Southern Ocean fisheries

A Patagonian toothfish on the electronic measuring board Photo: AFMA

Southern Ocean fisheries research underpins the management of the Antarctic krill fishery and Antarctic and subantarctic fisheries on icefish and toothfish. Research also includes the development of ecosystem-based fishery management procedures and methods for reducing bycatch. 

Research in this stream will feed into Australia’s domestic fisheries forums and into the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR). Fishing in the Southern Ocean is managed by CCAMLR and ongoing scientific research is necessary to ensure that CCAMLR can achieve its three principles of conservation: 

• preventing a decrease in the size of any harvested population to unsustainable levels
• maintaining the ecological relationships between harvested, dependent and related populations and restoring depleted populations
• preventing changes or minimising of the risk of changes in the marine ecosystem which are not potentially reversible over two or three decades. 

The research is divided into two key areas:

• Krill and fish stocks
• Bycatch

Stream Leader: Dr Dirk Welsford

Stream Implementation Plan: Stream 3.3 Southern Ocean fisheries

Krill and fish stocks

Antarctic krill (Euphausia superba). Photo: Steve Nicol

The Antarctic krill fishery currently catches around 150 000 tonnes a year, yet the precautionary catch limits total some 6.5 million tonnes a year. This is the only fishery in the world that has such potential for massive expansion. There are signs that this expansion is underway, so the task of conducting the research to ensuring sustainable management of this fishery is urgent. There is no current fishery for krill off East Antarctica and the catch limits off the Australian Antarctic Territory (AAT) total three million tonnes. Re-commencement of a krill fishery off the AAT would require data collection and research to ensure that it remained within sustainable limits.

There are active fisheries targeting toothfish and icefish at Heard Island and Macdonald Islands (HIMI), on the Kerguelen Plateau, on the continental shelf and slope of East Antarctica (off the AAT) and at Macquarie Island (outside the CCAMLR Area). Australian fishing vessels, which caught around 2500 tonnes of fish in the Southern Ocean in 2008, are the primary sampling platform for fisheries research in the Southern Ocean. Much of this research occurs during routine fishing operations, which is a cost-effective way of gathering data on fisheries dynamics, on the biological status of the fish populations and on the ecological effects of fishing. Fishing vessels can also serve as ‘ships of opportunity’ for the deployment of instruments in the region, and underway data collection.

Our research will:

• provide revised catch limits for the krill fishery off the Australian Antarctic Territory (AAT )
• design a feedback management regime for the Antarctic krill fishery
• provide regular assessments of the status of fish stocks in the Australian Exclusive Economic Zone (EEZ) off HIMI
• incorporate regional-scale stock assessments into integrated management of the fish stocks on the Kerguelen Plateau.

Toothfish and icefish fisheries around Heard Island (pictured) are managed by CCAMLR. Photo: Gary Miller

The key research questions being investigated are: 

• What are the appropriate ecologically sustainable catch limits for krill and fish in the AAT and HIMI?
• Can estimates of krill biomass be significantly improved by revising estimates of key biological parameters (such as biomass estimates, growth, mortality and recruitment)? 
• What is the stock structure of harvested species and the degree of interchange between regional populations?
• What are the potential effects of habitat change brought about by climate change and ocean acidification on the capacity of the krill and fish stocks to sustain current and projected harvesting levels? 
• Can a modelling framework be developed to evaluate the impact and sustainable harvest levels of fishing in the Southern Ocean? 

CCAMLR-focussed research will concentrate on the species being commercially fished (krill, icefish and toothfish) and on ecosystems and species that are potentially vulnerable to the effects of fishing, or which have been selected by CCAMLR as indicator species. A monitoring program will provide useful feedback to CCAMLR on the effects of fishing on indicator species. The data from this will be used in ecosystem models to evaluate management procedures.

The research feeds into:

•   Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR)
•   Australian Fisheries Management Authority (AFMA)

 

Bycatch

Seabirds, non-target fish species and organisms living on the ocean floor (‘benthos’) are affected by fishing practices.

Seabird bycatch

Albatross caught on long line Photo: Graham Robertson

Several species of Southern Ocean seabirds have been severely depleted through their incidental mortality in longline fishing. CCAMLR manages Southern Ocean fisheries with the aim of reducing or eliminating seabird bycatch in the Southern Ocean, and the Agreement on the Conservation of Albatrosses and Petrels (ACAP) aims to achieve a favourable conservation status for the 29 species of albatrosses and petrels listed in the agreement.

Because these seabird species are highly migratory, conservation activities must focus within and outside the CCAMLR Area. These activities include:

• monitoring breeding populations and related demographic research
• eliminating introduced species (such as rats and mice) at breeding sites
• tracking studies to determine the overlap between the species’ foraging range and longline fisheries
• bycatch mitigation research.

Research conducted in collaboration with fishing industries  is providing effective solutions to the problem of seabird bycatch in fisheries. Our research projects aim to determine the effectiveness of avoidance measures, including new technologies, in reducing the mortality of seabirds that interact with fisheries. These projects save the lives of thousands of seabirds annually.

Fish and invertebrate bycatch

Sea floor communities are vulnerable to fishing gear. Photo: Andrew Tabor

Benthic (sea floor) trawls, and demersal longlines, may cause significant damage to the seafloor communities and can harvest high quantities of bycatch. Pelagic (above the sea floor) trawls can yield significant bycatch of vulnerable early life history stages of fish and other invertebrates, and there can be significant mortality of the target species that does not result in their harvest. All of these effects could lead to failure to meet CCAMLR’s conservation principles.

Incidental effects of fishing have been internationally highlighted as an area where quality scientific observations can result in changes in fishing practices and/or spatial management measures which can have direct conservation outcomes. Better information on Antarctic and subantarctic marine biodiversity is required to underpin this bycatch research

Our key research questions are:

• How effective are the seabird mitigation devices used by fishing vessels in the areas where seabirds are most vulnerable?
• What are the benthic ecosystem effects of different fishing techniques relative to their fishing efficiency in Antarctic waters?
• What are the effects of bycatch removals on the populations of vulnerable benthic species?

The research feeds into:

• Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR)
• Agreement on the Conservation of Albatrosses and Petrels (ACAP)
• Australian Fisheries Management Authority (AFMA)