Drivers of spatiotemporal variability in bycatch of a top marine predator: First evidence for the role of water turbidity in protected species bycatch ...

• Main Authors: Luck, Cian, Cronin, Michelle, Gosch, Martha, Healy, Kieran, Cosgrove, Ronan, Tully, Oliver, Rogan, Emer, Jessopp, Mark
• Format: Dataset
• Language: English
• Published: Dryad 2019
• Subjects: bycatch; grey seal; Harbour seal; gillnet; Turbidity; Earth observation; harbour seal
• Online Access: https://dx.doi.org/10.5061/dryad.z34tmpg8c; https://datadryad.org/stash/dataset/doi:10.5061/dryad.z34tmpg8c

1. Bycatch of protected species in static net fisheries is a global conservation concern and is currently considered the dominant anthropogenic threat to many marine mammal species worldwide. Effective bycatch mitigation remains challenging, contingent on an understanding of the underlying mechanisms that cause individuals to become entangled. 2. We combined data collected by scientific observers and fishers to identify predictors of seal bycatch in static net fisheries along the west, southwest, and south coasts of Ireland. We first analysed the broad regional and seasonal trends in seal bycatch before identifying environmental variables that could potentially explain these patterns. 3. Based on negative binomial generalised linear mixed effects models, the rate of seal bycatch significantly varied with season and region, and decreased at greater distances to major seal colonies and lower water turbidity. 4. Synthesis and applications. Our results suggest that distance to major seal colonies was a ... : Field descriptors: vessel_id - unique identifier for each fishing vessel net_type - one of four entangling net types (see paper for more detailed description): gill - gillnets tangle - tangle nets trammel - trammel nets spider - spider nets (large mesh tangle nets) year - year data was recorded effort_km - net length in km soak_days - number of days the net has been left to soak in the water unattended effort_soak_km - fishing effort as the product of effort_km and soak_days depth - depth of the seafloor where the nets were set mesh_size_cm - mesh size of the nets in cm. Note for tangle nets this refers to the mesh size of the central net wall seal_byc - was a seal caught in the net: TRUE - seal bycatch FALSE - no seal bycatch seals - number of seals caught in net dist_colony_km - distance to nearest major grey seal colony in km colony_size - minimum estimate for number of breeding seals at nearest major grey seal colony (see paper for sources) colony_size_prop - approximate proportion of national population ...