1. Krill, Climate, and Contrasting Future Scenarios for Arctic and Antarctic Fisheries Margaret McBride, Padmini Dalpadado, Ken Drinkwater, Alistair Hobday, Trond Kristiansen, Eugene Murphy, Sam Subbey, Anne Hollowed, Eileen Hofmann, and Harald Loeng 2013 ICES Annual Science Conference 23 – 27 September

2. Arctic & Antarctic Systems –Fundamental differences –Response to climate forcing  Food webs and fishery productivity –Fisheries Past & Present –Future prospects  Fishery resource productivity –Considerations for Management

3. Fundamental Differences The Arctic is a frozen ocean surrounded by continents. Antarctica is a frozen continent surrounded by oceanic waters

4. Circulation & Inflow Arctic Antarctic

5. Primary Production Primary production in both Regions is strongly seasonal & controlled largely by light. Specialized communities of ice-endemic organisms contribute largely to primary production in the Arctic. In Antarctica, iron is in short supply & represents a limiting factor on the total amount of primary production. In contrast, there is sufficient iron in the Arctic, but nutrients may be limited.

6. Secondary Production Zooplankton link primary producers and higher trophic levels Copepods typically predominate throughout the Arctic Most marine species in the Southern Ocean feed on krill – including fish, whales, seals, penguins, albatrosses, petrels, squid & many others

7. Arctic Marine Food Web

9. Endemism and K-Selection Currently, few existing species are endemic to the Arctic, and new species are moving in. In the Southern Ocean endemic species predominate. More K-Selected species occur in the Antarctic

10. Temporal variation in the biomass of mesozooplankton, krill, and shrimp in the Barents Sea JOHANNESEN ET AL. 2012

11. Euphausia superba. (A) Change in mean density of post-larval krill (ind. m−2) within the SW Atlantic sector (30 to 70° W) between 1976 and 2003 (modified from Atkinson et al. 2008; © Inter-Research 2008). (B) Reported krill catches (MT) in FAO Statistical Area 48, 1973 to 2011 (CCAMLR 2010, 2011b). Flores et al. 2012

12. Circumpolar Arctic Fisheries Target Species Capelin ( Mallotus villosus ) Greenland halibut ( Reinhardtius hippoglossoides ) Northern shrimp ( Pandalus borealis ) & Polar cod ( Boreogadus saida )

13. Southern Ocean Fisheries 4 main target species: – Antatctic Krill ( Euphausia superba) – Antarctic toothfish ( Dissostichus mawsoni) – Patagonian toothfish – (D. eleginoides) & – Mackerel icefish (Champsocephalus gunnari)

14. Vanishing Sea Ice In the future, waters in both the Arctic & Antarctic are expected to become warmer with further reductions in the extent of sea ice cover and thickness

15. Can Copepods Cope? What’s ill with Krill? ≈354 Species Zooplankton Calanus are less ice dependent Differing copepods have different / distinct life histories and strategies Different timing and dependence on food for reproduction could have a positive affect at higher trophic-level C. glacialis & C. finmarchicus are hybridizing. This may contribute to increased local productivity Southern Ocean ≈85 Species (Under investigation) Krill larvae are ice dependent Krill larvae have limited physiological flexibility Success of krill recruitment will depend on availability of suitable spawning grounds and transport of larvae into favorable feeding grounds Adaptive capacity of krill will be increasingly challenged with changes in the physical environment, changes in the food web, and new competitors Arctic

16. High Potential to Move into the Arctic Snow crab (Chionectes opilio) Bering flounder (Hippoglossoides elassodon Greenland shark – (Somniosus microcephalus) Arctic skate (Amblyraja hyperborea) & Beaked redfish (Sebastes mentella) (Hollowed et al. Submitted)

17. Mixed Potential to Move into the Southern Ocean King crabs (Lithodids) (Paralomis birsteini) (Neolithodes yaldwyni) Durophagous (shell-crushing) sharks

18. Modeling Studies Difficult to simulate & project long-term changes based on forces that have been measured/monitored over relatively short time spans. Current climate models do not include scenarios for ocean temperatures, watermass mixing, upwelling, or other relevant ocean variables such as primary and secondary production, on either a global or regional basis. As fisheries often depend on such variables, any predictions concerning fisheries in a changing climate can only be of a very tentative nature. (Vilhjálmsson and Hoel 2007)

19. Mangement Considerations Marine ecosystems in both Arctic and Antarctic regions should be regarded as stressed ecosystems and managed as such. Recognize the vulnerabilities of individual species to fisheries exploitation based on its ecology, life strategy, other pressures that affect it, and the resilience/elasticity within each system. There are important lessons to be learned from the Southern Ocean fishing history — K-selected fish species overfished during the 1970s still have not recovered, and some are still declining. Oil & Gas and Shipping activities in the Arctic carry with them the risks of contaminated waters & invasive species. Illegal, unreported, and unregulated fishing is an imminent threat.

20. Summary Arctic and Antarctic marine systems have in common polar positions and cold temperatures; otherwise they are strikingly different. Systems within these regions are responding differently to the effects of climate change, and all areas within each of these regions are responding to climate forcing in the same manner. Zooplankton species in both regions, form the critical link between primary production and upper trophic level production; and are exposed to many of the same threats. Differences in community structure, life strategies, and adaptive response to climate forcing for key zooplankton species is likely to be a key factor determining future fisheries scenarios in both regions.

21. Thank You for Your Attention! margaret.mcbride@imr.no