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

Abstract

Since the 1970s the role of fishery bycatch as a factor reducing, or limiting the recovery of, marine mammal populations has been increasingly recognized. The proceedings of a 1990 International Whaling Commission symposium and workshop summarized fishery and bycatch data by region, fishery, and species, and estimated the significance of the 'impacts' of bycatch in passive gear on all cetacean species and subspecies or geographically defined populations. A global review of pinniped bycatch in 1991 concluded that incidental mortality in passive gear had contributed to declines of several species and populations. Here we update the information on cetacean gillnet bycatch, assess bycatch data on marine mammals other than cetaceans (i.e. pinnipeds, sirenians, and 2 otter species), determine where important data gaps exist, and identify species and populations known or likely to be at high risk from bycatch in gillnets. We found that at least 75% of odontocete species, 64% of mysticetes, 66% of pinnipeds, and all sirenians and marine mustelids have been recorded as gillnet bycatch over the past 20-plus years. Cetacean bycatch information in some areas has improved, facilitating our ability to identify species and populations at high risk, although major gaps remain. Understanding of the scale of pinniped and sirenian bycatch has also improved, but this bycatch remains poorly documented, especially at the population level. This study reveals how little is known about marine mammal bycatch in gillnets in much of the world. Even as other significant threats to marine mammals have become better documented and understood, bycatch remains a critical issue demanding urgent attention if there is to be any hope of preventing further losses of marine mammal diversity and abundance, and of protecting, or restoring, ecological health.

Disentangling the causes of protected‐species bycatch in gillnet fisheries

“…The surge of research interest seen during that period may now be beginning to slow, though the issue of bycatch remains of key importance to the conservation of many marine species Žydelis et al 2009;Gilman et al 2010;Reeves et al 2013) .…”

“…The incidental capture or bycatch of non-commercial species in fishing gear is widely recognized as an important threat to the conservation status of many animal populations Žydelis et al 2009Gilman et al 2010;Reeves et al 2013). Air breathing taxa including birds, turtles and marine mammals are particularly vulnerable because of their requirement to surface at regular intervals.…”

Rebuttal to published article “A review of ghost gear entanglement amongst marine mammals, reptiles and elasmobranchs” by M. Stelfox, J. Hudgins, and M. Sweet

“…Entanglement is a significant conservation and welfare issue which is limiting the recovery of a number of marine species, including marine mammals (e.g., Reeves et al, 2013;Rojas-Bracho and Reeves, 2013;van der Hoop et al, 2013). It is therefore important to reliably identify the causes of these events, including the nature of the entangling gear, in order to reduce or prevent them in the future.…”

Modeling habitat and bycatch risk for dugongs in Sabah, Malaysia

“…The unintentional catch of non-target marine mammals in fishing gear, termed bycatch (Reeves et al 2013), is a global problem. While commercial and industrial fisheries bycatch has been the target of many conservation efforts, small-scale fisheries bycatch is, based on available data, substantial and more difficult to regulate (Moore et al 2010).…”