and fins, which are used in highly controversial shark-fin soup. Sharks are also accidentally caught and killed in the course of fishing operations targeting other species. Experts consider fishing the greatest threat to all sharks," the Friends of Animals said in their response to the final listing.
The NMFS noted that catch rates have declined dramatically from historic levels. "Specifically, declines of 99 percent, 86 percent, and 64 percent have been estimated for S. lewini from catch rates in shark nets deployed off the beaches of South Africa from 1952-1972, 1961-1972, and 1978-2003, respectively," according to the action.
More troubling is the decrease in relative size of the sharks caught. Because the sharks are long-lived, slow-growing and late-maturing, the loss of reproductively mature fish decreases the viability of the population.
"Scalloped hammerhead sharks are valued for their large fins, which fetch a high commercial value in the Asian shark fin trade and comprise the second most traded fin category in the Hong Kong market. Due to this profit incentive, there have been many reports of finning and seizures of illegally gained shark fins," according to the final listing action.
"The practice of 'finning' is of particular concern for scalloped hammerheads and other sharks. In this practice, crews land the sharks and remove only their fins, disposing of the remainder of the animals overboard and leaving disabled sharks to drown or die of starvation. By taking the fins only, crews catch and kill many more sharks than their boats could otherwise hold-and many more than can be officially recorded as losses to the bio-community," the WildEarth Guardians said in their response to the listing proposal last year.
The NMFS did not find that other factors such as habitat destruction, climate change or disease were significantly contributing to the sharks' decline.
The agency plans to determine critical habitat in a separate action.
The final listings are effective Sept. 2, 2014.