Species specific geographical distribution patterns in a warm Barents Sea: haddock vs. cod Nordic Climate-Fish 2nd Conference: Latitudinal changes in marine resources, exploitation and society within the Nordic and adjacent Seas 15-17 August 2012, Risør, Norway Geir Odd Johansen & Camilla Stegen Landa
Overview Species differences in geographic distribution Distribution of cod and haddock Background and objectives Results Age dependencies Seasonal patterns Species differences Conclusions Speculations about the future Further work
Species differences Does taxonomy matter? Different species have different life histories spawning growth phenology Temperature Food and habitat Consequences Ecological interactions Community structure Change in ecosystem functioning
Background: cod vs. haddock General geographic distribution Olsen et al. 2010. ICES Journal of Marine Science, 67: 87 101.
Background: cod vs. haddock Stock abundance NEA haddock NEA cod
Background: cod vs. haddock Other differences Haddock smaller max size than cod Spawning Haddock spawns a bit later in the season Haddock mature at an earlier age Haddock diet: invertebrates Cod diet: fish
Background: cod vs. haddock Objectives Exploratory study of the age dependent, seasonal geographic distribution of cod and haddock based on survey data maps simple geographic analyses 2004-2010 Winter survey, autumn ecosystem survey Describe age specific seasonal variation Are there species differences?
Method The spatial database The FishExChange grid: 25x25 km squares Grid for the Barents Sea with average depth for each grid cell
Age specific distribution of NEA cod 1-9 yr in winter 2004
Results Age specific distribution of NEA cod 0-9 yr in autumn 2010
2004 Species differences 0-group 2010 Cod Haddock
Seasonality and species differences 1 yr 2004 Winter Autumn Cod Haddock
Seasonality and species differences 2 yr 2004 Winter Autumn Cod Haddock
Seasonality and species differences 3 yr 2004 Winter Autumn Cod Haddock
Seasonality and species differences 4 yr 2004 Winter Autumn Cod Haddock
Seasonality and species differences 5 yr 2004 Winter Autumn Cod Haddock
Seasonality and species differences 6 yr 2004 Winter Autumn Cod Haddock
Seasonality and species differences 7 yr 2004 Winter Autumn Cod Haddock
Seasonality and species differences 8 yr 2004 Winter Autumn Cod Haddock
Seasonality and species differences 9 yr 2004 Winter Autumn Cod Haddock
Seasonality and species differences 1 yr 2010 Winter Autumn Cod Haddock
Seasonality and species differences 2 yr 2010 Winter Autumn Cod Haddock
Seasonality and species differences 3 yr 2010 Winter Autumn Cod Haddock
Seasonality and species differences 4 yr 2010 Winter Autumn Cod Haddock
Seasonality and species differences 5 yr 2010 Winter Autumn Cod Haddock
Seasonality and species differences 6 yr 2010 Winter Autumn Cod Haddock
Seasonality and species differences 7 yr 2010 Winter Autumn Cod Haddock
Seasonality and species differences 8 yr 2010 Winter Autumn Cod Haddock
Seasonality and species differences 9 yr 2010 Winter Autumn Cod Haddock
Seasonality and species Winter distribution differences Quite stable for cod, but slightly towards west with age Haddock compressed towards the coast with age Autumn distribution 0-group cod further east than haddock Older cod towards NE in autumn compared to haddock Cod spreading towards the edges in autumn in 2010 (donut)
Seasonality and species General patterns differences Haddock occurs more in SW compared to cod from 1 to 3-4 yr Cod distributed further north
Distribution centres
Distribution centres
Distribution centres
Distribution centres
Distribution centres
Distribution centres
Distribution centres
Distribution centres
Distribution centres
Distribution centres
Distribution centres
Distribution centres
Distribution centres Cod always further north compared to haddock Small and variable differences in the east-west direction Strong year-class effects on distribution of haddock
Difference between cod and haddock in distribution centres
Difference between cod and haddock in distribution centres
Summing up Conclusions Haddock more stable distribution than cod Cod more dynamic and always further north compared to haddock Strong year-class effect on haddock Important to analyse both maps and geographic parameters
Summing up 2 E 12 E 22 E 32 E 42 E 52 E 62 E 72 E 82 E 65 N 65 N 67 N 67 N 69 N 69 N 71 N 71 N 73 N 73 N 75 N 75 N 77 N 77 N 8 W 79 N 8 W 79 N Speculations about the future 22 E 32 E 42 E 52 E
Summing up 2 E 12 E 22 E 32 E 42 E 52 E 62 E 72 E 82 E 65 N 65 N 67 N 67 N 69 N 69 N 71 N 71 N 73 N 73 N 75 N 75 N 77 N 77 N 8 W 79 N 8 W 79 N Speculations about the future 22 E 32 E 42 E 52 E
Summing up Speculations about the future Predictions for autumn Some strong constraints Habitat in new areas Availability of prey Can they return to the spawning areas in winter? If not, can they find new? What about ecosystem functioning?
Summing up Further work Better quantitative analyses of geographic pattern (depth, prey etc.) Including more data We know something about WHERE We seriously lack knowledge about WHY, even on single species level Need in-depth studies of the mechanisms driving geographic distributions