Antarctic toothfish

‎Fishery: The reference is not that definitive. The key phrase - from areas in the eastern Ross Sea contribute disproportionately to the spawning population, and areas in the southwestern Ross Sea may supply fisheries in the southern Indian Ocean.

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	== Fishery ==		== Fishery ==
−	A fishery for Antarctic toothfish, managed by the [[Convention for the Conservation of Antarctic Marine Living Resources]] (CCAMLR), has existed since 1996. The existence of this fishery in the Ross Sea, the area where most Antarctic toothfish are caught, is very contentious owing to the lack of accurate population parameters, such as original [[Fish stock|stock size]], fecundity, and recruitment. Moreover, the main fishing grounds cover the area through which the entire stock of Antarctic toothfish passes,<ref>Ashford, J.; Dinniman, M.; Brooks, C.; Andrews, A.H.; Hofmann, E.; Cailliet, G.; Jones, C.; and Ramanna, N. (2012). Does large-scale ocean circulation structure life history connectivity in Antarctic toothfish (''Dissostichus mawsoni'')? Can. J. Fish. Aquat. Sci. 69: doi:10.1139/f2012-111</ref> adding further challenge to management owing to the indiscriminate nature of benthic [[longline fishing]]. The bycatch of other fish can also be substantial, with the ratio to tonnes of toothfish caught ranging from 5–35%.<ref name="Ainley&Pauly">Ainley, D.G.; and Pauly, D. (2012) Fishing down the foodweb of the Antarctic shelf and slope. [[Polar Record]], in press.</ref> CCAMLR is allowing the original, hypothetical spawning [[Biomass (ecology)|biomass]] to be reduced by 50%, which is done by targeting the oldest, largest, and potentially most fecund fish in the stock. In just 15 years, the average age of fish has decreased about 10 years.<ref>Ainley, D.G.; Brooks, C.M.; Eastman, J.T.;, and Massaro, M. (2012). Unnatural selection of Antarctic Toothfish in the Ross Sea, Antarctica. F. Huettmann (ed.), Protection of the Three Poles, pp. 53-75. DOI 10.1007/978-4-431-54006-9_3, Springer, Tokyo.</ref>	+	A fishery for Antarctic toothfish, managed by the [[Convention for the Conservation of Antarctic Marine Living Resources]] (CCAMLR), has existed since 1996. The existence of this fishery in the Ross Sea, the area where most Antarctic toothfish are caught, is very contentious owing to the lack of accurate population parameters, such as original [[Fish stock|stock size]], fecundity, and recruitment. Moreover, the main fishing grounds cover the area through which the entire stock of Antarctic toothfish is presumed to pass,<ref>Ashford, J.; Dinniman, M.; Brooks, C.; Andrews, A.H.; Hofmann, E.; Cailliet, G.; Jones, C.; and Ramanna, N. (2012). Does large-scale ocean circulation structure life history connectivity in Antarctic toothfish (''Dissostichus mawsoni'')? Can. J. Fish. Aquat. Sci. 69: doi:10.1139/f2012-111</ref> adding further challenge to management owing to the indiscriminate nature of benthic [[longline fishing]]. The bycatch of other fish can also be substantial, with the ratio to tonnes of toothfish caught ranging from 5–35%.<ref name="Ainley&Pauly">Ainley, D.G.; and Pauly, D. (2012) Fishing down the foodweb of the Antarctic shelf and slope. [[Polar Record]], in press.</ref> CCAMLR is allowing the original, hypothetical spawning [[Biomass (ecology)|biomass]] to be reduced by 50%, which is done by targeting the oldest, largest, and potentially most fecund fish in the stock. In just 15 years, the average age of fish has decreased about 10 years.<ref>Ainley, D.G.; Brooks, C.M.; Eastman, J.T.;, and Massaro, M. (2012). Unnatural selection of Antarctic Toothfish in the Ross Sea, Antarctica. F. Huettmann (ed.), Protection of the Three Poles, pp. 53-75. DOI 10.1007/978-4-431-54006-9_3, Springer, Tokyo.</ref>
	Consistent with this apparent loss of large fish , an independent study was reported to have detected the disappearance of large fish at the southern periphery of its range in the McMurdo Sound area.<ref name="Ainley">Ainley, D.G.; Nur, N.; Eastman, J.T.; Ballard, G.; Parkinson, C.L.; Evans, C.W.; and DeVries, A.L. (2012). Decadal trends in abundance, size and condition of Antarctic toothfish in McMurdo Sound, Antarctica, 1972-2011. Fish & Fisheries, DOI: 10.1111/j.1467-2979.2012.00474.x.</ref>. However more recent work has shown this not to be the case <ref>Antarctic toothfish, lost - and found. http://ift.tt/1JHBfvT;. Other studies have shown that the prevalence of [[Killer whale#Taxonomy and evolution|fish-eating killer whales]] has been apparently decreasing in the southern Ross Sea, foraging efficiency of [[Weddell seal]]s is decreasing, and numbers of [[Adélie penguin]]s (competitors for silverfish) have been increasing.<ref name="Ainley" /><ref>Ainley, D.G.; Ballard, G. (2012) Trophic interactions and the decrease in Killer Whale (''Orcinus orca'') prevalence with reduced availability of large fish in the southern Ross Sea. Aquatic Mammals 38:153-160.</ref>. More recent studies have confirmed visual sightings of Weddell seals and Type-C killer whales holding and consuming large toothfish in the McMurdo Sound area and raise questions over the previously assumed importance of assumed dominance of Antarctic silverfish (Pleuragramma antarcticum) in the diet of Weddell seal and Type-C Killer whales <ref>Eisert R., M.H. Pinkerton, S.D. Newsome, O.T. Oftedal. (2013) A Critical Re-examination of the Evidence for a Possible Dependence of Weddell Seals (Leptonychotes weddellii) on Antarctic toothfish (Dissostichus mawsoni) in the Ross Sea, Antarctica. http://ift.tt/1KA2ddZ; <ref>Torres L., Matt H. Pinkerton, R. Pitman, J. Durban, Regina Eisert. (2013) To what extent do type C killer whales (Orcinus orca) feed on Antarctic toothfish (Dissostichus mawsoni) in the Ross Sea, Antarctica?</ref>. These trends indicate the problem of managing this fishery in the [[Ecosystem approach to fisheries|best interests of the ecosystem]] in the face of a paucity of life history information.		Consistent with this apparent loss of large fish , an independent study was reported to have detected the disappearance of large fish at the southern periphery of its range in the McMurdo Sound area.<ref name="Ainley">Ainley, D.G.; Nur, N.; Eastman, J.T.; Ballard, G.; Parkinson, C.L.; Evans, C.W.; and DeVries, A.L. (2012). Decadal trends in abundance, size and condition of Antarctic toothfish in McMurdo Sound, Antarctica, 1972-2011. Fish & Fisheries, DOI: 10.1111/j.1467-2979.2012.00474.x.</ref>. However more recent work has shown this not to be the case <ref>Antarctic toothfish, lost - and found. http://ift.tt/1JHBfvT;. Other studies have shown that the prevalence of [[Killer whale#Taxonomy and evolution|fish-eating killer whales]] has been apparently decreasing in the southern Ross Sea, foraging efficiency of [[Weddell seal]]s is decreasing, and numbers of [[Adélie penguin]]s (competitors for silverfish) have been increasing.<ref name="Ainley" /><ref>Ainley, D.G.; Ballard, G. (2012) Trophic interactions and the decrease in Killer Whale (''Orcinus orca'') prevalence with reduced availability of large fish in the southern Ross Sea. Aquatic Mammals 38:153-160.</ref>. More recent studies have confirmed visual sightings of Weddell seals and Type-C killer whales holding and consuming large toothfish in the McMurdo Sound area and raise questions over the previously assumed importance of assumed dominance of Antarctic silverfish (Pleuragramma antarcticum) in the diet of Weddell seal and Type-C Killer whales <ref>Eisert R., M.H. Pinkerton, S.D. Newsome, O.T. Oftedal. (2013) A Critical Re-examination of the Evidence for a Possible Dependence of Weddell Seals (Leptonychotes weddellii) on Antarctic toothfish (Dissostichus mawsoni) in the Ross Sea, Antarctica. http://ift.tt/1KA2ddZ; <ref>Torres L., Matt H. Pinkerton, R. Pitman, J. Durban, Regina Eisert. (2013) To what extent do type C killer whales (Orcinus orca) feed on Antarctic toothfish (Dissostichus mawsoni) in the Ross Sea, Antarctica?</ref>. These trends indicate the problem of managing this fishery in the [[Ecosystem approach to fisheries|best interests of the ecosystem]] in the face of a paucity of life history information.

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