According to recent estimates, 25% of the worlds sharks, skates and rays are threatened with extinction, driven by habitat loss and overexploitation among other factors. In trawling fisheries, demersal elasmobranch species such as skates and rays constitute a large portion of non-target biomass landed as bycatch. Many of these species remain unassessed by COSEWIC or the IUCN Red List of Endangered Species; those that have had population trends assessed are largely decreasing. In the Northwest Atlantic, two species of skate, the thorny skate (Amblyraja radiata) and the smooth skate (Malacoraja senta) have shown steady declines across the last two decades. The winter skate (Leucoraja ocellata) is currently the subject of nationwide consultations to be added to the List of Wildlife Species at Risk under the Species At Risk Act. All other species of skate in Canadian waters have not been assessed, and the contribution of bycatch to population trends is unresolved.

 

My Master’s research involves using novel geostatistical tools to estimate the exploitation rate of skates and rays over space and time in Canadian trawling fisheries. In collaboration with researchers in Dalhousie’s Department of Mathematics and Statistics, we will build a spatiotemporal hierarchical model from fisheries observer data to evaluate and predict patterns of bycatch of skate and ray species over space and time in the Canadian Atlantic. Using this model I aim to overlay indices of fishing effort over space and time from trawling vessel tracks acquired from satellite Automatic Identification System (S-AIS) readings. Upon combining bycatch estimates with fishing effort indices, the goal of this project is to extract a spatiotemporally dynamic rate of exploitation for demersal elasmobranchs across the Canadian Atlantic to aid in investigating conservation concerns of Atlantic skates and rays.

 

The Canadian government has put forward a mandate to protect 10% of it’s national waters by 2020, a push which has led to several areas of interest in the Atlantic region being considered for marine protected area (MPA) designation. The overarching goal of this project is to develop methods to support dynamic management strategies to complement MPA’s as a conservation tool. This research is funded through the Ocean Frontiers Institute, and is made possible through partnerships between the Worm Lab, DFO, and Global Fishing Watch.