1. Impact of Climate on Distribution and Migration of North Atlantic Fishes George Rose, Memorial University, NL Canada

2. Table of Contents A few platitudes Brief history of the North Atlantic Where are the fish? “Grouping” analysis of species “Event” analysis: the 1920-1940 warming “Species” analysis: capelin “Ripple” effects: food webs

3. Fish distributions and migrations NOT random the result of evolution of the physiology of the species “tuned to the particular biotic and abiotic environment of the stock” variable at several time scales early indicator of ecosystem change “On the cod highway” 1992 2000

4. Migration links Abiotic: depth temp salinity currents oxygen Biotic: fishing prey predators density- dependence spawning feeding juvenile Environmental unit

5. History of North Atlantic

6. Long-term climate change

7. Most North Atlantic species have Pacific origins (Ekman, 1953) The gadoids are likely the only major fish group whose evolutionary center is the North Atlantic

8. Where are the fish?

9. # of species with latitude in N. Atlantic (data from Briggs, 1974; Cech, 2000)

10. Sea temperatures in mid-Atlantic (data from Ekman, 1953)

11. Depth: Number of species in the North Atlantic (data from Challenger cruise, 1800s) Depth

12. Number of species at depth in North Atlantic (from 150 species documented in this study)

13. Lower and upper temperature limits: cumulative # of species

14. Spawning temperature limits

15. Spawning salinity limits

16. “Grouping” analysis All North Atlantic Species - catalogued 146

17. Can species be grouped into response categories? Feeding period requirements (temperature, depth) Spawning requirements (temperature, salinity, depth, timing)

18. Warmer Shallower Principle Components 1: Min and Max depth 2: Min and Max temperature

19. Salinity Deeper Spawning Components 1: salinity 2: depth 3: temp, timing

20. General limits: F1 with pop’n doubling time

21. Spawning limits: PCs and pop’n doubling time (depth,temp,timing)

22. “Event” analysis

23. An old problem “there have been certain periods of years in northern seas with higher temperatures and simultaneously increasing occurrence of southern species, for instance in the years of about 1820-30, 1840-50, 1870-80, and 1920-” Rollefsen and Taning, 1948

24. A warm water “event” in the north Atlantic 1920-1940 (or thereabouts)

25. According to Taning, 1948 “Simultaneous with this scarcity of ice in the waters around Iceland the winters have been exceedingly mild, especially during February and March, when the mean temperature was some 4 to 7 o C above the normal” “This increase of the surface temperature has amounted to about 0.5-4.0 o above the normal”

26. Annual air temperature St. John’s, NL Godthab, Greenland Akureyi, Iceland Bodo, Norway

27. The warm 1930s mid- N. Atl.

28. Species distribution changes (data from Saemundsson, 1932; Taning, 1948; Fridriksson, 1948; Rollefsen, 1948; others)

29. Norwegian skrei fishery landings, Lofoten (N) and More (S) (data from Nakken, 1994)

30. No warming: No fish change Warming: fish change 1920s

31. Species analysis

32. A keystone species: Capelin

33. The dispersal of capelin from their north Pacific origin (from Vilhjalmsson, 1994)

34. Present distribution of capelin (from Vilhjalmsson, 1994)

35. Documented capelin shifts

36. Extension of capelin spawning grounds from cold period (1900-1920) to warm period (1920-1940); from Vilhjalmsson 1997 cold warm

37. Capelin: distance moved and temperature change

38. Capelin: distance moved and persistence

39. Ripple effects

40. North Atlantic food web

41. Capelin is key to: Many fishes (e.g., cod, greenland halibut, salmon, charr, winter flounder) Seabirds Marine Mammals

42. Templeman, 1948, on Newfoundland caplin “not only does it provide the nourishment on which the great bulk of inshore running codfish recover condition in June and July after spawning, but it is very likely in the main responsible for the attraction of the huge shoals of cod to the coast”

43. Extension of capelin spawning grounds from cold period (1900-1920) to warm period (1920-1940); from Vilhjalmsson 1997 cold warm

44. Extension of cod spawning grounds from cold period (1900-1920) to warm period (1920- 1940); from Vilhjalmsson 1997 cold warm

45. Capelin movements late 1980s Northern cod movements early 1990s Grand Banks Hamilton Bank Flemish Cap

46. Cod and capelin on Newfoundland shelf in early 1990s (from O’Driscoll & Rose, 2001)

47. Effects of lack of capeln: weight of cod in winter: Iceland data from Vilhjalmsson, 2002

48. Northern cod liver index and capelin availability (from Rose & O’Driscoll, 2002)

49. Cod stock historical range and biomass (from Robichaud & Rose, in press)

50. Conclusions Distribution changes important - early indicator of ecosystem change Response differences (pelagics faster; demersals slower, some maybe not at all) Capelin fast - “canary in the mine” Ripple effects: capelin changes affect many species