Southern Ocean fisheries
Dr Andrew Constable - Southern Ecosystems Change Theme Leader
My name is Andrew Constable. I am a theme leader in the Australian Antarctic science program responsible for studying Southern Ocean ecosystems and that theme has a number of elements. The first element is to understand how southern ocean ecosystems are responding to climate change. The second thing is to look at how do we conserve whales, albatross and other species like that? And then a big responsibility is how do you manage fisheries in the Southern Ocean so as they remain ecologically sustainable?
One of the main parts of our work is to do field work in the Southern Ocean. That involves going to sea on ships for maybe up to three months at a time and what we try to do there is we are sampling the animals and plants in the ocean to better understand how they work with the ocean, what sort of impacts changes in the ocean might have and in particular what things might happen as a result of climate change.
The last thing that we do is we try to look at undertaking laboratory studies that help us better understand the exact mechanisms of impact. That is how we know about the effects of acidification on krill, for example. That was done here at the Australian Antarctic Division.
For example we know the Southern Ocean ecosystem is becoming more acidic which there are some animals at the bottom end of the food chain, they’re not doing so well. So krill, for example, their embryos don’t survive very well in a super acidic environment.
One of the big challenges is being able to do science at a sufficiently large scale, so operating ships or being able to sample in many different places that give us very good information that we can feed into our models and basically help management make the right decisions.
The more we are able to forecast what is going to happen in the future, the more that we can adjust our management practices and the more that we can make better decisions in advance and make sure that fisheries remain ecologically sustainable.
I’m never bored. It’s a fantastic place to work, the work is very challenging, one of the great things about this work is the people that I work with. It is those partnerships that matter. That’s what makes the science very enjoyable and we can overcome the challenges together. In the end it will be a community enterprise to overcome these challenges and to better understand what we have in the future.
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.
Our research feeds 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
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 research to ensure sustainable management of this fishery is urgent. There is no current fishery for krill off East Antarctica.
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 Australian Antarctic Territory) and at Macquarie Island (outside the CCAMLR Area).
Australian fishing vessels are the primary sampling platform for fisheries research in the Southern Ocean. Most research occurs during routine fishing operations, providing a cost-effective way to gather data on fisheries dynamics, the biological status of the fish populations, and 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
- 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 management of the fish stocks on the Kerguelen Plateau.
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.
Seabirds, non-target fish species and organisms living on the ocean floor (‘benthos’) are affected by fishing practices.
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
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 catch 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 with direct conservation outcomes. Better information on Antarctic and subantarctic marine biodiversity is required to underpin this bycatch research.