Globally, sharks are likely not reproducing fast enough to maintain stable populations in the face of widespread fishing.
Indonesia is the world’s largest source of shark fins and fishers targeting sharks.
A new study based on 2012 research found more sharks in two no-take zones compared with an open-access fishing area in West Papua, Indonesia, justifying a regency-wide ban on shark fishing implemented the same year.
However, fishermen and other members of fishing communities interviewed for the study felt marginalized by the process of protecting sharks and the study authors conclude that shark conservation measures may inadvertently result in displacing fishing effort to unprotected regions.
Protected waters contain more sharks than open-access fishing zones, concluded a recently released study based in the waters of West Papua, Indonesia. The research adds to mounting evidence that “spatial closures,” such as no-take zones, are an effective marine conservation measure.
The authors, Murdoch University graduate student Vanessa Jaiteh and five collaborators, compared shark abundance in two privately-managed no-take zones and one open-access fishing area in Raja Ampat, a biodiversity hotspot and world-famous diving destination. Raja Ampat implemented a regency-wide ban on shark fishing in 2012 — the same year Jaiteh conducted her research — making it the only shark sanctuary in Indonesian waters. The new measure came as a boon, particularly for the habitats in the open-access fishing area where shark numbers are troublingly low.
“Sharks are apex predators that play a huge role in maintaining ecological balance in the region’s marine ecosystems,” said Sangeeta Mangubhai, director of Wildlife Conservation Society-Fiji and one of the study’s co-authors, in a press release.
The most recent global estimate of shark populations found that “the average exploitation rate ranged between 6.4% and 7.9% of sharks killed per year” — a catch rate the authors deemed “unsustainable.” Given that sharks have long gestation periods (hammerheads carry their young for 7 months. Dogfish sharks carry them for two years), sharks are likely not reproducing fast enough to maintain stable populations in the face of widespread fishing.
And how do you count sharks in a remote marine protected area? Apparently the same way you tally up alley cats. Set out some tuna.
Jaiteh’s team built “baited remote underwater video systems”: plastic frames hung with dive weights, two Go-Pro cameras, and a kilogram of flaked skipjack tuna. The researchers dropped the devices at 20 regular fishing sites off Raja Ampat’s Misool Island and 20 sites in two adjacent no-take zones around Batbitim and Daram islands.
Sharks came for the feast. The Go-Pros recorded the carnage in 45-minute sequences. Back in her lab, Jaiteh analyzed 144 hours of footage to identify 50 sharks, 3 stingrays (relatives of sharks) and 1,274 reef fish.
Out of 50 sharks she sighted, 48 were caught on camera in the no-take zones and only two in the open-access area. Jaiteh also found more reef fish in the no-take zones, notably economically important species, such as snapper, and the endangered humphead wrasse (Cheilinus undulatus). The finding was even more surprising given that the total no-take zone area surveyed was just one-quarter of the size of the open-access area.
The authors conclude that the difference was due to successful conservation in the no-take zones coupled with ongoing shark fishing in the open-access area.
However, fishermen and other members of fishing communities interviewed for the study felt marginalized by the process of protecting sharks. Sixty-seven percent of respondents in Osi, a community of shark-fishers in Central Maluku islands who have targeted the region near Misool Island, reported being affected by the 2012 Raja Ampat regency-wide ban on shark fishing. Most reported a loss of income because the ban forced them to shift to less productive fishing grounds or more remote ones that meant higher fuel costs. Others said the ban made them stop fishing altogether or refocus their efforts on catching smaller, less valuable reef fish closer to their own island. And still others said they chose to become illegal petrol dealers or to shift their shark fishing to areas where it remained legal.
“In a western country, it is unlikely that fishers would simply be told about a new fishing ban or protected area without having any avenue of voicing their opinion about it, or without having some form of income protection or at least fair warning,” Jaiteh told Mongabay by email. “As our study shows, not understanding or considering fishers’ dependence on their livelihoods — which is of course not always possible — might lead to adverse adaptation.”
Indonesia is the world’s largest source of shark fins and fishers targeting sharks. Jaiteh’s research was done in 2012, seven and two years, respectively, after the Batbitim and Daram shark no-take zones were set aside. The open-access area around Misool was rezoned as a limited-access fishing area shortly after Jaiteh’s research concluded. She has yet to gather data on the effect of the new management system.
- Jaiteh, V.F., Lindfield, S.J., Mangubhai, S., Warren, C., Fitzpatrick, B., Loneragan, N. (2016). Higher abundance of marine predators and changes in fishers’ behavior following spatial protection within the world’s biggest shark fishery. Frontiers in Marine Science 3:43.
- Worm, B., Davis, B., Kettermer, L., Ward-Paige, C.A., Chapman, D., Heithaus, M.R., Kessel, S.T., Gruber, S.H. (2013). Global catches, exploitation rates, and rebuilding options for sharks. Marine Policy 40:194–204.