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Age and growth studies of Gummy Shark, Mustelus antarcticus Gunther, and School Shark, Galeorhinus galeus (Linnaeus), from Souther Australian Waters

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Marine and Freshwater Research
Authors:
PL Moulton
PL Moulton
PL Moulton
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Terence Ivan Walker at University of Melbourne
Terence Ivan Walker
SR Saddlier
SR Saddlier
SR Saddlier
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Abstract

Age-length data were derived from counting stained bands on whole vertebral centra obtained from gummy shark, Mustelus antarcticus, captured by gill-nets during 1973-76 in Bass Strait and from gummy shark and school shark, Galeorhinus galeus, captured during 1986-87 in Bass Strait and waters off South Australia. The data were fitted to the von Bertalanffy growth equation after adopting the Francis reparametrization and correcting for sampling bias caused by the selectivity effects of the gill-nets of various mesh sizes used to capture the sharks. The von Bertalanffy growth curves of male and female gummy shark were significantly different, but the growth curves of male and female school shark were not. The growth curves suggest that growth rates of male and female gummy shark in Bass Strait were lower during 1986-87 than during 1973-76 and that the growth rates of male and female gummy shark and school shark in Bass Strait during 1986-87 were lower than those in South Australia at the same time. These apparent temporal and spatial differences in growth patterns of gummy shark are explained by the 'Phenomenon of Apparent Change in Growth Rate'. It is concluded that the growth curves determined for 1986-87 are distorted by the effects of a long history of high and length-selective fishing mortality and that actual growth patterns of gummy shark are better represented by the von Bertalanffy growth equation determined for shark caught in Bass Strait during 1973-76, when fishing mortality was much lower. Verification of age estimates was attempted by comparing von Bertalanffy growth curves derived from age-length data with those derived from tag release-recapture length-increment data, but these comparisons highlight the limitations of using tag data for this purpose. Although reasonable agreement was found between such growth curves for gummy shark, it appears that school shark older than 11 years cannot be aged accurately from stained whole or sectioned vertebrae. Sectioned vertebrae from a school shark recaptured 35.7 years after being tagged and released and calculated as having an age exceeding 45 years gave estimates of only 18-20 years of age.
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... Estudios de edad y crecimiento fueron realizados en otras latitudes para distintas especies del género Mustelus , Moulton et al. 1992, Yamaguchi et al. 1996, Francis y Maolagain 2000, Farrel et al. 2010, del género Callorhinchus (Sullivan 1977, Bell, 2012Alarcón et al. 2014) y diversas especies de rayas , Walmsley-Hart et al. 1999, Francis et al. 2001, Bellodi et al. 2016. Acompañando esta tendencia, en el último tiempo comenzaron a incrementarse los estudios sobre edad y crecimiento de los condrictios del Mar Argentino , Perez Comesaña et al. 2011, Hozbor y Massa 2011). ...
... Diferentes estudios indican variaciones geográficas en las características de historia de vida de la especie, reportando un aumento en la talla media con la latitud en el área de la provincia de Buenos Aires (Cousseau 1986 En cuanto a edad y crecimiento existe un estudio realizado a partir de lectura de edades en la región costera de la provincia de Buenos Aires (34°-41°S) (Hozbor et al. 2010) y recientemente se ha publicado un estudio para la zona de Bahía Anegada al sur de la provincia de Buenos Aires (Molina et al. 2017). A su vez, para otras especies del género Mustelus se han realizado diversos estudios de edad y crecimiento a partir de la lectura de edades en los centros vertebrales (Tanaka y Mizue 1979, Yudin y Cailliet 1990, Moulton et al. 1992, Yamaguchi et al. 1996, Farrel et al., 2010. ...
... Finalmente, varios estudios han validado que la edad en el género Mustelus puede ser determinada enumerando los pares de bandas de crecimiento en los centros vertebrales (Tanaka y Mizue 1979, Yudin y Cailliet 1990, Moulton et al. 1992, Officer et al. 1997, Yamaguchi et al. 1996. Basándonos en estos trabajos en este estudio se asumió que cada el conjunto de bandas de crecimiento (compuesta por un anillo opaco/grueso y un anillo traslucido/fino) representa un año de edad. ...
Características de historia de vida del Tiburón gatuzo, Mustelus schmitti, en el Golfo San Matías, Argentina: Life history traits of the Narrownose smoothhound Mustelus schmitti at San MatíasGulf, Argentina
Article
Full-text available
  • Oct 2022
En el presente trabajo se estudiaron las características de historia de vida en cuanto a edad, crecimiento, longevidad y talla-edad de madurez del Tiburón gatuzo, Mustelus schmitti, en el Golfo San Matías, Argentina. La edad y crecimiento fueron calculadas a partir de la lectura de bandas en secciones vertebrales evaluando cinco modelos de crecimiento. El rango de tallas registrado en los muestreos de los desembarques comerciales fue de 37 y 89 cm de longitud total (LT) para machos y entre 39 y 106 cm para hembras. Las edades observadas fueron entre 1 a 15 años para machos y 1 a 21 años para hembras. El modelo de von Bertalanffy de 2 fases para ambos sexos juntos fue seleccionado como el más adecuado según el ajuste estadístico y el criterio biológico, estimándose los siguientes parámetros: edad a la talla cero t0= -3,56 años (talla de nacimiento L0= 35,7cm); talla asintótica L∞= 103,12cm; y coeficiente de crecimiento K= 0,12 años-1. La longevidad estimada fue de 21 años. Los machos y hembras maduran a una edad y talla media similar de 5,6 años y LT50% de 66,9 cm. No se encontraron diferencias entre sexos en las curvas de crecimiento. Este estudio contribuye al conocimiento de las características de historia de vida de la especie en el sur del Atlántico sudoccidental (ASO) reportando que M. schmitti tiene un crecimiento moderado, es una de las especies más longevas dentro del género y tiene una edad media de madurez temprana que representa aproximadamente un cuarto de la longevidad estimada.
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... The gummy shark (Triakidae: Mustelus antarcticus) is endemic to Australia and has been the target of a commercial fishery since the 1920s (Moulton et al. 1992). The species occurs to a depth of 400 m (Kyne et al. 2021) in southern and north-eastern Australia between Geraldton, Western Australia (28°S), and Hinchinbrook Island in Queensland (~18°20 0 S; Kyne et al. 2021). ...
... However, the authors stated that improvements to life-history information for this, and other, species are required to ensure the accurate assessment of risk. Moulton et al. (1992) described the growth of M. antarcticus from a broad geographical range in southern Australia. These authors fit variants of the von Bertalanffy growth function (VBGF) to length-at-age and tag-recapture data and found that growth varied spatially and temporally, and by sex. ...
... These authors fit variants of the von Bertalanffy growth function (VBGF) to length-at-age and tag-recapture data and found that growth varied spatially and temporally, and by sex. The VBGF growth completion parameter derived in Moulton et al. (1992) varied between 0.047 and 0.304 year −1 . More recently, Rigby et al. (2016) reported the VBGF growth parameters for M. antarcticus, formerly M. walkeri, on the basis of length-at-age samples collected from the QECOTF in central Queensland, and found that the species was slow growing (k = 0.033 year −1 ) and late to mature (females: 10-14 years). ...
A re-examination of the growth of the gummy shark (Mustelus antarcticus) from Queensland, Australia
Article
Full-text available
  • Jul 2022
The gummy shark (Mustelus antarcticus) is endemic to Australia and is the target of commercial fisheries in southern Australia. However, the Queensland population is subjected to low levels of fishing mortality. The present study re-analysed a limited length-at-age dataset collected from central Queensland to estimate growth parameters in a Bayesian framework, with informative priors for size-at-birth and maximum size. Growth parameters were estimated using a multi-model approach. This study showed that M. antarcticus caught in Queensland exhibits slow growth compared with conspecifics in southern Australia, and females grow slower and larger than do males. The combined length-at-age data for males and females was best described by the von Bertalanffy growth function and the growth parameters were L∞ = 1852 mm (total length, TL), L0 = 261 mm TL and k = 0.044 year⁻¹ for males and females combined. The ‘BayesGrowth’ R package offers a simple method to minimise bias in the estimation of growth parameters from a limited length-at-age dataset in a Bayesian framework.
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... Additionally, and potentially in line with such clear genetic differentiation, substantially different growth parameters have been estimated between G. galeus populations worldwide. Within the Southern Hemisphere, sex-specific individual growth rates may vary by a factor of 2 or more between populations and asymptotic lengths by up to 40% (Ferreira & Vooren, 1992;Grant et al., 1979;Moulton et al., 1992). Comparatively, few studies have estimated individual growth rates in the Northeast Atlantic or Mediterranean (Dureuil & Worm, 2015;Henderson et al., 2003), and there remains a need for additional population-specific growth rate data. ...
... Sex-differentiated growth rates and differences in sizes at maturity have been widely documented in G. galeus populations globally (Dureuil & Worm, 2015;Ferreira & Vooren, 1992;Grant et al., 1979), albeit with some exceptions (Francis & Mulligan, 1998;Moulton et al., 1992;Olsen, 1954). Such differentiation may have an impact on this population's response to exploitationparticularly in combination with the large differences in sex-specific sizes-at-maturity (Dureuil, 2013) if the level of overall exploitation is high, or females face specific exploitation risks (e.g., due to sex-based spatial segregation; Haugen et al., 2017;Mucientes et al., 2009). ...
Movements, growth rates and strong sexual segregation in critically endangered tope sharks Galeorhinus galeus in the Northeast Atlantic
Article
Full-text available
The tope (Galeorhinus galeus, Linnaeus, 1758) is a critically endangered shark, which, like numerous elasmobranchs, faces severe global decline. There are, however, substantial disparities between this species' global conservation status and those of some local populations, with the Northeast Atlantic representing a relative stronghold for this species. However, several areas of uncertainty, particularly regarding individual movement patterns, currently hamper region‐specific conservation efforts. Therefore, utilising capture‐mark‐recapture tagging data, collected predominantly by recreational anglers in Ireland – but with recaptures throughout the Northeast Atlantic and Mediterranean – we investigated regional population structure, spatial segregation and individual movement patterns, and estimated sex‐specific individual growth rates. This revealed a marked pattern of sexual segregation, with females residing further south than males overall, and with an Irish‐specific trend towards male‐dominated catches in Atlantic regions versus more even sex ratios in the Irish and Celtic Seas. Recapture timings and locations suggest that female movements are more strongly driven by seasonal water temperatures changes, being broadly in line with the north–south migratory paradigm. Spatiotemporal overlap of mature individuals suggests that the North Channel, Irish Sea and northern Celtic Sea may constitute a key mating area. Female sharks may utilise southerly regions during gestation, with the presence of young‐of‐the‐year indicating that the Irish Sea and neighbouring regions subsequently act as parturition/nursery areas. Our results demonstrate the value of such long‐term programmes, in this case facilitated by citizen science, in identifying broad‐scale movement patterns in wide‐ranging species and specific regions of interest for further study and/or implementation of targeted conservation measures.
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... Gummy sharks are relatively fast growing and moderately long lived with males reaching at least 17 years and females 20 years (Moulton et al. 1992) with growth bands being formed annually (Walker, et al. 2001). Like most sharks, growth is sexually dimorphic and females grow larger and live longer than males. ...
... The effective, nominal and standardised catch rate series of gummy sharks appear to be poor indices of stock abundance, limiting the ability to represent population dynamics for any dynamic model fit to these time series. In addition, growth and gillnet mesh selectivity parameters are not available for gummy sharks in WA so information from gummy sharks from SA and Victoria was used (Kirkwood & Walker 1986;Moulton et al. 1992). In order to conduct stock assessments based on best available information (instead of only life history and catch as done in the SR model), it is suggested that field sampling be undertaken to collect samples of catch age-composition, biological and gillnet mesh selectivity information. ...
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... Data were generated for the gummy shark, Mustelus antarcticus, and school shark, Galeorhinus galeus, using parameters from studies conducted on southern Australian pop-ulations (Table 1) (Grant et al. 1979;Kirkwood and Walker 1986;Moulton et al. 1992;Walker 1992Walker , 2005Walker , 2007Punt and Walker 1998). Both species are well-studied and were chosen to be representative of fast and slow chondrichthyan life history styles, respectively (Stevens 1999). ...
Quantifying maternal reproductive output of chondrichthyan fishes
Article
Full-text available
  • Sep 2024
For the live-bearing and egg-laying class of chondrichthyan fishes a three parameter logistic ‘maternity’ function with a variable upper asymptote, PMax, can be used to predict the average probability of a female giving birth or laying eggs in a season. Although fundamental to calculating the reproductive capacity of a population, few studies report maternity functions, with maturity functions often used as a proxy. Applying logistic models to simulated and empirical data showed that it was feasible to estimate PMax from maternal data and that accuracy, bias, and confidence interval coverage often improved compared to when a fixed value was used. However, sample sizes of 100–200 maternal females were typically required for accurate estimation of PMax. While maturity parameters could be estimated with greater accuracy, substituting them for maternity parameters overestimated lifetime reproductive output. Greater use of maternity functions has the potential to improve calculation of reproductive output in quantitative populations models. In addition to improvements in parameter estimation, this method involves fewer assumptions and enables statistical inferences to be made on frequency of reproduction.
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... En el trabajo de Hozbor et al. (2010) se utilizó una prueba multivariada T2 de Hotelling con la formulación propuesta por Cerrato (1990), mientras que Molina et al. (2017), Bernasconi et al. (2022) y en este estudio se utilizó la prueba χ 2 de razón de verosimilitudes (Kimura 1980). Cerrato (1990) demostró que este enfoque es más confiable que las comparaciones simultáneas de dos o tres parámetros de vB basadas en la prueba de Hotelling (Moulton et al. 1992). Por otro lado, Goldman (2005) advierte que una prueba de razón de verosimilitud siempre igualará o superará a otros métodos en precisión y confiabilidad. ...
Edad y crecimiento del tiburón gatuzo Mustelus schmitti (Carcharhiniformes, Triakidae) en aguas costeras de la provincia de Chubut, Patagonia, Argentina
Article
Full-text available
  • Mar 2024
El gatuzo, Mustelus schmitti (Carcharhiniformes, Triakidae) es un tiburón endémico del Océano Atlántico Sudoccidental y está catalogado como en peligro crítico por la UICN. La edad y el crecimiento de M. schmitti se estudiaron utilizando cortes sagitales de vértebras de 102 hembras y 121 machos capturados incidentalmente por la pesquería de langostino y por pescadores deportivos costeros en la Patagonia Central (43-44° S). Las edades máximas observadas para hembras y machos fueron 18 y 16 años, respectivamente. Se ajustaron siete modelos de crecimiento (longitud a la edad). El modelo de dos fases de von Bertalanffy presentó el mejor ajuste para hembras y machos. No se encontraron diferencias significativas en el crecimiento entre sexos. Los parámetros fueron longitud asintótica (L∞)=916 mm; coeficiente de crecimiento (k)=0.12 años-1; edad a la que se produce la transición entre las dos fases de crecimiento (th)=5.26 años; talla al nacer (L0)=283.03 mm, y longevidad (tmáx)=21.92 años. La edad de madurez sexual se estimó en 8.86 y 8.48 años para las hembras y los machos, respectivamente. M. schmitti presenta un crecimiento moderado, una vida relativamente larga y una edad de madurez tardía, similar a otros elasmobranquios caracterizados como extremadamente vulnerables.
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... Our estimates of growth and longevity of the two Mediterranean smooth-hounds are also coherent with the patterns in life-history traits found for other smooth-hound species. For most of the species belonging to the genus Mustelus, the longevity seems to be between 10 and 20 years: 16 years: Mustelus antarcticus [47], M. canis [48], and M. walkeri [49]; 13 years: M. asterias [50] and M. henlei [51], and 12 years: M. lenticulatus [52]; 11 years M. schmitti [53]; 9 years: M. californicus [51] and M. manazo [54]. According to these findings, smooth-hounds cannot be considered long-living species as other Carchariniformes [55], and this, along with a rather fast growth, can be the main reason explaining the existence of productive fisheries exploiting these meso-predatory sharks in several marine areas (e.g., [56][57][58]). ...
Sharks Do Not Always Grow Slowly: Tagging Data Reveal a Different Pattern of Growth, Longevity and Maturity for Threatened Smooth-Hounds in the Central Mediterranean Sea
Article
Full-text available
  • Nov 2022
Elasmobranchs are among the marine species more threatened by overfishing. Their conservation is often impaired by the lack of knowledge of species’ life history traits. We filled knowledge gaps on age and growth of two threatened smooth-hound sharks (Mustelus mustelus, Mm; Mustelus punctulatus, Mp) in the central Mediterranean Sea, combining standard vertebrae analysis with growth increment data from a tagging survey. Our data revealed that the two species grow at a faster rate than previously estimated using vertebrae reading only. The maximum age/size found was higher for Mm (16 years, 170 cm TL) than Mp (8 years, 120 cm TL), the first species attaining larger size-at-age than the second one. Mp reaches maturity at earlier ages (A50 3 years for both females and males) than Mm (A50 females: 4 years; males: 3 years). The use of the tag-recapture method to validate the growth rate, firstly derived by sectioned vertebrae readings, highlighted the presence of false check marks. The new estimates of growth and longevity have important implications for the assessment of natural mortality, productivity, and stock resilience to fishing pressure which, combined with the high site fidelity highlighted by tagging data, may have crucial implications for the conservation of these two threatened sharks in the Mediterranean Sea.
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... Evaluating the use of multiple growth models is important in describing the growth of a species . Previous age and growth studies have esti-mated a wide range of values of k for genus Mustelus, from 0.1 to 0.695 year −1 for males and from 0.06 to 0.42 year −1 for females (tanaka & mizue, 1979;yuDin & Cailliet, 1990;FranCiS & FranCiS, 1992;moulton et al., 1992;yamaguChi et al., 1996;gooSen & Smale, 1997;. When compared to other species from the genus, M. punctulatus is among the larger, slower-growing (Tab. ...
Life history traits of the Blackspotted smooth-hound Mustelus punctulatus (Carcharhiniformes: Triakidae) in the Adriatic Sea
Article
  • Dec 2021
We present demographic and reproductive parameters of commercially exploited shark, blackspotted smooth-hound (Mustelus punctulatus), based on samples from 117 males and 108 females from the Adriatic Sea. Calculated size and age at maturity were 83.1 cm in total length (TL) and 6.6 years for males and 100.0 cm TL and 12.5 years for females. The oldest observed male and female were 14 and 19 years old, respectively. The Gompertz growth model provided the best fit and predicted a theoretical maximum size (L∞) of 129.3 cm TL and a growth coefficient (k) of 0.15 year–1 for males, and L∞ = 141.1 cm TL and k = 0.13 year–1 for females. Obtained life history traits classify smooth-hound as slow-growing species, extremely sensitive to fishing, and highlight the need for the development of management strategy for this vulnerable species.
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Density-dependent growth of silver hakes
Article
  • Jul 1986
The growth rate of the silver hake Merluccius bilinearis in the northern Georges Bank-Gulf of Maine stock appears to be highly density-dependent after fish reach the size at which they become piscivorous. The correlation between mean weight of age-2 through -5 fish and three estimates of relative stock density (catch per unit effort CPUE from commercial vessels, and virtual population analysis VPA of biomass and abundance) for the period 1962-1979 was analyzed by regression and Spearman rank correlation analyses. Mean weight at age was significantly and inversely correlated with estimates of stock density for all ages, although correlation coefficients were markedly lower for age-2 fish than for older age-groups. The lower correlation for age-2 fish may be due to reduced feeding competition with the adult stock, because silver hakes feed almost entirely upon invertebrates until becoming piscivorous after reaching 20-30-cm fork lengths between ages 1 and 2. Mean weight of age-2 fish was not correlated with year-class abundance, suggesting that growth rate may be density-independent for pre-adult life stages of this stock. Correlation was highest for age-3 fish; 84 and 75% of the variation in mean weight was explained by variation in CPUE and VPA biomass estimates, respectively. Growth of older fish seemed to be density-dependent only during periods when stock density was high. Mean weight at age was not correlated with CPUE for age-3 fish when data from only periods of low stock density were considered, but was significantly and inversely correlated when data from periods of high stock density were considered. The frequency with which density-independent growth has been identified in natural populations is probably due to the confounding effect that environmental variability and biological interactions have upon growth, and the probable reduction in intraspecific competitive pressure associated with exploited fish stocks maintained at low levels of density.
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Studies on Sharks-XV, Age and growth of Japanese dogfish Mustelus manazo Bleeker in the East China Sea
Article
  • Jan 1979
Vertebral centrums of Japanese dogfish Mustelus manazo which were caught in the East China Sea between July 1975 and February 1977 and collected at Nagasaki Fishmarket were used as the materials for age-determination and growth studies. One ring is formed once a year in both sexes from March to June. Von Bertalanffy growth equation of this species which was obtained by Allen's method is: Lt=71.4[1-exp(-0.695(t+0.734))]for males Lt=88.6[1-exp(-0.379(t+1.133))]for females where Lt is the total length in cm at age t and t is age in years. Estimating from growth curves, the sexual maturity of this species is at the age of two or three years in males as well as in females. The relationship between the total lengthL (cm) and the body weight W(g)is: W=6.41×10⁻³L2.8524 for males and W=9.98×10⁻⁴L3.3093 for females.
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