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The eels of Lake Kariba: distribution, taxonomic status, age, growth and density
Author(s) -
Balon Eugene K.
Publication year - 1975
Publication title -
journal of fish biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.672
H-Index - 115
eISSN - 1095-8649
pISSN - 0022-1112
DOI - 10.1111/j.1095-8649.1975.tb04651.x
Subject(s) - biology , fishery , population , population density , taxon , ecology , demography , sociology
It had been predicted that eels would disappear from Lake Kariba because juveniles would be unable to surmount the dam which was closed in 1958. This prediction has been proved wrong. In 1970–71 an abundant population of eels was discovered in the lake, mostly at depths from 25–40 m. The eels have intermingled characters of both the mottled Anguilla nebulosa labiata and the plain‐colored A. mossambica . A clear separation of these two taxa was impossible and therefore conspeciflc status of these two species is suspected; the name A. n. labiata is retained for the population. The age structure of the eel cohorts suggests that juveniles surmount the dam in their second year of life and then spend approximately 7 years in streams of the lake drainage. The fastest maturing individuals which are in best condition then emigrate to the ocean, whereas the slower maturing eels remain in the lake longer. The oldest eel in the samples was 18 years old. The catch per unit of effort for hoopnets was 2.35 kg in the upper part of the lake and 0.41 kg for the lower part of the lake. The density at Namazambwe was assessed at 46 eels per 1 ha. The unexploited eel population of Lake Kariba could form a valuable resource.