Antarctic Toothfish (Dissostichus mawsoni)

Mohamed bin Zayed Species project number 182519694

Improving the knowledge of the Antarctic toothfish life cycle to foster its conservation in a proposed marine protected area.

In recent years, polar regions have seen an increasing interest in their marine living resources as other traditionally fished species become scarce due to overfishing. This has occurred in parallel with easier and safer access to the polar regions as a consequence of climate change and the retreat of sea ice. In Antarctica, despite the establishment of the largest known Marine Protected Area (MPA) in the Ross Sea, commercial exploitation of marine living resources such as the Antarctic toothfish and krill continues (e.g. Nyman 2018, https://doi.org/10.1016/j.ocecoaman.2016.11.006).

A more recent proposal for a MPA in the Weddell Sea (Atlantic sector of the Southern Ocean), submitted for the first time in 2016 by Germany and the EU, still awaits the adoption by CCAMLR (Commission for the Conservation of Antarctic Marine Living Resources). The Weddell Sea is home to many different marine habitats, ecosystems and species. Thanks to the particular oceanography (the clock-wise Weddell Sea Gyre), the Weddell Sea region could be more resilient to the effects of climate change, making it an ideal refuge for cold-adapted Antarctic species (WG-EMM-16/01, CCAMLR Scientific background document in support of the development of a CCAMLR MPA in the Weddell Sea 2016, https://www.ccamlr.org/en/wg-emm-16).

 

Adult Antarctic toothfish (Dissostichus mawsoni) can reach over 2 m in length and can weigh more than 50 kilograms, which makes them the largest fish species in the Southern Ocean. In the last 25 years an economically viable fishery has been established under CCAMLR and the species is also increasingly targeted by illegal, unregulated and unreported (IUU) fishing operations. In many areas around Antarctica, the conservation status of Antarctic toothfish is unknown. The quotas of the fishery are based on biomass estimates that lack specificity because data collection is hampered by the harsh environment, which allows access to fishing grounds only in the Austral summer months. Taking into account that this fish is highly economically valuable and therefore sought after by commercial fishers (both legal and illegal), and that it has a slow growth rate and late maturity, making it particularly vulnerable to overfishing (Nyman 2018, https://doi.org/10.1016/j.ocecoaman.2016.11.006), the scientific community has raised concern about the fate of this species (e.g. http://science.sciencemag.org/content/330/6009/1316). This led to a call for a fishing ban in the Southern Ocean until further scientific studies can be conducted.

 

The toothfish is also a key species in the Antarctic marine ecosystems and food webs, both as prey and top predator of the deeper waters of the continental slope around Antarctica. The decline of some populations in recent years has coincided with a decrease in sightings of toothfish-eating killer whales and a demographic expansion of its trophic competitors (Lyver et al. 2014, https://doi.org/10.1371/journal.pone.0091188; Ainley et al. 2012, https://doi.org/10.1578/AM.38.2.2012.153).

With this project, we aim to collect and analyse life history traits and population genetic data to assess the toothfish conservation status in the light of fishing pressure and environmental parameters. In particular, we will focus on collecting parameters such as morphology, age, size and fecundity of all life stages to detect demographic and fecundity changes potentially caused by harvesting. We will also analyse the population genetic structure of the toothfish using samples from the Weddell Sea, the Antarctic Peninsula and the Ross Sea. In the course of the project, we will train a young research collaborator in the scientific techniques applied in the project and try to expand our international network of collaborations for a more effective development and implementation of the project. The possible presence of local populations of toothfish with different diet, life history traits and genetic variability in each of the different geographic target areas of this study would further boost the urgency for protection. Antarctic toothfish could become a flag species by promoting conservation of its whole ecosystem in areas of Antarctica not yet managed as MPAs, and help preventing further attempts to open more fisheries for this species in the Southern Ocean without proper background information.

 

Besides the scientists at the Biology Department of the University of Padova, our international team includes:

 

Magnus Lucassen (Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany);

Mario La Mesa (Institute of Marine Sciences – National Research Council – ISMAR-CNR, Ancona, Italy);

Emilio Riginella (Zoological Station Anton Dohrn, Naples, Italy);

Henrik Christiansen (Laboratory of Biodiversity and Evolutionary Genomics, Ku Leuven, Leuven, Belgium);

Santiago Ceballos (Centro Austral de Investigaciones Científicas – CADIC-CONICET, Ushuaia, Argentina).