Full text: http://archimer.ifremer.fr/doc/00118/22934/20757.pdf (Version "auteur", 0.44 Mo)International audienceSmall-scale fisheries have traditionally received less research effort than large-scale fisheries and are generally under-studied in Europe. In spite of their comparatively low volume of catches and economic importance, small-scale fisheries are socially important and an integral part of the European coastal zone. Considering the high heterogeneity of situations and the paucity of quantitative data, we used an analytical methodology based on the comparative method. We carried out an analysis of small-scale fisheries (SSFs) in Europe based on a selection of nine case studies. Our objective was to obtain a comprehensive description of small-scale fleets covering different areas/fisheries/species, encompassing the diversity and specific conditions under which SSFs operate, in order to demonstrate the ecological and social sustainability of this often overlooked fisheries segment. A common approach formulated so that the case studies could be compared with the case histories of other competing users, required that for each set of criteria - technical, biological, socio-economic, and institutional - a set of relevant items and indicators was established. An analysis of characteristics common to the selected case studies is conducted and an attempt made to extend our comparisons to the whole of the European Union. Our results show that (as compared with large-scale fleets, their main competitor) small-scale fleets: (i) are composed of smaller vessels and, consequently, travel lower distances to fishing grounds, and are more reliant on coastal areas; (ii) have smaller crews (although the global employment figure is similar to that of large-scale fleets in Europe); (iii) use mostly, but not exclusively, passive gears; (iv) use multi-purpose fishing approaches, and can change the fish species they target during the year; (v) have lower extraction rates; (vi) have lower total capital investments (including fishing rights), turnover and costs; and (vii) have lower fuel consumption, making them less sensitive to changing oil prices. Dependence on subsidies is lower (viii). Involvement in fisheries management is variable, conservation and access regulation measures are largely local in origin. For the selected case studies, the most significant competitors are large-scale fleets, and recreational fisheries, but other sources of interaction (water quality, invasive species, etc.) cannot be ignored

International audienceSea cruises were conducted for 57 days over 16 months to characterise pelagic fish aggregations around two moored fish aggregating devices (FADs) in Martinique (Lesser Antilles). Echosounder surveys run in a star pattern were used in conjunction with obliquely beamed sonar observations. An echo-integration-by-shoal algorithm was implemented to isolate pelagic fish shoals from sound scattering layers and to compute mean morphometric, positional and density parameters. Tree regressions were used to select and classify pelagic fish target strengths (TS), with reference to their spatial and temporal characteristics. The main type of pelagic fish aggregation was a large sub-surface aggregation. It was observed during all daytime periods within a radius of 400 m. of the FAD. A smaller type of aggregation was observed closer to the surface and to the FAD in 65% of daytime periods. Large scattered fish were observed in 16% of daytime periods. At night, a medium-sized aggregation was detected in the sub-surface in 75% of night-time periods. The sizes of the fish inside the aggregations (determined from TS values) were lower in the small near-surface aggregation than in the large sub-surface aggregation. Mean packing densities of sub-surface medium fish and near-surface small fish aggregations (determined from TS and shoal acoustic density) were respectively 0.2 and 1.3 fish per m(3). The acoustic methodology and results are discussed with reference to the characteristics and performance of the echosounder and to the spatial structure of pelagic fish aggregations around moored FADs in Martinique

The pathogenic virus Panulirus argus virus 1 (PaV1) was first discovered in Caribbean spiny lobsters Panulirus argus from the Florida Keys (USA) in 1999 and has since been reported in Belize, Mexico, and Cuba; its distribution in the wider Caribbean is unknown. We collected tissue samples from adult spiny lobsters from 30 locations in 14 countries bordering the Caribbean Sea and used molecular diagnostics to assay for the presence of PaV1. PaV1 occurred primarily in the northern areas of the Caribbean, where its prevalence was highest. The virus was not found in lobsters from the southeastern Caribbean, and its prevalence was lowest in the southwestern Caribbean. DNA sequence analysis was performed on a fragment of the viral DNA to examine the genetic diversity of PaV1 on a Caribbean-wide scale. Sequence variation in the viral DNA fragment was high, with 61 unique alleles identified from 9 areas. The sharing of viral alleles in lobsters from distant locations supports the hypothesis of a strong genetic connectivity among lobsters within the Caribbean, and further supports the hypothesis that postlarvae infected with PaV1 may serve to disperse the virus over long distances. KEY WORDS: Spiny lobster · Disease · Epidemiology · ConnectivityResale or republication not permitted without written consent of the publisher Dis Aquat Org 104: 129-140, 2013 the commercial harvest of P. argus in Florida, USA, totaled 42 million kg, valued at US$365.3 million (Florida Wildlife and Conservation Commission 2012). In 2010, more than 35 000 metric tons (t) of P. argus were landed worldwide (FAO Fisheries and Aquaculture Information and Statistics Service). Countries with the highest landings include Brazil, the Bahamas, Cuba, Nicaragua, Honduras, the Dominican Republic, and the USA (Vondruska 2010).In 1999, a pathogenic virus, Panulirus argus virus 1 (PaV1), was discovered infecting spiny lobsters from the Florida Keys (Shields & Behringer 2004). Prevalence of PaV1 is highest in early benthic juveniles (EBJs) and lower among larger juveniles and adults (Shields & Behringer 2004, LozanoÁlvarez et al. 2008. Lobsters with clinical disease have chalky-white hemolymph and often have a discolored carapace with a pink hue. Heavily infected lobsters are typically lethargic, cease grooming and foraging, and have lower hemolymph serum protein values compared to uninfected lobsters . Histologically, signs of PaV1 infection include a depletion of the reserve inclusion cells, hemocyte infiltration into the intertubular spaces of the hepatopancreas, focal necrosis of the hepatopancreas, and the presence of infected hemocytes in the heart, gills, and connective tissues (Li et al. 2008).Since its initial discovery in Florida, infections have been confirmed in Belize (Huchin-Mian et al. 2009), Mexico , Cuba (Cruz Quintana et al. 2011), and the US Virgin Islands . Prevalence of PaV1 in juvenile lobsters in Florida is patchy, but has historically ranged from 5 to 8%, with some locations exceeding 60% (Behringer et al. 2011). While typ...

Otolith chemistry of young-of-year (YOY) yellowfin tuna Thunnus albacares was examined to determine whether chemical signatures are distinct across major spawning areas in the Atlantic Ocean. YOY yellowfin tuna otoliths were collected from 4 locations in the Atlantic Ocean (Gulf of Mexico, Caribbean Sea, Cape Verde, and Gulf of Guinea) from 2013−2015, and trace element (Li, Mg, Mn, Sr, Zn, and Ba) and stable isotope (δ 13 C and δ 18 O) analyses were conducted to investigate regional variation in otolith chemical composition. Results indicated that significant regional differences in chemical signatures existed for each cohort of YOY yellowfin tuna investigated. Quadratic discriminant function analysis showed that nursery assignment accuracies based on otolith trace elements and stable isotopes were 64−85% for each cohort, justifying the use of these natural tracers as regional discriminators for yellowfin tuna. Significant interannual variability in regional signatures was also detected, highlighting the importance of age-class matching when using the baseline of nursery signatures to estimate the origin of sub-adult and adult yellowfin tuna. This study clearly demonstrates that baseline chemical signatures in the otoliths of YOY yellowfin tuna are distinct and can therefore serve as an effective tool for assigning older individuals to their nursery of origin, ultimately providing a way to improve our understanding of the population connectivity and mixing rates of this species in the Atlantic Ocean.