Quantifying post-release behaviour of a critically endangered elasmobranch over two capture events using...

Area of Science:

• Marine biology
• Fisheries science
• Animal behaviour

Background:

• Highly resident fish species face repeated capture during angling.
• Biologging provides insights into post-release behavior, but studies often focus on single events.

Purpose of the Study:

• To detail the post-release behavior of a flapper skate (Dipturus intermedius) subjected to two capture events.
• To analyze behavioral changes using high-resolution archival data and acoustic tracking.

Main Methods:

• Utilized archival satellite tagging and acoustic tracking for a single flapper skate.
• Analyzed movement patterns, depth changes, and mobility using generalized additive models and change point analysis.

Main Results:

• The flapper skate exhibited atypical movements, including increased mobility and vertical excursions, after both capture events.
• Behavioral changes, characterized by elevated activity, persisted for 9-10 hours post-capture before returning to settled behavior.
• Integrated Vertical Movement (IVM) was 441% higher in the 9-10 hours post-capture compared to baseline behavior.
• Acoustic tracking confirmed the skate remained in the vicinity of the capture area after both events.

Conclusions:

• Flapper skates exhibit a distinct, short-term behavioral response to capture and release, with elevated activity levels.
• Despite multiple capture events, the studied skate demonstrated site fidelity, remaining in the capture area.
• This research highlights the importance of considering repeated capture effects in fisheries management and conservation strategies for resident species.