Browsing by Author "Okera, Wazir"

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    Plankton analysis relative to the feeding habits of Sardinella in Dar es Salaam waters.
    (University of Dar es Salaam, 1971) Okera, Wazir
    This work has involved the study of the composition and temporal fluctuations of the in shore zooplankton and the role of the different zooplanktoners as food items of the two species of sardines. From December 1968 to January 1970, night zooplakton samples were collected in darkness and under artificial light from Msasani Bay and adjacent areas and once in the Sinda Kendwa waters using a planktonnet based on the designs of CF 70 and Indian Ocean Standard nets. Surface sea water temperature of the above areas was recorded on the sampling night and salinity determination of the water was carried out for the first seven months. Over approximately the same period of 14 months, the stomach content of the commercially important East Africa Sardinella gibbosa and Sardinella albella caught in the light fishery operating in Msasani Bay and Sida Kundwa waters was studied. Morphometrics, fat content and gonad condition of the two species of sardines were also recorded. The results show that the various species of calanoide are the most regularly abundant zooplanktoners, followed by larvaces, Cypridina simosa and Cory caeus spp;l Oithona spp; Sagita spp; Euterpina, Lucifer and Oncea spp, in that order. All these zooplanktoners had a mean percentage proportion in the plankton of more than 1%. Of the lawvac of benthic invertebrates, caridean lawvac were the most abundant (mean proportion of about 4%). The members of a great majority of zooplanktoners were generally higher during the North East Monsoon. Stomach contents of S albella and S. Gibbosa showed that these two species of sardines feed principlaly on about the same fifteen zooplanktoners which are also the more abundant. The sizes of the zooplanktoners consumed varied from about 0.5 mm to about 30mm and it is suggest that within the range or organisms consumed, either size nor shape seem to be of critical importance. Feeding was found to be continuous through out the sampling period. Fishes caught during the North East Monsoon months were found to have high fat content compared to those of South East Monsoon month whose gonads however were not mature than those of the N.E. M. months.