Distribution and seasonal variations of fisheries resources captured by the beam trawl in Namhae island, Korea

Abstract

It was turned out by the beam trawl survey in 2009 that flora of three phylum 16 species and fauna of eight taxa 68 families 97 species were inhabited in the Seomjin River estuary and western coastal waters of Namhae island. Winter season showed the most various appearance of species with 63 species and markedly several kinds of algae species, while summer season showed the lowest number of species with 44 species. However, the indices of species diversity and evenness were highest in summer, and vice versa in winter. Major dominant species were Crangon hakodatei, Leiognathus nuchalis, Asterias amurensis, Thryssa kammalensis, Luidia quinaria, Amblychaeturichthys hexanema, Oratosquilla oratoria, Charybdis bimaculata, Cynoglossus joyneri, Pennahia agentata. The 10 dominant species occupied at 81.4% of catch in number and 49.0% of catch in weight. There were seasonal fluctuations and differences by station in the Seomjin River estuary and western coastal waters of Namhae island, which brought to the difference of length structures, that is, bigger-sized individuals of major dominant species at station A (near to river estuary) than station C (near to ocean). Species compositions by season and by station were separated to two groups. Winter season showed a separated species composition from other seasons and station A exhibited a different species composition from other stations, which was located at near to the Seomjin River estuary.

Identifying patterns in the multitrophic community and food-web structure of a low-turbidity temperate estuarine bay

“…Clusters II–IV mainly depicted the seasonal transition of the deep-bay nekton assemblages. However, our IndVal analysis highlights extensive overlap in indicator species between clusters (at least two clusters share 18 of 21 taxa), and further multi-response permutation procedure (MRPP) testing concludes less clear seasonal than habitat environment-based patterns as previously observed 51 . The observed seasonal succession of the deep-bay assemblages, although not great, seems to be attributed to the addition of a few seasonal (or temporary) migrants.…”

“…The observed seasonal succession of the deep-bay assemblages, although not great, seems to be attributed to the addition of a few seasonal (or temporary) migrants. As a result, the nekton assemblages were characterized by rare species in the estuarine channel and by the predominance of year-round resident species, which occupied over 80% of the total abundances 51 , 52 , with a few transient migrants in the deep bay.…”

Data_Sheet_1.docx

“…Estuarine and coastal nekton communities are generally characterized by many rare species (Magurran and Henderson, 2003) and spatiotemporally distributed species assemblages (Whitfield et al, 2012;Rees et al, 2018). The low species abundance and the spatial pattern in community composition found here were very similar to other studies in GYB and surrounding coastal areas (Seo et al, 2013;Kim et al, 2018). However, we observed inconclusive seasonal patterns in species composition, which could arise from the highly random distribution of species, very low numbers of seasonal migrants, and stable prey communities for resident species.…”

“…Gwangyang Bay (GYB; Figure 1) in the Republic of Korea is a temperate embayment system with diverse habitats [e.g., common reed beds, bare intertidal mudflats covered with microphytobenthos (MPB), eelgrass beds] that is exposed to both riverine discharge and the open sea (Kim et al, 2010). GYB is known to be highly productive and provides habitats to numerous fish species (Jeong et al, 2005;Seo et al, 2013). Rainfall-induced variation in river discharge and seasonally variable autotroph biomass bring spatial and seasonal variabilities in OM composition in GYB (Choy et al, 2008;Sin et al, 2009).…”

Effects on bycatch reduction in a shaking cod end generated by canvas in a shrimp beam trawl

“…In Korea, the species distribution caught with a shrimp beam trawl has been investigated off the southern (Oh et al, 2003;Oh, 2010;Song et al, 2012;Park et al, 2013b;Seo et al, 2013) and the western coasts (Park et al, 2013a). Until recently, BRD experiments with shrimp trawls were mainly focused on separating demersal fish from the main shrimp catch and highlighting the fish passing out from the net (Jang et al, 2006;Balzano, 2011, 2013).…”