Bibliography: pages 70-74. / Feeding of the redeye roundherring Etrumeus whiteheadi Wongratana 1983, was investigated off the west and south coasts of the Cape Province of South Africa. Fish from the west coast were collected in April and May 1984, those from the south coast during November 1983 and 1984. Diet was determined from stomach contents. Dry mass and numbers of food items are presented. Copepods were the principal food off the south coast, constituting a mean of 67% (range: 60-75%) by mass of gut contents in juveniles, a mean of 59% (range 44-88%) in the transitional juvenile/adult size class and a mean of 43% (range: 30-73%) by mass in the adults. Adult and larval stages of euphausiids were also an important dietary component of these fish, comprising a mean of 10% (range: 0-18%) by mass in the juveniles, a mean of 14% (range: 7-18%) in the transitional juvenile/adult size class and a mean of 52% (range: 27-63%) by mass in the adults. On the west coast chaetognaths appeared to be the principal food item of the juvenile fish examined, yielding values as high as 99% by mass. Other less important prey in both areas included cladocerans, ostracods, fish eggs, pteropods, bivalve larvae, squid and juvenile fish. Phytoplankton formed a negligible component of the diet. It was present in minute quantities in the west coast fish only. Diurnal feeding patterns were investigated for both areas. Total mass of stomach contents constituted a maximum of 1.2% of total fish mass off the south coast in November 1983, and a maximum of 0.85% in November 1984. Off the west coast, where juveniles only were sampled, the stomach content mass made up to 7% of body mass. Stomachs were fullest in the afternoon and early evening and it is inferred that feeding takes place during daylight hours. Predator-prey size relationships were investigated using two methods. The first method involved testing the correlation between fish mass and prey mass and the second employed Ursin's procedure using predator-prey mass ratios. Predator size was found to have a small effect on diet composition.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:uct/oai:localhost:11427/22016 |
| Date | January 1987 |
| Creators | Wallace-Fincham, Beverley Pastorah |
| Contributors | Field, John G, Brownell, Charles L |
| Publisher | University of Cape Town, Faculty of Science, Department of Biological Sciences |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Master Thesis, Masters, MSc |
| Format | application/pdf |
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