CONSERVATION IN ACTION : Targeted Species for CCAMLR Actions

Antarctic Krill – Euphausia superba

Antarctic krill is a 5-6 centimetre long shrimp-like crustacean that is at the hub of much of the Antarctic food web.  Krill is important to predator species such as whales, Antarctic fur seals, and finfish. The krill fishery has been the largest fishery in the CCAMLR Area since the late 1970s.  Over-exploitation of this fishery would have wide-ranging effects on the ecosystem’s dynamics.  CCAMLR established an Ecosystem Monitoring Programme (CEMP) with the main aims of: a) detecting significant changes in critical components of the ecosystem; and b) distinguishing between changes due to harvesting and those due to environmental variability in order to investigate those ecosystem dynamics.

Of the main concerns relating to the management of the krill fishery, CCAMLR would appear to have succeeded in developing an agreed model, using precautionary approaches, and incorporating discount factors for the needs of dependent species, in its basic area-wide management procedures.  However, it has so far failed to develop appropriate ways of managing the fishery at the scales and places most relevant to dependent species, nor has it devised ways of incorporating data from dependent species into its krill management.  Much of the credibility of CCAMLR rests on its ability to manage krill stocks, especially in relation to likely future fishery expansion.  This makes it exceptionally important to negotiate now the appropriate decision rules and reference points before any new expansion takes place, as well as to acquire economic data to enable independent forecasting of fishery growth.

Icefish – Champsocephalus gunnari

Icefish are a midwater epipelagic species confined to continental shelves.  Many Antarctic species eat icefish but none seem to totally depend on it.  It has been subject to massive pulses of fishing using midwater trawls after which the stock has collapsed, recovered, collapsed again through over-fishing and latterly (last decade) has failed to recover.  The availability of krill may also be a contributing factor.  Species with relatively restricted foraging ranges may subsist on icefish when krill is unavailable, reducing their numbers.  Another possible influence relates to the role of Antarctic fur seals as predators.  Although icefish are only a very small part of their diet (perhaps less than 1% by mass), the consumption, particularly by male fur seals, of larger numbers of pre-recruiting icefish may have an effect both on recruitment and subsequent productivity.

CCAMLR’s experience with the icefish fishery highlights two fundamental issues: 

1. The need to understand tropho-dynamic relationships, where dependent species may switch to alternative prey in years where the biomass of their principal prey is unusually low, whether due to natural or anthropogenic causes; 

2. The need to identify management measures where a dependent species may also be harvested, such as with icefish which feed upon Antarctic krill.

Patagonia Toothfish – Dissostichus eleginoides

Patagonia toothfish are large demersal fish that can live up to 50 years.  Because of the long life span, these fish do not reach reproductive age until they are 6-9 years old.  Toothfish, typically prey for high level predators, can frequently be found in fish markets around the world; in Japan they are known as mero, and in the USA they are known as Chilean sea bass.  Because of its popularity, this species is commercially fished around most of the subantarctic islands, however, due to the long life-spans and slow growth, rapid expansion of this fishery is cause for major concern.  Although CCAMLR has developed two approaches to toothfish management: a model to estimate recruitment and regulations restricting the development of new fisheries, management has been severely compromised by difficulties relating to bycatch and incidental mortality of non-target species and by high levels of illegal, unregulated and unreported (IUU) fishing.