Svein Sundby, Geir Odd Johansen and Jan Erik Stiansen ESSAS Annual Science Meeting 30 August 1 September, 2010 Grand Hotel, Reykjavik, Iceland
Temperature of the Barents Sea 1978 2006 30 m depth Meeting place between arctic and boreal species 200 m depth
More than 200 species from 70 families have be en registered Boreal vs. arctic species Pelagic vs. benthic species Several of them have parts of their life cycle out side the Barents Sea 3 species have a more dominating role in the ecosystem
Cod Capelin (young) Herring Arcto-boreal Arctic Arcto-boreal
The diet of capelin
Themisto libellula Arctic Amphipodes - important prey species for capelin Themisto abyssorum Arctoboreal Dalpadado et al. (2001) IJMS
Gjøsæter et al. (2002) IJMS
The diet of young herring
Herring Capelin 1984 Overlap between capelin larvae and herring 1-year-old and older. Herring 1993 Capelin Gjøsæter and Bogstad (1998) Fisheries Research
Gjøsæter and Bogstad (1998) Fisheries Research
The diet of cod
Modeled Arcto-Norwegian 0-group cod (September 2008) Vikebø (2009)
Ambient water masses, temperature and main prey species of first-year Arcto-Norwegian cod C. finmarchicus T. inermis PELAGIC JUVENILES
PFI Partial stomach Fullness Index (PFI) for cod in the Barents Sea (January-April) 1984-1999 Length of cod (cm) Bogstad and Gjøsæter (2001) Fisheries Research
Dalpadado et al. (2001) IJMS
Barents Sea capelin Ushakov and Prozorkevich (2002) IJMS
Nakken (2008)
The diet of cod Larval and pelagic juvenile stages before settlement (< 9 cm): From C. finmarchicus to krill (boreal species). From 2-group fish (> 20 cm): Large diversity of prey: Capelin dominates in capelin-rich years Substituted by shrimp, krill and amphipodes in capelin-poor years From > 90 cm, the king : Larger fish.
Trophic level Cod Energy flow Top-down controls Herring Capelin Larval and pelagic juvenile Cod Larval and juvenile Herring Larval and juvenile Capelin Krill Amphipodes Boreal zooplankton Arctic zooplankton Boreal Ecosystem Characters Arctic
Climate change and changes in species distributions
Year-to -year variation Decadal variation Multidecadal variation Antropogenic? 5 o Temperature [ C] 4.5 4 3.5 3 2.5 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000
Cod and herring Capelin
Multidecadal climate oscillations and impacts on spawning areas of Arcto-Norwegian cod Warm periods - Displacement towards northeast - Increasing spawning biomass Cold periods: - Displacement towards southwest - Decreasing spawning biomass 5,0 4,5 4,0 3,5 3,0 2,5 1900 1920 1940 1960 1980 2000 Sundby and Nakken (2008) IJMS
Longitude (Cartesian x, unit: 25 km) Impacts of the recent warming on 0-group fish spatial distribution Centre of distribution (east) of 0-group cod, haddock, herring, and capelin Easterly shift in centre of distribution during the period 1980 2007 Magnitude of shift: Cod: 120 km Herring: 160 km Haddock: 90 km Capelin: 220 km 55 50 45 40 35 30 25 20 1980 1985 1990 1995 2000 2005 Johansen and Stiansen (2009) Unpubl.
70 N 70 N Centre of gravity >45 cm Centre of gravity, cod > 45 cm, N Ice cover - southern limit, N Southern limit of ice cover 75 N 75 N 10 E 30 E 50 E 1994 73.0 78 77 72.5 76 72.0 75 February 71.5 1980 1985 1990 1995 2000 2005 2010 74 30 E 50 E Year February Johansen and Stiansen (2009) Unpubl.
Some conclusions Spatial distribution and productivity of the boreal cod and herring are impacted by multidecadal climate variations. Too short time series for the arctic capelin to conclude, but indications of similar response with respect to spatial distribution and opposite response with respect to productivity. Adult cod benefit from high capelin events by increased growth (and egg production) - but cod have alternatives. Some examples of top-down controls: 1.High capelin events reduce the abundance of zooplankton prey. 2. High abundance of young herring reduces abundance of larval capelin and capelin recruitment. 3. From the Norwegian Sea: Emerging evidence of high abundance of herring graze down C. finmarchicus.
Future climate change in the Barents Sea Temperature climatology Temperature increase in 50 years C. finmarchicus to overwinter into the Arctic? Capelin spawning from Finmark to Novaja Semlya? 20C3M A1B - 20C3M