EFFECT OF CHANGING ECOLOGICAL CONDITIONS ON FISH POPULATIONS AND FISHING IN THE LAKE BAFA
Project no. 1130 · Status: Kapanmış · 2018
Summary
Bafa Lake is in great ecological destruction due to the drought periods in the Büyük Menderes River basin, reservoirs built on the river channel and the activities on the shore of the lake. This lake ecosystem is still not stable. Changes in the resources contributing to the water budget and the drought periods observed in recent years have caused a great change in the water quality of the lake, especially in the salinity. This study was carried out during the dry and wet periods of 2018-2019 in order to reveal the fish biodiversity that occurred in the lake in this process and how it affected fisheries. Environmental variables such as temperature, pH, salinity, electrical conductivity, dissolved oxygen were determined using the WTW Multi 3430 measuring device (as in situ). Standard benthic nets in accordance with the criteria of "TS-EN 14757 Water Quality-Taking fish samples with dense mesh nets with changing meshes" in fish sampling and 175 m long, (each of them 35 m long and 3 m high), node-to-node mesh width 10, 20, 30, 40, 50 mm mesh size of gill nets were used. Fishing equipment was determined by face to face interviews and on-site fishing gear. Salinity has increased by approximately 280% since the first intervention on the lake shore and reached 12.3‰. As a result of this change, while there were 17 species in the lake's ichthyofauna before 1990, this number has decreased to 12 today. In this process of change, approximately 60% of the species were eliminated from the environment, and today 3 new fish species have been identified in the lake. Due to the impact of environmental variables, Atherina boyeri, which is in the natural fauna of the lake, has become the dominant fish of the lake with 94.71% and has become the invasive fish of the lake. In addition, the fishing efficiency of the lake decreased by 90% from 312400 kg/year to 31125 kg/year. As a result of the study, 12 taxa belonging to the families Anguillidae, Mugilidae, Atherinidae, Syngnathidae, Cyprinodontidae, Moronidae, Sparidae and Gobiidae and Poeciliidae (Anguilla anguilla, Atherina boyeri, Aphanius fasciatus, Gambusia holbrooki, Synganthus abaster, Syngnathus acus, Mugil cephalus, Chelon ramada, Chelon auratus, Dicentrarchus labrax, Sparus aurata and Gobius niger) were identified from the lake. It has been determined that the most dominant species among these species is Atherina boyeri with a rate of 94.71%, and eel and grey mullet are the most caught species in the lake. This increase in salinity in the lake has caused significant changes in the lake biota. Some species have been eliminated due to the increase in salinity, while others have adapted very well to become invasive. Among the fish, the Atherina boyeri is an invasive species of this type. In addition to the existing fishing techniques in the lake, it should be ensured that hunting can be made on silver fish. Due to the closure of Sakızburnu Dalyan, it should be ensured that a new fishery management is carried out around the Serçin Connector to support fishing in the lake. Keywords: Climate change, fish fauna, influence of environmental variables, characters of local fishnets, Western Anatolia, Lake Bafa.