Age, growth and mortality of the garfish, Belone belone (L. 1761) in the Adriatic Sea

Author(s):  
Barbara Zorica ◽  
Vanja Čikeš Keč

A sample of 3393 garfish, Belone belone (Linnaeus, 1761) was captured using a seine net between January 2003 and December 2008, along the eastern Adriatic Sea. The range in total length was 20.8–75.4 cm and in weight was 12.21–639.25 g. Length–length equations for converting size measurements (standard length and fork length to total length (TL)) were linear. In the length–weight relationship, positive allometry was established (b = 3.4818). Age, determined from sagittal otoliths, ranged from 1+ to 8+ years. The estimated von Bertalanffy model growth parameters for garfish were L∞ = 90.3 cm, K = 0.158 year−1, t0 = −0.109. Otolith weight was endorsed as a possible age predictor, as it showed highly exponential correlation with total garfish length and age (Wo = 0.0012 TL2.189; Wo = 0.568t1.486). These findings were used to examine mortality rates and exploitation in order to improve conservation and management of this pelagic species.

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mehmet Zülfü Çoban ◽  
Mücahit Eroğlu ◽  
Mustafa Düşükcan

AbstractThis study was carried out to determine some bioecological characteristics of Mastacembelus mastacembelus, which is the only species of Mastacembelidae family living in Turkey. Fish samples were caught between 2014–2018 from Keban Dam Lake, one of the most important reservoirs of the upper Euphrates Basin. In totally, 348 Mastacembelus mastacembelus individuals were examined, including 178 males and 170 females. The age distributions were defined between the I–XV age groups. Total lengths ranged from 14.20 to 81.80 cm in males and from 15.60 to 77.30 cm in females. Total length–weight relationships were calculated as W = 0.0083 × TL2.6516 for males, W = 0.0043 × TL2.8310 for females and W = 0.0063 × TL2.7256 for all population, and the growth type was estimated as “negative allometric”. The von Bertalanffy growth parameters for all individuals were computed as L∞ = 90.99, k = 0.13, t0 = − 0.45. The total (Z), natural (M), fishing (F) mortality rates and exploitation rate (E) were estimated as Z = 0.313, M = 0.270, F = 0.043 and E = 0.137, respectively. The length at first capture (Lc) was found as 50.72. The optimum, maximum and economic yields were calculated as E0.5 = 0.361; Emax = 0.776; E0.1 = 0.664, respectively.


2016 ◽  
Vol 94 (7) ◽  
pp. 479-488
Author(s):  
J.A. Viccon-Pale ◽  
P. Ortega ◽  
L. Mendoza-Vargas ◽  
P. Castilla-Hernández ◽  
A. López-Cuevas ◽  
...  

Catch size, sex ratio, structure and dynamics, as well as mortality, of a population of the secondary burrower crayfish Procambarus acanthophorus Villalobos, 1948, from tropical wetland La Mixtequilla, Veracruz, Mexico, were examined. Monthly samples were taken from artisanal commercial captures. A total of 2141 individuals were caught. Although the total female:male ratio was 0.86, variation in sex ratios have also been found in monthly catches. Monthly polymodal frequency distributions of cephalothorax length (CL) were analyzed by the Bhattacharya method. Population catches consisted of six CL classes. The CL-class dynamic may show adaptations to the flood period. Growth parameters were estimated using the von Bertalanffy model. For females, K = 0.39 year−1, CL∞ = 57.30 mm, [Formula: see text] = 3.11, and tmax = 6.73 years were found; it is appropriate that for males, K = 0.40 year−1, CL∞ = 59.00 mm, [Formula: see text] = 3.14, and tmax = 6.59 years were found. We also examined whether water temperature influences the catches or sex ratio.


Author(s):  
El-Desoki Menna O ◽  
Younis Younis M ◽  
A Youssef El-Dakar ◽  
Ahmed Salem M ◽  
Ahmed Kassem S ◽  
...  

Age, growth, and mortality of European Seabass (Dicentrarchus labrax) were studied from a small-scaled fishery of Bardawil lagoon, (North Sinai, Egypt). 181 specimens (16.6 to 35 cm total Length and 39.8 to 367.2 g total weight). The relationship between length and weight was W = 0.0054L3.1428. Age was determined by otoliths and age groups I to IV years were observed. Growths in length and weight at the end of each year were calculated. The growth parameters of von Bertalanffy equation were calculated as (L∞ = 48.69 cm, K = 0.1677 yr -1 and t0 = -0.447 yr -1). Growth performance index was calculated (φ = 2.60 for length and 1.25 for weight). Mortality rates were 0.867 yr-1, 0.25 yr1and 0.617 yr-1 for total, natural and fishing mortality, respectively. The currently exploitation rate E = 0.712 yr-1 indicating that, the population of this species is being heavily exploited.


2020 ◽  
Author(s):  
Fabio P. Caltabellotta ◽  
Zachary A. Siders ◽  
Gregor Cailliet ◽  
Fabio S. Motta ◽  
Otto B. F. Gadig

AbstractDue to poorly mineralizing structures, ageing deep-water elasmobranchs requires nonconventional techniques. The aim of the present study was to develop a reliable ageing technique using the vertebral centrum to provide information about the age and growth parameters in the Goblin Shark, Mitsukurina owstoni (Jordan, 1898). One vertebral centrum from an individual measuring 315.2 cm in total length was analysed. A minimum age of 27 years was estimated. By incorporating priors based on the growth of deep-water sharks and an additional likelihood on L∞ using data on large male Goblin Sharks, a Bayesian von Bertalanffy growth model was estimated with a male L∞ of 364 cm total length, weigh 215 kg at L∞, grow slowly with a k equal to 0.049, mature at 16.5 years, and live up to 55 years. Our results are essential to provide useful life history information, with the aim of elucidating the cryptic ecology and biology of this deep-water shark.


2013 ◽  
Vol 93 (5) ◽  
pp. 1415-1421 ◽  
Author(s):  
Aymen Hadj Taieb ◽  
Mohamed Ghorbel ◽  
Nader Ben Hadj Hamida ◽  
Othman Jarboui

Samples of common two-banded seabream Diplodus vulgaris (N = 1097), used in this study, were caught in the Gulf of Gabès (Tunisia) from March 2008 to February 2010. Total length ranged from 7 to 25 cm. Diplodus vulgaris is a protandric hermaphrodite. The overall ratio of females to males was 1:1.66. The reproductive season extended from October to February, and the peak spawning activity occurred in December–January. The total length at which 50% of the population reached maturity was 14.14 ± 0.16 cm for females and 13.57 ± 0.01 cm for males. Parameters of the length–weight relationship (TW = aTLb) for all individuals were a = 0.0185 and b = 2.9319. The youngest specimen in this study was 0+ years, whereas the oldest one was 9 years. The von Bertalanffy growth parameters for the whole sample were: L∞ = 25.4 cm, k = 0.179 and t0 = −1.631 year. The instantaneous rate of natural mortality was: M = 0.333 year−1.


Author(s):  
Alexandra Garcia ◽  
João g. Pereira ◽  
Ângela Canha ◽  
Dália Reis ◽  
Hugo Diogo

Blue jack mackerel Trachurus picturatus monthly samples were collected between 1998 and 2011 to determine morphometric relationships, maturity, growth rates, reproduction and spawning seasonality in north-east Atlantic waters (ICES area Xa2). A total of 2895 specimens were sampled, ranging from 98 to 542 mm in fork-length (LF). The morphometric relationships (length-length and length-weight) showed statistically significant differences between sexes. Ages were estimated by counting growth bands on otoliths and verified by marginal increment analysis, with specimens ranging from 0 to 18 years. The von Bertalanffy models used to estimate growth parameters for both observed and back-calculated length-at-age data gave good fits. The gonads were analysed macroscopically and the spawning season found to occur from December to May. The length at 50% maturity for females and males occurred at 277 mm LF (4.3 years) and 288 mm LF (5.1 years), respectively. The results provide important biological information for fisheries assessment of a species that plays an important key role in the surrounding ecosystem.


2005 ◽  
Vol 62 (1) ◽  
pp. 215-223 ◽  
Author(s):  
Nathan G Taylor ◽  
Carl J Walters ◽  
Steven J.D. Martell

Gear selectivity and the cumulative effects of size-selective fishing produce bias in the length-at-age samples used to estimate the von Bertalanffy growth parameters. In fished populations, fast-growing young fish and slow-growing old fish are overrepresented in size–age samples. To account for such effects, we treated size-at-age observations as multinomial samples, with expected catches in each size–age category dependent on growth parameters, growth variation, size selectivity, abundance at age, and the history of exploitation. Using simulated data sets, estimated growth parameters using the multinomial likelihood were unbiased when fishing mortality was not too high and the shape of the vulnerability function was correct. In contrast, estimated growth parameters using a least squares approach overestimated the metabolic growth coefficient (K) and underestimated mean asymptotic length (L∞). Models that do not explicitly account for the effects of fishing and size selectivity underestimated L∞ and overestimated K. We estimate growth parameters for northern pikeminnow (Ptychocheilus oregonensis) as an example of the method and document a stunted "pigmy" population with an L∞ of 175-mm fork length, attributing its small size to effects of high density and (or) a short growing season.


2018 ◽  
Vol 35 ◽  
pp. 1-8
Author(s):  
Marcus Rodrigues da Costa ◽  
Rafael de Almeida Tubino ◽  
Cassiano Monteiro-Neto

Small-scale fisheries in Brazil contribute to a significant share of total fish production, accessing a large variety of species. Life history parameters from these resources are important for their management and conservation, based on primary data. The objective of this article is to generate growth parameters and mortality rates of ten fish populations from a coastal zone in Southeastern Brazil. Monthly samples were taken between January 2011 and November 2014 from landings of the beach-seine fishery in an area adjacent to the entrance of the Guanabara Bay. All fishes were measured (total length) and weighed. The length-weight relationships (LWR) were estimated by linear regression analysis on log-transformed data of the equation: W = aLb. The Von Bertalanffy Growth Function (VBGF) was fitted to size-at-age data to obtain growth parameters (K, L∞). The length-converted catch curve was used for estimating the instantaneous total mortality (Z). Taylor’s equations provided an independent estimate of the natural mortality (M) and longevity. The difference between Z and M derived Fishing mortality (F). A total of 2,938 individuals from ten fish species were used to determine the length-weight relationships. Harengulaclupeola (Cuvier, 1829) has a new maximum length record for the FishBase LWR database. Sardinellabrasiliensis (Steindachner, 1879) presented the smallest and largest size recorded for LWR observed in the literature and FishBase database. Upeneusparvus showed the greatest total length, while Trichiuruslepturus Linnaeus, 1758, Orthopristisruber (Cuvier, 1830) and Dactylopterusvolitans (Linnaeus, 1758) presented the smallest sizes for LWR in FishBase. The other species showed parameters within the expected values for each group. The performance index combining information from K and L∞ presented values between 2.32 and 3.76 and were considered appropriate for the populations evaluated. Fishing was the primary source of mortality for Caranxcrysos (Mitchill, 1815), Eucinostomusargenteus Baird & Girard, 1855, S.brasiliensis and U.parvus, and less important for Cynoscionjamaicensis (Vaillant & Bocourt, 1883), D.volitans, O.ruber, Selenesetapinnis (Mitchill, 1815), T.lepturus and H.clupeola. The parameters generated may be used for the management and conservation of the species’ stocks.


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.


2003 ◽  
Vol 60 (1) ◽  
pp. 55-66 ◽  
Author(s):  
Emily B Szalai ◽  
Guy W Fleischer ◽  
James R Bence

A concurrent increase in lakewide abundance and decrease in size-at-age of bloater (Coregonus hoyi) in Lake Michigan have suggested density-dependent growth regulation. We investigated these temporal patterns by fitting a dynamic von Bertalanffy model and length–weight relationship with time-varying parameters to mean length- and weight-at-ages (ages 1–7) from annual surveys (1965–1999). We modeled yearling length, asymptotic size (L[Formula: see text]), and the parameters of a power relationship between mean weight and mean length (α and β) as changing slowly over time using a random walk model. The Brody growth coefficient (k) was modeled as a linear function of L[Formula: see text] with year-specific random deviations. Our results support a positive relationship between L[Formula: see text] and k, indicating that under conditions supporting larger asymptotic lengths, individuals approach the asymptote more rapidly. We explored the relationship between year-specific growth parameters and indices of lakewide bloater abundance and found evidence of density-dependent growth. However, in the most recent years, L[Formula: see text] and yearling length have remained low in Lake Michigan despite low bloater abundances, suggesting the occurrence of a fundamental shift in the food web.


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