Papers in peer-reviewed journals

The global information system on small-scale fisheries (ISSF): A crowdsourced knowledge platform. Chuenpagdee R., Rocklin D., Bishop D., Hynes M., Greene R., Lorenzi M., Devillers R. (2017). Marine Policy, in press.


Sea bassCombining telephone surveys and fishing catches self-report: The French sea bass recreational fishery assessment.
Rocklin D., Levrel H., Drogou M., Herfaut J. & Véron G (2014). PLoS ONE 9(1): e87271.

Abstract: Fisheries statistics are known to be underestimated, since they are mainly based on information about commercial fisheries. However, various types of fishing activities exist and evaluating them is necessary for implementing effective management plans. This paper assesses the characteristics and catches of the French European sea bass recreational fishery along the Atlantic coasts, through the combination of large-scale telephone surveys and fishing diaries study. Our results demonstrated that half of the total catches (mainly small fish) were released at sea and that the mean length of a kept sea bass was 46.6 cm. We highlighted different patterns of fishing methods and type of gear used. Catches from boats were greater than from the shore, both in abundance and biomass, considering mean values per fishing trip as well as CPUE. Spearfishers caught the highest biomass of sea bass per fishing trip, but the fishing rod with lure was the most effective type of gear in terms of CPUE. Longlines had the highest CPUE value in abundance but not in biomass: they caught numerous but small sea bass. Handlines were less effective, catching few sea bass in both abundance and biomass. We estimated that the annual total recreational sea bass catches was 3,173 tonnes of which 2,345 tonnes were kept. Since the annual commercial catches landings were evaluated at 5,160 tonnes, recreational landings represent 30% of the total fishing catches on the Atlantic coasts of France. Using fishers’ self-reports was a valuable way to obtain new information on data-poor fisheries. Our results underline the importance of evaluating recreational fishing as a part of the total amount of fisheries catches. More studies are critically needed to assess overall fish resources caught in order to develop effective fishery management tools.

JacquelineA framework for mapping small-scale coastal fisheries using fishers’ knowledge. Léopold M., Guillemot N., Rocklin D., Chen C. (2014).  ICES Journal of Marine Science, 71(7): 1781-1792. doi.10.1093/icesjms/fst204.

Abstract: Collecting spatial information on fisheries catch and effort is essential to understanding the spatial processes of exploited population dynamics and to manage heterogeneously distributed resources and uses. The use of fishers’ knowledge through geographical information systems (GISs) is increasingly considered as a promising source of local information on small-scale coastal fisheries. In this paper we describe the first framework for mapping entire small-scale coastal fisheries using fishers’ knowledge on catch size and fishing effort. Four mangrove and coral reef fisheries targeting invertebrates or finfish in New Caledonia (southwest Pacific) were mapped following a five-step framework: (i) stratified random sampling of regular fishers; (ii) collection of fishers’ knowledge of fishing areas, fishing effort, and catch size through map-based interviews; (iii) data integration into a spatial geodatabase; (iv) statistical extrapolation of fisher data to the fishery scale; and (v) mapping of catch, effort, and catch per unit effort (CPUE) for each fishery using a GIS overlay procedure. We found evidence that fishers’ knowledge supplied precise and accurate quantitative and spatial information on catch size, fishing effort and CPUE for entire fisheries. Fisheries maps captured the fine-scale spatial distribution of fishing activities in a variety of ways according to target taxa, gear type, and home ports. Applications include area-based marine conservation planning and fishery monitoring, management, and governance. This integrated framework can be generalized to a large range of data-poor coastal and inland small-scale fisheries.

Recreational fishingUnexpectedly high catch-and-release rates in Euroopean marine recreational fisheries: Implications for science and management. Ferter K., Weltersbach M.S.,  Strehlow H.V., Volstad J.H., Alos J., Arlinghaus R., Armstrong M., Dorow M., De Graaf M., Van der Hammen T., Hyder K., Levrel H., Paulrud A., Radtke K., Rocklin D., Reedtz Sparrevohn C., Veiga P. (2013).  ICES Journal of Marine Science, 70(7): 1319-1329. doi: 10.1093/icesjms/fst104

Abstract: While catch-and-release (C&R) is a well-known practice in several European freshwater recreational fisheries, studies on the magnitude and impact of this practice in European marine recreational fisheries are limited. To provide an overview of the practice and magnitude of C&R among marine recreational anglers in Europe, the existing knowledge of C&R and its potential associated release mortality was collected and summarized. The present study revealed that in several European countries over half of the total recreational catch is released by marine anglers. High release proportions of >60% were found for Atlantic cod (Gadus morhua), European sea bass (Dicentrarchus labrax), pollack (Pollachius pollachius), and sea trout (Salmo trutta) in at least one of the studied European countries. In the case of the German recreational Baltic Sea cod fishery, release proportions varied considerably between years, presumably tracking a strong year class of undersized fish. Reasons for release varied between countries and species, and included legal restrictions (e.g. minimum landing sizes and daily bag limits) and voluntary C&R. Considering the magnitude of C&R practice among European marine recreational anglers, post-release mortalities of released fish may need to be accounted for in estimated fishing mortalities. However, as the survival rates of European marine species are mostly unknown, there is a need to conduct post-release survival studies and to identify factors affecting post-release survival. Such studies could also assist in developing species-specific, best-practice guidelines to minimize the impacts of C&R on released marine fish in Europe.

Drawn by Seppo (thanks you!!)

Drawn by Seppo (thank you!!)

A review of methods to assess connectivity and mobility of fish populations in the Mediterranean Sea. Caló A., Félix-Hackradt F.C., Garcia J., Hackradt C.W., Rocklin D., Treviño-Otón J. & García-Charton J.A. (2013)  Advances in Oceanography and Limnology, 4: 150-175.

Abstract: Fish populations are linked to each other via dispersal of individuals as eggs, larvae, juveniles or adults. The understanding of this process, known as connectivity, has a pivotal role for the management of overexploited fish stocks and the development of accurate conservation strategies. Knowledge on connectivity and fish movements is considered fundamental toward the correct design of marine protected area (MPA) networks for the achievement of the benefits of protection. Connectivity patterns are still largely unknown worldwide. A general lack of knowledge is particularly evident for the Mediterranean Sea where few studies dealing with this topic have been carried out and some methods, currently available for assessing connectivity, have not been used yet. In this review we present the methods used for studying connectivity patterns and fish movements at different life history stages and the main results achieved until now in the Mediterranean Sea. We encompass the pros and cons of each method, and conclude with future perspectives on the use of these methodologies in the Mediterranean context.

DSCF9128Spearfishing regulation benefits artisanal fisheries: The ReGS indicator and its application to a multiple use Mediterranean marine protected area. Rocklin D., Tomasini J-A., Culioli J-M., Pelletier D. & Mouillot D. (2011).  PLoS ONE 6(9): e23820.

Abstract: The development of fishing efficiency coupled with an increase of fishing effort led to the overexploitation of numerous natural marine resources. In addition to this commercial pressure, the impact of recreational activities on fish assemblages remains barely known. Here we examined the impact of spearfishing limitation on resources in a marine protected area (MPA) and the benefit it provides for the local artisanal fishery through the use of a novel indicator. We analysed trends in the fish assemblage composition using artisanal fisheries data collected in the Bonifacio Strait Natural Reserve (BSNR), a Mediterranean MPA where the spearfishing activity has been forbidden over 15% of its area. Fish species were pooled into three response groups according to their target level by spearfishing. We developed the new flexible ReGS indicator reflecting shifts in species assemblages according to the relative abundance of each response group facing external pressure. The catch per unit effort (CPUE) increased by ca. 60% in the BSNR between 2000 and 2007, while the MPA was established in 1999. The gain of CPUE strongly depended on the considered response group: for the highly targeted group, the CPUE doubled while the CPUE of the untargeted group increased by only 15.5%. The ReGS value significantly increased from 0.31 to 0.45 (on a scale between 0 and 1) in the general perimeter of this MPA while it has reached a threshold of 0.43, considered as a reference point, in the area protected from spearfishing since 1982. Our results demonstrated that limiting recreational fishing by appropriate zoning in multiple-use MPAs represents a real benefit for artisanal fisheries. More generally we showed how our new indicator may reveal a wide range of impacts on coastal ecosystems such as global change or habitat degradation.

poissonSimulation of the combined effects of artisanal and recreational fisheries on a Mediterranean MPA ecosystem using a trophic model. Albouy C., Mouillot D., Rocklin D., Culioli J-M. & Le Loc’h F. (2010). Marine Ecology Progress Series, 412: 207-221.

Abstract: Marine protected areas (MPAs) have the potential to enhance the long-term sustainability of coastal resources, and the artisanal fisheries which depend on them. However, recreational fisheries, which are increasing their impacts on coastal resources worldwide, may reduce the benefits that MPAs provide to declining artisanal fisheries. Here we used the Bonifacio Straits Natural Reserve (BSNR) Corsica as a study case to simulate the combined effects on coastal resources of artisanal and recreational fishing efforts. The BSNR ecosystem was modelled using mass-balance modelling of trophic interactions. This model was compared to another built on a non-protected area from the same region. We aggregated fishing fleets into artisanal and recreational categories, and we simulated various combinations of fishing effort over a 20 yr dynamic simulation using Ecosim. We showed that fishing activities have an additional top-down effect on the food web and that they decrease the targeted group’s biomass, such as piscivorous species. We found, for some trophic groups, non-trivial patterns of biomass variation through trophic cascades. Our trophic approach revealed that some groups may suffer a biomass decrease when MPAs are set or enforced, due to the combined effect of artisanal and recreational fisheries. Overall, our results illustrate the value of modelling to manage MPAs, as a complementary tool to surveys. Models provide the opportunity to anticipate the potential consequences, at the ecosystem level, of socio-political decisions that aim to sustain coastal resources while managing artisanal and recreational fisheries.

Tursiops truncatusChanges in the catch composition of artisanal fisheries attributable to dolphin depredation in a Mediterranean marine reserve. Rocklin D., Santoni M-C., Culioli J-M., Tomasini J-A., Pelletier D. & Mouillot D. (2009).  ICES Journal of Marine Science, 66: 699-707.

Abstract: There is increasing evidence from previous studies, and from fishers’ observations, that coastal dolphins use fishing nets as an easily accessible feeding source, damaging or depredating fish caught in the nets. This study investigates the impact of dolphin depredation on artisanal trammelnets by analysing the catch composition of 614 artisanal fishing operations in the Bonifacio Strait Natural Reserve (France). Common bottlenose dolphins (Tursiops truncatus) attacked, on average, 12.4% of the nets and damaged 8.3% of the catch. However, attacked nets were characterized by statistically significantly higher catch per unit effort than unattacked ones. Catch composition also differed significantly after dolphin attacks; bentho-pelagic fish were more represented and reef-associated fish less represented. Our results suggest that (i) dolphins are attracted by high fish densities in the fishing area and/or nets, and (ii) their attacks induce specific fish-avoidance behaviour, according to the fish position in the water column. Although dolphins depredate a small part of the catch, damage to nets, not yet assessed in this area, could weaken the benefits that reserves can provide to artisanal fisheries.

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