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Extracting fish abundance indices from recreational fishing competition data
Over-exploited fisheries result in global economic losses and can lead to the degradation of marine ecosystems. Commercial and recreational fisheries have grown substantially over the past decades placing fish stocks under increasing pressure. Fisheries management aims to conserve and restore stocks...
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| Format: | Thesis |
| Language: | Eng |
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Percy FitzPatrick Institute of African Ornithology
2016
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| _version_ | 1867613230552055808 |
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| access_status_str | Open Access |
| author | Dickens, John |
| author2 | Attwood, Colin |
| author_browse | Attwood, Colin Dickens, John |
| author_facet | Attwood, Colin Dickens, John |
| author_sort | Dickens, John |
| collection | Thesis |
| description | Over-exploited fisheries result in global economic losses and can lead to the degradation of marine ecosystems. Commercial and recreational fisheries have grown substantially over the past decades placing fish stocks under increasing pressure. Fisheries management aims to conserve and restore stocks to economically and environmentally sustainable levels. Stock assessments are mostly based on analyses of fishery-dependent data, however, this practice often neglects uneconomically important species, making ecosystem approaches to fisheries management challenging. Competitive recreational angling has the potential to provide accurate and consistent records of catch and effort data for a variety of unassessed fish species as well as data for currently assessed commercial species, but without the market influence on targeting. The data from five boat based recreational competitions in the Western Cape were studied. Records for the competitions varied in length with the longest dataset from running from 1994 to 2014, and the shortest from 2003 to 2014. The competitions were divided into three inshore and two offshore groups with each targeting different assemblages of fish. In total 38 species of teleost were caught, but at least 90% of the total catch for each competition was comprised of seven species or less. Catch composition was determined for each competition and the standardised catch per unit effort (CPUE) of the ten most abundant species across the competitions were assessed. CPUE trends for red roman, snoek and geelbek were comparable to commercial fishery-dependent CPUE data. The targeting of specific species in the multi-species fishery noticeably influenced CPUE values. Catch limits resulted in lower estimations of the CPUE for snoek, and potentially for red stump nose. Boat based competition data is accurate and consistent enough for the extraction of abundance indices for certain species. Further work on these data may involve the standardisation of CPUE values to account for targeting in the multi-species fishery. With a large number of boat based competitive anglers in the country, there is a scope for using these data for stock assessments, either as stand-alone data sources, or as an adjunct to well-established commercial catch time-series. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/19954 |
| institution | University of Cape Town (South Africa) |
| language | Eng |
| last_indexed | 2026-06-10T12:32:50.328Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2016 |
| publishDateRange | 2016 |
| publishDateSort | 2016 |
| publisher | Percy FitzPatrick Institute of African Ornithology |
| publisherStr | Percy FitzPatrick Institute of African Ornithology |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/19954 Extracting fish abundance indices from recreational fishing competition data Dickens, John Attwood, Colin Conservation Biology Over-exploited fisheries result in global economic losses and can lead to the degradation of marine ecosystems. Commercial and recreational fisheries have grown substantially over the past decades placing fish stocks under increasing pressure. Fisheries management aims to conserve and restore stocks to economically and environmentally sustainable levels. Stock assessments are mostly based on analyses of fishery-dependent data, however, this practice often neglects uneconomically important species, making ecosystem approaches to fisheries management challenging. Competitive recreational angling has the potential to provide accurate and consistent records of catch and effort data for a variety of unassessed fish species as well as data for currently assessed commercial species, but without the market influence on targeting. The data from five boat based recreational competitions in the Western Cape were studied. Records for the competitions varied in length with the longest dataset from running from 1994 to 2014, and the shortest from 2003 to 2014. The competitions were divided into three inshore and two offshore groups with each targeting different assemblages of fish. In total 38 species of teleost were caught, but at least 90% of the total catch for each competition was comprised of seven species or less. Catch composition was determined for each competition and the standardised catch per unit effort (CPUE) of the ten most abundant species across the competitions were assessed. CPUE trends for red roman, snoek and geelbek were comparable to commercial fishery-dependent CPUE data. The targeting of specific species in the multi-species fishery noticeably influenced CPUE values. Catch limits resulted in lower estimations of the CPUE for snoek, and potentially for red stump nose. Boat based competition data is accurate and consistent enough for the extraction of abundance indices for certain species. Further work on these data may involve the standardisation of CPUE values to account for targeting in the multi-species fishery. With a large number of boat based competitive anglers in the country, there is a scope for using these data for stock assessments, either as stand-alone data sources, or as an adjunct to well-established commercial catch time-series. 2016-06-09T11:10:02Z 2016-06-09T11:10:02Z 2015 Master Thesis Masters MSc http://hdl.handle.net/11427/19954 Eng application/pdf Percy FitzPatrick Institute of African Ornithology Faculty of Science University of Cape Town |
| spellingShingle | Conservation Biology Dickens, John Extracting fish abundance indices from recreational fishing competition data |
| thesis_degree_str | Master's |
| title | Extracting fish abundance indices from recreational fishing competition data |
| title_full | Extracting fish abundance indices from recreational fishing competition data |
| title_fullStr | Extracting fish abundance indices from recreational fishing competition data |
| title_full_unstemmed | Extracting fish abundance indices from recreational fishing competition data |
| title_short | Extracting fish abundance indices from recreational fishing competition data |
| title_sort | extracting fish abundance indices from recreational fishing competition data |
| topic | Conservation Biology |
| url | http://hdl.handle.net/11427/19954 |
| work_keys_str_mv | AT dickensjohn extractingfishabundanceindicesfromrecreationalfishingcompetitiondata |