Long-term catch and effort trends in Eastern Cape Angling Week competitions

Dicken, ML; Smale, M. J.; Booth, Anthony J.

doi:10.2989/1814232x.2012.709961

Cited by 13 publications

(3 citation statements)

References 34 publications

(64 reference statements)

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“…Both commercial and recreational fishermen in Algoa Bay have reported a decline in catch per unit effort (cpue), change in catch composition, and/or change in fishing pattern as a consequence of overfishing (Brouwer and Buxton , Dicken et al . ). In addition, a recent study by Rishworth et al .…”

Section: Discussionmentioning

confidence: 76%

Sixteen years later: Occurrence, group size, and habitat use of humpback dolphins (Sousa plumbea) in Algoa Bay, South Africa

Koper

Karczmarski

Preez

et al. 2015

Marine Mammal Science

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Coastal dolphins are more prone to cumulative impacts of environmental and anthropogenic changes than pelagic species. However, few studies use historical comparisons to evaluate those impacts across a temporal scale. The study presented here describes the pattern of occurrence, group size, behavior, and habitat use of humpback dolphins in Algoa Bay and compares these to a similar study conducted in the early 1990s. Results indicate a considerable change in the frequency of occurrence. Furthermore, the mean group size has decreased from six to three individuals, mainly due to an increase in occurrence of solitary individuals (36.3% vs. 15.4%). Foraging, which was previously the predominant activity (64%), has now been replaced by traveling (49%). Moreover, dolphins showed a negative reaction towards a variety of watercrafts and swimmers. These observed differences could be due to a change in prey abundance, direct anthropogenic disturbance, and/or population decline. We emphasize the need for long-term environmental and biological data series and long-term monitoring of the demographics of this population to accurately assess any changes observed in future.

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Section: Discussionmentioning

confidence: 76%

Sixteen years later: Occurrence, group size, and habitat use of humpback dolphins (Sousa plumbea) in Algoa Bay, South Africa

Koper

Karczmarski

Preez

et al. 2015

Marine Mammal Science

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show abstract

“…In South Africa, the KwaZulu-Natal beach meshing program has also been identified as a having a negative impact on this species, due to its very low intrinsic rate of population increase 34 . Despite the potential impact of these threats, no decline in catch rate or body size of C. taurus was detected in the competitive shorefishery 35 or beach meshing catches 34 . Population trends estimated from mark-recapture data also remained stable over a 20-year study period 36 .…”

Section: Introductionmentioning

confidence: 94%

A globally threatened shark,Carcharias taurus, shows no population decline in South Africa

Klein

Merwe

Dicken

et al. 2020

Preprint

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Knowledge about the demographic histories of natural populations helps to evaluate their conservation status, and potential impacts of natural and anthropogenic pressures. In particular, estimates of effective population size obtained through molecular data can provide useful information to guide management decisions for vulnerable populations. The spotted ragged-tooth shark Carcharias taurus (also known as the sandtiger or grey nurse shark) is widely distributed in warm-temperate and subtropical waters, but has suffered severe population declines across much of its range as a result of overexploitation. Here, we used multilocus genotype data to investigate the demographic history of the South African C. taurus population. Using approximate Bayesian computation and likelihood-based importance sampling, it was found that the population underwent a historical range expansion that may have been linked to climatic changes during the late Pleistocene. There was no evidence for a recent anthropogenic decline. Together with census data suggesting a stable population, these results support the idea that fishing pressure and other threats have so far not been detrimental to the local C. taurus 2 population. The results reported here indicate that South Africa could possibly harbour the last remaining, relatively pristine population of this widespread but vulnerable top predator.

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“…In South Africa, the KwaZulu-Natal beach meshing program has also been identified as a having a negative impact on this species, due to its very low intrinsic rate of population increase 34 . Despite the potential impact of these threats, no decline in catch rate or body size of C. taurus was detected in the competitive shore-fishery 35 or beach meshing catches 34 . Population trends estimated from mark-recapture data also remained stable over a 20-year study period 36 .…”

Section: Introductionmentioning

confidence: 94%

A globally threatened shark, Carcharias taurus, shows no population decline in South Africa

Klein

Merwe

Dicken

et al. 2020

Sci Rep

View full text Add to dashboard Cite

Knowledge about the demographic histories of natural populations helps to evaluate their conservation status, and potential impacts of natural and anthropogenic pressures. In particular, estimates of effective population size obtained through molecular data can provide useful information to guide management decisions for vulnerable populations. The spotted ragged-tooth shark, Carcharias taurus (also known as the sandtiger or grey nurse shark), is widely distributed in warm-temperate and subtropical waters, but has suffered severe population declines across much of its range as a result of overexploitation. Here, we used multilocus genotype data to investigate the demographic history of the South African C. taurus population. Using approximate Bayesian computation and likelihood-based importance sampling, we found that the population underwent a historical range expansion that may have been linked to climatic changes during the late Pleistocene. There was no evidence for a recent anthropogenic decline. Together with census data suggesting a stable population, these results support the idea that fishing pressure and other threats have so far not been detrimental to the local C. taurus population. The results reported here indicate that South Africa could possibly harbour the last remaining, relatively pristine population of this widespread but vulnerable top predator.

show abstract

Long-term catch and effort trends in Eastern Cape Angling Week competitions

Cited by 13 publications

References 34 publications

Sixteen years later: Occurrence, group size, and habitat use of humpback dolphins (Sousa plumbea) in Algoa Bay, South Africa

Sixteen years later: Occurrence, group size, and habitat use of humpback dolphins (Sousa plumbea) in Algoa Bay, South Africa

A globally threatened shark,Carcharias taurus, shows no population decline in South Africa

A globally threatened shark, Carcharias taurus, shows no population decline in South Africa

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