Browsing by Author "Aydin, Mehmet"
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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.
- Effects of fishery protection on biometry and genetic structure of two target sea cucumber species from the Mediterranean SeaPublication . Gonzalez-Wangueemert, Mercedes; Valente, Sara; Aydin, MehmetSea 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).
- Profitability of the Mediterranean and NE Atlantic new target sea cucumber species: some repercussions for their fisheries managementPublication . Gonzalez-Wanguemert, Mercedes; Dominguez-Godino, Jorge A.; Aydin, MehmetThe term profitability can be understood as the ratio in percentage between fresh weight of animals and the dry weight of the obtained beche-de-mer depending on the body wall thickness of sea cucumbers and water content. Specimens decrease their weight and length considerably, when they are processed. However, scarce information about profitability of commercial sea cucumber from Mediterranean and NE Atlantic has been published until now. In this study, we focused on Holothuria tubulosa, Holothuria polii, Holothuria mammata and Holothuria arguinensis. For most of the species considered, a good lineal regression was found between eviscerated length (EL) vs eviscerated weight (EW), and EW vs dried weight (DW)