Assessment of a data-limited, multi-species shark fishery in the Great Barrier Reef Marine Park and south-east Queensland

Harry, Alastair V.; Saunders, Richard; Smart, J. J. C.; Yates, Peter; Simpfendorfer, Colin A.; Tobin, Andrew J.

doi:10.1016/j.fishres.2015.12.008

Cited by 7 publications

(11 citation statements)

References 48 publications

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“…1250 km north of Moreton Bay. Little is known, however, about these species' reproductive biology in the sub‐tropical waters of southern Queensland, despite their abundance in Moreton Bay (Taylor et al ., ) and harvest by commercial gillnet fishers operating in the Queensland East Coast Inshore Finfish Fishery (Taylor & Bennett, ; Harry et al ., ). The aim of this study was to compare length at maturity, maximum size, fecundity and periodicity of the reproductive cycles of H. australiensis and R. taylori with previous studies conducted at lower latitudes.…”

Section: Introductionmentioning

confidence: 99%

Living on the edge: latitudinal variations in the reproductive biology of two coastal species of sharks

Taylor

Harry

Bennett

2016

Journal of Fish Biology

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Differences in the reproductive biology of both the Australian weasel shark Hemigaleus australiensis and the Australian sharpnose shark Rhizoprionodon taylori were apparent between individuals from the southern-most extent of their range in eastern Australia (Moreton Bay) and those from northern Australia. For H. australiensis from Moreton Bay the total length (L ) at which 50% of individuals were mature (L ) was 759 mm for females and 756 mm for males, values that were respectively 17-26% larger than reported for the species in northern Australia. The relatively low percentage (63%) of pregnant mature females and presence of small, similar-sized, embryos in utero in both May and November suggested a semi-synchronous, annual reproductive cycle in Moreton Bay, whereas a synchronous, biannual reproductive cycle occurred in northern Australia. It is likely that H. australiensis has a resting phase between gestation cycles at the southern-most extent of its range. For R. taylori from Moreton Bay the L s were 588 and 579 mm for females and males, respectively, values 2-3% larger than for individuals from the mid-Queensland coast and 31-35% larger than for individuals from northern Australia. The length at which 50% of the females were maternal (611 mm L ) in Moreton Bay was greater than the L , indicating that not all sharks mate immediately after maturing. Rhizoprionodon taylori in the south had an annual reproductive cycle incorporating a 7-8 month embryonic diapause, with pups probably born in February. A mean fecundity of 7·5 was almost double that reported from northern Australia. Regional variations in the reproductive characteristics of H. australiensis and R. taylori may influence their resilience to fishing and other anthropogenic pressures. The substantial differences reported here highlight the importance of region-specific life-history parameters to successful management and conservation.

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Section: Introductionmentioning

confidence: 99%

Living on the edge: latitudinal variations in the reproductive biology of two coastal species of sharks

Taylor

Harry

Bennett

2016

Journal of Fish Biology

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“…Such results would be expected when studying taxa that are frequently cited as having low productivity and are easy to overexploit (Holden 1974, Walker 1998, Stevens et al 2000, Dulvy et al 2014). However, results documenting an increasing population on the GBR (Espinoza et al 2014) refuted these findings and raised questions regarding which demographic parameters were responsible for underestimating k. When the same Leslie matrix models were applied to a different population of C. amblyrhynchos using the results of Smart et al (2016) in the present study, the inherent error within these models was far more apparent. Using life history estimates from the PNG population, the present study predicted negative population growth even if the population was unfished.…”

Section: Discussionmentioning

confidence: 48%

“…), mark and recapture (Harry et al. ), and catch curves (Simpfendorfer , Coelho et al. ) provide more robust estimates of Z .…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, litter size information from the GBR was also used for this population as preliminary data from a small number of samples (n = 7) from PNG are consistent with data on litter sizes from the GBR (W. White, unpublished data; Table 1). Age-specific maturity proportions for the PNG population were estimated from the coefficients of a logistic ogive (Smart et al 2016) using the equation: Age at maturity, P a , intercept, slope N 2 l ¼ À6:74 0:74 ; R ¼ 0:90 À0:008 À0:008 0:00008 Smart et al (2016) Litter size (both sexes) N (4, 1.2 2 ) Robbins (2006), Ebert et al (2013) Notes: Multivariate normal distributions were used for the von Bertalanffy growth parameters to account for covariance. Normal distributions were used for all other parameters except maximum age, which was based on a uniform distribution.…”

Section: Standard Demographic Model Parameterizationmentioning

confidence: 99%

“…Furthermore, this fishery may reopen in the near future. Recently, life history estimates for the PNG population became available (Smart et al 2016). However, accurate estimates of M are still lacking for this population, which ultimately prevents accurate population analyses and effective fisheries management from being undertaken.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Refining mortality estimates in shark demographic analyses: a Bayesian inverse matrix approach

Smart

Punt

Espinoza

et al. 2018

Ecological Applications

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Leslie matrix models are an important analysis tool in conservation biology that are applied to a diversity of taxa. The standard approach estimates the finite rate of population growth (λ) from a set of vital rates. In some instances, an estimate of λ is available, but the vital rates are poorly understood and can be solved for using an inverse matrix approach. However, these approaches are rarely attempted due to prerequisites of information on the structure of age or stage classes. This study addressed this issue by using a combination of Monte Carlo simulations and the sample-importance-resampling (SIR) algorithm to solve the inverse matrix problem without data on population structure. This approach was applied to the grey reef shark (Carcharhinus amblyrhynchos) from the Great Barrier Reef (GBR) in Australia to determine the demography of this population. Additionally, these outputs were applied to another heavily fished population from Papua New Guinea (PNG) that requires estimates of λ for fisheries management. The SIR analysis determined that natural mortality (M) and total mortality (Z) based on indirect methods have previously been overestimated for C. amblyrhynchos, leading to an underestimated λ. Updated distributions of Z and λ were produced for the GBR population and corrected obvious error in the demographic parameters for the PNG population. This approach provides opportunity for the inverse matrix approach to be applied more broadly to situations where information on population structure is lacking.

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Individual and Population Benefits of Marine Reserves for Reef Sharks

et al. 2020

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Assessment of a data-limited, multi-species shark fishery in the Great Barrier Reef Marine Park and south-east Queensland

Cited by 7 publications

References 48 publications

Living on the edge: latitudinal variations in the reproductive biology of two coastal species of sharks

Living on the edge: latitudinal variations in the reproductive biology of two coastal species of sharks

Refining mortality estimates in shark demographic analyses: a Bayesian inverse matrix approach

Individual and Population Benefits of Marine Reserves for Reef Sharks

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