Wild Fish Assemblages Associated with Tuna Cages in the Aegean Sea

Project no. 23853 · Status: Kapanmış (Yayın bekleniyor) · 2022

Summary

<p class="ql-align-justify">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Turkey,&nbsp;possessing&nbsp;favorable&nbsp;marine&nbsp;areas&nbsp;for&nbsp;cage&nbsp;aquaculture,&nbsp;is&nbsp;one&nbsp;of&nbsp;the&nbsp;three&nbsp;largest&nbsp;producers&nbsp;in&nbsp;Europe&nbsp;with&nbsp;nearly&nbsp;450&nbsp;offshore&nbsp;cage&nbsp;farms&nbsp;and&nbsp;a&nbsp;production&nbsp;capacity&nbsp;of&nbsp;405,742&nbsp;tons.&nbsp;While&nbsp;sea&nbsp;bream&nbsp;and&nbsp;sea&nbsp;bass&nbsp;constitute&nbsp;the&nbsp;majority&nbsp;of&nbsp;production,&nbsp;the&nbsp;farming&nbsp;of&nbsp;trout,&nbsp;tuna,&nbsp;meagre,&nbsp;and&nbsp;mussels&nbsp;has&nbsp;been&nbsp;increasing&nbsp;rapidly.&nbsp;Tuna&nbsp;farming&nbsp;in&nbsp;Turkey&nbsp;began&nbsp;in&nbsp;2002&nbsp;and&nbsp;has&nbsp;currently&nbsp;reached&nbsp;a&nbsp;total&nbsp;production&nbsp;level&nbsp;of&nbsp;6,226&nbsp;tons.&nbsp;It&nbsp;has&nbsp;long&nbsp;been&nbsp;recognized&nbsp;that&nbsp;offshore&nbsp;cages&nbsp;function&nbsp;as&nbsp;fish&nbsp;aggregating&nbsp;devices&nbsp;(FADs),&nbsp;attracting&nbsp;wild&nbsp;fish&nbsp;to&nbsp;their&nbsp;surroundings.&nbsp;Although&nbsp;research&nbsp;has&nbsp;traditionally&nbsp;focused&nbsp;on&nbsp;sea&nbsp;bream&nbsp;and&nbsp;sea&nbsp;bass&nbsp;cages,&nbsp;recent&nbsp;studies&nbsp;have&nbsp;expanded&nbsp;to&nbsp;include&nbsp;cages&nbsp;used&nbsp;for&nbsp;species&nbsp;such&nbsp;as&nbsp;tuna&nbsp;and&nbsp;salmon.&nbsp;However,&nbsp;to&nbsp;date,&nbsp;no&nbsp;study&nbsp;has&nbsp;specifically&nbsp;examined&nbsp;the&nbsp;effects&nbsp;of&nbsp;tuna&nbsp;cages&nbsp;on&nbsp;wild&nbsp;fish&nbsp;assemblages&nbsp;in&nbsp;Turkey.&nbsp;The&nbsp;aim&nbsp;of&nbsp;this&nbsp;study&nbsp;was&nbsp;therefore&nbsp;to&nbsp;determine&nbsp;the&nbsp;structure&nbsp;of&nbsp;wild&nbsp;fish&nbsp;assemblages&nbsp;around&nbsp;tuna&nbsp;cages&nbsp;in&nbsp;the&nbsp;Aegean&nbsp;Sea&nbsp;and&nbsp;to&nbsp;investigate&nbsp;their&nbsp;seasonal&nbsp;variation.</p><p class="ql-align-justify">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;The&nbsp;study&nbsp;was&nbsp;conducted&nbsp;at&nbsp;three&nbsp;tuna&nbsp;farming&nbsp;sites&nbsp;located&nbsp;in&nbsp;the&nbsp;Gerence&nbsp;and&nbsp;Sığacık&nbsp;Bays.&nbsp;Rapid&nbsp;Visual&nbsp;Counts&nbsp;(RVC)&nbsp;were&nbsp;employed&nbsp;as&nbsp;the&nbsp;sampling&nbsp;method.&nbsp;For&nbsp;the&nbsp;first&nbsp;time,&nbsp;surveys&nbsp;were&nbsp;carried&nbsp;out&nbsp;separately&nbsp;inside&nbsp;and&nbsp;around&nbsp;tuna&nbsp;cages.&nbsp;A&nbsp;total&nbsp;of&nbsp;26&nbsp;species&nbsp;belonging&nbsp;to&nbsp;14&nbsp;families&nbsp;were&nbsp;recorded.&nbsp;The&nbsp;highest&nbsp;abundances&nbsp;were&nbsp;observed&nbsp;for&nbsp;Scomber&nbsp;colias,&nbsp;Atherina&nbsp;boyeri,&nbsp;and&nbsp;Boops&nbsp;boops.&nbsp;Seasonal&nbsp;analysis&nbsp;of&nbsp;fish&nbsp;assemblages&nbsp;revealed&nbsp;that&nbsp;individual&nbsp;abundance&nbsp;was&nbsp;highest&nbsp;during&nbsp;summer&nbsp;and&nbsp;autumn,&nbsp;while&nbsp;a&nbsp;marked&nbsp;decline&nbsp;was&nbsp;observed&nbsp;with&nbsp;decreasing&nbsp;water&nbsp;temperatures.&nbsp;Biodiversity&nbsp;indices&nbsp;at&nbsp;the&nbsp;sampling&nbsp;stations&nbsp;also&nbsp;reached&nbsp;their&nbsp;highest&nbsp;values&nbsp;in&nbsp;summer&nbsp;and&nbsp;autumn.&nbsp;In&nbsp;addition,&nbsp;the&nbsp;mean&nbsp;number&nbsp;of&nbsp;individuals&nbsp;recorded&nbsp;inside&nbsp;the&nbsp;tuna&nbsp;cages&nbsp;was&nbsp;higher&nbsp;than&nbsp;that&nbsp;observed&nbsp;in&nbsp;the&nbsp;surrounding&nbsp;areas.</p><p class="ql-align-justify">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;In&nbsp;conclusion,&nbsp;this&nbsp;study&nbsp;provides&nbsp;the&nbsp;first&nbsp;comprehensive&nbsp;assessment&nbsp;of&nbsp;wild&nbsp;fish&nbsp;assemblages&nbsp;associated&nbsp;with&nbsp;tuna&nbsp;cages&nbsp;in&nbsp;Turkey&nbsp;and&nbsp;makes&nbsp;a&nbsp;significant&nbsp;contribution&nbsp;to&nbsp;the&nbsp;national&nbsp;and&nbsp;international&nbsp;literature.&nbsp;The&nbsp;findings&nbsp;highlight&nbsp;the&nbsp;ecological&nbsp;role&nbsp;of&nbsp;offshore&nbsp;aquaculture&nbsp;facilities&nbsp;within&nbsp;pelagic&nbsp;ecosystems.</p><p></p><p>Keywords:&nbsp;Offshore&nbsp;tuna&nbsp;cages,&nbsp;Wild&nbsp;fish&nbsp;assemblages,&nbsp;FADs,&nbsp;Aegean&nbsp;Sea</p>

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