dence that capelin migrated to the Norwegian spawning grounds during both periods. ..... The 1780-1800 period and the 1830s were probably cold on an ...
POSSIBLE
IMPLICATIONS
THE PRESENCE
OF C L I M A T I C V A R I A B I L I T Y O N
OF C A P E L I N
THE NORWEGIAN
(MALLOTUS VILLOSUS) O F F
COAST
K O N S T A N T I N O S I. S T E R G I O U National Center for Marine Research, Agios Kosmas, Hellinikon, Athens 16604, Greece
Abstract. The distribution of capelin in the southern Barents Sea shifts in the east-west direction in response to warming or cooling trends. The capelin arrives at the spawning grounds earlier and spawning takes place in deeper water in cold years as compared to warm years. Although the ultimate regulators of capelin distribution/abundance in the Barents Sea may involve complex interactions/responses between capelin and abiotic and biotic variables, water temperature was found to be a successful predictor and proximate regulator of capelin distribution/ abundance in that area. It has been maintained that capelin did not visit the Norwegian coastal waters during the turn of the 18th century and in 1830-1840. Yet, meteorological, oceanographic and ecological data hitherto presented provide cumulative evidence that capelin migrated to the Norwegian spawning grounds during both periods. Nevertheless, capelin arrived early in the year and remained and spawned further offshore in deeper waters. Since capelin in earlier fisheries were fished by means of land-fixed nets, the size of the catch depended on access by the capelin to the immediate coastal fishing areas. Thus, capelin were not accessible to Norwegian fishermen.
Introduction
The capelin, Mallotus villosus, a small ( --
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Fig. 4. 5-yr rnnning means of water temperature (0-200 m) at Kola section (reproduced from Harvey 1965) and annual air temperature at Vardo, 1921-1960 (credited to the first year of the 5-yr period).
means of the North Cape current and (b) increase the air-sea temperature gradient and speed up the rate of autumn-winter cooling (Jensen, 1939; Elliott, 1957; Dickson and Lee, 1969; Martin, 1972; Sarynina, 1979, 1980, 1981, 1983; Stergiou, 1984)9 On the contrary, when a low pressure system is located over the Barents Sea (e.g. warming of the 1930s and in 1971-1975; Dickson et al., 1976) S and SW winds predominate, water temperature increases and the warm Atlantic waters penetrate further eastwards. The facts presented above indicate that (a) long-term climatic variations are highly coherent in the northeast Atlantic, and (b) air temperatures may be used as an index of the Barents Sea climate for the years preceding 1925. The air temperature record at Vardo goes back to 1870. The only Norwegian air temperature record that goes back to the 18th century is that of Trondheim (Historical Statistics, 1978)9 Since the capelin in winter is found in the southern Barents Sea (Stergiou 1984) and temperature changes in Northeast Atlantic are more pronounced in the wintertime (Dickson and Lamb, 1972), the January air temperature at Trondheim (Figure 6) is used as an index of marine climatic change in the Barents Sea for the years 1780-1925. Climatic Change December 1991
377
Possible Implications of Climatic Variability
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Climatic Change December 1991
378
Konstantinos I. Stergiou
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