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Mette Skern-Mauritzen, Per Fauchald, Edda Johannesen, Ulf Lindstrøm SEAPOP, Tromsø, April 2011 NORWEGIAN INSTITUTE FOR NATURE RESEARCH August – september , 2003 – 2010 Synoptic, spatial data on: • Zooplankton • 0-group fish • Pelagic fish • Cod (also diet) • Seabirds • Marine mammals The joint Russian – Norwegian Ecosystem survey August – September, 2003 - 2010 Capelin – fluctuating key species Repeated stock collapses Adverse effects on top predators Collapse in 2003 – no effects? Capelin biomass, age 1+, acoustic survey 8 7 Million tonnes 6 Ecosystem survey 5 4 3 2 1 0 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 Year The joint Russian – Norwegian Ecosystem survey August – September, 2003 - 2010 Capelin – fluctuating key species Key questions: • How was the spatial structure of the pelagic community during the capelin poor years 2003-2007 • What are the implications for trophic interactions • How do top predators respond to the return of the capelin? Average distributions, the capelin poor years 2003 – 2007 Lower and mid trophic levels Blue whiting Herring Capelin Polar cod Pelagic fish: Geographically segregated 0-Cod 0-Herring Southern prey community Fish Northern prey community Zooplankton and fish 0-Capelin 0-Polar cod Amphipods Krill O-group fish: Geographically segregated Zooplankton: depleted in south and central BS predation Top predators Cod age2 Cod imm Cod maturing Cod mature Cod: Polar front and northwards Whiteb. dolphin Fin whale Minke whale Humpback whale Atl. puffin Com. guillemot Brün. guillemot Little auk Kittiwake Baleen whales: Limited and overlapping distributions Diving seabirds: Geographically segregated N. fulmar Surface feeding seabirds: Extensive distributions, overlapping Average distributions, the capelin poor years 2003 – 2007 TOP PREDATORS South North 0.5 1.0 Top predators vest L. auk Minke wh. 0.0 Fin wh. C. Guillem. T50 Kittiwake -0.5 Puffin Humpb. wh. Fulmar Cod50.75 Br. guillem. White-b. dolph. -1.0 c(0, 0) Depth Cod75 Cod20.50 Cod20 -1.0 -0.5 0.0 c(0, 0) 0.5 1.0 Principal component analyses of averaged distributions Top predators – a wide variety of spatial niches Average distributions, the capelin poor years 2003 – 2007 0.0 -0.5 SEABIRDS vs PREY South North Polar cod L. auk Blue whit. C. Guillem. Herring Amphipods 0-Polar cod Krill Fulmar Kittiwake 0-Haddock 0-Herring Puffin 0-Cod Br. guillem. Capelin 0-Capelin -1.0 -0.5 0.0 c(0, 0) 0.5 Principal component analyses of averaged distributions Top predators – a wide variety of spatial niches Northern top predators, associated with krill, amphipods, polar cod, many north of the capelin Southern top predators, associated with herring, 0-group fish -1.0 c(0, 0) 0.5 1.0 Bird prey vest 1.0 Average distributions, the capelin poor years 2003 – 2007 0.5 1.0 Whale prey vest SEABIRDS WHALES vs PREY South North Polar cod Blue whit. 0.0 -0.5 Herring Amphipods 0-Polar cod Humpb. wh. Krill 0-Haddock 0-Herring 0-Cod White-b. dolph. Capelin 0-Capelin -1.0 -0.5 0.0 c(0, 0) 0.5 Top predators – a wide variety of spatial niches Northern top predators, associated with krill, amphipods, polar cod, many north of the capelin Southern top predators, associated with herring, 0-group fish -1.0 c(0, 0) Minke wh. Fin wh. Principal component analyses of averaged distributions 1.0 • Northern community of generalist top predators: • Brünnichs guillemots, cod, baleen whales • Associated with zooplankton and pelagic fish: • Krill, amphipods and polar cod important alternative prey in capelin poor years • Southern community of piscivorous top predators: • Common guillemots, puffins, white-beaked dolphins • Associated with herring and 0-group fish • Cod: Dietary responses and energy consumed • Seabirds and baleen whales: Spatial responses Capelin biomass, age 1+, acoustic survey 8 Million tonnes 7 6 5 Ecosystem survey 4 3 2 1 0 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 Year 2004 2005 2006 Prey groups capelin polar cod herring krill amfipods shrimp 2007 2008 2009 other fish other inv 2007 2009 Individual consumption (wieght) for cod 50-75 cm average values for 35 x35 nm grid cell. Edda Johannesen et al. In prep. 2004 2005 2006 Prey groups capelin polar cod herring krill amfipods shrip 2007 2008 2009 other fish other inv More capelin in the diet with more capelin in the system 2009 2007 Individual consumption (wieght) for cod 50-75 cm average values for 35 x35 nm grid cell. Edda Johannesen et al. In prep. Eneregy consumption Does the annual, averaged energy consumption by the cod stock increase with increasing capelin abundance in the system? Log (Capelin abundance) Edda Johannesen et al. In prep. Thick-billed murre Yeart Yeart+1 - Year-to-year changes in distribution - 50 km grid cells Thick-billed murre Regression model: Δbirdx,y ~ Δfishx,y+ ΔFISH change in distribution change in abundance Per Fauchald et al. In prep. Fulmarus glacialis Larus hyperboreus Rissa tridactyla + - + - + + + - + + - YEAR Ice melting SPAT YEAR SPAT YEAR SST Herring - - SPAT Capelin YEAR + SPAT Alle alle Uria lomvia Fratercula arctica Uria aalge YEAR SPAT Polar cod Regression models: How is year-to-year changes related to changes in the spatial distribution (SPAT) and yearly average (YEAR) of pelagic fish and oceanography? + + + + + Per Fauchald et al. In prep. Do the whales respond to the return of the capelin? Sightings 2010 N Finnhval Fin wh. Whale observations 2010 Capelin distribution 2010 1 2-3 4-5 6 - 10 11 - 102 Knølhval Humpb. 1 2-3 4-5 6 - 10 11 - 102 Vågehval Minke 1 2-3 Green bacground shades: Mean distribution 2003 - 2007 4-5 6 - 10 11 - 102 - Stable late summer / autumn distributions - independent of changing capelin abundance - Increasing overlap with capelin due to northern capelin distribution shift Mette Skern-Mauritzen et al (2011) - Few positive, few negative, mostly no strong responses to changing capelin abundance - Northern top predators are generalists - availability of alternative prey species compensated for low capelin densities in 2003 - 2007 -Preliminary results: interactions with capelin much stronger in winter - limited extent of pelagic habitat due to sea ice - limited availability of alternative prey species Excellent platform for studies of large scaled ecosystem processes cross sector and institutional cooperation Required, in an ecosystem based approach to management Seabirds – high priority Nils Øien Takk for oppmerksomheten