Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 14-Day Trial for You or Your Team.

Learn More →

Movements and growth rates of the broadnose sevengill shark Notorynchus cepedianus in southern Africa: results from a long-term cooperative tagging programme

Movements and growth rates of the broadnose sevengill shark Notorynchus cepedianus in southern... Top predators are important components of healthy ecosystems but are at risk of overexploitation due to insufficient data on life-history characteristics and population dynamics to guide management. We investigated the movements and growth rates of the broadnose sevengill shark Notorynchus cepedianus in southern Africa, using data from the Oceanographic Research Institute’s Cooperative Fish Tagging Project (ORI-CFTP). A total of 3 513 N. cepedianus were tagged between 1984 and 2017, with 195 (5.6%) recaptured. Distribution ranged from Cape Fria, northern Namibia, to the Great Kei River, Eastern Cape, South Africa, representing a range extension of ∼200 km in comparison with that previously reported. Most captures occurred along the west coast of South Africa, and recaptures showed connectivity between the west and south coasts, but not between South Africa and Namibia. Site fidelity was evident, with the majority of recaptures (66.6%, n = 130) occurring <50 km from the release site, and many recaptures (32.8%, n = 64) occurring <1 km from the release site. Few sharks (22.6%, n = 44) were recaptured >100 km from the release site, while only three sharks (1.5%) were recaptured >500 km from the release site. Growth rates for N. cepedianus at reference precaudal lengths of 100 cm and 160 cm were estimated to be 4.7 cm y-1 and 4.0 cm y-1, respectively, which are lower than previous growth estimates. The slow growth rate and site fidelity evident in N. cepedianus, coupled with being captured in several commercial fisheries, necessitate the need for improved management of this species. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png African Journal of Marine Science Taylor & Francis

Movements and growth rates of the broadnose sevengill shark Notorynchus cepedianus in southern Africa: results from a long-term cooperative tagging programme

Download PDF

Movements and growth rates of the broadnose sevengill shark Notorynchus cepedianus in southern Africa: results from a long-term cooperative tagging programme

Abstract

Top predators are important components of healthy ecosystems but are at risk of overexploitation due to insufficient data on life-history characteristics and population dynamics to guide management. We investigated the movements and growth rates of the broadnose sevengill shark Notorynchus cepedianus in southern Africa, using data from the Oceanographic Research Institute’s Cooperative Fish Tagging Project (ORI-CFTP). A total of 3 513 N. cepedianus were tagged between 1984 and 2017,...
Loading next page...
 
/lp/taylor-francis/movements-and-growth-rates-of-the-broadnose-sevengill-shark-XEm7kDuIwa
Publisher
Taylor & Francis
Copyright
© 2020 NISC (Pty) Ltd
ISSN
1814-2338
eISSN
1814-232X
DOI
10.2989/1814232X.2020.1802776
Publisher site
See Article on Publisher Site

Abstract

Top predators are important components of healthy ecosystems but are at risk of overexploitation due to insufficient data on life-history characteristics and population dynamics to guide management. We investigated the movements and growth rates of the broadnose sevengill shark Notorynchus cepedianus in southern Africa, using data from the Oceanographic Research Institute’s Cooperative Fish Tagging Project (ORI-CFTP). A total of 3 513 N. cepedianus were tagged between 1984 and 2017, with 195 (5.6%) recaptured. Distribution ranged from Cape Fria, northern Namibia, to the Great Kei River, Eastern Cape, South Africa, representing a range extension of ∼200 km in comparison with that previously reported. Most captures occurred along the west coast of South Africa, and recaptures showed connectivity between the west and south coasts, but not between South Africa and Namibia. Site fidelity was evident, with the majority of recaptures (66.6%, n = 130) occurring <50 km from the release site, and many recaptures (32.8%, n = 64) occurring <1 km from the release site. Few sharks (22.6%, n = 44) were recaptured >100 km from the release site, while only three sharks (1.5%) were recaptured >500 km from the release site. Growth rates for N. cepedianus at reference precaudal lengths of 100 cm and 160 cm were estimated to be 4.7 cm y-1 and 4.0 cm y-1, respectively, which are lower than previous growth estimates. The slow growth rate and site fidelity evident in N. cepedianus, coupled with being captured in several commercial fisheries, necessitate the need for improved management of this species.

Journal

African Journal of Marine Science – Taylor & Francis

Published: Oct 1, 2020

Keywords: apex predator; displacement; population connectivity; range extension; site fidelity; tag-recapture data

References

  • Intrapopulation variations in diet and habitat use in a marine apex predator, the broadnose sevengill shark Notorynchus cepedianus
  • Non-lethal assessment of the reproductive status of broadnose sevengill sharks (Notorynchus cepedianus) to determine the significance of habitat use in coastal areas
  • Sequential movement into coastal habitats and high spatial overlap of predator and prey suggest high predation pressure in protected areas
  • Predator-prey relationships and foraging ecology of a marine apex predator with a wide temperate distribution
  • Non-lethal method to obtain stomach samples from a large marine predator and the use of DNA analysis to improve dietary information
  • Seasonal occurrence and population structure of the broadnose sevengill shark Notorynchus cepedjanus in coastal habitats of south-east Tasmania
  • Site fidelity and sex-specific migration in a mobile apex predator: implications for conservation and ecosystem dynamics
  • An overview on the role of Hexanchiformes in marine ecosystems: biology, ecology and conservation status of a primitive order of modern sharks
  • Carnivore conservation: shifting the paradigm from control to coexistence
  • Incorporating heterogeneity into growth analyses of wild and captive broadnose sevengill sharks Notorynchus cepedjanus
  • Growth and life history variability of the grey reef shark (Carcharhjnus amblyrhynchos) across its range
  • There and back again: a review of residency and return migrations in sharks, with implications for population structure and management
  • Standardized diet compositions and trophic levels of sharks
  • The current status and management of South Africa's chondrichthyan fisheries
  • Shark fishing effort and catch of the ragged-tooth shark Carcharjas taurus in the South African competitive shore-angling fishery
  • Spatial and seasonal distribution patterns of juvenile and adult raggedtooth sharks (Carcharjas taurus) tagged off the east coast of South Africa
  • You can swim but you can't hide: the global status and conservation of oceanic pelagic sharks and rays
  • Extinction risk and conservation of the world's sharks and rays
  • An assessment of participation, catch and effort in the KwaZulu-Natal shore-based marine linefishery, with comments on management effectiveness
  • A review of the Oceanographic Research Institute's Cooperative Fish Tagging Project: 27 years down the line
  • Life history of the sevengill shark, Notorynchus cepedjanus Peron, in two northern California bays
  • Diet of the sevengill shark Notorynchus cepedjanus in the temperate coastal waters of southern Africa
  • Biology of the sevengill shark Notorynchus cepedjanus (Peron, 1807) in the temperate coastal waters of southern Africa
  • Ontogenetic changes in the diet of the sevengill shark (Notorynchus cepedjanus)
  • Trophic downgrading of planet Earth
  • Properties and fitting of the von Bertalanffy growth curve
  • Maximum likelihood estimation of growth and growth variability from tagging data
  • Marine biodiversity in South Africa: an evaluation of current states of knowledge
  • Ecosystem function and services of aquatic predators in the Anthropocene
  • Predicting ecological consequences of marine top predator declines
  • Observations on the linefish resources of Namibia, 1990-2000 with a special reference to west coast steenbras and silver kob. In: Payne AIL, Pillar SC, Crawford RJM (eds), A decade of Namjbjan fisheries scjence
  • Nursery grounds, movement patterns and growth rates of dusky sharks, Carcharhjnus obscurus: a long-term tag and release study in South African waters
  • Habitat use, seasonality and demography of the broadnose sevengill shark Notorynchus cepedjanus in central Patagonia: another piece of the puzzle
  • Ontogenetic shifts in movement and habitat use of juvenile pigeye sharks Carcharhjnus ambojnensjs in a tropical nearshore region
  • Shark tagging: a review of conventional methods and studies
  • Preliminary observations of population genetics and relatedness of the broadnose sevengill shark, Notorynchus cepedjanus, in two Northeast Pacific estuaries
  • Reproduction, abundance and feeding habits of the broadnose sevengill shark Notorynchus cepedianus in north Patagonia, Argentina
  • Evaluation of participation in and management of the Transkei shore linefishery
  • Long-term movement patterns of tiger sharks Galeocerdo cuvier in Hawaii
  • Review of the projected impacts of climate change on coastal fishes in southern Africa
  • Long-term trends in the shore fishery of the Transkei coast, South Africa
  • Long-term trends in the competitive shore fishery along the KwaZulu-Natal coast, South Africa
  • The importance of research and public opinion to conservation management of sharks and rays: a synthesis
  • Intrinsic rebound potentials of 26 species of Pacific sharks
  • Complexities of coastal shark movements and their implications for management
  • Biogeography and the selection of priority areas for conservation of South African coastal fishes
  • Catch evaluation of target, by-product and by-catch species taken by gillnets and longlines in the shark fishery of south-eastern Australia
  • Scale and pattern of broadnose sevengill shark Notorynchus cepedianus movement in estuarine embayments