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Incidental collections of small and juvenile fishes from egg and larval surveys off South West Africa (1972-1974)
O'Toole, M.J. (1976). Incidental collections of small and juvenile fishes from egg and larval surveys off South West Africa (1972-1974). Fisheries Bulletin (South Africa) 8: 23-33
In: Fisheries Bulletin : Contributions to Oceanography and Fisheries Biology = Visserye-bulletin : bydraes tot oseanografie en visserybiologie. Department of Agriculture and Fisheries. Sea Fisheries Institute: Cape Town, more

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Keywords
    Biological sampling; Community composition; Ecological distribution; Ichthyoplankton surveys; Juveniles; Seasonal variations; Clupeidae Cuvier, 1816 [WoRMS]; Engraulidae Gill, 1861 [WoRMS]; Gadidae Rafinesque, 1810 [WoRMS]; Gonostomatidae Cocco, 1838 [WoRMS]; Merlucciidae Rafinesque, 1815 [WoRMS]; Myctophidae Gill, 1893 [WoRMS]; Scomberesocidae Bleeker, 1859 [WoRMS]; Stomiatidae; Marine

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  • O'Toole, M.J.

Abstract
    This report provides an indication of the presence and distribution of some fish spp in the Benguela Current system between latitudes 18°20'S and 24°40'S. The bearded goby, Sufflogobius bibarbatus, has emerged as an important component o the neritic ecosystem, a fact which prior to these surveys had not been fully realized. Little is known about the biology or the behavior of this sp, although it has been shown to be a significant component of the scattering layer off South West Africa. Net avoidance and diurnal migration appear to play an important role in determining the frequency of capture of some spp. For example, juveniles of the pilchard and anchovy were rarely taken in the samples, probably owing to their ability to avoid slow-moving collecting gear. Those few that were captured were caught at night. On the other hand, juveniles of the maasbanker were taken frequently in the collections and did not exhibit any diurnal variation in catch rate. This species would appear either to have a slow avoidance reaction or to be much more abundant than pilchard or anchovy in the upper 50 m layer during the day. Adult gobies showed marked diurnal variation in catch frequency. Those examined in aquaria on board ship were observed to have feeble swimming ability. This fact, together with their apparent movement to the upper layers at night would explain their frequent appearance in the collections during the hours of darkness and their general absence from the upper 50 m layer during the day. The lantern fish Lampanyctodes hectoris was captured at night and found to be the dominant myctophid in the survey region. Of the 25 spp identified 9 occurred only in the first survey, 3 only in the second survey and 13 were present during both surveys.

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