Age, growth and reproductive characteristics of chub, Leuciscus cephalus (L., 1758) in the İkizcetepeler dam lake (Balikesir), Turkey

In this study, the population structure, growth and reproduction characteristics of 414 chub (Leuciscus cephalus L., 1758) from the ?kizcetepeler dam lake were investigated monthly between January and December 2000. Age groups ranged between I and VI for this species in the reservoir, with the second and third year‐classes dominating. Sex ratio was 1 : 1.4 (M : F), corresponding to 58.4% males and 41.6% females. Females attained greater size and age than males. The largest female captured was 24.8 cm FL, the largest male was 24.1 cm FL, both age VI. The von Bertalanffy growth equations and length–weight relationships were found as: L_t = 28.89[1 ?e^{?0.224(t+1.55)}] for females, L_t = 26.71[1 ? e^{?0.259(t+1.55)}] for males; W_t = 347.386[1?e^{?0.224h (t+1.55)}]^2.86 for females, W_t =286.48[1?e^{?0.259 (t+1.55)}]^2.92 for males; W = 0.0227 × L^2.87 for females and W = 0.0194 × L^2.92 for males. Significant statistical differences in condition factors between age classes and sexes were not found (P > 0.05, t‐test). Spawning period of this species in the lake was between April and May.     

Age, growth and mortality of red bandfish, Cepola macrophthalma (L.), in the eastern Adriatic Sea (Croatian coast)

Age, growth and mortality were analysed for red bandfish, Cepola macrophthalma, collected in the eastern Adriatic from May 2002 to June 2003. The oldest male was estimated to be age 4, the oldest female age 3. Parameters of the von Bertalanffy growth equation are: L_∞ = 55.0 cm (SE = 0.1), K = 0.445 (SE = 0.074) and t₀ = ?0.1 (SE = 0.001) for males, and L_∞ = 48.9 cm (SE = 0.167), K = 0.395 (SE = 0.062) and t₀ = ?0.009 (SE = 0.02) for females. The overall sex ratio was 1.42 : 1 in favour of males. Total mortality, corresponding to the slope of the descending limb of the catch curve, was Z = 1.20 per year for females and Z = 1.23 per year for males. Exploitation ratios were E = 0.479 for females and E = 0.433 for males.     

Age,growth and mortality of common two‐banded seabream,Diplodus vulgaris (Geoffroy Saint‐Hilaire, 1817), in the eastern Adriatic Sea (Croatian coast)

Age, growth and mortality were analysed for the common two‐banded seabream, Diplodus vulgaris, collected in the eastern Adriatic (Croatian coast) from commercial fishery catches by ‘tramata’ fishing (2005–2006) to obtain growth estimation. The oldest female was estimated to be age 11, the oldest male age 10 years. The von Bertalanffy growth parameters estimated by reading scales were: L_∞ = 48.60 cm (SE = 1.101), K = 0.112 (SE = 0.005) and t₀ = ?2.366 (SE = 0.060) for all specimens; L_∞ = 51.96 cm (SE = 2.153), K = 0.095 (SE = 0.007) and t₀ = ?2.837 (SE = 0.120) for females and L_∞ = 56.25 cm (SE = 2.662), K = 0.084 (SE = 0.067) and t₀ = ?2.920 (SE = 0.117) for males. The overall sex ratio was 1.22 : 1 in favour of males. Total mortality, corresponding to the slope of the descending limb of the catch curve, was Z = 0.81 per year for females and Z = 0.85 per year for males. Exploitation ratios were E = 0.68 for females and E = 0.73 for males.     

Age,growth, reproduction and feeding of John Dory,Zeus faber (Pisces: Zeidae), in the Saros Bay (North Aegean Sea)

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*L^2.936. 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).     

Age and growth of the blackchin guitarfish Glaucostegus cemiculus (Geoffroy Saint-Hilaire, 1817) from Iskenderun Bay (Northeastern Mediterranean)

Between September 2010 and June 2012, a total 291 (166 females and 125 males) blackchin guitarfish Glaucostegus cemiculus were captured by a commercial bottom trawler (F/V Coşkun Reis) in Iskenderun Bay, Turkey (northeastern Mediterranean Sea). The total length (L) and total weight (W) of the female and male guitarfish ranged between 32.0–165.0 cm and 88 g–16.68 kg, and 34.3–128.3 cm and 112 g–6.00 kg, respectively. Vertebral age estimates ranged from 0 to 8 years for females and 0 to 5 years for males. The growth models of von Bertanlanffy and Gompertz were fitted to the length at age data using the nonlinear regression method. Model selection was based on the values of the residual standard error and the Akaike's information criterion corrected for small sample size (AIC_C) associated with each fit. The von Bertalanffy growth model provided the best fitting growth curves for each sex with parameters reaching L_∞ = 187.17 cm, K = 0.195 year^-1, t₀ = −1.38 year for females, and L_∞ = 144.85 cm, K = 0.321 year^-1, t₀ = −1.13 year^-1 for males. The W–L relationship parameters did not differ significantly between sexes, the estimated values of a and b were 0.0018 and 3.11, respectively. By using these values of a and b, and also respective estimates of L_∞, the values of W_∞ were obtained as 20.53 kg for females and 9.25 kg for males. The overall percentage ratios of females and males in the samples were 57% and 43% respectively.     

Growth and length–weight relationships of Sander lucioperca (Linnaeus, 1758) in the Alcántara Reservoir,south‐western Spain: comparison with other water bodies in Eurasia

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 TL^3.09 (r = 0.9865) for males and W = 0.00279 TL^3.16 (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.     

Age, growth and mortality of brown comber, Serranus hepatus (Linnaeus, 1758) (Pisces: Serranidae), in the eastern Adriatic (Croatian coast)

Age, growth and mortality were analysed for brown comber, Serranus hepatus, collected in the eastern Adriatic from May 2002 to June 2003. Fish aged 2–7 years were present in the samples. Growth in length including both sexes was expressed using the von Bertalanffy equation, L_∞ = 14.82, K = 0.217 and t₀ = −1.672. Age class 2, ranging in length from 5.8 to 9.0 cm TL, dominated the sample (29.3%). Total and natural mortality were Z = 1.73 year⁻¹ and M = 0.63 year⁻¹, respectively. The exploitation rate, E = 0.64, revealed a high fishing pressure on the stock in the studied area.     

Age and growth of the Black Sea turbot, Psetta maxima (Linneaus, 1758) (Pisces: Scophthalmidae), estimated by reading otoliths and by back-calculation

Age and growth of the Black Sea turbot, Psetta maxima, were determined from a total of 1445 individuals collected along the eastern Black Sea coast between 1990 and 1996. Age was estimated by interpreting growth rings in whole and broken sagittal otoliths. The former method underestimated the age over 5 years, and a maximum age of 11 years was observed by the latter. Marginal increment analysis clearly showed that a single annulus is formed in early summer each year. Growth in length differed between sexes, and females attained a larger size than males at the same age. No significant difference was found between the mean observed total length (TL), the back‐calculated TL derived from radius measurements and the TL estimated from otolith size–fish size relationship. The von Bertalanffy growth parameters estimated by the length‐at‐age data were: L_∞ = 96.24 cm; K = 0.119 year^?1; t₀ = ?0.01 year for the entire population.     

Age,growth and sexual development of solenette,Buglossidium luteum (Risso, 1810), in the central Aegean Sea

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 = 0.0101L^3.008 for all samples. Estimated von Bertalanffy growth parameters were L = 13.30 cm, t_o = ?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.     

Life‐history characteristics of the endangered Aristotle’s catfish (Silurus aristotelis Garman, 1890), Lake Pamvotis,north‐western Greece

The life history characteristics of Aristotle’s catfish, Silurus aristotelis (Agassiz 1856) were studied in Lake Pamvotis (northwestern Greece). Samples were collected on a monthly basis using gillnets, trammel‐nets and traps. Total lengths ranged from 11.1 to 36.7 cm. Sex ratio was biased toward females (F : M = 1.8 : 1) and was statistically different from unity (χ² = 46.94, P < 0.001). Spawning is from April to June. The relationship between total length and total weight showed positive allometric growth for males (TW = 0.0035 × TL^3.21, r² = 0.93, n = 198, P < 0.001) and females (TW = 0.0066 × TL^3.02, r² = 0.95, n = 363, P < 0.001). Age was determined on the annual growth marks formed on the spine of the pectoral fin. Based on cross‐section readings of the spine, lifespan of the Aristotle’s catfish was 5 years. Age classes 1 and 2 dominated the catches (39.1 and 40.0% of the total sample, respectively). Back‐calculated lengths at age showed a rapid increase in fish size during the first year of life, reaching 61.1% of maximum attainable length, and a declining growth rate thereafter. Growth parameters were calculated as L_∞ = 36.12 cm, K = 0.37 year^?1, t₀ = ?0.76 year based on the observed lengths at age and as L_∞ = 28.19 cm, K = 0.53 year^?1, t₀ = ?0.62 year based on the back‐calculated lengths at age. It seems that some of the life history traits (longevity, growth pattern, reproductive period) are influenced significantly by adverse effects of pollution and eutrophication on the lacustrine ecosystem.     

Some biological parameters of the Mediterranean sand smelt Atherina (Atherina) hepsetus, Linnaeus, 1758 (Pisces: Atherinidae) from the middle eastern Adriatic (Croatian coast)

Data on the length–weight relationship, age, growth, sex ratio and mortality were analysed for the Mediterranean sand smelt, Atherina (Atherina) hepsetus L. (total = 2805; males = 1258; females = 1547) collected in the eastern middle Adriatic island area during the reproductive period (February to April) in 2002. The total length of sampled specimens ranged from 3.8 to 14.5 cm and the weight from 0.28 to 22.39 g. The overall sex ratio was 1.23 : 1 in favour of females, significantly different from the expected 1 : 1 ratio (χ² = 29.76; P < 0.05). All individuals >13.4 cm were females. The oldest collected male and female specimens were 5 years old. The von Bertalanffy growth formula was estimated for females (L_∞ = 15.79 (1−e^{−0.43(t+0.049)}) and males (L_∞ = 15.25 (1−e^{−0.43(t+0.018)}). The power values (b) of the length–weight relationship were very similar for both sexes (b = 3.14) and indicated a slightly allometric growth. The instantaneous rates of mortality for all collected fish were Z = 1.44 year⁻¹; M = 0.94 year⁻¹ and F = 0.50 year⁻¹. The exploitation ratio was E = F/Z = 0.35. The value for M is highly uncertain, however, as well as those values for F and E.     

Reproductive biology,growth, and age composition of non‐native Indian glassy fish Parambassis ranga (Hamilton, 1822) in Haebaru Reservoir,Okinawa‐jima Island,southern Japan

Age composition, growth, and reproductive biology of the non‐native Indian glassy fish Parambassis ranga (Hamilton, 1822) were surveyed in the Haebaru Reservoir on Okinawa‐jima Island, southern Japan. Standard lengths (SLs) of males and females ranged from 19.7 to 44.0 mm and from 19.2 to 52.4 mm, respectively. The overall sex ratio was significantly female‐biased, with the monthly percentage of females ranging from 71.4 to 100.0. Marginal growth analysis of sectioned otoliths revealed opaque zones formed annually from November to May. Observed age ranged from 0 to 3 years for both sexes, although the 1‐year age class comprised the majority of the sampled population. Von Bertalanffy growth parameters were L_∞ = 48.8 mm (SL), K = 0.43 year^?1, and t₀ = ?1.47 years for males, and L_∞ = 43.7 mm, K =0.72 year^?1, and t₀ = ?1.29 years for females. Length at 50% maturity was estimated to be 25.8 mm SL, and maturation was within 1 year after hatching. The main spawning season of P. ranga was estimated to occur from February to October, peaking in April.     

Age and growth in pink cusk-eel (Genypterus blacodes) off the Chilean austral zone: evaluating differences between management fishing zones

The von Bertalanffy (vB) growth parameters for pink cusk‐eel (Genypterus blacodes) were estimated for the Chilean austral‐zone (41°28′–57°00′S) by gender and management fishing zones. A total of 47 026 samples were collected between March 1982 and May 2004, with total length ranging from 19 to 154 cm. Age determinations, based on the reading of saggital otoliths, were between 1 and 14 years in males and between 1 and 16 years in females. Statistical differences in growth were found between the sexes and management fishing zones. For the combined sexes the vB growth parameters for the northern‐austral zone (41°28′–47°00′S) were: l_∞=111.452 cm, k = 0.186 year⁻¹, t₀ = −0.912 year; and for the southern‐austral zone (47°00′–57°00′S): l_∞ = 123.447 cm, k = 0.147 year⁻¹, t₀ = −1.779 year.     

Population biology and status of exploitation of introduced garfish Belone belone euxini (Günther, 1866) in the Black Sea

The garfish Belone belone euxini (Günther, 1866) is a commercially important pelagic fish species in Sinop artisanal fishery, which is showing a decreasing trend in catch results. As a basis for fisheries management a sampling program was carried out between October 2000 and September 2001 along the Turkish coast of the Black Sea, to study the population structure, growth, and reproduction cycle of garfish in the area, and to achieve a rough estimate of exploitation. The length–weight relationship and von Bertalanffy growth parameters were estimated as W = 0.00076 L^3.137, L_∞ = 74.64 cm, K = 0.13 year^?1, t_o = ?3.67, respectively. First sexual maturity was estimated at age 2 and at a total length of 38.8 cm for females. The spawning period was from May to September. The total fecundity–length relationship was estimated as F = 0.0041 L^4.1086 (r² = 0.92). Mortality rates were Z = 1.24 year^?1, M = 0.23 year^?1and F = 1.01 year^?1 for total, natural, and fishing mortality, respectively. The exploitation ratio E = 0.81 indicates that the population is heavily exploited.     

Age and growth validation of the small spotted grunt Pomadasys commersonnii (Lacepède, 1801) from the northwestern coast of the Arabian Sea of Oman

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 16^o 33′N and 22^o 21′N and longitude 53^o 09′ and 59^o 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), k = 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, k = 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.     

Age and growth of the smooth hammerhead,Sphyrna zygaena,in the Atlantic Ocean: comparison with other hammerhead species

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 L_inf?=?285?cm FL, k?=?0.09 year^?1 for males and L_inf?=?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.     

Age,growth and reproduction in creole perch (Percichthys trucha) in the Negro River,Argentinean Patagonia

Age, growth and reproductive characteristics of creole perch, Percichthys trucha, were investigated in the Negro River, southern Argentina from samples collected seasonally, December 1994–December 1995. Age was estimated via scale and whole otolith reading methods. Total length (n = 413) ranged from 103 to 432 mm, and weight from 12 to 1042 g. Significant differences between the length‐weight relationships of males and females were detected (P < 0.05). Isometric growth was observed in juveniles and males, whereas total population and females exhibited positive allometric growth. The marking pattern in scales and otoliths followed an annual rhythm, with the formation of only one annulus in scales and only one hyaline band in otoliths during autumn‐winter. The oldest males were 5 years old whereas maximum age in females was 12 years from scales and 15 years from otoliths. Because scales were found to underestimate age in individuals older than 4 years, otoliths were considered to be the best structures for creole perch age determination. Gompertz growth parameters based on otolith data were L∞: 428.0 mm, k = 0.46 and t₀ = 0.43 for total population (r = 0.90), L∞: 410.7 mm, k = 0.42 and t₀ = 0.46 for males (r = 0.91), and L∞: 434.1 mm, and k = 0.49 and t₀ = 0.43 for females (r = 0.91). Lengths at first maturity (TL₅₀) were 260 and 241 mm in males and females, respectively, both of which corresponded to ages between 1 and 2 years. Macroscopic gonad inspection and the high percentage of juveniles captured during summer indicated that spawning begins at the end of spring.     

Age and growth of the hollowsnout grenadier, Caelorinchus caelorhincus (Risso, 1810), in the Aegean Sea

Age and growth of the hollowsnout grenadier was studied based on samples collected seasonally in the Agean Sea between March 2003 and January 2004. Total length ranged from 9.0 to 21.6 cm. Length–weight relationship was described as a = 0.0032, and b = 3.008. Age determinations based on otolith readings were between 1 and 10 years. The von Bertalanffy growth curve fitted to observed lengths‐at‐age provided parameters of L_∞ = 24.9 cm, k = 0.115 and t_o = ?3.494.     

Age estimation and specific growth pattern of boxlip mullet,Oedalechilus labeo (Cuvier, 1829) (Osteichthyes,Mugilidae), in the eastern Adriatic Sea

The main objective of this study was to investigate boxlip mullet, Oedalechilus labeo (Cuvier, 1829), a species that lives in open, oligotrophic and stenohaline waters, exhibits slower growth rates and has a longer life span than other mugilids. A total of 1662 specimens ranging from 2.2 to 24.4 cm TL were obtained by beach seine in the eastern Adriatic Sea. The overall sex ratio was unbalanced in favour of females (1.0 : 1.3) and differed statistically from the expected 1 : 1. The reproductive season extended through summer and autumn. All specimens above 15 cm TL were sexually mature. Length‐weight relationship for males was TW (g) = 0.010 × TL (cm)^2.975 and TW (g) = 0.009 × TL (cm)^3.014 for females. The age study comprised 150 (38.5%) males, 192 (49.4%) females, and 47 (12.1%) immature O. labeo, for a total of 389 individuals. Age of the fish was determined by scale readings, with the maximum age of 10⁺ observed for both sexes. A predominance of age classes 1⁺ and 2⁺ (71.0%) in the total catch was noted. Parameters of the von Bertalanffy growth equation for combined samples were: L_∞ = 25.93 cm, k = 0.192 year^?1 and t₀ = ?1.427 year. The growth parameters showed that males grew at a slightly lower rate than females. The size and age frequency distributions of both sexes were not significantly different. When compared to other mugilids, O. labeo reaches the lowest maximum body length and has a relatively slower growth and a longer life span.     

Age,growth, reproduction and feed of longnosed skate,Dipturus oxyrinchus (Linnaeus, 1758) in Saros Bay,the north Aegean Sea

The age, growth, reproduction, and feeding of longnosed skate (Dipturus oxyrinchus) were studied using 179 specimens from the Saros Bay (North Aegean Sea) between March 2005 and December 2007. Composition was 49.7% females and 50.3% males. Total length of females ranged from 14.9 to 100 cm (disc width, 9.8–65 cm), and of males from 15.2 to 86.5 cm (disc width, 10–57.5 cm). Total length‐weight and disc width‐weight relationships are described by the equations W = 0.0008*TL^3.35 and W = 0.0043*DW^3.29, respectively. The age data, derived from vertebrae readings, were used to estimate the growth parameters of the von Bertalanffy equation: L_∞ = 256.46 cm, K = 0.04 year^?1, t₀ = ?1.17year. The maximum age was 9 years. Males matured at 64–65 cm (disc width, 43.5 cm) and females at 82–83 cm TL (disc width, 53 cm). The stomach contained mainly Parapenaus longirostris, IRI: 93.47%.