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Decline in whale shark size and abundance at Ningaloo Reef over the past decade: The world's largest fish is getting smaller

Bradshaw, Corey J. A., Fitzpatrick, B., Steinberg, C., Brook, Barry William and Meekan, Mark G. (2008). Decline in whale shark size and abundance at Ningaloo Reef over the past decade: The world's largest fish is getting smaller. Biological Conservation,141(7):1894-1905.

Document type: Journal Article
Citation counts: Scopus Citation Count Cited 26 times in Scopus Article | Citations
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IRMA ID A00003xPUB63
Title Decline in whale shark size and abundance at Ningaloo Reef over the past decade: The world's largest fish is getting smaller
Author Bradshaw, Corey J. A.
Fitzpatrick, B.
Steinberg, C.
Brook, Barry William
Meekan, Mark G.
Journal Name Biological Conservation
Publication Date 2008
Volume Number 141
Issue Number 7
ISSN 0006-3207   (check CDU catalogue  open catalogue search in new window)
Scopus ID 2-s2.0-46749138989
Start Page 1894
End Page 1905
Total Pages 12
Place of Publication Netherlands
Publisher Elsevier B.V.
Field of Research 0501 - Ecological Applications
0608 - Zoology
0707 - Veterinary Sciences
HERDC Category C1 - Journal Article (DEST)
Abstract Over-exploitation of whale sharks threatens the future of these wide-ranging pelagic fish. A long-term continuous record (4436 sightings) from a large aggregation (300–500 resident individuals) of whale sharks at Ningaloo Reef, Western Australia shows that mean shark length declined linearly by nearly 2.0 m and relative abundance measured from ecotourism sightings (corrected for variation in search effort and environmental stochasticity) has fallen by approximately 40% over the last decade. This population-level result confirms previous predictions of population decline based on projection models parameterised using mark-recapture estimates of survival. The majority of these changes are driven by reductions in the number of large individuals in the population. Phenomenological time series models support a deterministic (extrinsic) decline in large females, although there was some evidence for density dependence in large males. These reductions have occurred despite the total protection of whale sharks in Australian waters. As this species is highly migratory, the rapid change in population composition over a decade (<1 whale shark generation) supports the hypothesis of unsustainable mortality in other parts of their range (e.g., overfishing), rather than the alternative of long-term abiotic or biotic shifts in the environment. As such, effective conservation of whale sharks will require international protection, and collaborative tagging studies to identify and monitor migratory pathways.
DOI http://dx.doi.org/10.1016/j.biocon.2008.05.007   (check subscription with CDU E-Gateway service for CDU Staff and Students  check subscription with CDU E-Gateway in new window)
 
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