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Baited remote underwater survey of chondrichthyans in False Bay, South Africa
Worldwide, numerous shark populations are in rapid decline due to chronic overfishing. Their slow reproductive capacity make them susceptible to extinction. To monitor the status of chondrichthyan species, the method or combination of methods used should be non-selective, applicable in a variety of...
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| Format: | Thesis |
| Language: | English |
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Department of Biological Sciences
2015
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| _version_ | 1867613205226848256 |
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| access_status_str | Open Access |
| author | Watson, Ralph Gareth Andrew |
| author2 | Attwood, Colin |
| author_browse | Attwood, Colin Watson, Ralph Gareth Andrew |
| author_facet | Attwood, Colin Watson, Ralph Gareth Andrew |
| author_sort | Watson, Ralph Gareth Andrew |
| collection | Thesis |
| description | Worldwide, numerous shark populations are in rapid decline due to chronic overfishing. Their slow reproductive capacity make them susceptible to extinction. To monitor the status of chondrichthyan species, the method or combination of methods used should be non-selective, applicable in a variety of habitats and under most environmental conditions. Baited Remote Underwater Video (BRUV) surveys have shown major benefits over traditional capture-based survey methods in multiple areas. They have been shown to be non-extractive, causing no major disturbance to the substrata and its epibenthos. Large, mobile animals that avoid divers and active fishing surveys are detected. The recorded video removes the need for specialist observers to conduct all the fieldwork. The video allows impartial and repeatable measurements and standardizes data collection and training in association with remote taxonomists. The method is also cheaper than alternatives. Ninety-five sites were sampled with 60 minute video recordings across the whole of False Bay during the period of June-July 2012. Fifteen species of chondrichthyans were recorded, of which Haploblepharus edwardsii was the most abundant, being observed at 83 of 95 sites. One hour was sufficient to capture all the chondrichthyans within the observed area as the average time of arrival was about half an hour into the recording. The distribution of the chondrichthyan population was remarkably uniform across the bay. Depth, habitat and substrate type were significant predictors of species composition (P = 0.004, 0.025 and 0.001 respectively). Opportunistic encounters (one individual observed) included Carcharodon carcharias, Squalus megalops, Rhinobatos annulatus and Myliobatis aquila. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/14022 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:32:26.116Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2015 |
| publishDateRange | 2015 |
| publishDateSort | 2015 |
| publisher | Department of Biological Sciences |
| publisherStr | Department of Biological Sciences |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/14022 Baited remote underwater survey of chondrichthyans in False Bay, South Africa Watson, Ralph Gareth Andrew Attwood, Colin Applied Marine Science Worldwide, numerous shark populations are in rapid decline due to chronic overfishing. Their slow reproductive capacity make them susceptible to extinction. To monitor the status of chondrichthyan species, the method or combination of methods used should be non-selective, applicable in a variety of habitats and under most environmental conditions. Baited Remote Underwater Video (BRUV) surveys have shown major benefits over traditional capture-based survey methods in multiple areas. They have been shown to be non-extractive, causing no major disturbance to the substrata and its epibenthos. Large, mobile animals that avoid divers and active fishing surveys are detected. The recorded video removes the need for specialist observers to conduct all the fieldwork. The video allows impartial and repeatable measurements and standardizes data collection and training in association with remote taxonomists. The method is also cheaper than alternatives. Ninety-five sites were sampled with 60 minute video recordings across the whole of False Bay during the period of June-July 2012. Fifteen species of chondrichthyans were recorded, of which Haploblepharus edwardsii was the most abundant, being observed at 83 of 95 sites. One hour was sufficient to capture all the chondrichthyans within the observed area as the average time of arrival was about half an hour into the recording. The distribution of the chondrichthyan population was remarkably uniform across the bay. Depth, habitat and substrate type were significant predictors of species composition (P = 0.004, 0.025 and 0.001 respectively). Opportunistic encounters (one individual observed) included Carcharodon carcharias, Squalus megalops, Rhinobatos annulatus and Myliobatis aquila. 2015-09-15T10:33:06Z 2015-09-15T10:33:06Z 2013 Master Thesis Masters MSc http://hdl.handle.net/11427/14022 eng application/pdf Department of Biological Sciences Faculty of Science University of Cape Town |
| spellingShingle | Applied Marine Science Watson, Ralph Gareth Andrew Baited remote underwater survey of chondrichthyans in False Bay, South Africa |
| thesis_degree_str | Master's |
| title | Baited remote underwater survey of chondrichthyans in False Bay, South Africa |
| title_full | Baited remote underwater survey of chondrichthyans in False Bay, South Africa |
| title_fullStr | Baited remote underwater survey of chondrichthyans in False Bay, South Africa |
| title_full_unstemmed | Baited remote underwater survey of chondrichthyans in False Bay, South Africa |
| title_short | Baited remote underwater survey of chondrichthyans in False Bay, South Africa |
| title_sort | baited remote underwater survey of chondrichthyans in false bay south africa |
| topic | Applied Marine Science |
| url | http://hdl.handle.net/11427/14022 |
| work_keys_str_mv | AT watsonralphgarethandrew baitedremoteunderwatersurveyofchondrichthyansinfalsebaysouthafrica |