Survivability of spurdog (Squalus acanthias) in an inshore otter trawl fishery

Spurdog ( Squalus acanthias ) was previously fished by European Union (EU) vessels, but the fishery closed in 2011 due to poor stock status. Following positive advice on spurdog stock recovery, the fishery reopened in 2023 prompting assessments of management measures and post-capture survival. We assessed spurdog survivability in an inshore bottom otter trawl fishery using condition assessments and survivorship pop-up satellite archival tags (sPATs). We used a five-point scale (excellent, good, poor, moribund and dead) to categorise vitality of 463 sampled spurdog. Twenty spurdog in excellent, good and poor condition were tagged with sPATs. Moribund fish were assumed to have died. Tagged fish size was restricted to 80–100 cm total length (TL) in line with the size of fish capable of carrying tags, the maximum conservation reference size and condition assessments results. The observed fish vitalities were: 9.9 % excellent, 17.3 % good, 34.6 % poor, 38 % moribund and 0.2 % dead. We used a Kaplin-Meier estimator to assess survival of tagged fish over a 30-day period and estimated an overall survival rate of 78 % for spurdog between 80 and 100 cm. Study results provide important input towards enhanced management of spurdog fisheries in the North-East Atlantic. • Survival of trawl-caught spurdog was assessed using condition assessments and survivorship pop-up satellite tags • An estimated 78 % of spurdog between 80 – 100 cm survived capture onboard an inshore otter trawler • Tag depth data greatly assisted in elucidating spurdog survival • Appropriate methods for estimating survival of other spurdog size classes and the need for broader observations are discussed