{"id":{"repo_id":"cape-town","oai_identifier":"oai:open.uct.ac.za:11427/6738"},"canonical_url":"https://search.dev.ndltd.org/etd/cape-town/oai:open.uct.ac.za:11427/6738","repository":{"repo_id":"cape-town","name":"University of Cape Town","base_url":"https://open.uct.ac.za/oai/request"},"display":{"title":"Estimates of numbers of White sharks (Carcharodon carcharias) in Eastern and Southern South Africa : a post-moratorium assessment","abstract":"A moratorium was placed on fishing for white sharks (Carcharodon carcharias) in South Africa in 1991 prior to knowing the population status of this species. A mathematical model was developed to estimate the total numbers of white sharks from 1950 to 2050 in the presence of fishing (F = 0.055 year-I) and without fishing (moratorium). The total number of white sharks from Richard's Bay to Struis Bay, South Africa was estimated to be 1,954 (range= 1,855-2,050) for the year 2004. If the moratorium was to be lifted and fishing was to resume, the results of the model indicate that the instantaneous fishing mortality rate F of 0.035 year-l or less allows the population to increase in numbers from 2004 to 2050. A sensitivity analysis determined that the instantaneous natural mortality rate M (tested range=0.070-0.l90 year-I) and the average number of pups per mature pupping female (tested range=4-14 pups) were highly sensitive parameters of the model. The maturity age span (maturity minimum age=13 and 16 years; longevity=23, 36, and 60 years) and timeframe of the female reproductive cycle (two or three years) were the least sensitive parameters of the model.","abstract_html":"A moratorium was placed on fishing for white sharks (Carcharodon carcharias) in South Africa in 1991 prior to knowing the population status of this species. A mathematical model was developed to estimate the total numbers of white sharks from 1950 to 2050 in the presence of fishing (F = 0.055 year-I) and without fishing (moratorium). The total number of white sharks from Richard's Bay to Struis Bay, South Africa was estimated to be 1,954 (range= 1,855-2,050) for the year 2004. If the moratorium was to be lifted and fishing was to resume, the results of the model indicate that the instantaneous fishing mortality rate F of 0.035 year-l or less allows the population to increase in numbers from 2004 to 2050. A sensitivity analysis determined that the instantaneous natural mortality rate M (tested range=0.070-0.l90 year-I) and the average number of pups per mature pupping female (tested range=4-14 pups) were highly sensitive parameters of the model. The maturity age span (maturity minimum age=13 and 16 years; longevity=23, 36, and 60 years) and timeframe of the female reproductive cycle (two or three years) were the least sensitive parameters of the model.","abstract_has_math":false,"creators":["Tress, Mary Elizabeth"],"institution":"Department of Biological Sciences","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["Govender, Anesh"],"committee_chairs":[],"committee_members":[],"year":2004,"date_issued":"2004","date_published":"2004","updated_at":"2026-07-22T22:23:35Z","subjects":[],"languages":["eng"],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/11427/6738","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Govender, Anesh"]},{"key":"dc:creator","label":"Author","values":["Tress, Mary Elizabeth"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2014-08-28T14:26:11Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2014-08-28T14:26:11Z"]},{"key":"dc:date.issued","label":"Date","values":["2004"]},{"key":"dc:publisher.department","label":"Dc Publisher Department","values":["Department of Biological Sciences"]},{"key":"dc:publisher.institution","label":"Dc Publisher Institution","values":["University of Cape Town"]},{"key":"dc:type","label":"Dc Type","values":["Master Thesis"]},{"key":"dc:type.qualificationlevel","label":"Dc Type Qualificationlevel","values":["Masters"]},{"key":"dc:type.qualificationname","label":"Dc Type Qualificationname","values":["MSc"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["eng"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/11427/6738"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["A moratorium was placed on fishing for white sharks (Carcharodon carcharias) in South Africa in 1991 prior to knowing the population status of this species. A mathematical model was developed to estimate the total numbers of white sharks from 1950 to 2050 in the presence of fishing (F = 0.055 year-I) and without fishing (moratorium). The total number of white sharks from Richard's Bay to Struis Bay, South Africa was estimated to be 1,954 (range= 1,855-2,050) for the year 2004. If the moratorium was to be lifted and fishing was to resume, the results of the model indicate that the instantaneous fishing mortality rate F of 0.035 year-l or less allows the population to increase in numbers from 2004 to 2050. A sensitivity analysis determined that the instantaneous natural mortality rate M (tested range=0.070-0.l90 year-I) and the average number of pups per mature pupping female (tested range=4-14 pups) were highly sensitive parameters of the model. The maturity age span (maturity minimum age=13 and 16 years; longevity=23, 36, and 60 years) and timeframe of the female reproductive cycle (two or three years) were the least sensitive parameters of the model."]},{"key":"dc:title","label":"Title","values":["Estimates of numbers of White sharks (Carcharodon carcharias) in Eastern and Southern South Africa : a post-moratorium assessment"]}]}],"canonical_facts":{"dc:contributor.advisor":["Govender, Anesh"],"dc:creator":["Tress, Mary Elizabeth"],"dc:date.accessioned":["2014-08-28T14:26:11Z"],"dc:date.available":["2014-08-28T14:26:11Z"],"dc:date.issued":["2004"],"dc:description.abstract":["A moratorium was placed on fishing for white sharks (Carcharodon carcharias) in South Africa in 1991 prior to knowing the population status of this species. A mathematical model was developed to estimate the total numbers of white sharks from 1950 to 2050 in the presence of fishing (F = 0.055 year-I) and without fishing (moratorium). The total number of white sharks from Richard's Bay to Struis Bay, South Africa was estimated to be 1,954 (range= 1,855-2,050) for the year 2004. If the moratorium was to be lifted and fishing was to resume, the results of the model indicate that the instantaneous fishing mortality rate F of 0.035 year-l or less allows the population to increase in numbers from 2004 to 2050. A sensitivity analysis determined that the instantaneous natural mortality rate M (tested range=0.070-0.l90 year-I) and the average number of pups per mature pupping female (tested range=4-14 pups) were highly sensitive parameters of the model. The maturity age span (maturity minimum age=13 and 16 years; longevity=23, 36, and 60 years) and timeframe of the female reproductive cycle (two or three years) were the least sensitive parameters of the model."],"dc:identifier.uri":["http://hdl.handle.net/11427/6738"],"dc:language.iso":["eng"],"dc:publisher.department":["Department of Biological Sciences"],"dc:publisher.institution":["University of Cape Town"],"dc:title":["Estimates of numbers of White sharks (Carcharodon carcharias) in Eastern and Southern South Africa : a post-moratorium assessment"],"dc:type":["Master Thesis"],"dc:type.qualificationlevel":["Masters"],"dc:type.qualificationname":["MSc"]},"updated_at":"2026-07-22T22:23:35Z"}