Length and age compositions and growth rates of the Australian herring Arripis georgiana in different regions

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.


2011 ◽  
Vol 32 (4) ◽  
pp. 550-556 ◽  
Author(s):  
Marcello Mezzasalma ◽  
Fabio Maria Guarino ◽  
Angelica Crottini ◽  
Franco Andreone ◽  
Philip de Pous

AbstractAge structure and growth in the Moroccan spadefoot toad, Pelobates varaldii were estimated by skeletochronology and reported for the first time for a population living in NW Morocco. Snout vent length and body mass did not significantly differ between the sexes, although females appeared larger and heavier than males. Age ranged 2-7 years in males (mean age±SD: 4.5±1.2, n = 66) and 2-10 years in females (4.7±2.4, n = 20). The difference in age was not significant between the sexes. The modal age was 5 years for males and 3 years for females. The age distributions significantly differed between the sexes. Von Bertalanffy growth curves showed a similar profile between the sexes although growth coefficient was higher in males than in females. Longevity and growth rates of P. varaldii were compared with those of other species of the genus Pelobates.



1999 ◽  
Vol 50 (2) ◽  
pp. 103 ◽  
Author(s):  
P. L. Horn ◽  
R. J. Hurst

Age determination of gemfish by counting hyaline zones in otoliths was validated by following the progression of modes in length–frequency distributions and the progression of strong and weak year classes in age–frequency distributions. Length–frequency and otolith samples were examined from four areas (west Northland, east Northland and Bay of Plenty, Wairarapa coast, and the Stewart- Snares shelf). Age–frequency distributions and von Bertalanffy growth parameters were calculated and compared between areas. Two gemfish stocks are indicated on the basis of patterns of year class strengths, trends in commercial landings and likely spawning areas; one off the east and north of the North Island, and another off the west and south of the South Island. Estimates of natural mortality are presented for the two stocks.



1987 ◽  
Vol 38 (2) ◽  
pp. 225 ◽  
Author(s):  
JP Glaister ◽  
T Lau ◽  
VC McDonall

Growth rates and migration of P. plebejus were investigated by a series of tagging experiments. Growth records of 157 recaptured, streamer-tagged prawns from 2450 releases were analysed for estimates of von Bertalanffy growth parameters by Fabens method. The size-age relationship differed between sexes with males attaining only 75% of the maximum size of female prawns. There was no appreciable size-related mortality of tagged individuals. Recaptured tagged prawns confirmed the previously determined northerly movement and showed little movement toward deeper water off New South Wales. Once past the easternmost point of the continent dispersal into a range of depths occurred. There was no apparent relationship between rates of movement and size, suggesting that fluctuations in the intensity of the East Australian Current were responsible for variations in these rates. Based on the results of this and other tagging studies, a two-substock hypothesis, defined by the origins of the bulk of recruits, is postulated.



2015 ◽  
Vol 66 (6) ◽  
pp. 535 ◽  
Author(s):  
Lauren Veale ◽  
Peter Coulson ◽  
Norman Hall ◽  
Alex Hesp ◽  
Ian C. Potter

This study of Pelates octolineatus is the first to use individually aged fish to describe the life cycle of a terapontid, a speciose and abundant Indo-West Pacific family. On the lower west Australian coast, this species uses dense seagrass as a nursery area and, after ~1 year of life when approaching 100mm in total length (TL), moves into deeper waters over sparser seagrass where it matures at the end of its second year at ~140–170mm. The maximum TL and age were 256mm and 10 years. A modified von Bertalanffy curve, allowing for a linear increase in the growth coefficient with age, improved the fit to the lengths at age of older P. octolineatus. Growth was even better described by extending this model to allow for seasonality through incorporating a sine-based curve. This model described well the seasonality exhibited by modal progressions in monthly length–frequency distributions. Instantaneous growth rates, particularly of the youngest age classes, peaked in the warm, summer months and the amplitude of seasonal change in these rates declined with increasing age. Gonadal recrudescence occurred in early spring as temperature and day length increased and spawning peaked in late-spring to mid-summer when temperatures were approaching their maxima.



1988 ◽  
Vol 45 (6) ◽  
pp. 936-942 ◽  
Author(s):  
R. I. C. C. Francis

The two most common ways of estimating fish growth use age–length data and tagging data. It is shown that growth parameters estimated from these two types of data have different meanings and thus are not directly comparable. In particular, the von Bertalanffy parameter l∞ means asymptotic mean length at age for age–length data, and maximum length for tagging data, when estimated by conventional methods. New parameterizations are given for the von Bertalanffy equation which avoid this ambiguity and better represent the growth information in the two types of data. The comparison between growth estimates from these data sets is shown to be equivalent to comparing the mean growth rate of fish of a given age with that of fish of length equal to the mean length at that age. How much these growth rates may differ in real populations remains unresolved: estimates for two species of fish produced markedly different results, neither of which could be reproduced using growth models. Existing growth models are shown to be inadequate to answer this question.



2020 ◽  
Vol 71 (7) ◽  
pp. 810
Author(s):  
M. SriHari ◽  
Y. Gladston ◽  
S. M. Ajina ◽  
G. B. Sreekanth ◽  
Rajeev Raghavan ◽  
...  

The indigo barb Pethia setnai is a threatened small cyprinid endemic to the Western Ghats biodiversity hotspot of India. In this study, the length–weight relationship and length–frequency-based population dynamics of this species, which are important prerequisites for effective fisheries management, were investigated for the first time based on specimens collected from the Mhadei River in the northern part of the Western Ghats. Estimated von Bertalanffy growth parameters were as follows: theoretical maximum length, L∞, 70.88 mm; growth coefficient, k, 1.50 year–1; and theoretical age at length 0, t0, –0.016 years. Natural mortality of P. setnai was higher than fishing mortality, and the present exploitation level (0.37) was less than 60% of the predicted maximum exploitation, suggesting that the species is not exploited to a level that is detrimental to the local population.



Assessment of the growth and mortality parameters of Fenneropenaeus indicus and Metapenaeus monoceros was conducted. Samples for the study were collected during two ship surveys conducted in February and June 2011 and from land-based surveys on two sites at Bagamoyo and Nyamisati, which was conducted between February 2011 and December 2012. Lengthbased stock assessment FiSAT II software package was used for assessment. The growth parameters which were asymptotic size (L∞), growth coefficient (K), total (Z) and natural (M) mortality, exploitation rate (E) and recruitment pattern were estimated. The results of analysis indicate that asymptotic size (L∞) for F. indicus was 44.1 mm CL for zone 1, zone 2 and Bagamoyo while Nyamisati was 48.3 mm CL. The growth coefficient (K) was 0.42, 0.83, 0.3 and 0.65 per year for zone 1, zone 2, Bagamoyo and Nyamisati respectively. The natural mortality (M) value was low in Bagamoyo and high in zone 2 while exploitation rate (E) and was high at Nyamisati area and low at Bagamoyo site. The study observed high exploitation levels on the two land-based sites (Bagamoyo and Nyamisati) despite the existing moratorium on prawn commercial fishing activities since 2008 hence seasonal closure for artisanal fishers was recommended.



2019 ◽  
Vol 66 (4) ◽  
Author(s):  
Ali Salarpouri ◽  
Ehsan Kamrani ◽  
Farhad Kaymaram ◽  
Rasool Mahdavi Najafabadi ◽  
Mehrnaz Ghanbarzadeh

The population dynamics of Sardinella sindensis (Day, 1878) was studied from samples in the commercial fishery in the coastal waters of the Persian Gulf and Oman Sea. A total of 12,898 specimens were collected through monthly sampling of boat purse seine and beach seine catches. Total length of the sampled fishes ranged from 5.0 to 19.9 cm. The von Bertalanffy growth parameters determined using monthly length frequency distribution were asymptotic length (L∞ = 21 cm), growth coefficient (K = 1.2 year-1) and age at zero length (t0 = -0.14 year). The estimated value for longevity (tmax) was 2.5 years. The probability of capture was calculated as Lc25=10.2 cm, Lc50=10.9 cm and Lc75=11.8 cm total length. Four cohorts with mean lengths of 7.2, 11.7, 15.7 and 18.6 cm were discerned in a year, with two recruitment peaks. The calculated length-weight equation was W= 0.0078 L3.02. The instantaneous rates of mortality (Z) was estimated as 4.02, with natural mortality M=2.19 and fishing mortality F=1.83 year-1. The exploitation rate (E) was 0.46, which was found to be reasonable for current fishing effort. From the yield-per-recruit analysis, Emax was estimated as 0.79, confirming that the stock is under optimum exploitation.



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.



2001 ◽  
Vol 52 (4) ◽  
pp. 641 ◽  
Author(s):  
Alan R. Jordan

Transverse sections of sagittae were examined. The first and second annual increments were defined by examination of the progression of otolith radius and length of the 0+ and 1+ cohorts. Growth in both sexes is rapid until ~5 years old (32–35 cm), and then slows appreciably. There was a broad range of lengths within individual age-classes, with a maximum of 12 age-classes present in a 1 cm length-class. Maximum ages of males and females were 41 and 30 years, respectively, which is considerably higher than previously estimated from whole otoliths. There was no significant difference in the growth curves between males and females, although this is influenced by the large number of juveniles and by the examination of relatively few large, older fish. The sex-specific von Bertalanffy growth parameters are: L∞ 38.4 cm FL, t0 –0.07 years, K 0.36 year–1 for females and L∞ 36.2 cm FL, t0 0.15 years, K 0.42 year–1 for males. The age composition was dominated by 4–7 year olds but showed evidence of considerable recruitment variability, particularly in the strong 1988 year-class. The relationship between the life-history strategy of N. macropterus and recruitment variability is discussed.



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