Preliminary assessment of the impact on UK seabird populations of mortality from incidental bycatch occurring in UK waters

As a first step to develop and implement a UK Plan of Action on incidental bycatch of seabirds in UK waters, an assessment is required of the impact of bycatch on UK seabird populations. To date no comprehensive assessment has been made, so the scale of any "problem" is unclear, as are what management or further monitoring should be sought (if any) and how bycatch should be prioritised in relation to other pressures.

The aims of the Project are:

1. To ascertain whether current levels of bycatch are causing a reduction in population growth rate of marine bird populations; 2. Predict what would happen to population growth rates of marine bird populations in the event that bycatch mitigation measures were deployed across relevant fisheries.

Estimates of overall mortality of marine birds (species by species) occurring within UK marine waters will be provided to the contractor (to be delivered under a separate contract), using estimates of bycatch rates from the Protected Species Bycatch Monitoring Programme and estimates of fishing effort.

The main challenges of this work are incomplete knowledge/understanding in four areas: A. Magnitude of bycatch B. Size of the seabird population exposed to risk of bycatch in UK waters C. Status/demographic parameters of seabird populations D. Inability to forecast seabird population size into the future

The proposed contract is to account for lack of knowledge and uncertainty around the above parameters, using the general approach of running a range of plausible scenarios, even though we don't know which scenario is closest to reality. This allows us to investigate under which scenarios bycatch would be a problem, requiring for example further monitoring and/or management.