Impact of Climate on Distribution and Migration of North
Atlantic Fishes George Rose, Memorial University, NL Canada Slide 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 Slide 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 Slide 4 Migration links Abiotic: depth
temp salinity currents oxygen Biotic: fishing prey predators
density- dependence spawning feeding juvenile Environmental unit
Slide 5 History of North Atlantic Slide 6 Long-term climate change
Slide 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 Slide 8 Where are the
fish? Slide 9 # of species with latitude in N. Atlantic (data from
Briggs, 1974; Cech, 2000) Slide 10 Sea temperatures in mid-Atlantic
(data from Ekman, 1953) Slide 11 Depth: Number of species in the
North Atlantic (data from Challenger cruise, 1800s) Depth Slide 12
Number of species at depth in North Atlantic (from 150 species
documented in this study) Slide 13 Lower and upper temperature
limits: cumulative # of species Slide 14 Spawning temperature
limits Slide 15 Spawning salinity limits Slide 16 Grouping analysis
All North Atlantic Species - catalogued 146 Slide 17 Can species be
grouped into response categories? Feeding period requirements
(temperature, depth) Spawning requirements (temperature, salinity,
depth, timing) Slide 18 Warmer Shallower Principle Components 1:
Min and Max depth 2: Min and Max temperature Slide 19 Salinity
Deeper Spawning Components 1: salinity 2: depth 3: temp, timing
Slide 20 General limits: F1 with popn doubling time Slide 21
Spawning limits: PCs and popn doubling time (depth,temp,timing)
Slide 22 Event analysis Slide 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 Slide 24 A warm water event in the north
Atlantic 1920-1940 (or thereabouts) Slide 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 Slide 26 Annual air
temperature St. Johns, NL Godthab, Greenland Akureyi, Iceland Bodo,
Norway Slide 27 The warm 1930s mid- N. Atl. Slide 28 Species
distribution changes (data from Saemundsson, 1932; Taning, 1948;
Fridriksson, 1948; Rollefsen, 1948; others) Slide 29 Norwegian
skrei fishery landings, Lofoten (N) and More (S) (data from Nakken,
1994) Slide 30 No warming: No fish change Warming: fish change
1920s Slide 31 Species analysis Slide 32 A keystone species:
Capelin Slide 33 The dispersal of capelin from their north Pacific
origin (from Vilhjalmsson, 1994) Slide 34 Present distribution of
capelin (from Vilhjalmsson, 1994) Slide 35 Documented capelin
shifts Slide 36 Extension of capelin spawning grounds from cold
period (1900-1920) to warm period (1920-1940); from Vilhjalmsson
1997 cold warm Slide 37 Capelin: distance moved and temperature
change Slide 38 Capelin: distance moved and persistence Slide 39
Ripple effects Slide 40 North Atlantic food web Slide 41 Capelin is
key to: Many fishes (e.g., cod, greenland halibut, salmon, charr,
winter flounder) Seabirds Marine Mammals Slide 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 Slide 43 Extension of capelin spawning grounds from cold
period (1900-1920) to warm period (1920-1940); from Vilhjalmsson
1997 cold warm Slide 44 Extension of cod spawning grounds from cold
period (1900-1920) to warm period (1920- 1940); from Vilhjalmsson
1997 cold warm Slide 45 Capelin movements late 1980s Northern cod
movements early 1990s Grand Banks Hamilton Bank Flemish Cap Slide
46 Cod and capelin on Newfoundland shelf in early 1990s (from
ODriscoll & Rose, 2001) Slide 47 Effects of lack of capeln:
weight of cod in winter: Iceland data from Vilhjalmsson, 2002 Slide
48 Northern cod liver index and capelin availability (from Rose
& ODriscoll, 2002) Slide 49 Cod stock historical range and
biomass (from Robichaud & Rose, in press) Slide 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
