Movement patterns and population dynamics of four catsharks endemic to South Africa

Escobar-Porras, Jessica (2009) Movement patterns and population dynamics of four catsharks endemic to South Africa. Masters thesis, Rhodes University.

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Abstract

Sharks are particularly vulnerable to over-exploitation. Although catsharks are an important component of the near-shore marine biodiversity in South Africa and most of the species are endemic, little is known about their movement patterns, home range and population size. With an increasing number of recreational fishers this information is crucial for their conservation. The aims of this study were threefold. Firstly, to identify and analyze existing data sources on movement patterns and population dynamics for four catshark species: pyjama (Poroderma africanum), leopard (P. pantherinum), puffadder (Haploblepharus edwarsii ) and brown (H. fuscus). This highlighted a number of shortcomings with existing data sets, largely because these studies had diverse objectives and were not aimed solely at catsharks. Secondly, a dedicated study was carried out for a limited area, testing a number of methods for data collection, and where appropriate the data was analyzed to determine movement patterns and population numbers. Thirdly, the most appropriate methodology for future studies (with similar objectives) was identified, and the results of the study were used to propose a number of conservation measures. All species of catsharks exhibited strong site fidelity and limited dispersal for extended periods. A few individuals did, however, travel distances in excess of 150 km. Significant trends in temporal abundance were not observed, nevertheless, there was some evidence for higher catches from September to December. Population estimates for the study area were low, with P. africanum having the smallest population size while H. fuscus had the highest population size within the restricted study area. Limited movements, high site fidelity and small population sizes emphasize their vulnerability and suggest that catsharks would benefit from no-take marine protected areas.

Item Type:Thesis (Masters)
Uncontrolled Keywords:Chondrichthyes, Fish populations, Fishes, South Africa
Subjects:Q Science > QL Zoology > Chordates. Vertebrates > Fishes
Q Science > QL Zoology > Animal behaviour
Divisions:Faculty > Faculty of Science > Ichthyology & Fisheries Science
ID Code:2144
Deposited By: Ms Chantel Clack
Deposited On:01 Nov 2011 09:39
Last Modified:06 Jan 2012 16:22
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