[MARMAM] New paper - Toothed whale depredation mitigation device

Njaratiana Rabearisoa njaratiana.rabearisoa at gmail.com
Thu Jan 22 03:11:32 PST 2015


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 
njaratiana.rabearisoa at gmail.com and I would be happy to send you a pdf copy.

All the best,

Njaratiana
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