Difference in age,growth, and sexual demography of black‐spot tuskfish,Choerodon schoenleinii (Valenciennes, 1839), in two adjacent populations,Ryukyu Archipelago,southern Japan

To better understand the plasticity of life history traits in the blackspot tuskfish, Choerodon schoenleinii (Valenciennes, 1839), the characteristics of the population around the Yaeyama Islands (24°N, 124E) were examined and compared to those around Okinawajima Island (26°N, 128E) that had been investigated in a previous study. Age and growth of the Yaeyama population were examined based on 103 specimens collected at fish markets between 2006 and 2016. Specimens included 83 females (25.2–69.0 cm total length [TL]), and 20 males (43.1–71.8 cm TL). Ages determined from sectioned otoliths ranged from 1–9 for females, and 4–15 for males. Values for von Bertalanffy growth functions were L_t = 74.2 {1?exp[?0.23 (t + 0.38)]}, and the growth of the Yaeyama population was significantly faster than that of the previously studied population. Sexual demography of the two populations was compared using body length data on landings measured at the fish markets. In the Yaeyama population, females and males ranged from 24–65 cm TL and 39–75 cm TL, respectively; length at 50% individual sex change size was estimated at 54.7 ± 0.56 cm (±95% C.I.). In contrast, in the Okinawajima population, females and males ranged from 16–65 cm TL and 30–75 cm TL, respectively; meanwhile, 50% sex change size was estimated to be 50.0 ± 0.25 cm. There were thus significant differences in the size at sex change between the two populations. This difference may be related to the difference in population density between the sites.     

The relationship between otolith size and estimated age of tigertooth croaker (Otolithes ruber Bloch and Schneider, 1801) in Oman Sea,Iran

The relationships between somatic growth and otolith dimensions, otolith size to estimated age and growth parameters of the tigertooth croaker (Otolithes ruber) were investigated in 100 specimens (size range: 19.1–52.0 cm, total length) from the Oman Sea area, September 2014. All 100 otoliths were sectioned and determined by age. The oldest specimen was a 4.5‐year‐old female with a total length of 40.6 cm; the youngest specimen was also a female estimated at 1 year of age with a total length of 19.1 cm. The von Bertalanffy growth equation was estimated as L_t = 54.70 (1 ? exp (?0.37 (t + 0.21))). Concluded was that there is a significant relationship between body size, otolith dimensions and estimated age of Otolithes ruber.     

Age and growth characteristics of Schizopygopsis younghusbandi Regan, 1905 in the Yarlung Tsangpo River in Tibet,China

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 SL^3.030 for sexes combined. The von Bertalanffy growth function was used to model back‐calculated lengths as L_t = 338.4 (1?e^{?0.233 (t + 0.403)}) for males, and L_t = 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.     

Growth and reproduction of Chelidonichthys lucerna (Linnaeus) (Pisces: Triglidae) in the Gulf of Gabès,Tunisia

Growth and reproduction of Chelidonichthys lucerna is reported from Tunisian waters. A total of 286 specimens was collected from landings of bottom trawlers between January 2003 and November 2004. The total length ranged from 16 to 36 cm in females and from 17 to 26 cm in males. Marginal increment analysis of otoliths showed that the translucent zone was laid from October to May and the opaque zone laid from June to September. Females were from 0.5 to 9 years and males from 1 to 7 years old. Growth parameters of the von Bertalanffy growth function were TL_∞ = 40.26; K = 0.06 and t₀ = ?3.03 in females and TL_∞ = 46.16; K = 0.059 and t₀ = ?1.32 in males. The coefficient of the allometric length–weight relationships differed significantly by sex. Females with mature gonads were observed between October and May, with peaks in January and February. Length at which 50% of specimens were mature was 21.6 cm TL (estimated age about 3 years) in females and 19.2 cm TL (estimated age about 1.5 years) in males.     

Age determination and growth of turbot and brill in the Adriatic Sea: reversal of the seasonal pattern of otolith zone formation

The growth of two commercially important flatfish, turbot ( Psetta maxima ) (L.) and brill ( Scophthalmus rhombus ) (L.), was investigated in the Adriatic using whole otoliths (sagittae) and stained otolith sections. At variance with the pattern usually observed in temperate seas, the opaque zone was found to be laid down in autumn and winter, and the translucent zone in spring and summer. Growth rates differed according to sex, with the females attaining greater body lengths. The von Bertalanffy growth parameters were: L_∞=66.2 cm, K=0.31 years^–1, and t₀=–0.14 years for turbot males, L_∞=81.5 cm, K=0.21 years^–1, and t₀=–0.48 years for turbot females; L_∞=40.2 cm, K=0.49 years^–1, and t₀=–1.03 years for brill males; L_∞=50.1 cm, K=0.27 years^–1, and t₀=–1.75 years for brill females. Growth rates and maximum age recorded for turbot were comparable to those reported in the North Sea.     

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 and growth of <Emphasis Type="Italic">Schizothorax waltoni</Emphasis> in the Yarlung Tsangpo River in Tibet,China

Age and growth were studied for Schizothorax waltoni in the middle reaches of the Yarlung Tsangpo River in Tibet, southwest of China, from April 2004 to September 2006. A total of 201 specimens were collected ranging from 110 to 580 mm in standard length (SL). In contrast to other otoliths, sectioned lapillus showed a clear pattern of alternating opaque and hyaline zones. Marginal increment analyses showed that the increments, each composed of one opaque and one hyaline zone, are deposited annually. Opaque edges were prevalent from May to August. The von Bertalanffy growth parameters based on sectioned otolith data were L _t  = 689.8{1 − exp[0.051 (t + 3.275)]} for males, and L _t  = 691.1{1 − exp[0.056 (t + 2.466)]} for females. The slow growth and long life indicate that S. waltoni is vulnerable to overfishing and that harvesting strategies for the species should be conservative.     

Age determination,growth and mortality of Gerres subfasciatus Cuvier, 1830 in southeast Australia

Commercial beach‐seine (30–50 mm cod‐end mesh) catches of Gerres subfasciatus in Lake Macquarie southeast Australia were sampled monthly between December 2000 and April 2002 to investigate species age, growth and mortality characteristics using sectioned sagittal otoliths. Inclusion of fishery‐independent length data of young‐of‐the year collected from littoral seagrass beds with fine meshed beach seines augmented growth analyses. Fifty otoliths each month (total 448 female and 402 male) were examined with sections displaying alternating opaque and translucent zonation. Formation of otolith opaque zones occurred annually between August and December as determined by monthly marginal increment analyses. Spawning occurred between October and February, and a universal birth date of 1 December was assigned that allowed counts of opaque zones to be converted to age estimates in years and months (decimal ages). The von Bertalanffy growth function identified that both genders grew fast for their initial 2 years, but thereafter slowed. Females grew faster, had a greater mean fork length‐at‐age, estimated L_∞ and an observed greater maximum fork length in samples compared to males. Nevertheless, observed longevity was 10⁺ years for both genders. Commercial catches of both genders were dominated by the 2⁺ and 3⁺ year age classes. Catch curve analyses identified the instantaneous rate of total annual mortality to be ~0.8 and an exploitation rate of <0.5 for both genders. The data form a basis for developing assessment and management strategies of G. subfasciatus fisheries.     

Age, growth, mortality and population characteristics of the pearl perch, Glaucosoma buergeri Richardson 1845, from deeper continental shelf waters off the Pilbara coast of north-western Australia

Pearl perch, Glaucosoma buergeri Richardson 1845, from deeper waters (> 100 m depth) on the continental shelf of north-western Australia were aged by examining transverse sections of their sagittal otoliths. Ages were assigned based on counts of alternating opaque and translucent zones (annuli). Otolith length and breadth (width) increased linearly with fish length, whereas otolith weight increased linearly with fish age. The continuous growth of the otoliths provides some evidence that the opaque and translucent zones used to estimate age in this study are formed on a regular basis. Parameters of the length–weight relationship were estimated, along with parameters of the von Bertalanffy growth function. The generalised von Bertalanffy growth function (total length-at-age, both sexes combined) for G. buergeri was L _t=512.7 (1 – e^{–0.139( t  + 0.89)}). There was no significant differential growth between the sexes in observed length-at-age. The oldest individual found was a male G. buergeri estimated to be 26 years of age. The annual instantaneous rate of natural mortality ( M ) was estimated to be 0.14. The slow growth, long life and low natural mortality rate indicate that G. buergeri is vulnerable to overfishing and that harvest strategies for this species should be conservative, given its low production potential.     

Age,growth and reproduction of the sand smelt Atherina boyeri Risso, 1810 in Mellah Lagoon (Eastern Algeria)

This aim of this paper was the study of the reproductive biology and growth of the sand smelt, Atherina boyeri, in Mellah Lagoon (Algeria). These data are important for the sustainable exploitation of the stocks of this species. Examined was a total of 1402 Atherina boyeri specimens captured monthly from March 2010 to March 2011, in a population with a 3‐year life cycle. Length–weight relationship was estimated as W = 0.0047 L^3.077 (r² = 0.935) for males and W = 0.0047 L^3.176 (r² = 0.935) for females. Using scales, the von Bertalanffy growth function fitted to back‐calculated size‐at‐age data was Lt = 9.49 [1 ? e^{?0.316 (t + 0.928)}] for males, and Lt = 11.67 [1 ? e^{?0.179 (t + 1.514)}] for females; using otoliths this was Lt = 9.68 [1 ? e^{?0.3 (t + 1.02)}] for males, and Lt = 11.93 [1 ? e^{?0.171 (t + 1.55)}] for females. The growth performance index (Φ) indicated that males (Φ_scales = 3.34, Φ_otoliths = 3.33) grew at the same rate as females (Φ_scales = 3.19, Φ_otoliths = 3.24), with a sex ratio of 1 : 1.6 in favor of females. The reproductive season extended from February to June. Individual length at first sexual maturity was 4.20 cm for 1‐year‐old males and 4.35 cm for 1‐year‐old females.     

Comparative study of the molting cycle of wild and reared swimming crabs Callinectes danae (Crustacea: Portunidae)

Specimens of Callinectes danae Smith 1869 were caught in northeastern Brazil (2178 males, 2031 females); of these, 24 males and 24 females were reared for 6 months. Water temperature (T) and salinity (S) showed a significant effect on the average ecdysis in wild crab (μ), with a model obtained that was: μ = exp(?0.12268T + 0.06148S)/(1 + exp(?0.12268T + 0.06148S)). Size at morphometric maturity was significantly larger for wild males and females (9.45 and 8.38 cm, respectively) than for reared individuals (8.95 and 7.93 cm). Females of sizes above CW₅₀ (carapace width at maturation) showed an increased ecdysis activity, whereas males showed a decrease in ecdysis frequency in sizes over CW₅₀. Five and six molts were observed for females and males, respectively, in both wild and reared crabs; the modal classes of the reared crabs were shifted to smaller sizes. In reared females the terminal‐pubertal molt occurred at 107 days of age and at 148 days, on average, in males. The intermolt period varied from 8 to 41 days and increased with age.     

Age and growth of damselfish Chromis notata (Temminck & Schlegel, 1843), Jeju Island,Korea

This study investigated the age and growth of damselfish, Chromis notate, from Jeju Island in Korea. Samples were collected monthly by lift net from September 2013 to August 2014. Total lengths of the damselfish ranged from 6.4 to 15.3 cm. The relationship between total length and wet weight was WW = 0.0125TL^3.1631 for females, and WW = 0.0091TL^3.2769 for males. The slopes in the relationship between length and weight were not significantly different between sexes, but were significantly different in the intercepts. There were more female than male specimens (1.3:1). Age determination was conducted using the otoliths. Marginal increment (MI) declined in summer and winter, which suggests that two rings are formed each year. Ages of sampled individuals ranged from 1 to 5 years. Length‐at‐age data were fitted using the von Bertalanffy growth model. The estimated growth functions were L_t = 19.93 [1 ? exp^{?0.21 (t + 0.811)}] total length and wet weight was females, and L_t = 16.47 [1 ? exp^{?0.32 (t + 0.499)}] for males.     

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.     

The growth of the common two-banded seabream, Diplodus vulgaris (Teleostei, Sparidae), in Canarian waters, estimated by reading otoliths and by back-calculation

The yearly nature of increment formation in the otoliths of 1–9‐year‐old seabream, Diplodus vulgaris (E. Geoffrey Saint‐Hilaire 1817), from the Canary Islands was validated. The marginal increment method showed that the opaque rings were formed in summer, and the translucent rings in winter. The Brody Proportional Hypothesis and the power length–radius relationship used to back‐calculate the growth trajectories of D. vulgaris showed that this growth model could provide reasonable growth estimates in this species. Growth back‐calculation and growth estimates obtained by direct otolith readings were similar. Data on age and size used to estimate the parameters of the von Bertalanffy growth model for D. vulagris from the Canary Islands showed that males and females had similar growth rates.     

Population structure,length–weight relationship and growth of white seabream,Diplodus sargus sargus (Linneaus, 1758), in Beymelek Lagoon,Turkey

The main objective of this study was to investigate the population structure, length–weight relationship (LWR) and growth of white seabream, Diplodus sargus sargus (L., 1758) in Beymelek Lagoon, Turkey. Samples were collected by gill‐ and trammel nets of various mesh sizes, February 2006 to January 2007. A total of 355 specimens (51 males; 34 females; 270 unidentified) were collected. Male to female ratio was 1.50 : 1. Ages ranged from 0 to 3 years; about 70% were juveniles. Most fish were between 13 and 16 cm in total length and below 90 g in weight. The LWR of all individuals was W = 0.0140 × L^3.1028. The von Bertalanffy growth equation was calculated as L_t = 39.9 × [1 – exp(?0.268 × (t + 1.753)] and the growth performance index (Φ′) was 6.056.     

Age estimation,growth and maturity of the Argentine hake (Merluccius hubbsi Marini, 1933) along the northernmost limit of its distribution in the south-western Atlantic

Age, growth and length-at-maturity of the Argentine hake (Merluccius hubbsi) were studied in the northernmost limit of the species distribution in the south-western Atlantic. A total of 351 otoliths and information from 1610 specimens sampled from the industrial double-rig trawl landings between May 2013 and April 2014 were used. Age and growth were estimated by counting and measuring increments in sectioned sagittae otoliths, and length at maturity was estimated based on macroscopic gonadal analysis. For both sexes, hepatosomatic index and condition index increased mainly during spring, reaching a maximum at the end of summer before the subsequent spawning season began. Gonadosomatic index was highest in April, believed to correspond with peak spawning. The annual periodicity of alternate opaque and translucent zones was validated by marginal increment analysis. Growth curves were fitted to back-calculated size at age by fitting the three-parameters von Bertalanffy growth function. The maximum age was 5 years in fish of either sex. Females attained larger sizes than males. The parameters of the von Bertalanffy growth equations were: L∞?=?533?mm, k?=?0.231 year^?1 and t₀?=??0.935 year for females; L∞?=?394?mm, k?=?0.405 year^?1 and t₀?=??0.463 year for males. The mean length and age at first maturity was 273?mm at 1.9 years for males and 274?mm at 2.0 years for females.     

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.     

Aspects of the Life History of the Salema, Sarpa salpa (Pisces, Sparidae), off the Canarian Archipelago (Central-East Atlantic)

Life history of the salema, Sarpa salpa, off the Canarian archipelago was studied from samples collected between January 1998 and December 1999. Fish ranged from 119 to 452 mm in total length and from 24.9 to 1491.7 g in weight. The species was characterized by a protandric hermaphroditism. The overall sex ratio was unbalanced in favour of males (1 : 0.41). The reproductive season extends from September to March, with a peak in spawning activity in December–January. Males reached maturity at a smaller length (226 mm, 2 years old) than females (294 mm, 3 years old). Males, females and all fish showed an isometric growth. The morphometric relationship between length and mass for the whole population was described by the parameters: a = 0.0000134 and b = 3.01. A concentric pattern of opaque and translucent zones was readily distinguishable on the otoliths. Two rings, one opaque and one translucent, were laid down each year on the otoliths; the opaque zone was formed during the summer months, and the translucent zone during the winter months. Individuals aged 0 to 11 years were found. The parameters of the von Bertalanffy growth equation for all individuals were: L = 479 mm, k = 0.212 year^–1, and t₀ = –1.08 year.     

Age determination and growth estimates of the white‐spotted conger eel,Conger myriaster (Brevoort, 1856) in marine waters of South Korea

The age and growth of conger eel, Conger myriaster, were investigated by measuring transversely sectioned sagittal otoliths samples from 635 individuals. Sample ages ranged from 1 to 13 years in the female data. Parameters of the von Bertalanffy growth function were estimated using nonlinear regression from back‐calculation, mean length of samples at age relationships, and otolith weight‐at‐age relationships. Best‐fitting value of the three methods was the otolith weight‐at‐age relationship (r² = .87). Parameters of otolith weight‐at‐age were estimated as L_∞ = 143.76 cm, K = 0.081, and t₀ = ?1.285. Maximum oocyte diameter (MOD) ranged from 50 to 430 μm. Reproductive traits of ovaries showed a positive relationship between GSI and MOD (r² = .8515). It is suggested that oogenesis begins to develop from 4 years of age and at lengths of about 45 cm TL. In conclusion, these data provide reliable fundamental data for the fish stock management of Conger myriaster in South Korea.     

Age, growth, sexual maturity and food composition of Sciaena umbra in the south-eastern Black Sea, Turkey

Studied were the age, growth, maturity and food composition of the brown meager, Sciaena umbra, caught off Trabzon, south-eastern Black Sea (Turkey) in 2002–2003. A total of 329 individuals was collected by spear fishing and hand nets. The thin sectioning method was used for aging the fish otoliths. Fitted von Bertalanffy growth parameters for all fish were: L _∞ = 51.14 (±1.19) cm, k  =   0.27 (±0.02) year⁻¹ and t ₀ = −0.93 (±0.07) year. This study revealed that S. umbra is a relatively slow-growing and long-lived species with a life span in excess of 18 years. Sexual maturity begins when they reach a length of about 15 cm. Lengths at which 50% of brown meagre become mature are 19.50 for males and about 22 cm for females. Spawning begins in June, when the temperature is approximately 18°C, and ends in August. Gut content analysis indicated that this species feeds mainly on crustaceans, then switches to fish as they grow. Sciaena umbra appears to be an apex predator in the upper littoral zone.