Survivorship of discarded cuckoo ray in bottom trawl fisheries in the northern Bay of Biscay, Southern Celtic and Irish Seas

• Published in: Fisheries Research
• Main Authors: Baulier, Loic, McHugh, Matthew, Minto, Cóilín, Morandeau, Fabien, Murphy, Shane, Sourget, Quiterie, Oliver, Martin, Morfin, Marie
• Other Authors: Dynamique et durabilité des écosystèmes : de la source à l’océan (DECOD), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut Agro Rennes Angers, Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro), Bord Iascaigh Mhara, Atlantic Technological University (ATU Galway), Association grand littoral Atlantique (AGLIA)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2024
• Subjects: Cuckoo ray; Leucoraja naevus; Discard survival; Captivity experiment; Bottom trawl fisheries; Vitality; [SDV]Life Sciences [q-bio]; North East Atlantic
• Online Access: https://hal.science/hal-04573208; https://doi.org/10.1016/j.fishres.2024.106971

International audience Estimating the survivorship of discarded fish is often crucial for stock assessment and resultant management of fisheries resources. In order to assess the survivorship of cuckoo ray (Leucoraja naevus) caught in commercial bottom trawl fisheries, experiments involving French and Irish fisheries were conducted. These experiments were particularly challenging considering the fisheries are offshore. Data from these experiments were analysed jointly in this study. Results from monitoring of individuals held in captivity in onshore facilities and observations of vitality status were combined to produce estimates of long-term survival rates across fishing trips in all four seasons. These rates varied greatly between fishing trips and ranged between 3.6% and 26%. Based on indications that the observed mortality may be at least partly attributable to the conditions of captivity, we propose an approach to reduce the underestimation bias when estimating discard survival. This approach produced higher bounds for the estimated discard survival rates. The estimated survival rates are lower than those of other skate species in the North-East Atlantic, suggesting the cuckoo ray is less resilient to trawl-and-release, although previous studies were conducted in shallower water and with shorter haul duration.