Research published today in the journal Conservation Biology presents the most comprehensive assessment of the status of Pacific shark populations to date. The paper, authored by Dr. Shelley Clarke and a team from the Secretariat of the Pacific Community in New Caledonia, shows significant declines in catch rates for blue, mako, and oceanic whitetip sharks, as well as declining average sizes of oceanic whitetip and silky sharks, indicating heavy fishing. These results, along with evidence of shark targeting reported by Dr. Clarke and other scientists in the western North Pacific, heighten concerns for the sustainability of Pacific shark populations.
“Our research reveals alarming declines of 17% per year in populations of the oceanic whitetip shark, a species highly valued for its fins,” explained Dr. Clarke. “Also of serious concern are declines of 5% per year for North Pacific blue sharks, considering that this species is known as one of the most productive and abundant pelagic sharks. Overall, the data we analyzed show consistent trends for each species and area, even though they were collected from different fisheries.”
The paper also suggests that bans on shark finning (slicing off a shark’s fins and discarding the carcass at sea), as currently implemented, are doing little to reduce the number of sharks killed in international longline fisheries, likely due to a combination of poor enforcement and increasing markets for shark meat. Finning bans for international Pacific waters include a complicated fin-to-carcass weight ratio for enforcement and depend on follow-up domestic actions which to date have been lacking. The oceanic whitetip is the only shark species currently subject to international Pacific catch limits.
“These findings underscore conservationists’ messages that most finning bans are not properly enforced, and alone are not sufficient to reverse shark population declines,” said Sonja Fordham, President of Shark Advocates International. “Prohibitions on at-sea removal of shark fins not only bolster finning ban enforcement, but also facilitate collection of species-specific shark fisheries data that are key to refining population assessments and informing the establishment of urgently needed shark catch limits.”
In a 2006 landmark study, Dr. Clarke revealed the main species in the Hong Kong shark fin trade – including blues, makos, and oceanic whitetips – and estimated the associated global mortality at 26-73 million sharks per year.