Life history of the red-banded seabream Pagrus auriga (Sparidae) from the coasts of the Canarian archipelago

Red‐banded seabream Pagrus auriga (N = 615) were caught off the Canary Islands from January 2003 to December 2004. Total length ranged from 120 to 780 mm. The species was characterized by protogynous hermaphroditism. The male :female ratio was in favour of females (1 : 8.2). The reproductive season extended from September to February, with a peak in spawning activity in October–November. Fifty percentage maturity was reached at 387 mm total length by females and 533 mm by males. The length–weight relationship for all individuals was described by the parameters: a = 0.0086 and b = 3.014, when length is given in mm and weight in grams. Otolith age readings indicated that the population consists of 19 age groups, including a very high proportion of individuals between 0 and 7 years old. Growth analysis reveals that the species is slow‐growing and relatively long lived (18 years). The von Bertalanffy growth parameters for the entire population were: L_∞ = 803 mm, k = 0.081 year⁻¹ and t₀ = −2.17 year. Growth differed between males and females. The instantaneous rate of natural mortality for all fish was: M = 0.164 year⁻¹.     

Life history traits of Aphanius ginaonis Holly, 1929 (Cyprinodontidae) and potential risks of extinction in the Geno hot spring (Iran) population

This study presents some traits of the Aphanius ginaonis life history in the Geno hot spring and explains the potential risks of its extinction. Sampling was from March 2009 to February 2010. A total of 61 males and 71 females were measured (total length) and weighed, with data on reproductive biometry also taken. Growth parameters were determined in addition to weight–length relationships: W (t) = 0.012TL^3.42, R² = 0.96 for females and W (t) = 0.0101TL^3.38, R² = 0.94 for males. A. ginaonis females showed an asymptotic total length (TL_∞) of 53.03 mm; the growth coefficient, K (year^?1) 0.15, t₀ (year) 1.01; and natural mortality coefficient M (year^?1) 0.62. In males the value for TL_∞ was 48.83 mm; for K (year^?1) 0.2, t₀ (year) 0.44; and M (year^?1) 0.49. The relationship between absolute fecundity and fish size (total length, body weight or age) showed a strong correlation to body weight. The A. ginaonis population is threatened with extinction – and a co‐management in cooperation with the local population for strong protection measures is urgently needed.     

Age,growth, mortality and sex ratio of the inshore population of the edible crab,Cancer pagurus (Linnaeus 1758) in South Wales (UK)

Age, growth, and mortality of the edible crab, Cancer pagurus, were determined for the native population in South Wales (UK). Sampling was carried out on a monthly basis between February 2001 and September 2002. Carapace width ranged between 10.4 and 163 mm. Based on the carapace width frequency distribution, the Swansea and Gower population was composed mainly of males belonging to the first and second age‐class (1 and 2), and of females belonging to the third and fourth age‐class (3 and 4). Sex ratio was 1.126 ± 0.27 in favour of males. Carapace width frequency distributions and weight‐at‐age data were used to estimate the von Bertalanffy growth equation parameters. For the population as a whole, these were: L∞ = 199 mm, W∞ = 1179.56 g, K = 0.24 year^?1, t₀ = ?0.1004 years. The overall carapace width–weight relationship was: W = 0.38(CW^2.69). Analysis of covariance indicated a significant difference in the carapace width–weight relationship between males and females in the study area. Total mortality Z and natural mortality M rates for combined sexes were 1.245 year^?1 and 0.567 year^?1, respectively. The exploitation ratio E was estimated to be 54.43%.     

Age and growth of the endemic Xingu River stingray Potamotrygon leopoldi validated using fluorescent dyes

Between 2003 and 2005, vertebrae of 151 Xingu River Potamotrygon leopoldi (Potamotrygonidae) (75 males and 76 females) were analysed to derive a growth curve for this species. The disc width (W _D) was significantly different between sexes, with females measuring 149–700 mm W _D and males 109–500 mm W _D. The average percentage error for vertebrae readings of the whole sample was 2·7%. The marginal increment ratio (R _MI) showed an increasing trend with the highest value in November, decreasing from December on. The majority of vertebrae displaying R _MI zero, occurred in September, but the annual periodicity of ring deposition throughout the year was not conclusive. Tetracycline (TCN) injected specimens were held in captivity for 13 months and displayed a fluorescent mark in vertebrae confirming a yearly periodicity of band pair formation with the translucent ring deposited in September–October. The Akaike information criterion (AIC) showed that, among the seven models considered, the best fit was obtained for the von Bertalanffy modified with W ₀ (where W ₀ = W _D at birth) for both sexes. Growth parameters for females were: W ₀ = 149 mm; W _∞ = 763·06 mm; k = 0·12 year^{– 1}, whereas for males: W ₀ = 109 mm; W _∞ = 536·4 and k = 0·22 year^?1. Maximal ages were 7·2 years in males and 14·3 years in females. The species shows sexual dimorphism expressed in the growth pattern, size at maturity, longevity and asymptotic sizes. Concern for sustainability is raised due to the construction of the Belo Monte Hydroelectric Power Plant (2015 and 2016) in the State of Pará causing changes to the habitat of this species, which is endemic to the Xingu River and two of its tributaries.     

Slow growth of the overexploited milk shark Rhizoprionodon acutus affects its sustainability in West Africa

Age and growth of Rhizoprionodon acutus were estimated from vertebrae age bands. From December 2009 to November 2010, 423 R. acutus between 37 and 112 cm total length (L_T) were sampled along the Senegalese coast. Marginal increment ratio was used to check annual band deposition. Three growth models were adjusted to the length at age and compared using Akaike's information criterion. The Gompertz growth model with estimated size at birth appeared to be the best and resulted in growth parameters of L_∞ = 139·55 (L_T) and K = 0·17 year^?1 for females and L_∞ = 126·52 (L_T) and K = 0·18 year^?1 for males. The largest female and male examined were 8 and 9 years old, but the majority was between 1 and 3 years old. Ages at maturity estimated were 5·8 and 4·8 years for females and males, respectively. These results suggest that R. acutus is a slow‐growing species, which render the species particularly vulnerable to heavy fishery exploitation. The growth parameters estimated in this study are crucial for stock assessments and for demographic analyses to evaluate the sustainability of commercial harvests.     

Biology of red mullet,Mullus barbatus (L. 1758), in the Gulf of Castellammare (NW Sicily,Mediterranean Sea) subject to a trawling ban

Under‐or non‐exploited areas are useful to aid in evaluating the potential productivity of fish stocks for sustainable fisheries. The Gulf of Castellammare (NW Sicily), where trawling has been banned since 1990, is a good site to study the biology and dynamics of low impacted fish populations. A total of 661 (595 female and 66 male) specimens of red mullet Mullus barbatus (95–245 mm total length, TL) obtained by monthly sampling from trammel net artisanal fishery, was collected in the Gulf of Castellammare from April 2006 to June 2007. Mature females occurred from April to September, with a peak in May. The mean Gonado‐somatic index (GSI) also showed a May peak for both sexes. From Sagittae (642) readings the age structure ranged from age class I to VII in females and I to V in males. Female growth parameters, estimated according to the classic von Bertalanffy model, were: L_∞ = 221.2 ± 11.51 mm standard error (SE), k_y^?1 = 0.38 ± 0.09 SE, t₀y = ?0.94 ± 0.38 SE. The growth performance index (ø’ = 2.27) was included in the range of values obtained by hard structure readings in the Central Mediterranean. Natural mortality (M_y^?1) of females estimated by different methods ranged between 0.62 and 0.87 (mean value = 0.71 ± 0.06 SE).     

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 histories of two deep‐water Australian endemic elasmobranchs: Argus skate Dipturus polyommata and eastern spotted gummy shark Mustelus walkeri

Two Australian endemic elasmobranchs, the Argus skate Dipturus polyommata and the eastern spotted gummy shark Mustelus walkeri, were collected from the by‐catch of a prawn Melicertus plebejus trawl fishery off Queensland. Age and growth parameters were estimated from growth band counts in vertebral sections of 220 D. polyommata and 44 M. walkeri. Dipturus polyommata males and females had an observed maximum age of 10 years and reached maximum sizes of 369 and 371 mm total length (L_T), respectively. Mustelus walkeri lived longer, with the oldest female aged 16 years and measuring 1050 mm stretched total length (L_ST), and oldest male aged 9 years and 805 mm L_ST. Dipturus polyommata grew relatively fast with a von Bertalanffy growth completion parameter of k = 0·208 year^?1 with males reaching maturity at 4·0 years (c. 278 mm L_T) and females at 5·1 years (c. 305 mm L_T). Mustelus walkeri grew more slowly with k = 0·033 year^?1 with males estimated to mature at 7–9 years (670–805 mm L_ST) and females at 10–14 years (833–1012 mm L_ST). Length at birth inferred from neonate D. polyommata was 89–111 mm L_T while for M. walkeri it was estimated to be 273 L_ST based on the value of L₀ from the von Bertalanffy growth model. Both species appeared to have continuous reproductive cycles and low fecundity with an average ovarian fecundity of eight follicles for D. polyommata and a litter size of five to seven pups for M. walkeri. Based on these life‐history traits, D. polyommata is more resilient to fishing pressure than M. walkeri.     

Age,growth and sex ratio of tench Tinca tinca (L., 1758) in Seyhan Dam Lake,Turkey

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 × L^2.51 (r = 0.981), and L = 50.86 cm, k = 0.112 year^?1, t_o = ?1.551 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.     

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,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).     

Population structure and growth of the Japanese littleneck clam <Emphasis Type="Italic">Ruditapes philippinarum</Emphasis> in Amursky Bay,Sea of Japan

This paper deals with the size, age, and sex structure of population and growth of the Japanese littleneck clam Ruditapes philippinarum in Amursky Bay (Peter the Great Bay, Sea of Japan). One-year-olds and individuals with a shell length less than 19.8 mm were not found in the population under study. The population consisted mostly of 3-4-year-old clams (72.4%) with a shell length of 35–45 mm (67.8%). The maximum recorded age of R. philippinarum was 7 years, and maximum shell length was 52.7 mm. The male to female ratio was approximately 2: 1. Hermaphroditism (2.1%) and parasitic castration (1.4%) were observed. Linear growth rates of clams were found to increase until the age of three years old (11.6 ± 0.6 mm/year). Mollusks reach a commercial size of over 35 mm in shell length in the fourth year of life. The parameters of the von Bertalanffy equation describing group linear growth were L _∞ = 56.6 mm, k = 0.302 year^?1, and t ₀ = 0.468 year. The relationship between the shell length and the wet body weight is described by the equation W = 0.000253L^2.954.     

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%.     

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.     

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.     

Reproduction, growth, mortality and yield of Tilapia mariae Boulenger 1899 (Cichlidae) in a Nigerian rainforest wetland stream

The biology and fisheries of Tilapia mariae, the only tilapiine cichlid fish in the Iba Oku (Uyo, Nigeria) wetland stream was studied. There were more females than males in the population. The smallest sexually mature female fish was 11.0 cm total length (TL) while the size at 50% maturity was 17.1 cm TL. Absolute fecundity (F_e) ranged from 953 to 3200 eggs and was positively correlated with TL. The fish bred year‐round with peaks in November, March–April and July–September. The seasonalized von Bertalanffy growth function (VBGF) was fitted to the 12 consecutive months length–frequency data (n = 2439) to obtain a VBGF with the following parameters: L∞ (asymptotic length) = 30.4 cm TL, K (growth coefficient) = 0.4 year^?1, C (amplitude of growth oscillation) =0.4, and WP (winter point) = 0.9. The seasonalized length‐converted catch curve method gave Z (instantaneous total mortality coefficient) as 1.75 year^?1, M (instantaneous natural mortality coefficient) was 0.99 year^?1 while F (instantaneous fishing mortality coefficient) was 0.76 year^?1 and E (=F/Z the current exploitation rate) was 0.43. Length at first capture (Lc) was 17.7 cm TL. The fish was recruited to the fishery year‐round with two pulses. From the Beverton and Holt relative yield per recruit analysis via the selection ogive procedure, E_max (predicted maximum exploitation rate) was 0.54. The stock was not overexploited, since E < E_max. This study also showed that the fish is an r‐selected species with a few K‐selected traits.     

Growth and production of a tropical predatory shrimp, Macrobrachium hainanense (Palaemonidae), in two Hong Kong streams

1. Macrobrachium hainanense is a predatory palaemonid shrimp (total length >7 cm) that can be abundant [density 3–5 m^?2; biomass 484–606 mg ash‐free dry mass (AFDM) m^?2] in forest streams in Hong Kong, China. This study investigated the growth and production of M. hainanense during 2001 and 2002 in pools of two forested streams (one third‐ and one fourth‐order). 2. The growth of tagged individuals was recorded in situ and compared with that of tagged and untagged shrimps in laboratory tanks. Field and laboratory estimates yielded similar growth rates of 0.7 mm carapace length (CL) per month, and instantaneous growth rate was 0.004 g AFDM g^?1 day^?1. Tagging did not affect growth in the laboratory. Cohort analysis of field populations produced similar estimates of growth to that of tagged individuals, and the growth of M. hainanense was generally slower than has been reported for other Macrobrachium species. Mass‐specific growth rate of M. hainanense in the field varied with size and was two to five times higher in small individuals (<10 mm CL). In addition, growth rate varied with season and was 40% lower in the dry season when temperature was at the annual minimum. 3. Males grew bigger than females (36 versus 25 mm CL). The minimum lifespan of M. hainanense in the field, calculated from size‐specific growth rates, ranged from 29.3 months (females) to 47.6 months (males). Male lifespan derived from cohort analysis was estimated as 48 and 46 months in the two streams. Females reached maturity in 17–18 months (at 15–17 mm CL) while males matured at 24–26 months (at 18–22 mm CL). Females bred twice (at 2 and 3 years of age) while males probably bred three times (at 2, 3 and 4 years) in both streams. 4. Macrobrachium hainanense production in the fourth‐order stream, calculated by the size‐frequency method, was 900 and 1096 mg AFDM m^?2 year^?1 (for 2001 and 2002, respectively) with a production/biomass (P/B) of 2.1–2.3 year^?1. In the third‐order stream, production was 987 and 1304 mg AFDM m^?2 year^?1 (for 2001 and 2002, respectively) with a P/B of 1.7–2.1 year^?1. Production estimates based on the instantaneous growth method were half of those obtained by the size‐frequency method. 5. Although M. hainanense production at the third‐order stream exceeded that in the fourth‐order, growth rates showed the opposite pattern and were 0.31–0.43 mm CL month^?1 and 0.56–0.65 mm CL month^?1 in the third‐ and fourth‐order streams, respectively. Greater mortality in the latter may account for low production at a site where growth rate was high. 6. Production of M. hainanense in both streams was lower during 2001 when rainfall was higher. This may reflect the influence of spates associated with monsoonal rains, which could have reduced M. hainanense production through spate‐induced mortality or by reducing the abundance of prey. This study provides the first in situ estimate of secondary production by a non‐commercial Macrobrachium species in Asia or elsewhere. It involved a whole‐pool approach to sampling that allowed the estimation of production and population parameters on a realistic scale.     

Size, growth and reproductive biology of the giant mudskipper, Periophthalmodon schlosseri (Pallas, 1770), in Malaysian waters

The size, growth and reproductive biology of the giant mudskipper, Periophthalmodon schlosseri, was studied in the inter‐tidal mudflat of a mangrove swamp along a 0.4–0.6 × 5 km stretch of the Sepang coastal waters, Selangor Malaysia. The size ranges of the giant mudskipper specimens caught in the study area were between 10–27.5 cm TL (20.6 ± 3.1 cm) for males and 14.5–28.5 cm TL (21.9 ± 2.3 cm) for females. Male to female sex ratio during the study was 1 : 1.1. The estimated von Bertalanffy growth parameters were L_∞ = 29 cm and K = 1.4 year^?1, with a growth performance index of Ø′ = 3.1. Otolith microstructure analysis revealed a strong correlation (Female: r = 0.920, n = 35; Male: r = 0.943, n = 41, P < 0.05) between the number of daily rings (number of days old) over the respective size ranges of male (8.5–19.5 cm SL) and female fish (11.8–22.3 cm SL). Four maturity stages were described to follow gonadal development based on external features; these stages were further validated through histological examination of the ovary and oocyte diameter measurements. The gonadal development cycle of P. schlosseri was asynchronous, as marked by the random mixture of early stages oocytes (diameter: 70.7 ± 14.9 μm) to matured stages (356.9 ± 20.2 μm), and had a prolonged spawning season extending from June to October. Monthly fluctuation of the gonadosomatic and hepatosomatic indices for this species was highly correlated (r = 0.126, P < 0.05).     

Population parameters of stargazer (Uranoscopus scaber Linnaeus, 1758) in the southeastern Black Sea region during the 2011–2012 fishing season

The population parameters of stargazer (Uranoscopus scaber Linnaeus, 1758) were studied regarding age composition, sex ratio, growth, survival and mortality rates, and the exploitation rate in the southeastern Black Sea near the coast of Turkey during the 2011–2012 fishing season. According to ageing analysis of the samples, age group 1 is the most abundant (47.76%), followed by age 2 (41.04%), age 3 (9.33%), age 0 (1.12%) and age 4 (0.75%). Mean totals as well as total lengths and weights for males and females were 14.5 ± 0.22 cm and 12.9 ± 0.19 g, 16.6 ± 0.24 cm and 62.1 ± 2.76 g, and 37.2 ± 1.92 cm and 87.1 ± 3.88 g, respectively. The mean condition factor was K = 0.0167, while the sex ratio was 53.98% female, 38.75% male and 7.27% immature. Length‐weight, age‐length and age‐weight equations were W = 0.014 × L^3.059, L_(t)=44.5*[1?e^{?0.148*(t +1.242)}] and W_(t)=1544.4*[1?e^{?0.148*(t + 1.242)}]^3.059, respectively. The computed survival rate (S), instantaneous total mortality rate (Z), annual mortality rate (A), natural mortality rate (M) and fishing mortality rate (F) were S = 28.94%, Z = 1.24 year^?1, A = 71.06%, M = 0.26 year^?1 and F = 0.98 year^?1, respectively. The exploitation rate was 0.79, which is above the optimum exploitation levels.