Northwest Fisheries Science Center

Anthropogenic threat exposure of seabirds in the California Current

Seabird populations worldwide are confronted by a multitude of anthropogenic threats. Commercial fisheries bycatch, resource competition, habitat disturbance and global climate change are examples of some of these threats. Few studies have addressed the potential vulnerability of seabird species to a suite of anthropogenic threats over a large marine ecosystem. A recent development in ecosystem risk assessment is a modification of productivity-susceptibility analyses, which has been used to evaluate exposure and sensitivity to fisheries and non-fisheries threats. We are using a modified exposure-sensitivity approach to provide information on relative exposures to various anthropogenic threats for seabird species in the California Current. Relative density estimates for each species and the overlap of each species' distribution with the spatial distribution and intensity of non-fisheries threats were used to determine the exposure to each threat. Our initial evaluation of seabird vulnerability to non-fisheries risks indicates that seabirds appear to be at highest risk from large-scale, systemic threats like sea surface temperature anomalies and ocean acidification. Common murres were the most exposed to the non-fisheries threats examined, followed by sooty shearwaters and rhinoceros auklets. This evaluation is a first step towards evaluating the vulnerability of many seabird species to such threats.


William Sydeman – Farallon Institutes
Jameal Samhouri – Conservation Biology Division, NWFSC