Catch composition and some other aspects of bottom trawl fishery in Sığacık Bay, central Aegean Sea, eastern Mediterranean

Abstract

The objective of the study was to determine the features of the bottom trawl fishery such as catch composition, catch per unit effort (CPUE) and the discard ratios in the Sı gacık Bay fishery, central Aegean Sea. A commercial trawler conducted trawl operations from October 2008 to April 2009, with a total of 18 trawls in autumn, winter and spring (six hauls per season). In total, 84 species were identified, 47 of which belonged to the bony fishes, while other groups contributed nine (cartilaginous fish), 10 (cephalopods), 13 (crustaceans), four (echinoderms) and one (porifera) species. Some 49 species were discarded regardless of length. Total catch was 3693.2 kg of which 66.8% was marketed. Among the commercial species, rose shrimp (Parapenaeus longirostris) dominated the catch composition with 998 kg. However, discards accounted for 33.2% of the total catch biomass, with the majority represented by Lampanyctus crocodilus with 97 kg total weight. The study area is considered one of the most efficient trawling zones in the Aegean Sea and thus requires long-term monitoring in terms of fish stocks and trawl discards for the preparation of well-informed decisions for a sustainable fishery.

How Fishery Collapses: The Case of Lepidopus caudatus (Pisces: Trichiuridae) in the Strait of Sicily (Central Mediterranean)

“…Across the Mediterranean Sea, the knowledge on discarding of L. caudatus is scattered and scarce (e.g., Sánchez et al, 2004;Tzanatos et al, 2007;Soykan et al, 2016;Carbonnel and Mallol 2012). The discard rates are affected by gears, target species, fishing ground depth, as well as the request of the local market.…”

“…Tzanatos et al (2007) in the Aegean Sea and Sánchez et al (2004) in the Catalan Sea reported that the whole catch of L. caudatus was discarded by gillnet and by trawlers, respectively. Conversely, Carbonell and Mallol (2012) provided discard rate estimation by trawlers of 7% in Catalonia waters and 100% in Balearic island, while Soykan et al (2016) estimated a discard rate of about 30% in Turkish waters.…”

Bathymetric distribution of macroinvertebrates in the Northeastern Levantine Sea and the Northeastern Aegean Sea based on bottom-trawl surveys

“…JICA (1993) conducted surveys in territorial waters of Turkey as well as in international waters at a depth of 20-500 m. There were 24 and 20 invertebrate species observed in the Northern Aegean Sea and the South Aegean Sea, respectively. Soykan et al (2016) conducted studies in Sığacık Bay (Central Aegean Sea) using a commercial trawler, in which a total of 28 invertebrate species, 10 cephalopods, 13 crustaceans, 4 echinoderms and one porifera were captured. Kallianiotis et al (2000) reported 26 invertebrate species off Heraklion Bay between 50 and 1000 m.…”

Untitled

“…It is known that about 88 cartilaginous species inhabit the Mediterranean Sea (FAOa, 2018;FAOb, 2018), and that 75% of these species are also found in the Aegean Sea (Eronat & Bizsel, 2015). This group contributes a considerable part of by-catch in Turkish trawl fisheries (Gurbet, Akyol, Yalçın, & Özaydın, 2013;Soykan, Akgül, & Kınacıgil, 2016). According to Eronat and Özaydın (2011) at least 15 chondrichthyan species are regularly presented in the fishery of study area.…”