Browsing by Author "Conand, Chantal"
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- Assessment of sea cucumber populations from the Aegean Sea (Turkey): first insights to sustainable management of new fisheriesPublication . Gonzalez-Wangueemert, Mercedes; Aydin, Mehmet; Conand, ChantalSea cucumber stocks have been overfished in many countries. As a consequence, several species (Holothuria polii, Holothuria tubulosa and Holothuria mammata) are now caught in Turkish waters without adequate knowledge on their biology and ecology. Here, we address their morphometry, relationships among gutted length and weight, population dynamics, temporal evolution of catches, and we provide the first insights about technical aspects of their fisheries. The largest size classes of H. polii are missing from our sampling collection, possibly due to the heavy fishery pressure on this species. Significant differences in the eviscerated length and weight were found among the Turkish sampled localities for H. polii and H. tubulosa, respectively. These differences could be explained by higher food availability in some areas and/or differential fishery pressure. The size and weight of H. tubulosa specimens were smaller than those registered for the same species in Greek waters, where this species is not fished. All the studied species showed allometric growth. In the last two years, the sea cucumber fishery in Turkey has been increasing rapidly, reaching a total production of ca. 555 000 kg in 2012 (80% H. polii and 20% H. tubulosa plus H. mammata). For a correct management of these species, we recommend: 1) the reestablishment of species-specific closed fishery season according to the specific reproductive cycle; 2) the assessment of the exploited stocks from the Northern Turkish coasts with estimates of recovery time of their populations; 3) the reduction of fishery efforts, mainly on H. polii and H. tubulosa and 4) the establishment of protected areas (where sea cucumber fisheries are forbidden) to conserve healthy populations which will favour the recruitment on nearby areas.
- Sea cucumbers, Holothuria arguinensis and H-mammata, from the southern Iberian Peninsula: variation in reproductive activity between populations from different habitatsPublication . Marquet, Nathalie; Conand, Chantal; Power, Deborah; Canario, Adelino; Gonzalez-Wanguemert, MercedesNew fisheries in the western Mediterranean and north eastern Atlantic target the sea cucumbers Holothuria arguinensis and H. mammata; however, lack of biological information hinders management decisions. Here, the reproductive biology of populations the two species was investigated in the southern Iberian Peninsula. Different populations located along a narrow latitudinal range displayed the same general reproductive pattern of summer-autumn spawning. However, significant differences in size, gonadal production and maturity profile between locations suggests the influence of site-specific factors. In Sagres and Ria Formosa H. arguinensis individuals were larger and had larger gonads than in Olhos de Agua, which had relatively more immature animals. The spawning and active gametogenesis periods were also longer in Sagres, possibly linked to specificity of food availability and tidal conditions. Ria Formosa also had larger H. mammata individuals with larger gonads than in Murcia and Olhos de Agua, possibly reflecting differences in feeding activity in different substrates (muddy/sandy vs rocky). Gametogenesis in H. arguinensis may be triggered by decreasing photoperiod and temperature, and spawning by increasing temperature. Altogether, these results, which include fecundity and size at first maturity, provide an important basis for the scientific management of sea cucumber fisheries in the region. (C) 2017 Elsevier B.V. All rights reserved.