Cetacean mortality due to interactions with fisheries and marine litter ingestion in the Croatian part of the Adriatic Sea from 1990 to 2019

• Published in: Veterinarski arhiv
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2021
• Subjects: bycatch; entanglement; fishing gear; marine litter; cetaceans; Adriatic Sea; slučajni ulov; zapletanje u mrežu; ribolovni alati; morski otpad; kitovi; Jadransko more; Balaenoptera physalus
• Online Access: https://hrcak.srce.hr/258466; https://hrcak.srce.hr/file/375835

Various anthropogenic threats negatively influence the survival of cetaceans in all world seas. Thanks to a long- running marine mammal surveillance program, we are able to report the results of a detailed analysis of the influence of cetacean-fisheries interactions and marine litter ingestion on cetacean mortality in the Croatian part of the Adriatic Sea over the last three decades. The total number of dead cetaceans was 459, and included 334 bottlenose dolphins (Tursiops truncatus), 40 striped dolphins (Stenella coeruleoalba), ten Risso’s dolphins (Grampus griseus), six Cuvier’s beaked whales (Ziphius cavirostris) and four fin whales (Balaenoptera physalus). Three hundred of them were examined postmortally. Cetacean-fisheries interaction occurred frequently in the Adriatic Sea, being detected in 96 (20.9%) of the recorded cases. Bycatch was the most abundant cetacean-fisheries interaction, with 66 (14.4%) cases recorded. Good nutritional condition and evidence of recent feeding were the most common findings recorded in bycatch cases, followed by persistent froth in the airways, edematous lungs, bruises and an amputated fluke or tail. Cetacean-fisheries interactions other than bycatch affected 30 animals and included larynx strangulations, long- term tail entanglement and fishing gear in the stomach. Ingestion of marine litter that was not related to fisheries was recorded in four animals. This study reveals the considerable negative anthropogenic influence on cetaceans in the Adriatic Sea, especially the bottlenose dolphin that is considered to be the most numerous cetacean species therein, and demonstrates the need for the urgent development of a cetacean bycatch reduction program. Finally, it also shows the importance of sustaining national surveillance programs to gain scientifically based knowledge important for cetacean protection and prospects for their long-term survival. Različiti antropogeni čimbenici negativno utječu na preživljavanje kitova u svim svjetskim morima. U ovom istraživanju prikazujemo utjecaj ribolova i ingestiju morskog otpada na preživljavanje kitova u razdoblju od 1990. do 2019. u hrvatskom dijelu Jadranskoga mora. Analizirani podaci prikupljeni su dugogodišnjim praćenjem stanja morskih sisavaca u ovom području. Ukupan broj nalaza uginulih kitova jest 459 te uključuje 334 dobra dupina (Tursiops truncatus), 40 plavobijela dupina (Stenella coeruleoalba), deset glavatih dupina (Grampus griseus), šest krupnozubih dupina (Ziphius cavirostris) i četiri velika sjeverna kita (Balaenoptera physalus). Tristo jedinki postmortalno je pregledano. Interakcije kitova i ribolova učestale su u Jadranskome moru s obzirom na to da su utvrđene u 20,9 % uginulih kitova. Ukupan broj dupina stradalih kao slučajan ulov jest 66 (14,4 % svih nalaza). Osrednje gojno stanje i neprobavljeni/poluprobavljeni plijen u želucu najučestaliji su nalazi u dupina stradalih kao slučajan ulov. Od ostalih nalaza ističu se pjena u dišnim putevima, edematozna pluća, podljevi te odrezana repna peraja ili cijeli rep. Interakcije kitova i ribolova koje se ne smatraju slučajnim ulovom opisane su u 30 jedinki i uključuju strangulaciju grkljana, dugotrajan zapletaj repa i ribolovni alat u želucu. Ingestija morskog otpada utvrđena je u četiri jedinke. Ovo istraživanje potvrđuje negativan antropogeni utjecaj na kitove u Jadranskome moru, osobito na dobrog dupina, te upućuje na potrebu hitnog razvoja mjera za smanjenje broja dupina stradalih kao slučajan ulov. Ono također ističe važnost nacionalnih protokola za praćenje kitova kao izvora znanstvenih podataka potrebnih za predlaganje i provedbu mjera zaštite koje će povećati izglede za njihovo dugoročno preživljavanje.