[MARMAM] New paper on responses of Burmeister's porpoise to pingers

[Clay, Thomas]

Hi all,



We are pleased to share with you our new paper:

Clay TA, Alfaro-Shigueto J, Godley BJ, Tregenza N, Mangel JC (2019) Pingers 
reduce the activity of Burmeister’s porpoises around small-scale gillnet 
vessels. Marine Ecology Progress Series, 626:198-208 - 
https://www.int-res.com/abstracts/meps/v626/p197-208/

Abstract:
Incidental mortality (bycatch) in gillnet fisheries is a major threat to many 
cetacean populations. Acoustic alarms or pingers are a widely adopted 
management tool used to deter dolphins and porpoises from nets; however, their 
efficacy is largely species- and fishery-dependent. As such, results from 
experimental trials may have limited transferability to poorly studied species 
or fisheries. Here, we investigated the effect of pingers on the behaviour of 
Burmeister’s porpoise Phocoena spinipinnis in the vicinity of the Peruvian 
small-scale driftnet fleet. Over a 4 yr period (2009-2012), 116 control 
(without pingers) and 94 experimental (with pingers) fishing sets were 
observed, and porpoise acoustic activity around nets was recorded using passive 
acoustic loggers (C-PODs). We modelled variation in detection rates as a 
function of pinger use and habitat covariates, and found that in regions of 
preferred habitat associated with cooler (17-18°C), shallow waters (within the 
100 m isobath), the use of pingers lead to an 86% reduction in porpoise 
activity around nets. Our results suggest that pingers are likely to be 
particularly effective at deterring Burmeister’s porpoises from fishing nets, 
and given the vast capacity of this and other fleets in the region, may 
substantially reduce mortality. This study also emphasizes the potential of 
passive acoustic monitoring to determine the effectiveness of bycatch 
mitigation measures, both for species for which visual observations are scarce, 
and also in regions where gathering statistically meaningful bycatch rates is 
logistically challenging.

This work is part of an ongoing collaboration between ProDelphinus and the 
University of Exeter.

Best regards,

Tommy Clay

Postdoctoral Research Associate
School of Environmental Sciences
University of Liverpool

Liverpool
L69 3GP, UK


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[MARMAM] New paper on Burmeister's porpoise habitat, monitored from small-scale fisheries

[Clay, Thomas]

Greetings all,

We are pleased to share with you our new paper:

Clay, T.A., J. C. Mangel, J. Alfaro-Shigueto, D.J. Hodgson & B. J. Godley 
(2018). "Distribution and Habitat Use of a Cryptic Small Cetacean, the 
Burmeister’s Porpoise, Monitored From a Small-Scale Fishery Platform." 
Frontiers in Marine Science 5: 220.

Abstract:
There is widespread evidence that small-scale fisheries (SSF) bycatch threatens 
many populations of small cetaceans, yet conservation efforts are often limited 
by a lack of basic knowledge regarding their abundance, distribution, and 
habitat use. Here, we used passive acoustic monitoring from an SSF 
platform-of-opportunity to better characterize the distribution and habitat use 
of small cetaceans in northern Peru, focussing on the little-known Burmeister’s 
porpoise Phocoena spinipinnis. From 2009 to 2012, acoustic click detectors 
(C-PODs) were attached to fishing nets for the duration of 116 fishing sets (30 
fishing trips). Dolphins (unspecified delphinids) and porpoises were recorded 
around 71 and 22% of fishing sets, respectively. The probability of occurrence 
and buzzing behavior (a proxy for foraging), and time spent, were linked to 
both static and dynamic environmental variables to examine the drivers of 
habitat use. Dolphin activity was spread evenly throughout the fishing area and 
was not linked to any habitat variables. In contrast, porpoises were detected 
in neritic waters, and habitat models performed well, identifying preferences 
for shallow (<200 m depth) and cooler (17–18◦C) waters, close (<50 km) to 
shore. The high bycatch rate of small cetaceans in Peruvian SSF gave us the 
unique opportunity to investigate the link between bycatch and cetacean 
activity around vessels. We found a positive relationship between the 
likelihood of a bycatch event and acoustic presence for both dolphins and 
porpoises, however as we did not know the timing of entanglement, we could not 
link vocalization rates to mortality events. Nonetheless, as small cetaceans 
(particularly dolphins) frequently encounter fishing boats, the likelihood of 
entanglements may be reduced through effective efforts to alert animals to the 
presence of the net, either acoustically (using acoustic alarms) or visually. 
This study demonstrates that passive acoustic monitoring from a fisheries 
platform can provide insights into the distribution and habitat use of small 
cetaceans at relatively low cost, and is likely to be suitable in regions with 
low monitoring effort and high fishing pressure

The paper is freely available here - https://doi.org/10.3389/fmars.2018.00220

This work is part of an ongoing collaboration between ProDelphinus and 
University of Exeter.

Kind regards,


Tommy Clay

Postdoctoral Research Associate
School of Environmental Sciences
University of Liverpool

Liverpool
L69 3GP, UK


Join us this September in Liverpool for the 14th International Seabird Group 
Conference
www.segul.org.uk

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