Study

Lessons learnt from experimental temporary octopus fishing closures in south-west Madagascar: benefits of concurrent closures

  • Published source details Benbow S., Humber F., Oliver T., Oleson K., Raberinary D., Nadon M., Ratsimbazafy H. & Harris A. (2014) Lessons learnt from experimental temporary octopus fishing closures in south-west Madagascar: benefits of concurrent closures. African Journal of Marine Science, 36, 31-37.

Actions

This study is summarised as evidence for the following.

Action Category

Establish temporary fisheries closures

Action Link
Subtidal Benthic Invertebrate Conservation
  1. Establish temporary fisheries closures

    A before-and after, site comparison study in 2004–2005 in a coral reef area in the Velondriake Locally Managed Marine Area, southwestern Madagascar, Mozambique Channel (Benbow et al. 2014a) found that temporarily closing an area to a reef octopus Octopus cyanea fishery did not lead to a significant increase in the weight of octopus, and did not increase their abundance, compared to before closure and to continuously fished areas. Across fishing events during the first spring tide following the temporary closure, the average weight of caught octopus was 64% higher than before closure (before: 719 g; after: 1,120 g) but this was not statistically significant. In addition, the percentage of caught octopus over 2 kg increased from 8% to 20%. However, this increase in weight was not observed across the second spring tide (data not shown). Abundance (as biomass of octopus caught) did not change before and after closure in either temporarily closed sites or continuously fished sites and was similar at all sites (closed before: 3, closed after: 2–3.5; fished before: 2.7, fished after: 2–2.5 kg/fisher/day). An octopus fishery was closed at one site between November 2004 and June 2005 by means of a Dina (a traditional local law). Fishery data, including octopus weight, catch/unit effort and location of landing, were collected on a regular basis across nine nearby villages from September 2004 (before closure) and until at least two spring tides after reopening. These data included the closed site and 14 continuously fished sites (where spear fishing was the only practice).

     

    A replicated, before-and after, site comparison study in 2005–2006 in a coral reef area in the Velondriake Locally Managed Marine Area, southwestern Madagascar, Mozambique Channel (Benbow et al. 2014b) found that temporarily closing areas to a reef octopus Octopus cyanea fishery led to an increase in the weight of octopus, but not abundance, compared to before closure and to continuously fished areas. Across fishing events during the first spring tide following the temporary closure, the average weight of caught octopus was 160% higher at one of the three sites than before closure (before: 436 g; after: 1,136 g). However, this effect was not observed across the second spring tide (data not shown). At the two other closed sites, octopus weight was similar before closure (893 g and 997 g) and directly after reopening (889 g and 988 g). However, on reopening, octopus at all closed sites were 21–56% bigger (by weight; 889–1,165 g) than at fished sites (737 g). Following closure, abundance (as biomass of octopus caught) had increased by 88–146% in the closed sites (before: 1.3–1.6; after: 3–3.2 kg/fisher/day), while abundance did not change at fished sites and was lower (before: 2.4; after: 2.8 kg/fisher/day). This effect was also observed in the following tides. A state-enacted closure of octopus fishery was set across southwest Madagascar between early December 2005 and end of January 2006. This closure was extended at three sites and set between November 2005 and April 2006 by means of a Dina (a traditional local law). Fishery data, including octopus weight, catch/unit effort, and location of landing, were collected on a regular basis across nine nearby villages from September 2004 (before closure) until September 2006 (at least two spring tides after reopening). These data included the closed sites and 14 continuously fished sites (where spear fishing wass the only practice).

    (Summarised by: Anaëlle Lemasson)

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