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Positive catch & economic benefits of periodic octopus fishery closures: do effective, narrowly targeted actions ‘catalyze’ broader management?

18
Jun

Positive catch & economic benefits of periodic octopus fishery closures: do effective, narrowly targeted actions ‘catalyze’ broader management?

Thomas A. Oliver, Kirsten L.L. Oleson, Hajanaina Ratsimbazafy, Daniel Raberinary, Sophie Benbow, Alasdair Harris (2015) Positive catch & economic benefits of periodic octopus fishery closures: do effective, narrowly targeted actions ‘catalyze’ broader management? PLOS ONE.

Eight years of octopus fishery records from southwest Madagascar reveal significant positive impacts from 36 periodic closures on: (a) fishery catches and (b) village fishery income, such that (c) economic benefits from increased landings outweigh costs of foregone catch. Closures covered ~20% of a village’s fished area and lasted 2-7 months.

Fishery catches from each closed site: Octopus landings and catch per unit effort (CPUE) significantly increased in the 30 days following a closure’s reopening, relative to the 30 days before a closure (landings: +718%, p<0.0001; CPUE: +87%, p<0.0001; n=36). Open-access control sites showed no before/after change when they occurred independently of other management (“no ban”, n=17/36). On the other hand, open-access control sites showed modest catch increases when they extended a 6-week seasonal fishery shutdown (“ban”, n=19/36). The seasonal fishery shutdown affects the entire region, so confound all potential control sites.

Fishery income in implementing villages: In villages implementing a closure, octopus fishery income doubled in the 30 days after a closure, relative to 30 days before (+132%, p<0.001, n=28). Control villages not implementing a closure showed no increase in income after “no ban” closures and modest increases after “ban” closures. Villages did not show a significant decline in income during closure events.

Net economic benefits from each closed site: Landings in closure sites generated more revenue than simulated landings assuming continued open-access fishing at that site (27/36 show positive net earnings; mean +$305/closure; mean +57.7% monthly). Benefits accrued faster than local fishers’ time preferences during 17-27 of the 36 closures. High reported rates of illegal fishing during closures correlated with poor economic performance.

We discuss the implications of our findings for broader co-management arrangements, particularly for catalyzing more comprehensive management.



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