Species specific geographical distribution patterns in a warm Barents Sea: haddock vs. cod

Transcription

1 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 August 2012, Risør, Norway Geir Odd Johansen & Camilla Stegen Landa

2 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

3 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

4 Background: cod vs. haddock General geographic distribution Olsen et al ICES Journal of Marine Science, 67:

5 Background: cod vs. haddock Stock abundance NEA haddock NEA cod

6 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

7 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 Winter survey, autumn ecosystem survey Describe age specific seasonal variation Are there species differences?

8 Method The spatial database The FishExChange grid: 25x25 km squares Grid for the Barents Sea with average depth for each grid cell

9 Age specific distribution of NEA cod 1-9 yr in winter 2004

10 Results Age specific distribution of NEA cod 0-9 yr in autumn 2010

11 2004 Species differences 0-group 2010 Cod Haddock

12 Seasonality and species differences 1 yr 2004 Winter Autumn Cod Haddock

13 Seasonality and species differences 2 yr 2004 Winter Autumn Cod Haddock

14 Seasonality and species differences 3 yr 2004 Winter Autumn Cod Haddock

15 Seasonality and species differences 4 yr 2004 Winter Autumn Cod Haddock

16 Seasonality and species differences 5 yr 2004 Winter Autumn Cod Haddock

17 Seasonality and species differences 6 yr 2004 Winter Autumn Cod Haddock

18 Seasonality and species differences 7 yr 2004 Winter Autumn Cod Haddock

19 Seasonality and species differences 8 yr 2004 Winter Autumn Cod Haddock

20 Seasonality and species differences 9 yr 2004 Winter Autumn Cod Haddock

21 Seasonality and species differences 1 yr 2010 Winter Autumn Cod Haddock

22 Seasonality and species differences 2 yr 2010 Winter Autumn Cod Haddock

23 Seasonality and species differences 3 yr 2010 Winter Autumn Cod Haddock

24 Seasonality and species differences 4 yr 2010 Winter Autumn Cod Haddock

25 Seasonality and species differences 5 yr 2010 Winter Autumn Cod Haddock

26 Seasonality and species differences 6 yr 2010 Winter Autumn Cod Haddock

27 Seasonality and species differences 7 yr 2010 Winter Autumn Cod Haddock

28 Seasonality and species differences 8 yr 2010 Winter Autumn Cod Haddock

29 Seasonality and species differences 9 yr 2010 Winter Autumn Cod Haddock

30 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)

31 Seasonality and species General patterns differences Haddock occurs more in SW compared to cod from 1 to 3-4 yr Cod distributed further north

32 Distribution centres

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44 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

45 Difference between cod and haddock in distribution centres

46 Difference between cod and haddock in distribution centres

47 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

48 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

49 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

50 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?

51 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