Gillnetting yields one of the highest portions of total fisheries catch worldwide and is a prevalent fishing method among the thousands of small-scale and localized fisheries in developing countries; where the annual catch can exceed that of the larger-scale industrialized commercial sector. Bycatch in gillnets often results in high collateral mortality of non-target marine species and is a major threat to many endangered marine mammals. For species such as the Gulf of California porpoise (or vaquita, Phocoena sinus), it is the most immediate threat to species recovery, or indeed continued existence.

This Theme Section of ESR features papers that evaluate various techniques for reducing marine mammal bycatch in gillnets, including acoustic deterrents, non-acoustic gear deterrents (such as modifications to gillnet material), time-area closures, and gear switching (for example, from gillnets to hook-and-line). It assembles papers presented at the International Marine Mammal-Gillnet Bycatch Mitigation Workshop, convened in October of 2011 (see http://bycatch.org/marine_mammal_gillnet_bycatch).

Editorial Team for the Theme Section: Dr. Simon Northridge, University of St. Andrews (Guest Editor); Dr. William Perrin, NOAA (Guest Editor); Dr. Andy Read, Duke University; Dr. Randall Reeves, Okapi Associates (Guest Editor); Tim Werner, New England Aquarium (Guest and Contact Editor; twerner(at)neaq.org)

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Kindt-Larsen L, Dalskov J, Stage B, Larsen F

Observing incidental harbour porpoise Phocoena phocoena bycatch by remote electronic monitoring

ESR 19:75-83 | Full text in pdf format

Niemi M, Auttila M, Viljanen M, Kunnasranta M

Movement data and their application for assessing the current distribution and conservation needs of the endangered Saimaa ringed seal

ESR 19:99-108 | Full text in pdf format

Erbe C, McPherson C

Acoustic characterisation of bycatch mitigation pingers on shark control nets in Queensland, Australia

ESR 19:109-121 | Full text in pdf format

Dawson SM, Northridge S, Waples D, Read AJ

REVIEW: To ping or not to ping: the use of active acoustic devices in mitigating interactions between small cetaceans and gillnet fisheries

ESR 19:201-221 | Full text in pdf format

Reeves RR, McClellan K, Werner TB

REVIEW: Marine mammal bycatch in gillnet and other entangling net fisheries, 1990 to 2011

ESR 20:71-97 | Full text in pdf format

Slooten E

REVIEW: Effectiveness of area-based management in reducing bycatch of the New Zealand dolphin

ESR 20:121-130 | Full text in pdf format

Larsen F, Krog C, Ritzau Eigaard O

Determining optimal pinger spacing for harbour porpoise bycatch mitigation

ESR 20:147-152 | Full text in pdf format

Read AJ

REVIEW: Development of conservation strategies to mitigate the bycatch of harbor porpoises in the Gulf of Maine

ESR 20:235-250 | Full text in pdf format

Orphanides CD, Palka DL

REVIEW: Analysis of harbor porpoise gillnet bycatch, compliance, and enforcement trends in the US northwestern Atlantic, January 1999 to May 2010

ESR 20:251-270 | Full text in pdf format

Berg Soto A, Cagnazzi D, Everingham Y, Parra GJ, Noad M, Marsh H

Acoustic alarms elicit only subtle responses in the behaviour of tropical coastal dolphins in Queensland, Australia

ESR 20:271-282 | Full text in pdf format

Bordino P, Mackay AI, Werner TB, Northridge SP, Read AJ

Franciscana bycatch is not reduced by acoustically reflective or physically stiffened gillnets

ESR 21:1-12 | Full text in pdf format

Rojas-Bracho L, Reeves RR

Vaquitas and gillnets: Mexico’s ultimate cetacean conservation challenge

ESR 21:77-87 | Full text in pdf format