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Longline hook testing in the mouths of pelagic odontocetes

Publication ,  Journal Article
McLellan, WA; Arthur, LH; Mallette, SD; Thornton, SW; McAlarney, RJ; Read, AJ; Pabst, DA
Published in: ICES Journal of Marine Science
April 23, 2015

Several species of odontocete cetaceans depredate bait and catch and, as a result, become hooked and entangled in pelagic longline fisheries. The present study measured how selected commercial longline hooks, including "weak hooks", behaved within odontocete mouths. Five hooks (Mustad-16/0, Mustad-18/0, Mustad J-9/0, Korean 16, and Korean 18) were tested on three species of odontocetes known to interact with longline fisheries - short-finned pilot whales (Globicephala macrorhynchus), Risso's dolphins (Grampus griseus), and false killer whales (Pseudorca crassidens). Specimens were secured to a stanchion, hooks were placed in the mouth at multiple positions along the dorsal lip, and the force required to pull each hook free was measured. The soft tissue lips of these odontocetes were capable of resisting forces up to 250 kg before failing. The polished steel M-16, M-18, and J-9 hooks straightened at forces between 50 and 225 kg, depending on hook gauge. When straightened, these hooks exposed the sharpened barb, which sliced through the lip tissue, usually releasing the hook intact. The K-16 and K-18 hooks behaved very differently, breaking at higher forces (110-250 kg) and consistently just at the barb; usually, there was measurable soft-tissue loss and often shards of the hook were retained within those soft tissues. The different behaviours of these two hook types - the M and J type polished steel vs. the K type carbon steel - were consistent across all species tested. Mechanical tests were also conducted to determine if hooks could fracture the mandible of these same odontocetes. Only the M-18 and K-18 hooks had sufficiently large gapes to hook around the mandible, and both hook types fractured bone in short-finned pilot whales and Risso's dolphins. These results support other lines of evidence indicating that longline hooks can cause serious injury to these species, and suggest possible steps to mitigate these impacts.

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Published In

ICES Journal of Marine Science

DOI

EISSN

1095-9289

ISSN

1054-3139

Publication Date

April 23, 2015

Volume

72

Issue

5

Start / End Page

1706 / 1713

Related Subject Headings

  • Fisheries
 

Citation

APA
Chicago
ICMJE
MLA
NLM
McLellan, W. A., Arthur, L. H., Mallette, S. D., Thornton, S. W., McAlarney, R. J., Read, A. J., & Pabst, D. A. (2015). Longline hook testing in the mouths of pelagic odontocetes. ICES Journal of Marine Science, 72(5), 1706–1713. https://doi.org/10.1093/icesjms/fsu181
McLellan, W. A., L. H. Arthur, S. D. Mallette, S. W. Thornton, R. J. McAlarney, A. J. Read, and D. A. Pabst. “Longline hook testing in the mouths of pelagic odontocetes.” ICES Journal of Marine Science 72, no. 5 (April 23, 2015): 1706–13. https://doi.org/10.1093/icesjms/fsu181.
McLellan WA, Arthur LH, Mallette SD, Thornton SW, McAlarney RJ, Read AJ, et al. Longline hook testing in the mouths of pelagic odontocetes. ICES Journal of Marine Science. 2015 Apr 23;72(5):1706–13.
McLellan, W. A., et al. “Longline hook testing in the mouths of pelagic odontocetes.” ICES Journal of Marine Science, vol. 72, no. 5, Apr. 2015, pp. 1706–13. Scopus, doi:10.1093/icesjms/fsu181.
McLellan WA, Arthur LH, Mallette SD, Thornton SW, McAlarney RJ, Read AJ, Pabst DA. Longline hook testing in the mouths of pelagic odontocetes. ICES Journal of Marine Science. 2015 Apr 23;72(5):1706–1713.
Journal cover image

Published In

ICES Journal of Marine Science

DOI

EISSN

1095-9289

ISSN

1054-3139

Publication Date

April 23, 2015

Volume

72

Issue

5

Start / End Page

1706 / 1713

Related Subject Headings

  • Fisheries