Comparative rates of growth of the Port Jackson shark throughout its southern Australian range

2012 ◽  
Vol 63 (8) ◽  
pp. 687 ◽  
Author(s):  
Christopher Izzo ◽  
Kate R. Rodda

Port Jackson sharks are distributed throughout southern Australia, with evidence suggesting that potential subpopulations exist. If subpopulations are evident, then phenotypic variation among groups should result in differences in life-history parameters. The present study tested for patterns of spatial variability of life-history parameters among regional Port Jackson shark populations. Rates of growth from Port Jackson sharks caught in the gulf waters of South Australia were calculated on the basis of counts of vertebral increments. Growth parameters were obtained by fitting the length-at-age data to von Bertalanffy and Gompertz growth functions. While the derived growth curves fit the length-at-age data well (r2 ranged from 0.87 to 0.91), parameters showed considerable differences between the two functions, with the von Bertalanffy function providing the more realistic estimates of growth (combined sexes: k = 0.081 year–1, L∞ = 1232 mm total length and t0 = –1.937 years). Life-history parameters for South Australian Port Jackson sharks were collated with the available data for the species, facilitating comparisons among regional populations. Growth curves among populations varied significantly; however, considerable overlap in the length ranges of size at birth and sizes at maturity among populations were evident. Overall, the data presented here do not provide definitive support for the presence of subpopulations across the distribution of the Port Jackson shark, suggesting that molecular analysis maybe required to directly test for structuring.

2003 ◽  
Vol 60 (5) ◽  
pp. 1086-1102 ◽  
Author(s):  
C Piñeiro ◽  
M Saínza

Abstract Difficulties in age estimation for hake (Merluccius merluccius) have hampered the assessment of stocks. Here, we describe new, agreed ageing criteria based on the interpretation of the pattern of otolith growth. Improved estimates of von Bertalanffy growth parameters, and new estimates of maturity ogive parameters and length–weight relationships for European hake from Iberian Atlantic waters are presented. The results came from a study carried out during 1996–1997 and provide the first published account of the main life history traits of Southern stock hake. von Bertalanffy growth parameters of males were L∞ = 70cm, K = 0.18 year−1, and t0=−0.97 year, and those of females were L∞ = 89cm, K = 0.13 year−1, and t0 = −1.15 year. Growth of sexes differed from age 3 onwards, with females being on average larger and heavier than males. The estimated total length (L, cm)–total weight (W, g) relationships were W=0.0132135L2.8134246 for males and W=0.0086471L2.942563 for females. Spawning took place from December to May with a peak in February. The mean length and age at first maturity were 32.8 cm at 2.5 years for males and 45 cm at 4.4 years for females. Application of new ageing criteria showed that otolith sections may be used to determine ages up to 5 years in a consistent manner. These results indicate that hake of the Southern stock grow at higher rates and mature earlier than previously considered. Summaries of hake's life history parameters from other marine regions are also presented in order to make information that belongs largely to the grey literature available.


2011 ◽  
Vol 62 (6) ◽  
pp. 548 ◽  
Author(s):  
S. Tanaka ◽  
T. Kitamura ◽  
T. Mochizuki ◽  
K. Kofuji

The white shark, a top predator inhabiting the world’s oceans, is an endangered species. However, knowledge of its life-history traits and population structure is still limited. We hypothesised that life-history traits would vary among populations because the species’ various habitats are diverse and change through time. Age was estimated by counting growth bands in the centra of white sharks caught in Japan. The von Bertalanffy growth parameters were estimated at L∞ = 455 cm TL, k = 0.196 year–1 and t0 = –1.92 years for males and L∞ = 607 cm TL, k = 0.159 year–1 and t0 = –1.80 years for females. The growth rate to maturity was higher than that known for individuals from California and South Africa. Male sharks matured at 310 cm TL at 4 years of age and females began to mature at ~450 cm TL and 7 years. The D-loop-region sequences of mitochondrial DNA extracted from Japanese white sharks and GenBank datasets from sharks of California, Australia, New Zealand and South Africa indicate that Japanese white sharks form a monophyletic clade separate from the populations of other regions. The results suggest that unique life-history traits of Japanese white sharks may be caused by genetic differences.


1980 ◽  
Vol 37 (12) ◽  
pp. 2266-2271 ◽  
Author(s):  
Donald R. Gunderson

Theory on r-K selection is used as a basis for examining correlations between instantaneous rate of natural mortality (M), gonad-body weight index, age at maturity, longevity, and Bertalanffy growth parameters (k, L∞) for 10 species of marine fish. All correlations were consistent with r-K selection theory. The gonad-body weight index was found to be more highly correlated with M than any of the other life history parameters examined (r2 = 0.62), and stepwise multiple regression showed that additional variables added little to the predictive ability of the model. The gonad-body weight index appears to be quite useful in predicting M, and development of an analogous index on an energetics basis might enhance its utility in this regard.Key words: natural mortality, r-K selection, life history parameters


Fishes ◽  
2019 ◽  
Vol 4 (3) ◽  
pp. 44
Author(s):  
Michael L. Burton ◽  
Jennifer C. Potts ◽  
Andrew D. Ostrowski

Ages of margate, Haemulon album (n = 415) and black margate, Anisotremus surinamensis (n = 130) were determined using sectioned sagittal otoliths collected from the Southeastern United States Atlantic coast from 1979 to 2017. Opaque zones were annular, forming between January and June for both species, with peaks in occurrence of otoliths with opaque margins in April for margate and March for black margate. The observed ages for margate were 0–22 years, and the largest fish measured 807 mm TL (total length). Black margate ranged in age from 3 to 17 years, and the largest fish was 641 mm TL. Weight–length relationships were: margate, ln(W) = 2.88 ln(TL) − 10.44 (n = 1327, r2 = 0.97, MSE = 0.02), where W is total weight (grams, g); black margate, ln(W) = 3.02 ln(TL) − 11.10 (n = 451, r2 = 0.95, MSE = 0.01). Von Bertalanffy growth equations were Lt = 731 (1 − e−0.23(t+0.38)) for margate, and Lt = 544 (1 − e−0.13(t+2.61)) for black margate. After re-estimating black margate growth using a bias-correction procedure to account for the lack of younger fish, growth was described by the equation Lt = 523 (1 − e−0.18(t+0.0001)). Age-invariant estimates of natural mortality were M = 0.19 y−1 and M = 0.23 y−1 for margate and black margate, respectively, while age-varying estimates of M ranged from 2.93 −0.23 y−1 for fish aged 0–22 for margate and 7.20 − 0.19 y−1 for fish aged 0–18 for black margate. This study presents the first documentation of life-history parameters for margate from the Atlantic waters off the Southeastern United States, and the first published estimate of black margate life history parameters from any geographic region.


1992 ◽  
Vol 43 (5) ◽  
pp. 1241 ◽  
Author(s):  
PL Moulton ◽  
TI Walker ◽  
SR Saddlier

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.


2021 ◽  
Vol 8 ◽  
Author(s):  
Kwang-Ming Liu ◽  
Ya-Wen Huang ◽  
Hua-Hsun Hsu

The life history (age and growth and reproduction) parameters of 35 species (41 stocks) of skates and rays were analyzed using multivariate analyses. Three groups were categorized by cluster analysis (CA) based on principal component scores. Empirical equation was developed for each group to describe the relationships between the predicted a finite rate of population increase (λ′) and the life history parameters: growth coefficient (k), asymptotic length (L∞), age at maturity (Tm), annual fecundity (f/Rc), ratio between size at birth (Lb), and L∞ (Lb/L∞), and ratio between size at maturity (Lm) and L∞ (Lm/L∞). Group 1 included species with slow growth rates (k < 0.011 year–1), early maturity (Lm/L∞ < 0.62), and extended longevity (Tmax > 25 years); Group 2 included species with intermediate growth rates (0.080 year–1 < k < 0.190 year–1), intermediate longevity (17 years < Tmax < 35 years), and late maturity (Lm/L∞ > 0.60); Group 3 included species with a fast growth rate (k > 0.160 year–1), short longevity (Tmax < 23 years), and large size at birth (Lb/L∞ > 0.18). The λ′ values estimated by these empirical equations showed good agreement with those calculated using conventional demographic analysis, suggesting that this approach can be applied in the implementation of management measures for data-limited skates and rays in a precautionary manner.


2019 ◽  
pp. 23-31 ◽  
Author(s):  
George N. Hotos

Growth and mortality of L. aurata (Risso,1810) were estimated in the lagoon of Klisova-Messolonghi (W. Greece), based on age estimation from scale readings of a total of 1048 individuals, ranging between 10 and 59 cm in total length (TL). Age determination revealed nine age classes (0+ to 8+). Maximum age was found to be 8 years for females and 6 years for males respectively. The growth pattern of L. aurata exhibited allometry (b=3.26). The species seems to achieve 34% of its growth during the first year; thereafter the annual growth rate drops. Both sexes presented similar von Bertalanffy growth curves. The von Bertalanffy growth function for the estimated total length-at-age was found Lt = 70.78 [1 - e -0.129(t+1.345)] for the combined sexes. Otolith weight, length and width were tested and they were found to be very good predictors for age. Between the present L. aurata growth parameters and those of other Mediterranean, Caspian and Atlantic Sea for the same species, there were found significant differences in its growth parameters. The total (Z) and natural (M) mortality rate was found to be 0.54 years-1 and 0.33 years-1 respectively. The estimated exploitation rate was found to be E=0.395 which suggests that the existing fishing pressure on L. aurata is rather moderate in the investigated region.


2000 ◽  
Vol 51 (6) ◽  
pp. 631 ◽  
Author(s):  
D. V. Fairclough ◽  
W. F. Dimmlich ◽  
I. C. Potter

Arripis georgiana was collected from coastal waters in Western Australia and South Australia. The opaque zones on the otoliths were shown to be formed annually and thus their number could be used to age the individuals of this species. Although the catches of A. georgiana in south-western Australia, where spawning occurs, were dominated by the 0+ to 5+ age classes, they did contain females and males up to ten and nine years old, respectively. The von Bertalanffy growth parameters for the two sexes in this region differed significantly, with the asymptotic length (L∞) being significantly greater for females (262 mm) than for males (239 mm), whereas the reverse was true for the growth coefficient (k), i.e. 0.813 v. 0.992. The catches of A. georgiana eastwards of 121˚44′E on the south coast of Western Australia, where spawning does not occur, were dominated by the 0+ to 2+ age classes. The above data, when taken in conjunction with earlier tagging experiments and the marked decline that occurs in the number of 2+ fish in South Australia in summer, imply that, during this period, many two-year-old individuals of A. georgiana start migrating towards their spawning areas in south-western Australia.


2007 ◽  
Vol 5 (4) ◽  
pp. 485-490 ◽  
Author(s):  
Giovana Bervian ◽  
Nelson F. Fontoura

The growth of Atherinella brasiliensis (Quoy & Gaimard, 1824) was studied through monthly samples taken at Tramandaí Lagoon, Imbé County, Rio Grande do Sul, Brazil. Animals were captured using a beach seine net. Length-weight relationships and age- growth curves for males and females were adjusted. The growth parameters of the von Bertalanffy growth formulae are Linf=16.0 and k=0.883 for males and Linf=17.0 and k=0.825 for females. First reproduction occurred one year after recruitment. Once reaching maturity, adults of A. brasiliensis reproduced once more in the next spring with two-year-olds and disappeared soon after from size frequency distributions. A few captured animals showed a size compatible with an age of three years.


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