Latitudinal variation in aspects of the biology of Cyclothone braueri and C. microdon (Pisces: Gonostomatidae) in the eastern North Atlantic Ocean |
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Authors: | D S McKelvie |
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Institution: | (1) Deacon Laboratory, Institute of Oceanographic Sciences, Wormley, GU8 5UB Godalming, Surrey, England |
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Abstract: | Samples from a series of RMT-8 tows along 20°W in spring and autumn of various years were used to study the variability in aspects of the breeding biology of two species of Cyclothone: C. braueri and C. microdon in the eastern North Atlantic Ocean. Variables compared within each species included length-frequency distribution, maximum size, size at maturity, sex ratio, egg size and fecundity. Populations of both species at lower latitudes were generally smaller, reached maturity at a smaller size, and probably spawned earlier in the year and over a longer period than populations at higher latitudes. In both species, fecundity was highest at 40°N in the spring. The results suggested that C. microdon may not spawn at the northern extent of its range. |
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