Identification et distribution saisonnière de larves de Carangidés au large du Sénégal et de la Gambie

... Une étude a été entreprise sur les larves de Carangidés. Les renseignements trouvés dans la bibliographie, et les observations morphologiques et biométriques permettent l'identification des larves de #Trachurus spp., #Caranx rhoncus, #Chloroscombrus chrysurus, #Vomer setapinnis, #Lichia glauca, #Scyris alexandrinus, #Pomatomus saltatrix et #Caranx sp. (aff. #Carangus). L'étude de la distribution saisonnière a montré que sur les côtes du Sénégal, les #Trachurus se reproduisent de décembre à mai dans les eaux froides du large, #Caranx rhonchus et #Pomatomus saltatrix de mai à novembre dans les zones frontales, et les autres espèces de juin à novembre dans les eaux chaudes du plateau continental. Les données de la pêcherie montrent que, pour #Trachurus et #Chloroscombrus, les concentrations d'adultes coïncident avec la ponte. #Trachurus spp., #C. rhonchus et #C. chrysurus$ constituent les 9/10 des larves de Carangidés récoltées. (D'après résumé d'auteur

Les holothuries aspidochirotes du lagon de Nouvelle-Calédonie :biologie, écologie et exploitation

Certaines holothuries aspidochirotes (Echinodermes) sont pêchées et transformées en bêche-de-mer (ou trépang) pour la consommation humaine. Les 48 espèces récoltées en Nouvelle-Calédonie sont d'abord présentées et leur classement en catégories commerciales établi . L'étude autoécologique a montré les caractéristiques de la répartition et de l'abondance de ces espèces, dans les divers biotopes récifaux et lagonaires ... Plusieurs peuplements en holoturies (taxocénoses) ont été définis ... L'étude de la biologie des populations des neuf principales espèces commerciales a permis de préciser les principaux paramètres de leur biométrie, reproduction, croissance et mortalité ... Les exploitations en Nouvelle-Calédonie et dans d'autres pays du Pacifique Tropical Sud, sont décrites et les causes de leurs fortes variations sont analysées, en relation avec celles des marchés mondiaux de Hong-Kong et Singapou

A new species of <i>Bohadschia</i> (Echinodermata, Holothuroidea) from the Western Indian Ocean with a redescription of <i>Bohadschia subrubra</i> (Quoy & Gaimard, 1833)

Bohadschia atra sp. nov. from the Western Indian Ocean is described and compared with Bohadschia subrubra (Quoy & Gaimard, 1833). B. subrubra is redescribed and compared to the new species and related Bohadschia species. The shape of the ossicles varies with body size for both species

Mobility, Expansion and Management of a Multi-Species Scuba Diving Fishery in East Africa

Background: Scuba diving fishing, predominantly targeting sea cucumbers, has been documented to occur in an uncontrolled manner in the Western Indian Ocean and in other tropical regions. Although this type of fishing generally indicates a destructive activity, little attention has been directed towards this category of fishery, a major knowledge gap and barrier to management. Methodology and Principal Findings: With the aim to capture geographic scales, fishing processes and social aspects the scuba diving fishery that operate out of Zanzibar was studied using interviews, discussions, participant observations and catch monitoring. The diving fishery was resilient to resource declines and had expanded to new species, new depths and new fishing grounds, sometimes operating approximately 250 km away from Zanzibar at depths down to 50 meters, as a result of depleted easy-access stock. The diving operations were embedded in a regional and global trade network, and its actors operated in a roving manner on multiple spatial levels, taking advantage of unfair patron-client relationships and of the insufficient management in Zanzibar. Conclusions and Significance: This study illustrates that roving dynamics in fisheries, which have been predominantly addressed on a global scale, also take place at a considerably smaller spatial scale. Importantly, while proposed management of the sea cucumber fishery is often generic to a simplified fishery situation, this study illustrates

Effects of fishery protection on biometry and genetic structure of two target sea cucumber species from the Mediterranean Sea

Sea cucumber fisheries are now occurring in most of the tropical areas of the world, having expanded from its origin in the central Indo-Pacific. Due to the overexploitation of these resources and the increasing demand from Asian countries, new target species from Mediterranean Sea and northeastern Atlantic Ocean are being caught. The fishery effects on biometry and genetic structure of two target species (Holothuria polii and H. tubulosa) from Turkey, were assessed. The heaviest and largest individuals of H. polii were found into the non-fishery area of Kusadasi, also showing the highest genetic diversity. Similar pattern was detected in H. tubulosa, but only the weight was significantly higher in the protected area. However, the observed differences on the fishery effects between species, could be explained considering the different percentage of catches (80% for H. polii and 20% for H. tubulosa)

Seagrass debris as potential food source to enhance Holothuria arguinensis' growth in aquaculture

Holothuria arguinensis aquaculture started to be developed in 2014, being the first sea cucumber species from Europe. However, some aspects of its aquaculture biotechnology, such diets, need to be assessed. This work aimed to evaluate seagrass debris of Zostera noltii and Cymodocea nodosa as food source for broodstock maintenance in tanks, during breeding periods. The given feed rations per tank were calculated as the 30% of the total sea cucumber biomass in each tank and reviewed each week. Then, feed rations of seagrass and sediment were calculated from this value, according to the following percentages: 40% sediment, 15% Z. noltii, 40% Z. noltii, 15% C. nodosa and 40% C. nodosa. H. arguinensis growth, feeding rate and nutritional value were assessed under these diets. H. arguinensis fed with 40% of Z. noltii showed the highest growth (specific growth rate = 0.09 +/- 0.06%/day, absolute growth rate = 0.11 +/- 0.07 g/day) increasing their final weight in 5.86 +/- 3.57% in 57 days. However, the individuals fed with C. nodosa showed a negative growth. H. arguinensis showed a reduction in its feeding rate as the organic matter content in the diets increased. H. arguinensis did not show any important change on proximate composition, protein, lipid, mineral contents and fatty acids profile among the feeding groups, or in comparison with the individuals collected from wild habitat. Therefore, H. arguinensis could be fed with Z. noltii debris during tanks maintenance along breeding period, ensuring its growth and maintaining its nutritional profile.Fundacao para a Ciencia e a TecnologiaPortuguese Foundation for Science and TechnologyEuropean Commission [CCMAR/SC/BI/02/2016, FRH/BD/105541/2014, IF/00049/2012, IF/00998/2014, PTDC/MAR-BIO/5948/2014, PTDC/MAR/119363/2010, SFRH/BPD/70689/2010]http://creativecommons.org/licenses/by/4.0

Temporal variability of settlement in Carapidae larvae at Rangiroa atoll

Carapidae (or pearlfish) are eel-like fishes living inside different invertebrates, such as holothurians, sea stars or bivalves. In some Polynesian areas where they live in sympatry, several species (Carapus homei, Carapus mourlani, Carapus boraborensis and Encheliophis gracilis) are able to inhabit the same host species. The heterospecific infestation rate is very rare, suggesting that the four species can compete for their hosts. Some differences in settlement period, breeding period and in pelagic larval duration (PLD) could allow better characterisation of the life history of each species. More than 700 larvae were collected during an entire year on the Rangiroa atoll (French Polynesia). Each species was identified; their settlement pattern was examined and their PLD was deduced from otolith (sagittae) increments. In the four collected species, the settlement pattern differed: C. homei and C. mourlani settle on the reef during the entire year, and show an asynchronous and diffuse breeding cycle. C. boraborensis and E. gracilis have a shorter settlement period which could be compatible with breeding synchronisation. As most reef fishes, Carapidae larvae mainly settle during moonless nights. Moreover, each species presents some plasticity, allowing it to settle on the reef under suitable conditions