İstilacı Gümüşi Havuz Balığının (Carassius gibelio Bloch, 1782) Sakarya İlindeki İçsu Balıkçılığına Etkisinin Araştırılması
Thesis Type: Doctorate
Institution Of The Thesis: Ataturk University, Su Ürünleri Fakültesi, Su Ürünleri Yetiştiriciliği, Turkey
Approval Date: 2021
Thesis Language: Turkish
Student: Erdinç AYDIN
Co-Supervisor: Şerife Gülsün Kırankaya
Supervisor: Murat Arslan
Open Archive Collection: AVESIS Open Access Collection
Abstract:Purpose: The gibel carp (Carassius gibelio) is one of the alien species with the highest risk for inland waters due to its several biological advantages. The gibel carp have also commercial value in Turkey. However, there are no data about its impact on the commercially valuable fish species and overall commercial fisheries. In this study, we aimed to analyze the structure of commercial fisheries as well as the population structure and growth characteristics of C. gibelio, and its interactions with other fish species with commercial value in Büyük Akgöl, Sapanca Lake and Küçükboğaz Lakes in Sakarya province in order to determine the impact of this invasive species on other fish populations and overall local inland fisheries. Method: In the present study, sampling was carried out seasonally between February 2018 and February 2020, using plain gillnets with mesh sizes of 24, 32, 40 and 50 mm. Population structure and growth performance of each species was determined based on standard models/formulas. One hundred twenty four fishermen were inteviewed in order to analyze the socio-economical structure of local inland fisheries. Findings: A total of 15 fish taxa were identified in three lakes. C. gibelio comprimized more than 20% of total catch in Büyük Akgöl and Sapanca lakes and it was over 70% in Küçükboğaz Lake, with catch per unit effort values maximum in spring and summer. More than 90% of C. gibelio samples were female in all study areas. Growth performance of C. gibelio and commercially valuable local species were similar in all sites. Growth of C. gibelio was isometric in Küçükboğaz Lake while it was positive allometric in other two lakes. C. gibelio's share in total fisheries income was 18.4% in Büyük Akgöl, 4.3% in Sapanca Lake and 40.3%, quite important, in Küçükboğaz Lake. Results: The invasive C. gibelio was determined to be a fast growing population in all lakes. Thus, its presence poses a potaential threat to natural species in terms of land use, especially in the spring and summer, risking sustainability of natural fish stocks in the long-term. We suggest strategies to be developed in order to incerase fishing pressure on C. gibelio as target species. Keywords: Alien species, Catch per unit effort, Growth, Inland fisheries, Sapanca Lake, Büyük Akgöl Lake, Küçükboğaz Lake, Age Distribution, Fisheries Management