Cited by 51Ichthyology and Marine BiologyMarine and fisheries researchFish Ecology and Management Studies

Potential detection of illegal fishing by passive acoustic telemetry

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Tickler, David M., Carlisle, Aaron B., Chapple, Taylor K., Curnick, David J., Dale, Jonathan J., Schallert, Robert J., Block, Barbara A.·2019·Animal Biotelemetry

Abstract

Acoustic tagging is typically used to gather data on the spatial ecology of diverse marine taxa, informing questions about spatio-temporal attributes such as residency and home range, but detection data may also reveal unanticipated insights. Many species demonstrate predictable site fidelity, and so a sudden cessation of detections for multiple individuals may be evidence of an atypical event. During 2013 and 2014, we acoustically tagged 47 grey reef sharks ( Carcharhinus amblyrhynchos ) and 48 silvertip sharks ( Carcharhinus albimarginatus ) near reefs in the British Indian Ocean Territory (BIOT) Marine Protected Area (MPA). From March 2013 to November 2014 inclusive, tags were ‘lost’, i.e. permanently ceased to be detected within the monitoring area, at an average rate of 2.6 ± 1.0 tags per month. Between 1 and 10 December 2014, detection data suggest the near-simultaneous loss of 15 of the remaining 43 active tagged sharks, a monthly loss rate over five times higher than during the previous 21 months. Between 4 and 14 December of 2014, the BIOT patrol vessel encountered 17 vessels engaged in suspected illegal fishing in the northern BIOT MPA; such sightings averaged one per month during the previous 8 months. Two of these vessels were arrested with a total of 359 sharks on board, of which grey reef and silvertip sharks constituted 47% by number. The unusual and coincident peaks in tag loss and vessel sightings, and the catch composition of the arrested vessels, suggest illegal fishing as a plausible explanation for the unusual pattern in our detection data. A Cox proportional hazards model found that the presence of fishing vessels increased the risk of tag loss by a factor of 6.0 (95% CI 2.6–14.0, p < 0.001). Based on the number of vessels sighted and the average number of sharks on vessels arrested in BIOT during 2014, we conservatively estimate that over 2000 sharks may have been removed during the suspected fishing event. Based on average catch compositions, over 1000 would have been grey reef and silvertip sharks. Assuming a closed population mark-recapture model, over one-third of the locally resident reef sharks may have been removed from the monitoring area. The data suggest that even sporadic fishing events may have a marked impact on local reef shark populations, but also demonstrate the potential of electronic tagging a tool for detecting illegal or otherwise unreported fishing activity.

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  • Various supervised machine learning methods have shown potential in automating behavior analysis from accelerometer data, identifying behavioral state from trajectories, and predicting animal movement.

    “Various supervised ML methods have shown their potential in automating behavior analysis from accelerometer data68,69, identifying behavioral state from trajectories70, and predicting animal movement71.”

    From Perspectives in machine learning for wildlife conservation (2022) · cites this paper as [69]

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  1. Rechisky EL, Welch DW. Surgical implantation of acoustic tags: influence of tag loss and tag-induced mortality on free-ranging and hatchery-held spring Chinook salmon (O. tshawytscha) smolts. In: Wolf KS, O'Neal JS (eds) PNAMP special publication: tagging, telemetry and marking meas- ures for monitoring fish populations-a compendium of new and recent science for use in informing technique and decision modalities 2010-002, pp. 69-94.

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Authors
Tickler, D. M., Carlisle, A. B., Chapple, T. K., Curnick, D. J., Dale, J. J., Schallert, R. J., & Block, B. A.
Affiliations
  • The University of Western Australia (AU)
  • University of Delaware (US)
  • Hopkins Marine Station (US)
  • Zoological Society of London (GB)
Corresponding author
Tickler, David M.
Venue
Animal Biotelemetry
Published
2019-01-11
Volume
7
Issue
1
ISSN
2050-3385 (ISSN-L)
OpenAlex
W2910700109
Cited by
51
References
42
Citations by year
2026: 3 · 2025: 4 · 2024: 6 · 2023: 10 · 2022: 7 · 2021: 9 · 2020: 11 · 2019: 1
FWCI
5.00
Type
journal article
Language
en
Open access
Locations
  • Animal Biotelemetry (publishedVersion, cc-by)
  • UWA Profiles and Research Repository (UWA) (submittedVersion, cc-by)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
  • UCL Discovery (University College London) (submittedVersion)
Funders
Fondation Bertarelli
Topics
  • Physical Sciences › Environmental Science › Nature and Landscape Conservation › Ichthyology and Marine Biology
  • Physical Sciences › Environmental Science › Global and Planetary Change › Marine and fisheries research
  • Physical Sciences › Environmental Science › Nature and Landscape Conservation › Fish Ecology and Management Studies
Keywords
illegal fishing detection, passive acoustic telemetry, grey reef shark, Carcharhinus amblyrhynchos, Carcharhinus albimarginatus, shark fisheries, shark bycatch, site fidelity

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