Overfishing aff inherency
Fishing hurts marine mammal populations
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- Fishing practices are the primary threat to marine mammal populations
MammalsFishing hurts marine mammal populationsGales et al 2003 (Nick, Mark Hindell, Roger Kirkwood, “Marine Mammals : Fisheries, Tourism and Management Issues”, Collingwood, Vic : Eurospan. 2003, EBSCO) The situation described by Oppian represents but one of several potential conflicts between marine mammals and fisheries. For convenience, these conflicts are usually divided into two categories: operational conflicts and ecological conflicts (Anonymous 198 la; bvignc 1982; Ferd 2002; see Table 3). Operational conflicts involve physical encounters between marine mammals and fishing gear, broadly defined. They arise, for example, when marine mammals damage fishing gear or aquaculture facilities, and when the damage fish caught in the gear or cause the fish to escape (either from fishing gear or from aquaculture facilities). resulting ultimately in economic losses to commercial enterprises They also arise when marine mammals are taken incidentally in commercial fisheries resulting in their injury or death (X’oodley and Lavigne 1993; Perrin # al 1994) or become entangled in discarded fishing gear. including ‘ghost’ nets (Gui land 1986; Laist ‘tal 1999). Those conflicts that are perceived to damage fisheries or aquaculture facilities typically result in calls for culling the marine mammal population(s) involved (Table 3). Those that potentially harm marine mammals do not, and will not he discussed further in this chapter. Ecological conflicts include those that arise because of predation by marine mammals on commercially important fish stocks or their prey. While attention has tended to focus on the potential defects of marine mammals on commercial fisheries (Fcrtl 2002), there is another side to this coin: the potential effects of commercial fisheries on marine mammals, particularly endangered species (Northridge 2002). Such suspected interactions have been a source of conflict. for example, in the case of the endangered Steller sea lion, Eumetopias jubatus. in western Alaska (National Research Council 1996; National Marine Fisheries Service 2000); and of the Hawaiian monk seal, M. schauinclondi. in the North-western Hawaiian Island chain (Lavigne 1999; US District Court 2000). In both cases, concern has been expressed that commercial fisheries are contributing to the decline, or pre venting the recovery, of depleted marine mammal populations. [šur once again, the latter conflicts do not result in calls for culling marine mammals, so they will not be discussed further here. The effects of ecological conflicts involving predation (or competition) may be either ‘direct’ (e.g. marine mammals eat commercially important fish stocks, or a commercial fishery’ reduces the availability of an important marine mammal prey species) or ‘indirect’ (e.g. marine mammals eat the prey of commercially important fish stocks or commercial fisheries reduce the availability of food for marine mammal prey). Fishing practices are the primary threat to marine mammal populationsPolidoro et al 2011 (Beth A., UCN Species Programme/Conservation International Global Marine Species Assessment, Biological Sciences, Old Dominion University, Norfolk, Cristiane T. Elfes, IUCN Species Programme/Conservation International, Biodiversity Assessment Unit, Jonnell C. Sanciangco, UCN Species Programme/Conservation International Global Marine Species Assessment, Biological Sciences, Old Dominion University, Helen Pippard, IUCN Regional Office for Oceania, Kent E. Carpenter, IUCN Species Programme/Conservation International Global Marine Species Assessment, Biological Sciences, Old Dominion University, “Conservation Status ofMarine Biodiversity in Oceania: An Analysis of Marine Species on the IUCN Red List of Threatened Species.”, Journal of Marine Biology. 2011, Vol. 2011, p1-14. 14p. 1 Chart, 4 Maps, p 6-7, EBSCO) Almost one-fifth of marine mammals present in Oceania are in threatened categories, and over 50% (19 of 36 species) of marine mammals in Oceania are listed as Data Deficient, again because threats to many of these pelagic and/or highly migratory species cannot be adequately quantified 1281. No marine mammals are known to be endemic to Oceania, and major threats to these species are global or historic. The primary threats to marine mammals in Oceania and around the globe are accidental mortality through entanglement in fishing gear, the effects of noise pollution from military and seismic sonar, or boat strikes 128, 511. In many regions, including Oceania. manne mammals are also threatened by habitat loss from coastal development, loss of prey or other food sources due to poor fisheries management, and historical or current effects of hunting [34). Hunting of large whales does not occur in the region, and countries including Cook Islands, Fiji, French Polynesia, Samoa and Niue have declared whale sanctuaries (521. However. several Pacific Island countries have recently joined the International Whaling Commission and voted with Japan in favor of commercial whaling. Dolphin hunts have occurred traditionally throughout Oceania, and still remain in the Solomon Islands where they are thought to be contributing to population declines [53, 54]. Dugongs, Dugong dugon, are also traditionally hunted in many areas for their meat, bones, and skin [55, 56]. Although there are no estimates of the numbers of dugong caught, the species is likely very vulnerable to hunting and other human impacts due to its restricted coastal habitat, dependence on sea grasses, and low reproductive rates [571. The most threatened marine mammal in Oceania is the Hawaiian monk seal, Monachus schauinslandi, listed as Critically Endangered. Mortality rates from birth to maturity of monk seals in the northwestern Hawaiian Islands are very high, and disproportionally impact juveniles. Causes of mortality are thought to include food limitation, predation on suckling and recently weaned pups. and entanglement in marine debris. There are currently less than 600 mature individuals of this species, and declines are expected to continue into the near future despite the species being primarily found within the Northwestern Hawaiian Islands National Marine Monument [581. 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