Marc Léopold

Integrated coastal zone management perspectives to ensure the sustainability of coral reefs in New Caledonia.

Based on a pluridisciplinary research programme on New Caledonias lagoon (2004-2008), this paper addresses economic, ecological and political issues in order to implement integrated coastal zone management (ICZM) in this French Pacific territory. The nickel mining industry constitutes the core of the re-balancing economic and social strategy between the Northern and Southern provinces. But major impacts on the coastal environment of metal-processing plants, harbours, and decades of mine exploitation have released a controversy. A short diachronic analysis suggests that such environmental concerns prompted the emergence of collective actions to among civil society, customary and institutional stakeholders. The inscription of New Caledonia lagoon and reef areas in the UNESCO World Heritage List in 2008 would be both an outcome and a catalyst of this on-going process. Looking beyond the reefs towards the mainland and watersheds for the construction of local socio-ecological systems, we assume that the current stakes could result in the initiation of ICZM in New Caledonia.

Does herbivorous fish protection really improve coral reef resilience? A case study from new caledonia (South Pacific).

Parts of coral reefs from New Caledonia (South Pacific) were registered at the UNESCO World Heritage list in 2008. Management strategies aiming at preserving the exceptional ecological value of these reefs in the context of climate change are currently being considered. This study evaluates the appropriateness of an exclusive fishing ban of herbivorous fish as a strategy to enhance coral reef resilience to hurricanes and bleaching in the UNESCO-registered areas of New Caledonia. A two-phase approach was developed: 1) coral, macroalgal, and herbivorous fish communities were examined in four biotopes from 14 reefs submitted to different fishing pressures in New Caledonia, and 2) results from these analyses were challenged in the context of a global synthesis of the relationship between herbivorous fish protection, coral recovery and relative macroalgal development after hurricanes and bleaching. Analyses of New Caledonia data indicated that 1) current fishing pressure only slightly affected herbivorous fish communities in the country, and 2) coral and macroalgal covers remained unrelated, and macroalgal cover was not related to the biomass, density or diversity of macroalgae feeders, whatever the biotope or level of fishing pressure considered. At a global scale, we found no relationship between reef protection status, coral recovery and relative macroalgal development after major climatic events. These results suggest that an exclusive protection of herbivorous fish in New Caledonia is unlikely to improve coral reef resilience to large-scale climatic disturbances, especially in the lightly fished UNESCO-registered areas. More efforts towards the survey and regulation of major chronic stress factors such as mining are rather recommended. In the most heavily fished areas of the country, carnivorous fish and large targeted herbivores may however be monitored as part of a precautionary approach.

Effectiveness of village-based marine reserves on reef invertebrates in Emau, Vanuatu

Despite the current expansion of community-based marine conservation initiatives in the Pacific, few studies have specifically addressed their ecological efficiency to restore or enhance reef invertebrate resources. This paper investigated the effects of two very small (< 0.05 km 2 ) recent village-based marine reserves (tabu areas) located along the shallow fringing reef of Emau island, Vanuatu. Surveys focused on heavily harvested species (namely trochus, giant clams and green snails) and involved both experienced scientists and local villagers. Abundance, density and individual size data were collected by snorkelling along random transect belts located inside and outside the tabu areas, using simple PVC measuring tools specifically developed for participative monitoring. Habitat was assessed using a photographic method to quantitatively describe varied reef substrata. Resource recovery varied between the areas as a result of species-specific responses to contrasted reserve characteristics and local management practices. Fast-growing mobile Trochus niloticus exhibited strong positive abundance and size responses only within the older larger tabu area through the combined effects of protection from harvesting and translocation actions by local fishers. Similar trends were observed to a lesser extent for sessile slow-growing giant clams (Tridacna spp.), but these were not significant after four years of closure. Despite historical evidence of their presence in the area, surveys emphasized the severe population collapse of the heavily targeted green snail (Turbo marmoratus). Under certain conditions, very small-scale reserves, such as those implemented by village-based conservation initiatives, can rapidly and efficiently enhance local reef invertebrate resources. It is still unclear whether the changes are sufficient to restore critical levels of spawning biomass at larger scale and reverse the severe depletion of invertebrate resources occurring in Vanuatu.

Comanaging small-scale sea cucumber fisheries in New Caledonia and Vanuatu using stock biomass estimates to set spatial catch quotas

Many sea cucumber fisheries have dramatically declined worldwide due to rapid overexploitation and ineffective management. This study designed an innovative management strategy for small-scale, data-limited sea cucumber fisheries in Pacific Island countries. Firstly, a local quota-based comanagement system was implemented in New Caledonia to manage a small-scale sandfish Holothuria scabra fishery. A habitat map derived from high-resolution satellite imagery was used to stratify survey sampling and assess the harvestable stock biomass. The latter has been monitored as the reference biomass (RB) since 2008 and repeatedly used by the local fishers’ organization and Fisheries Department officers to set adaptive total allowable catches and regulations of fishing effort. Results showed the excellent performance of this fishery between 2008 and 2012, both biologically (167% increase in total stock biomass) and economically (146% increase in annual returns from catches). Secondly, the assessment of the RB was generalized to multispecies sea cucumber fisheries in Vanuatu in 2011 before the proposed lifting of a five-year national moratorium. Building upon these practical case studies in New Caledonia and Vanuatu, this paper outlines an operational framework to inform sea cucumber fisheries policy in these two countries and discusses the upscaling of the proposed management strategy.

Geographical aspects of informal reef fishery systems in New Caledonia.

The coral reefs in New Caledonia have long been used by the local population for subsistence as well as commercial and recreational purposes. The impact of informal fisheries on reef ecosystems illustrated the idiosyncrasies of New Caledonian fisheries in the southwest Pacific. This paper compared informal fishery systems on the southwest coast (close to the capital and economic center of the country) and the northwest coast (where an industrial mining complex has been under development) of New Caledonia to analyze their spatial structure and characteristics. Four geosystems were defined. These depended on the natural, social and economical environments as well as management strategies. The way of life of the fishers proved to be a major factor in how the informal fishery systems were structured. Our observations suggested that ongoing socio-economic changes in New Caledonia have shaped informal fishing activities since the 1900s. The findings from this study validate the suitability of spatial approaches to coral reef fisheries and provide local stakeholders with original management clues for marine resources sustainability.

Modulation of Habitat-Based Conservation Plans by Fishery Opportunity Costs: A New Caledonia Case Study Using Fine-Scale Catch Data

Numerous threats impact coral reefs and conservation actions are urgently needed. Fast production of marine habitat maps promotes the use of habitat-only conservation plans, where a given percentage of the area of each habitat is set as conservation objectives. However, marine reserves can impact access to fishing grounds and generate opportunity costs for fishers that need to be minimized. In New Caledonia (Southwest Pacific), we used fine-scale fishery catch maps to define nineteen opportunity costs layers (expressed as biomass catch loss) considering i) total catches, ii) target fish families, iii) local marine tenure, and iv) gear type. The expected lower impacts on fishery catch when using the different cost constraints were ranked according to effectiveness in decreasing the costs generated by the habitat-only scenarios. The exercise was done for two habitat maps with different thematic richness. In most cases, habitat conservation objectives remained achievable, but effectiveness varied widely between scenarios and between habitat maps. The results provide practical guidelines for coral reef conservation and management. Habitat-only scenarios can be used to initiate conservation projects with stakeholders but the costs induced by such scenarios can be lowered by up to 50–60% when detailed exhaustive fishery data are used. When using partial data, the gain would be only in the 15–25% range. The best compromises are achieved when using local data.

Tectus (Trochus) niloticus search for suitable habitats can cause equivocal benefits of protection in village-based marine reserves

In the Pacific, the protection of coral reef resources is often achieved through the implementation of village-based marine reserves (VBMRs). While substantial fisheries benefits are often reported, results of quantitative approaches are controversial for benthic macroinvertebrates, whose life history traits may cause low congruence with protective measures implemented at non-ecologically relevant scales. This study investigated the structural and behavioral responses of the exploited topshell Tectus niloticus within a very small (0.2 km2) VBMR in Vanuatu, south Pacific. The results of underwater surveys and a nine-month tagging experiment emphasized contrasted, scale-dependent responses. At the reserve scale, our results failed to demonstrate any positive effect of protection after three years of closure. In contrast, abundance, density and biomass increased more than ten-fold in the southern part of the reserve, along with significantly larger (25%) individual sizes. The dispersal of tagged specimens was also consistently lower after 2, 4 and 9 months in the latter zone. Analyses of 17 substratum variables revealed a marked small-scale patchiness delineating contrasted benthic microhabitats, the distribution of which closely matched that of trochus. We advocate that i) VBMRs have inherently unequal ecological potentials for protecting and managing highly habitat-dependent species such as trochus; ii) ‘success’ or ‘failure’ is to a certain extent pre-determined by the trajectory of species-specific microhabitats, which may outreach protection effects. This has strong implications in the Pacific where the location and size of reserves primarily depends upon marine tenure, and communities have little flexibility in setting reserve boundaries.

An improved reconstruction of total marine fisheries catches for the New Hebrides and the Republic of Vanuatu, 1950-2014

1. Abstract For many small island nations, fisheries provide residents with both food security and economic stability. However, in order to create effective and sustainable fisheries policies and management that will ensure a growing population can prosper, policy makers need to know what is being fished and how much is fished. Vanuatu, the smallest country in Melanesia, has a declared and claimed Exclusive Economic Zone (EEZ) of over 820,000 km2 and fisheries resources play a large part in the food security and economic stability of this country. This reconstruction of total marine fisheries catch of Vanuatu for 1950 to 2014 faced major data gaps. It showed that the reconstructed total catches of nearly 1.4 million t were 40% higher than the 977,997 t reported by the Food and Agriculture Organization (FAO) on behalf of Vanuatu for the same period. However, if large-scale industrial catches are excluded, the reconstructed small-scale fisheries catches (~ 270,000 t) were over 200% higher than the 114,862 t of reported catch that were assumed to represent the small-scale sector in FAO data. Subsistence catches made up almost 93% of small-scale catches, followed by artisanal and recreational catches with ~7% and less than 1%, respectively. By continuously improving the fisheries data of Vanuatu for both the past and the present, policy makers, stakeholders and fishers can make better decisions that will maintain the benefits of marine fishery resources.