Magister Scientiae (Biodiversity and Conservation Biology) - MSc (Biodiv and Cons Biol) / The objective of this thesis was to elucidate intra- and interspecific variability in the
distribution patterns and diet of the two most common demersal catsharks taken as
by-catch by the commercial trawling industry targeting the two Cape hake species
off the West and South coasts of South Africa. Samples and data were collected
during routine demersal hake biomass surveys conducted by DAFF, with distribution
data collected from 1994 to 2015 and stomach content and stable isotope data
collected from 2014 to 2015. On examination of the distribution data,
Holohalaelurus regani was found to be more abundant on the West Coast and
Scyliorhinus capensis was found to be more abundant on the South Coast. Both
catsharks were observed to display size-based segregations, with catshark size
increasing with depth in both species. Differences in the distribution patterns of male
and female H. regani were also noted, with female catsharks inhabiting inshore areas
and male catsharks inhabiting offshore areas. The two catsharks appeared to display
high levels of dietary overlap, with individuals feeding on the most abundant
crustaceans and cephalopods caught as by-catch in the trawl on each coast.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:uwc/oai:etd.uwc.ac.za:11394/5776 |
| Date | January 2017 |
| Creators | van der Heever, Grant Mark |
| Contributors | Gibbons, Mark |
| Publisher | University of the Western Cape |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Rights | University of the Western Cape |
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