Interactions Between a Large Marine Protected Area, Pelagic Tuna and Associated Fisheries

Curnick, David J.; Collen, Ben; Koldewey, Heather J.; Jones, Kate E.; Kemp, Kirsty M.; Ferretti, Francesco

doi:10.3389/fmars.2020.00318

Cited by 18 publications

(19 citation statements)

References 62 publications

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“…Extending out to the full 200-nm EEZ, the MPA surrounding it totals approximately 640,000 km 2 and encompasses over 60,000 km 2 of shallow coral reefs. Prior to MPA establishment, licenses were granted to an international fleet of longliners and purse seiners targeting tuna and billfish (Koldewey et al 2010;Curnick et al 2020). The purse seine fishery was highly seasonal, associated with the fleet migrating across the western Indian Ocean and fishing in the territory during the winter monsoon season, November to January (Davies et al 2014;Dunn & Curnick 2019).…”

Section: Methodsmentioning

confidence: 99%

Risks to large marine protected areas posed by drifting fish aggregation devices

Curnick

Cavalcante

2021

Conservation Biology

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Mapping and predicting the potential risk of fishing activities to large marine protected areas (MPAs), where management capacity is low but fish biomass may be globally important, is vital to prioritizing enforcement and maximizing conservation benefits. Drifting fish aggregating devices (dFADs) are a highly effective fishing method employed in purse seine fisheries that attract and accumulate biomass fish, making fish easier to catch. However, dFADs are associated with several negative impacts, including high bycatch rates and lost or abandoned dFADs becoming beached on sensitive coastal areas (e.g., coral reefs). Using Lagrangian particle modeling, we determined the potential transit of dFADs in a large MPA around the Chagos Archipelago in the central Indian Ocean. We then quantified the risk of dFADs beaching on the archipelago's reefs and atolls and determined the potential for dFADs to pass through the MPA, accumulate biomass while within, and export it into areas where it can be legally fished (i.e., transit). Over one-third (37.51%) of dFADs posed a risk of either beaching or transiting the MPA for >14 days, 17.70% posed a risk of beaching or transiting the MPA for >30 days, and 13.11% posed a risk of beaching or transiting the MPA for >40 days. Modeled dFADs deployed on the east and west of the perimeter were more likely to beach and have long transiting times (i.e., posed the highest risk). The Great Chagos Bank, the largest atoll in the archipelago, was the most likely site to be affected by dFADs beaching. Overall, understanding the interactions between static MPAs and drifting fishing gears is vital to developing suitable management plans to support enforcement of MPA boundaries and the functioning and sustainability of their associated biomass.

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Section: Methodsmentioning

confidence: 99%

Risks to large marine protected areas posed by drifting fish aggregation devices

Curnick

Cavalcante

2021

Conservation Biology

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“…For example, we cannot rule out seasonal variation in silky shark catch rates. The longline hook survey only spanned three years and all sets surveyed were carried out between November and January, the traditional peak fishing season around the Chagos Archipelago (Dunn and Curnick, 2019;Curnick et al, 2020), when migrating tuna are thought to pass through the area (Pearce, 1996). This may in turn lead to increased catch rates of pelagic predators during this time, especially silky sharks who associate with these target species.…”

Section: Discussionmentioning

confidence: 99%

“…Extending out to the full EEZ, the BIOT MPA covers 640,000 km 2 of ocean, with the vast majority being deep oceanic water with maximum depths of over 5,000 m. The BIOT MPA was declared a notake protected area in 2010 with the exclusion of all industrial fishing practices. Prior to the establishment of the MPA, the main licensed commercial fishery was for tunas and billfishes, using both longline and purse seine methods (Dunn and Curnick, 2019;Curnick et al, 2020), with considerable shark bycatch (Koldewey et al, 2010).…”

Section: Study Sitementioning

confidence: 99%

“…Large no-take MPAs that encompass vast swathes of open ocean could be part of the solution for the conservation of sharks (Wood et al, 2008;Game et al, 2009;Koldewey et al, 2010). Yet there is limited evidence that large no-take MPAs can protect mobile pelagic species such as sharks or tunas, with protected areas potentially displacing fishing effort to other areas (De Santo et al, 2011;Kaplan et al, 2014;Curnick et al, 2020). Therefore, the efficacy of MPAs for pelagic sharks will be dependent on the spatial relationship between the habitats of sharks and protected area coverage.…”

Section: Introductionmentioning

confidence: 99%

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Behavior and Ecology of Silky Sharks Around the Chagos Archipelago and Evidence of Indian Ocean Wide Movement

et al. 2020

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Silky sharks (Carcharhinus falciformis) represent a major component of global shark catch, both directly and as bycatch, and populations are declining as a result. An improved understanding of their movement ecology is needed to support conservation efforts. We deployed satellite and acoustic tags (2013–2018) and analyzed historical fisheries records (1997–2009), to investigate the spatial ecology of silky sharks in the central Indian Ocean and a large Marine Protected Area (MPA; 640,000 km2) around the Chagos Archipelago. We observed high fidelity to the MPA, and a sustained diurnal association with a seamount complex, with individuals moving off at night and returning at sunrise. Yet, we also observed large-scale divergent movements in two satellite tagged individuals and documented the furthest recorded displacement distance for a satellite tagged silky shark to date, with one individual moving from the MPA to the Kenyan coast—a displacement distance of 3,549 km (track distance ∼4,782 km). Silky sharks undertook diel vertical migrations and oscillatory diving behavior, spending > 99% of their time in the top 100 m, and diving to depths of greater than 300 m, overlapping directly with typical deployments of purse seine and longline sets in the Indian Ocean. One individual was recorded to a depth of 1,112 m, the deepest recorded silky shark dive to date. Individuals spent 96% of their time at liberty within water temperatures between 24 and 30°C. Historic fisheries data revealed that silky sharks were a major component of the shark community around the archipelago, representing 13.69% of all sharks caught by longlines before the fishery closed in 2010. Over half (55.88%) of all individuals caught by longlines and purse seiners were juveniles. The large proportion of juveniles, coupled with the high site fidelity and residence observed in some individuals, suggests that the MPA could provide considerable conservation benefits for silky sharks, particularly during early life-history stages. However, their high mobility potential necessitates that large MPAs need to be considered in conjunction with fisheries regulations and conservation measures in adjacent EEZs and in areas beyond national jurisdiction.

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“…This finding differs from those reporting increases in catch abundance inside protected areas [12,26,35], which might be due to the relatively old age of the Cerbère-Banyuls reserve established in 1974. Indeed, marine reserves promote prolific marine populations, including large predatory species that take longer to re-establish and, through time, are expected to increasingly regulate the abundance of smaller assemblages via trophic cascades [17,23,25,[39][40][41]. For example, the Cerbère-Banyuls marine reserve hosts a recovering population of the large predator dusky grouper (Epinephelus marginatus) whose abundance has been increasing from 10 individuals in 1986 to more than 650 in 2020 (the population abundance over our study period being 202 in 2006 and 429 in 2014; www.gemlemerou.org).…”

Section: Effectiveness Of the Reservementioning

confidence: 99%

Marine reserve benefits and recreational fishing yields: The winners and the losers

et al. 2020

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Marine reserves constitute effective tools for preserving fish stocks and associated human benefits. However, not all reserves perform equally, and predicting the response of marine communities to management actions in the long run is challenging. Our decadal-scale survey of recreational fishing yields at France’s 45-year old Cerbère-Banyuls marine reserve indicated significant protection benefits, with 40–50% higher fishing yields per unit effort in the partial-protection zone of the reserve (where fishing is permitted but at a lower level) than in surrounding non-reserve areas. Over the period 2005–2014, catch per unit effort (CPUE) declined both inside and outside the reserve, while weight per unit effort (WPUE) increased by 131% inside and decreased by 60% outside. Different CPUE and WPUE trajectories among fish families indicated changing catch assemblages, with yields increasing for the family most valued by fisheries, Sparidae (the ecological winners). However, reserve benefits were restricted to off-shore fishermen (the social winners), as on-shore yields were ~4 times lower and declining, even inside the reserve. Our study illustrates how surveys of recreational fishing yields can help evaluate the effectiveness of marine protected areas for key social and ecological protagonists. We show that, more than four decades after its establishment, fishing efficiencies at the historical Cerbère-Banyuls marine reserve are still changing, but benefits in terms of catch abundance, weight, and composition remain predominantly restricted to off-shore fishermen. Further regulations appear necessary to guarantee that conservation strategies equitably benefit societal groups.

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Interactions Between a Large Marine Protected Area, Pelagic Tuna and Associated Fisheries

Cited by 18 publications

References 62 publications

Risks to large marine protected areas posed by drifting fish aggregation devices

Risks to large marine protected areas posed by drifting fish aggregation devices

Behavior and Ecology of Silky Sharks Around the Chagos Archipelago and Evidence of Indian Ocean Wide Movement

Marine reserve benefits and recreational fishing yields: The winners and the losers

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