Effective number of white shark (<i>Carcharodon carcharias,</i> Linnaeus) breeders is stable over four successive years in the population adjacent to eastern Australia and New Zealand

Davenport, Danielle; Butcher, Paul A.; Andreotti, Sara; Matthee, Conrad A.; Jones, Andrew; Ovenden, Jennifer R.

doi:10.1002/ece3.7007

Cited by 9 publications

(9 citation statements)

References 78 publications

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“…Although fewer studies have explored N b in marine species, due to the close relationship between N e and N b , similar trends to those described above occur between our results and similar studies with regard to in N b (Whiteley et al 2015, Puritz et al 2016, Waples et al 2018a, Davenport et al 2021, King et al 2023.…”

Section: Effective Number Of Breeders (N B ) In a Single Reproductive...supporting

confidence: 91%

Estimation of effective population size and effective number of breeders in an abundant and heavily exploited marine teleost

Bertram,

Bell,

Brauer

et al. 2023

Preprint

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Obtaining reliable estimates of the effective number of breedersN(b) and generational effective population size (Ne) for fishery-important species is challenging because they are often iteroparous and highly abundant, which can lead to bias and imprecision. However, recent advances in understanding of these parameters, as well as the development of bias correction methods, have improved the capacity to generate reliable estimates. We utilized samples of both single-cohort young of the year and mixed-age adults from two geographically and genetically isolated stocks of the Australasian snapper (Chrysophrys auratus) to investigate the feasibility of generating reliableNbandNeestimates for a fishery species. Snapper is an abundant, iteroparous broadcast spawning teleost that is heavily exploited by recreational and commercial fisheries. Employing neutral genome-wide SNPs and the linkage-disequilibrium method, we determined that the most reliableNbandNeestimates could be derived by genotyping at least 200 individuals from a single cohort. Although our estimates made from the mixed-age adult samples were generally lower and less precise than those based on a single cohort, they still proved useful for understanding relative differences in genetic effective size between stocks. The correction formulas applied to adjust for biases due to physical linkage of loci and age structure resulted in substantial upwards modifications of our estimates, demonstrating the importance of applying these bias corrections. Our findings provide important guidelines for estimatingNbandNefor iteroparous species with large populations. This work also highlights the utility of samples originally collected for stock structure and stock assessment work for investigating genetic effective size in fishery-important species.

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Section: Effective Number Of Breeders (N B ) In a Single Reproductive...supporting

confidence: 91%

Estimation of effective population size and effective number of breeders in an abundant and heavily exploited marine teleost

Bertram,

Bell,

Brauer

et al. 2023

Preprint

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“…The multispecies eDNA assay developed in this study will add to the shark detection capabilities of bather protection programs and provide an alternative tool for monitoring shark populations, that currently includes drumlines for capture (Tate et al, 2019), acoustic and satellite tagging and detection (Spaet et al, 2020a(Spaet et al, , 2020b, and drones (Butcher et al, 2019;Colefax et al, 2020), all paired with the SharkSmart app to provide real-time updates to the general public. Current automated acoustic monitoring techniques are limited to the detection of tagged individuals, which are likely to be only a small fraction of the total shark population present in eastern Australia (Davenport et al, 2021). Our eDNA assay has the potential to monitor a greater proportion of the shark population, particularly along coastal regions in hotspot areas at a fraction of the cost of current traditional monitoring approaches.…”

Section: Discussionmentioning

confidence: 99%

Development of an environmental DNA assay for detecting multiple shark species involved in human–shark conflicts in Australia

Rooyen¹,

Miller

Clark

et al. 2021

Environmental DNA

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“…White shark conservation frameworks are urgently needed in Australia where major declines have been observed over the past five decades, largely due to targeted hunting and commercial fishing operations (Roff et al, 2018). The species was formally recognized as “endangered” in Australia in the 1980s, and with the population growth trajectories in Australia remaining largely uncertain (Davenport et al, 2021; Hillary et al, 2018), the species remains listed as “vulnerable” in Australia under the Environment Protection and Biodiversity Conservation Act (1999). Effective conservation planning for Australian white shark populations and appreciating the effects of shark decline on the marine ecosystem through trophic cascades are compromised by a lack of information on the species biology and ecology (Huveneers et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Insights into the diet and trophic ecology of white sharks (Carcharodon carcharias) gained through DNA metabarcoding analyses of cloacal swabs

et al. 2023

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The white shark (Carcharodon carcharias) is one of the world's largest apex predators found throughout the world's temperate and subtropical marine environments. However, the species has suffered significant declines in recent decades and effective conservation programs require a sound knowledge of white shark biology and ecology. In particular, information on white shark diet across life stages and the species' range is needed to identify critical trophic interactions supporting shark populations and to predict the resilience of white sharks to environmental changes. In this study, we reassess the diet and trophic ecology of white sharks via the genetic analyses of cloacal swabs from 214 juvenile and subadult sharks from eastern Australia. Our findings are largely consistent with those of previous studies based on visual analyses of gut contents but highlight the unprecedented taxonomic resolution of prey items offered by genomic assessments of shark cloacal swabs. Diets consisted primarily of ray‐finned fishes, with Mugiliformes, Carangiformes, Perciformes, and Scombriformes being dominant prey taxa, but with elasmobranchs, marine mammals, and birds also being common dietary constituents. Statistical analyses revealed a significant effect of sex and sampling location on diet composition, indicating biological and spatial variability in diets and predatory behavior. Overall, these findings support the notion that juvenile and subadult white sharks are opportunistic predators, which may provide some level of resilience to shifts in marine resources. However, frequently consumed ray‐finned fishes, many of which are commercially targeted, may be key to supporting white shark populations in eastern Australia. This study represents the most comprehensive analysis of juvenile and subadult white shark diets performed to date and provides added confidence in the genomic analysis of cloacal swabs for dietary assessments of predatory species. These results are expected to help inform management geared toward conserving this important marine predator across the world's oceans.

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Effective number of white shark (Carcharodon carcharias, Linnaeus) breeders is stable over four successive years in the population adjacent to eastern Australia and New Zealand

Abstract: This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Cited by 9 publications

References 78 publications

Estimation of effective population size and effective number of breeders in an abundant and heavily exploited marine teleost

Estimation of effective population size and effective number of breeders in an abundant and heavily exploited marine teleost

Development of an environmental DNA assay for detecting multiple shark species involved in human–shark conflicts in Australia

Insights into the diet and trophic ecology of white sharks (Carcharodon carcharias) gained through DNA metabarcoding analyses of cloacal swabs

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