Dear all,
We are pleased to announce the publication of the following article in
the ICES Journal of Marine Science:
Rabearisoa, N., Bach, P., and Marsac, F. 2015. Assessing interactions
between dolphins and small pelagic fish on branchline to design a
depredation mitigation device in pelagic longline fisheries. ICES
Journal of Marine Science. doi:10.1093/icesjms/fsu252
**Abstract*
*
Depredation by false killer whales (/Pseudorca crassidens/) and
short-finned pilot whales (/Globicephala macrorhynchus/) in pelagic
longlining is an issue leading to negative impacts on the economics of
the fishery and on odontocetes themselves. We investigated the efficacy
of a new depredation mitigation device called "DEPRED" in the
interaction between bottlenose dolphins (/Tursiops aduncus/), spinner
dolphins (/Stenella longirostris/), and small pelagic fish (SPF)
attached to branchlines to simulate caught fish. We suggest implications
for DEPRED efficacy with larger toothed whales interacting with pelagic
longline capture in the open ocean. The design of the device uses
streamers to both deter cetaceans and protect fish from predation. In
controlled experiments, we tested its efficacy by observing changes in
the dolphin's behaviour brought on by the presence or absence of the
device on branchlines. First, dolphin--SPF interactions were observed at
the small scale using video footage recorded with an underwater
camcorder. Second, the efficacy of the device was quantified from
interactions between dolphins and 80 branchlines deployed on a longline
500 m long baited with SPF. One half of the SPF on successive
branchlines was protected by DEPRED and the other half was not. A total
of 707 branchlines were set when dolphins interacted with SPF, and among
them, 355 were equipped with DEPRED. Encouraging results were obtained:
over the short term, the number of damaged unprotected SPF was on
average more than twice the number of protected ones. Nevertheless,
habituation behaviour was observed for a resident group of /T. aduncus/
in the experimental area. The relation between the deterrent effect of
the device and constraints related to the design of such a device to be
used at a commercial operational level are discussed.
The early version of the paper is available from:
http://icesjms.oxfordjournals.org/content/early/2015/01/21/icesjms.fsu252.full?keytype=ref&ijkey=P6zv6zr4jaYVP2z
If you have any trouble to download the article, please contact me at
[email protected] and I would be happy to send you a pdf copy.
All the best,
Njaratiana
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