Post-release survival of seabirds

Publication details

INT2019-06: Post-release survival of seabirds (PDF, 2,039 K)

Summary 

This report reviews methodologies and tracking devices used to study seabird survival and assesses their suitability for development of a future field-based project to determine post-release survival rates.With recent technological advances the use of miniature satellite tracking devices was determined to be the most effective method to assess the fate of released seabirds following accidental capture by fishing vessels.A range of operational, biological and environmental factors may constrain a tracking study of injured seabirds. Some of these factors have the potential to significantly impact the likelihood of successfully monitoring the post-release survival, and these are discussed.

Assessment of the health of live seabirds that have interacted with fishing vessels will first need to be carried out to select suitable individuals to track survival and ensure tracking maximisesidentifying cryptic mortality rates. Individuals with severe injuries that will not survive, and those with no injuries that will likely survive, should not be tracked. Birds with moderate injures wheresurvival probability is uncertain should be tracked, as these provide the best opportunity to understanding true cryptic mortality rates. To achieve this a “Seabird Heath Assessment Tool” has been developed to guide future research.

It is recommended that a review be undertaken of existing seabird injury data, held by Fisheries NZ (FNZ) as recorded by fisheries observers on Observer Protected Species Interaction (PSI) forms, and electronic monitoring (EM) video footage, to categorise (using the health assessment tool presented here) and investigate the number, nature and extent of injuries sustained byseabirds returned alive at-sea, in order to refine the following field-based recommendation.

Considering the above factors, a field-based programme utilising satellite tracking with Teleonics TAVseries Platform Transmitter Terminals (PTTs) is recommended as the best method to assess post-release survival of seabirds that interact with commercial fisheries. Although relatively expensive, this method provides the only method which is likely to return sufficient data on behaviour and post-release survival. Target species for tracking should include control groups (healthy seabirds), medium sized seabirds (i.e. black petrel, flesh-footed shearwater, and Buller’s shearwater) in FMA1 and FMA9, and albatross species in FMA5 and FMA6. The study should aim to track ≥30 birds from each group which would likely require a 3-5 year study period.

Publication details

Bell, M.D. 2020. Investigation of options for assessing the post-release survival of seabirds that interact with commercial fisheries in New Zealand. Final Report for project INT2019-06 prepared by Wildlife Management International Ltd for the Conservation Services Programme, Department of Conservation. 33 p.