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1.
The age, growth, reproduction, sexual maturity and stomach content of John Dory (Zeus faber), caught in the Bay of Saros (North Aegean Sea) between September 2006 and September 2008, were investigated. The female‐male ratio was 1.6 : 1. The total length of females ranged from 13.8 cm to 52.8 cm, and of males from 12.2 cm to 42.9 cm. The length‐weight relationship was W = 0.0174*L2.936. Age data derived from vertebral centra readings were used to estimate the growth parameters of the von Bertalanffy equation. Growth parameters for females were L = 58.50 cm K = 0.11 year?1, t0 = ?0.99 year and for males L = 45.01 cm, K = 0.13 year?1, t0 = ?1.17 year. Maximum age was 18 years for females and 17 years for males. Length at first maturity for both females and males was 25.4 cm. Monthly values of the gonadosomatic index indicated that spawning occurred mainly in two peaks: one between January and June, and the other from August to September. Stomach content analysis showed the most‐preferred prey to be Pisces (IRI% 97.3).  相似文献   

2.
In order to update existing life history parameters, age and growth patterns were determined for Giant Kelpfish, Heterostichus rostratus sampled from nearshore kelp forest and estuary habitats in southern California (USA) from April 2012 through June 2015. Fish were collected by pole spear, beach seine, beam trawl, purse seine, and square enclosure. Using age‐at‐length data derived from otolith readings, Giant Kelpfish were found to have a relatively short life span with the largest examined fish reaching a maximum total length of 413 mm at an age of 5 years. Von Bertalanffy growth parameters estimated for this species were: L = 45.1 cm, = 0.25, t0 = ?0.66. Standard length (SL, cm)‐total length (TL, cm) and total length (TL, cm)‐weight (W, g) relationships were described by the equations: SL = 0.90 TL – 1 and = 2.21 × 10?3 TL3.39, respectively. Wild juvenile Giant Kelpfish collected for this study had a higher growth rate than laboratory‐reared fish from a previous study.  相似文献   

3.
Age structure and growth parameters were determined for a population of small spotted grunt, Pomadasys commersonnii in the Arabian Sea. Small spotted grunt samples were collected monthly between September 2007 and August 2008 by beam trawl [40 mm cod‐end mesh size] surveys conducted along the Arabian Sea coast of Oman from Ras Al‐Had in the north to the Oman‐Yemen border in the south west of Salalah between latitudes 16o 33′N and 22o 21′N and longitude 53o 09′ and 59o 55′ E and from depths of 20 to 250 m respectively. Marginal increment analysis of the sagittal otolith confirmed the deposition of annual increments on transverse sections, validating this technique for age and growth studies. Fish size (Fork Length, FL) ranged between 33–78 cm and age of fish ranged between 2 and 14 years with 5–9 years old fish comprising the majority of the catch. Both males and female exhibited asymptotic patterns of growth and the combined growth curve for both sexes provided von Bertalanffy growth (VBG) parameters of L = 77.2 cm FL (≡83.8 cm Total Length), = 0.232/y and t0 = ?0.058 y. VBG parameters, derived from Length‐Frequency Distribution Analysis (LFA) using ELEFAN1, PROJMAT and SLCA, obtained similar values (average values for the 3 methods: L = 78.8 cm FL,= 0.35/y and t0 = ?0.64 y) to those obtained from otolith analysis. A strong linear relationship was observed between otolith weight and age, and although age residuals ±4 years was observed between sagittal otolith age and estimated age (depending on sex and otolith weight), the results indicated that otolith weight could be used as a rapid proxy to estimate age and derive VBG parameters. In conclusion, both otolith ageing and LFA methods provided similar L and k values and the average values derived from all 4 methods lies within the auximetric plot for the species providing confidence in the VBG parameters obtained for small spotted grunt in the Arabian Sea.  相似文献   

4.
Growth parameters in pikeperch may be affected by several factors. The purpose of this study was to investigate the growth and length–weight of pikeperch in a reservoir in south‐western Spain and compare the results with previous published data. Age and growth are described for Sander lucioperca from the Alcántara Reservoir (south‐western Spain) from March to October 2009. A total of 285 fish were examined; the ratio of males to females was estimated as 0.78:1 and age ranges as 1–5 years. Total lengths ranged from 16.1 to 52.5 cm. The length–weight relationships were described as W = 0.00 462 TL3.09 (r = 0.9865) for males and W = 0.00279 TL3.16 (r = 0.9921) for females. Growth was expressed in length and the von Bertalanffy growth parameters were estimated as L∞ = 92.14 cm, k = 0.09, t0 = ?1.05 for males and L∞ = 107.72 cm, k = 0.08, t0 = ?1.16 for females. Growth performance indexes were also estimated as Φ’ = 2.88 for males and Φ’ = 2.96 for females. Differences in growth and length–weight relationships between sexes were not found.  相似文献   

5.
This study examines age and growth of Brauer's lanternfish Gymnoscopelus braueri and rhombic lanternfish Krefftichthys anderssoni from the Scotia Sea in the Southern Ocean, through the analysis of annual growth increments deposited on sagittal otoliths. Otolith pairs from 177 G. braueri and 118 K. anderssoni were collected in different seasons from the region between 2004 and 2009. Otolith-edge analysis suggested a seasonal change in opaque and hyaline depositions, indicative of an annual growth pattern, although variation within the populations of both species was apparent. Age estimates varied from 1 to 6 years for G. braueri (40 to 139 mm standard length; LS) and from 0 to 2 years for K. anderssoni (26 to 70 mm LS). Length-at-age data were broadly consistent with population cohort parameters identified in concurrent length-frequency data from the region for both species. The estimated values of von Bertalanffy growth curves for G. braueri were L = 133.22 mm, k = 0.29 year−1 and t0 = −0.21 year and the values for K. anderssoni were L = 68.60 mm, k = 0.71 year−1 and t0 = −0.49 year. There were no significant (P > 0.05) differences in growth between sexes for either species, suggesting that males and females have similar growth and development trajectories in the Scotia Sea. A positive allometric relationship between LS and wet mass was found for each species, as well as a significant (P < 0.0001) linear relationship between otolith size and LS. Growth performance (Ф′) was similar between the two species and congruent with other myctophid species across the Southern Ocean. This study provides important parameters for future Southern Ocean ecosystem studies in a resource management context.  相似文献   

6.
It is hypothesized that Capoeta antalyensis (Battalgil, 1943) and Pseudophoxinus antalyae (Bogutskaya, 1992) might display specific growth characteristics that differ from other species of their genus. Age and growth were described for species from Duden Creek (Antalya, Turkey) from February 2008 to January 2009. The length–weight relationship for all individuals were described by the parameters: a = 0.0143 and b = 2.946 for C. antalyensis and a = 0.0084 and b = 3.251 for P. antalyae. The von Bertalanffy growth parameters based on data from scales were L∞ = 35.78 cm, k = 0.251 year?1 and t0 = ?0.30 for C. antalyensis and L∞ = 22.59 cm, k = 0.232 year?1 and t0 = ?0.78 for P. antalyae. The growth characteristics for these two species are not much different from those of closely related species from the same genus.  相似文献   

7.
The study investigated the age, growth and sex ratio of Tinca tinca L., 1758 in Seyhan Dam Lake, Turkey and determined its first population structure data in the lake. Fishermen had introduced tinca into the lake between 2001 and 2002. A total of 1284 T. tinca (778 males and 506 females) were captured between January and December 2007 by gill nets of various mesh sizes. The sex ratio was 1 : 1.53 females to males. Total lengths and weights ranged from 12 to 29 cm and 27 to 403.3 g. Ages in both sexes ranged from 1 to 5 years. For all individuals the length‐weight relation and von Bertalanffy growth parameters were W = 0.063 × L2.51 (r = 0.981), and L = 50.86 cm, k = 0.112 year?1, to = ?1.551 year.  相似文献   

8.
This paper provides data on age, growth and diet of the bluemouth rockfish, Helicolenus dactylopterus dactylopterus (Scorpaenidae), central Mediterranean Sea. Estimated by otolith readings, ages ranged from 0 to 21 years. Parameters of the von Bertalanffy growth curves were Linf = 26.1 cm, k = 0.14 year?1, t0 = ?1.92 years and the growth performance index was Φ = 1.98. The weight‐length relationship, W = 0.016 TL2.99; R2 = 0.99, described an isometric growth of the species. This species is a carnivore focusing mainly on the crustaceans Goneplax rhomboides and Lophogaster typicus. Statistical analysis showed an ontogenetic shift between small (4.0–6.3 cm) and larger fishes. Significant differences were also found in relation to the sampling depth.  相似文献   

9.
Population dynamics of 1482 specimens of painted comber, Serranus scriba (Linnaeus, 1758), caught in the Trogir Bay area (eastern mid‐Adriatic) from June 2001 to May 2002 were studied to provide information on age, growth, length–weight relationship, mortality and exploitation rate of the species’ stock. Annuli on otholiths indicated the presence of seven age‐classes. Obtained von Bertalanffy growth parameters were: L = 30.36 cm, K = 0.192 year?1 and t0 = ?0.366.  相似文献   

10.
The objective of this study was to determine the basic population‐specific parameters necessary for fish stock assessment in the Gulf of Annaba and to compare these with data from other Mediterranean regions. Black sea bream Spondyliosoma cantharus (Linnaeus, 1758) (N = 501) were collected monthly from January to December 2008 along the Algerian eastern coasts. More than 22 fish were collected each month and ranged in size from 13.4 to 40 cm total length, weighing from 36 to 1080 g eviscerated weight. Biological sampling included weighing and measuring the fish, gonad weighing, sex and maturity stage determination, and age estimation through otolith readings. Validity of the otolith readings for estimating age and growth was supported using the back‐calculation method. Estimated parameters of the von Bertalanffy model are: L = 33.54 cm, W = 633.46 g, = 0.52 year?1 and to = ?0.04 year. The growth performance index (φ) is: 2.76. The length‐weight relationship is: EW = 4.4.10?6 TL3.23. The spawning period occurred from February to May, while the gamete emission peaked in April. Females reached sexual maturity at 19.3 cm (2 years) and males at 21.3 cm (3 years). Sexual inversion occurs at approximately 24.3 cm. Spondyliosoma cantharus was characterized as being a protogynic hermaphrodite.  相似文献   

11.
The present study provides fisheries biology knowledge which will allow the implementation of regulatory measures contributing to the sustainability of the fisheries and the conservation of the stout beardfish Polymixia nobilis Lowe, 1838 off the Canary Islands, north eastern Atlantic Ocean. Males ranged between 16.5 and 38.4 cm fork length (FL) and females from 14.2 to 46.5 cm FL. Sex ratio by size classes provided significant differences in classes higher than 36 cm, being clearly unbalanced in favour of females. Individuals in maturing and mature stages were present during all months sampled, although a spawning peak is evident between April and June. Size at first maturity was estimated as 26 cm FL for females and 30 cm FL for males. Age was determined from annuli in whole otoliths. Age range was found to be 0–14 years for fish measuring 14.2 to 46.5 cm FL. It is a slow‐growing and long‐lived species. Significant differences in the growth parameters between sexes were detected. The von Bertalanffy growth parameters estimated for females (n = 213) were L = 45.92 cm LF, k = 0.16 years?1 and t0 = ?2.84 years; and for males (n = 186) L = 36.44 cm LF, k = 0.26 years?1 and t0 = ?2.16 years. Stomach analysis indicated some variations in the feeding habits with growth: individuals of small and medium sizes preyed on crustaceans and fishes, while large specimens preyed mainly on fishes.  相似文献   

12.
The population dynamics parameters of scaldfish, Arnoglossus laterna, from the Adriatic Sea were studied. Specimens ranging from 4.5 to 17.1 cm in total length were collected from commercial bottom‐trawl catches (2000–2006). Spawning from April through the end of August with a peak in May, A. laterna is one of the non‐target species usually present in mixed bottom trawl catches. The overall male to female ratio was 1.00 : 0.61. The oldest individual was 6 years of age. Length–weight relationships showed positive allometric growth (b = 3.36 for males and b = 3.39 for females). Parameters of the von Bertalanffy growth equation were: L= 17.3 cm; K = 0.258 per year; t0 = ?1.0026 year; R2 = 0.925. The relatively low value of total mortality (Z = 0.90) and relatively high value of constant rate of natural mortality (M = 0.64) was estimated. Presumed calculated fishing mortality (F = 0.26) and the consequently estimated exploitation ratio (E = 0.29) indicated no danger of an over‐exploitation of this species in the study area at the current level of fishing pressure. The low T max and correspondingly high M suggest that this small benthic predator plays an important role in the Adriatic ecosystem as a prey species for large benthic predators. However, the estimates include uncertainties and require further confirmation, especially with regard to natural mortality.  相似文献   

13.
Age, growth, spawning period and maturity of the solenette (Buglossidium luteum Risso, 1810) were studied in the central Aegean Sea to provide fisheries managers with essential data for science‐based management. A total of 1220 samples were collected by trawl hauls from July 2004 to June 2007 in ?zmir Bay (Turkey). Sample sizes ranging from 5.3 to 11.6 cm total length were composed of 46% females, 32% males and 22% immature individuals, with a female to male ratio of 1 : 0.7. Age composition stages of the females were from I to IV, and males between I and III. The length–weight relationship was calculated as W = 0.0101L3.008 for all samples. Estimated von Bertalanffy growth parameters were L = 13.30 cm, to = ?0.440 year and k = 0.481 year?1, with a growth performance index of 1.93 (?’). The spawning period began in April and continued until July. Lengths at first maturity of females and males were 8.1 and 7.9 cm total length, respectively. Both sexes matured at the age of 2 years.  相似文献   

14.
The age and growth parameters of Dipturus chilensis were estimated by counting growth rings from thin sections of vertebral centra from 400 fish (246 females and 154 males), ranging from 23 to 124 cm total length (LT), and backcalculating fish lengths at previous ages. Marginal increment analysis lent support to the hypothesis of annual deposition of band‐pairs, which formed during the winter months. The oldest female D. chilensis aged in this study was 21 years and 117 cm LT, whereas the oldest male was 18 years and 93 cm LT. A 4·7% index of average per cent error (IAPE) suggested that this is a precise method for calculating the age of D. chilensis. Observed LT were lower than backcalculated LT, which implies the influence of Lee's phenomenon. The von Bertalanffy growth equations, based on mean length‐at‐age data, were estimated as Lt = 128·3 (1 ? e?0·112 (t + 0·514)) for females and Lt = 107·8 (1 ? e?0·134 (t + 0·862)) for males where t is age (years). Growth was significantly different between sexes: females reached a larger adult size. Ages and lengths at 50% maturity were estimated at 14 years of age and 106 cm LT for females and 11 years of age and 86 cm LT for males. At c. 14 years, there was a decline in growth rates in females. The factor most likely responsible for this was sexual maturity, which caused a discontinuity in growth of female fish. These results show that this species is slow‐growing, long‐lived, relatively large and of delayed maturity, characteristics that make it vulnerable to exploitation.  相似文献   

15.
The present study was conducted to determine the age relationships in lengths and weights of Boops boops (Linneaus, 1756) in Izmir Bay, central Aegean Sea. A total of 932 specimens (503 females and 429 males) were caught by gillnet, trammel net and a combination thereof on a monthly sampling basis from November 2008 through October 2009. Total length and weight of sampled fish ranged from 11.3 to 27.9 cm and from 12.2 to 261.7 g, with a mean of 19.6 cm and 82.7 g, respectively. Length‐weight relationships for all individuals were described by the parameters = 0.0050, = 3.237 and r² = 0.956. The von Bertalanffy growth curve fitted to the lengths‐at‐age provided parameters of L = 29.87 cm = 0.243 and to = ?0.98 for males and L = 30.79 cm, = 0.239 and to = ?0.90 for females. Based on otolith readings, age determinations varied from 1 to 5 years. Maximum age was 5 years in age group 2, with 29.84 and 37.97% for males and females, respectively. The overall 1 : 1.17 sex ratio of males to females was significantly biased toward females (P < 0.05). There was no statistical difference in the mean condition factor (P > 0.05), with a value of 1.028 for the entire population. The growth performance index (Φ) was 2.33 and 2.36 for males and females, respectively. Results were similar to other geographical areas, which suggests that a common fisheries management might be possible.  相似文献   

16.
The smooth hammerhead Sphyrna zygaena (Sphyrnidae) is a pelagic shark occasionally caught as bycatch in pelagic longline fisheries, but is one of the least studied of all pelagic sharks. Age and growth of S. zygaena was studied along a wide Atlantic region covering both the northern and southern hemispheres. Data from 304 specimens, caught between October 2009 and September 2014, ranging in size from 126 to 253?cm fork length (FL), were analysed. Growth models were fitted using the three-parameter von Bertalanffy growth function (VBGF) re-parameterized to calculate L0 (size at birth). Growth models were fitted to the sample data and data from several back-calculation models. The model fit to the quadratic modified Dahl-Lea back-calculated data seems to be the most appropriate to describe growth in this species, with resulting growth parameters of Linf?=?285?cm FL, k?=?0.09 year?1 for males and Linf?=?293?cm FL, k?=?0.09 year?1 for females. Compared with other species of the same genus, estimated growth coefficients for S. zygaena seem to fall in the low to middle range. Although further work is still needed, this study adds to knowledge of the vital life-history parameters of smooth hammerheads in the Atlantic Ocean, which can be used in the management and conservation of this species.  相似文献   

17.
Russian sturgeon (Acipenser gueldenstaedti Brandt & Ratzeburg, 1833) is one of the major commercial sturgeon species, but there is no adequate information and previous‐published about population dynamics and stock assessment of this species in the southern Caspian Sea. This paper examines the age structure, growth parameters, maturity, age at first capture, optimum length, natural and fishing mortality and amount of biomass in the southern Caspian Sea (Iranian waters), during a two decades time series period from 1990–1991 to 2008–2009. For a pooled data, the growth parameters were estimated as L = 214.0 cm, = 0.054, t0 = ?4.5 year. Size at fifty percent sexual maturity was at FL = 118 cm for females and 113 cm for males. The age at first capture (tc) estimated to be 12.1 years. In the catch composition, bulk of the catch (75%) belonged to 13–17 years old. The instantaneous coefficient of natural mortality (M) was estimated as 0.120 year?1 and the instantaneous coefficient of fishing mortality (F) varied during the 19‐year period between 0.130 to 0.505 year?1. The biomass showed a descending trend from 1,941.2 mt in 1990–1991 collapsed to about 55 mt in 2004–2005, and then decreased to the lowest level and represented 18.5 mt in 2008–2009. The result revealed that, the stock of Russian sturgeon is being over‐fished. We concluded that to manage the sturgeons stocks, a coordinated regional and international effort are needed to provide immediate implementation of stock enhancement and management in the Caspian Sea.  相似文献   

18.
The growth pattern of the endemic Neretvan roach, Rutilus basak from the Hutovo Blato wetlands was analyzed. A total of 441 specimens ranging from 6.0 to 21.7 cm TL were obtained by electro fishing between December 2007 and November 2008. The male:female ratio for all fish combined was 0.34 : 1.00 but changed across length classes. The spawning period extended from February to April, with a peak in the first half of March. Maximum observed age was 10 years. Predominance of age classes 1–5 in the catch (77.0% of individuals) was noted. The length–weight relationship showed a positive allometric growth (b = 3.321; R2 = 0.957). Parameters of the von Bertalanffy equation were: L = 20.201 cm; K = 0.257 per year; t0 = ?1.554 year; R2 = 0.977. This study revealed that R. basak invests energy in reproduction rather than in body size and thus has a relatively fast growth, short life span and precocious maturity. Moreover, elementary biological population parameters are provided that can be used for conservation purposes.  相似文献   

19.
The growth rate, reproductive aspects, and natural mortality of chimaeras and ratfish are poorly known. In this study, life-history parameters for cockfish Callorhinchus callorhynchus (Holocephali—Callorhinchidae) are estimated, which is an important fish resource exploited in Chile. Specimens were sampled from the artisanal fishery captures, from November 2006 to November 2007. The standard length (SL) of males fluctuated between 20 and 62 cm, and between 21 and 70 cm for females. Von Bertalanffy growth parameters were estimated through length-frequency data analysis using MULTIFAN. The length-weight relationship and von Bertalanffy growth parameters were significantly different for males and females, as well as the length at 50% maturity. For males a model with 5 age-classes was the best, with asymptotic length L  = 52 cm SL, growth coefficient K = 0.473 yr−1, and age at length zero t 0 = −0.690 yrs. For females the best model was represented by 10 age-classes (L  = 70.3 cm SL, K = 0.193 yr−1, t 0 = −1.158 yrs) in the length-frequency data sets. Length at 50% maturity of males was estimated in 43.7 cm SL, and in 50.2 cm SL for females. The natural mortality rate fluctuated between 0.42 and 0.82 yr−1 for males and between 0.12 and 0.37 yr−1 for females, depending upon the method used. It is concluded that C. callorhynchus is a species with life-history parameters significantly different between males and females, and such differences should be taken into account in future population dynamics analysis.  相似文献   

20.
To better understand the biology of Schizopygopsis younghusbandi Regan, 1905 and its relationship with management considerations, this study describes the relationships between otolith size and fish length and age, verifies annual periodicity of otolith annulus formation, and estimates the S. younghusbandi growth parameters. These age and growth characteristics were studied using 694 specimens collected from August 2008 to August 2009. Otoliths grew asymmetrically throughout the range of standard length (SL) studied, showing a clear pattern of alternating translucent and opaque bands. Marginal increment ration (MIR) analysis of specimens up to 6 years of age indicated that one opaque band and one translucent band were laid down each year. Maximum observed age was 17 years, corresponding to a female of 35.8 cm SL and 589.1 g body weight (BW). The SL‐BW relationship was described as BW = 1.122 × 10?5 SL3.030 for sexes combined. The von Bertalanffy growth function was used to model back‐calculated lengths as Lt = 338.4 (1?e?0.233 (t + 0.403)) for males, and Lt = 433.9 (1?e?0.194 (t + 0.397)) for females. Growth performance of S. younghusbandi was relatively higher than those of other Schizothoracinaes inhabiting the same river.  相似文献   

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