Age at maturity of Mediterranean marine fishes

In this review we collected data on the length at maturity (L m ) and maximum reported total length (L max ) of 565 Mediterranean marine fish stocks, representing 150 species, 68 families, 24 orders and 3 classes. Overall, L m ranged from 2 cm, for the males of the toothcarp Aphanius fasciatus, to 350 cm, for the females of the bluntnose sixgill shark Hexanchus griseus. L m was positively linearly related with L max for Actinopterygii (logL m = -0.123 ? 0.92 9 logL max ; r 2 = 0.87, n = 471, P \ 0.001) and Elasmobranchii (logL m = -0.008 ? 0.922 9 logL max ; r 2 = 0.90, n = 92, P \ 0.001) with the two slopes being significantly different (ANCOVA: F = 2,904, P \ 0.001). The reproductive load (L m /L max ) ranged between 0.23 (sand steenbras Lithognathus mormyrus) and 0.94 (angular roughshark Oxynotus centrina and thornback ray Raja clavata). The mean L m /L max was significantly (ANOVA, F = 34.14, P \ 0.001) lower for Actinopterygii (mean = 0.59, SD = 0.122, n = 471) compared to Elasmobranchii (mean = 0.70, SD = 0.132, n = 92) and Holocephali (mean = 0.77, SD = 0.077, n = 2). The L m /L max was significantly (ANOVA, F = 43.80, P \ 0.001) higher for species providing some form of parental care, i.e. guarders, bearers, nesters (mean L m /L max ± SD = 0.68 ± 0.141, n = 111) compared to non-guarders (mean L m /L max ± SD = 0.59 ± 0.123, n = 454). The mean L m /L max displayed a remarkable constancy with longitude (northern and southern Mediterranean coastline: ANOVA, F = 0.01, P = 0.93), latitude (western, central and eastern regions: ANOVA, F = 1.25, P = 0.29) and habitat (ANOVA, F = 0.85, P = 0.51).

We collected data on the age at maturity (tm) and maximum reported age (tmax) for 153 stocks of marine fishes in Turkey, belonging to 59 species, 24 families and 2 classes (Actinopterygii and Elasmobranchii). Among Actinopterygii tm had an average of 1.8 years (1 to 4 years) while among Elasmobranchii it had an average of 11.9 years (2 to 11.9 years). Overall, tmax ranged between two years (for Sarda sarda) and 34 years (for Squalus acanthias). Mean tmax was found to be 6.24 years for Actinopterygii and 10.11 years for Elasmobranchii. tm showed a positive linear correlation with tmax for both Actinopterygii and Elasmobranchii. Mean tm⁄tmax did not differ significantly with sex within the Actinopterygii and Elasmobranchii. The ratio tm⁄tmax was found to be significantly lower for Actinopterygii than for Elasmobranchii.

Scientia Marina

Maturity is one of the most important biological parameters used in stock assessment programmes. Indeed, the macroscopic stage of gonadal development is an essential feature in estimating the maturity ogive and spawning stock biomass. It is also useful for determining the spawning season of a species and for monitoring long-term changes in the spawning cycle as well as for many other research needs related to the biology of fish. Despite the efforts made during the last few decades to standardize maturity stage data among all the researchers, marine biologists continue without a manageable and unique maturity scale to describe the reproductive development of fish gonads. For these reasons, the objectives of this article are 1) to investigate the biological parameters of five selected key species (Mullus barbatus, Galeus melastomus, Etmopterus spinax, Aristeus antennatus, Loligo vulgaris) with different reproductive strategies following the macroscopic maturity scales based on the sa...

Fish and more: 3rd Mini …, 2005

Acta Ichthyologica et Piscatoria

Background. The Mugilidae is a widely distributed family in the tropical, subtropical, and temperate waters. These fish species have a global economic value because of the high quality of their flesh and caviar. This study provides new data on the age, growth, and reproduction parameters of commercially exploited grey mullets from the Köyceğiz Lagoon, Turkey, namely golden grey mullet, Chelon auratus (Risso, 1810), leaping mullet, Chelon saliens (Risso, 1810), thicklip grey mullet, Chelon labrosus (Risso, 1827), and flathead grey mullet, and Mugil cephalus Linnaeus, 1758. The obtained results are intended for fisheries management of golden mullets in the area. Materials and methods. A total of 1195 fish specimens were collected from the Köyceğiz Lagoon (south-western Anatolia). The mullets were caught monthly, between January 2017 and December 2017, using fish barrier, trammel net, beach seine, and cast-net. The fish age was determined from sagittal otoliths. Growth parameters were determined by applying the von Bertalanffy growth function. Reproduction period, mortality and exploitation, relative yield per recruit (Y′/R), and biomass per recruit (B′/R) were determined. Results. The most frequent mullet age groups were 3 + and 4 + (for M. cephalus and C. labrosus) and 4 + (for C. auratus and C. saliens). The following von Bertalanffy's growth models were calculated: L t = 58.78(1-e-0.163(t + 0.0195)) for C. auratus, L t = 59.99(11-e-0.169(t + 0.0132)) for M. cephalus, L t = 49.77(111-e-0.193(t + 0.0293)) for C. labrosus, and L t = 46.41(111-e-0.232(t + 0.0283)) for C. saliens. The growth performance index (Ø′) for C. auratus,

Acta Ichthyologica Et Piscatoria, 2012

Background. Though fishes grow indeterminately, very little is known of the effects of age on the morphometric indices (length, weight, and condition) in fishes as it is often difficult to cover the entire lifespan of a species in laboratory or nature. The presently reported study was thus conducted to elucidate the effects of age (and sex) on the growth indices using the annual fish and a laboratory model of aging. Materials and methods. Experimental fish-the redtail notho, Nothobranchius guentheri (Pfeffer, 1893), were obtained by hatching the diapause eggs of the same parental lineage and reared over their entire lifespan. Length-weight measurements were recorded from 3-12 months and various indices (length-weight relation, Fulton's condition factor, and relative condition factor) were computed and compared statistically. Results. Mean lengths, weights, length-weight relations (LWRs), Fulton's condition factor (K) and relative condition factor (K n) varied significantly leading to differential indices based on age and sex. Age influenced all indices positively, which is indicative of the indeterminate growth typical of fishes. Conclusion. Age was not seen to suppress the growth indices in the annual fish, which is suggestive of a healthy and delayed senescence in the annual fish N. guentheri. Whether other short-and long-lived finfish follow the same pattern needs further investigation.

We estimated the current level of knowledge concerning several biological characteristics of the Mediterranean marine fishes by carrying out a gap analysis based on information extracted from the literature, aiming to identify research trends and future needs in the field of Mediterranean fish biology that can be used in stock assessments, ecosystem modeling and fisheries management. Based on the datasets that emerged from the literature review, there is no information on any biological characteristic for 43% (n = 310) of the Mediterra-nean fish species, whereas for an additional 15% (n = 109) of them there is information about just one characteristic. The gap between current and desired knowledge (defined here as having information on most biological characteristics for at least half of the Mediter-ranean marine fishes) is smaller in length-weight relationships, which have been studied for 43% of the species, followed by spawning (39%), diet (29%), growth (25%), maturity (24%), lifespan (19%) and fecundity (17%). The gap is larger in natural mortality for which information is very scarce (8%). European hake (Merluccius merluccius), red mullet (Mullus barba-tus), annular seabream (Diplodus annularis), common pandora (Pagellus erythrinus), European anchovy (Engraulis encrasicolus), European pilchard (Sardina pilchardus) and bogue (Boops boops) were the most studied species, while sharks and rays were among the least studied ones. Only 25 species were fully studied, i.e. there was available information on all their biological characteristics. The knowledge gaps per characteristic varied among the western, central and eastern Mediterranean subregions. The number of available records per species was positively related to total landings, while no relationship emerged with its maximum reported length, trophic level and commercial value. Future research priorities that should be focused on less studied species (e.g. sharks and rays) and mortality/fecundity instead of length-weight relationships, as well as the economy of scientific sampling (using the entire catch to acquire data on as many biological characteristics as possible) are discussed.

Biological Letters

Based on length, weight, and age data, we examined allometry and growth parameters for common pandora, Pagellus erythrinus, commercially collected seasonally from northern and southern Tunisian coasts in 2007. A total of 370 specimens (14–27.5 cm in length) were used to assess the allometric variation at seasonal scales. The slope b values (regression coefficient) of the length-weight relationship varied between 2.494 to 3.237, indicating (roughly) an isometric to negative allometric growth pattern. The allometric relationship, as a proxy for fish condition, seems to be affected by seasons and sex in the northern population, while only seasons seem to have a strong effect in the southern population, as indicated by ANOVA. The von Bertalanffy growth parameters were identified at L∞ = 34.076 and 28.017 cm, k = 0.153 and 0.150/year, and t0 = −1.922 and −3.961 years for the northern and southern sample, respectively.

Acta Ichthyologica et Piscatoria, 2017

Background. In Turkey, the Mediterranean scaldfish, Arnoglossus laterna (Walbaum, 1792), is a discard fish species and it has a 'least concern' status on the IUCN Red List which indicates a low extinction risk. Although there are some studies investigating biology of this species, the knowledge of the mortality rates, spawning period, first maturity size, and age are not available for the study area. This paper, for the first time, provides some data on unknown population parameters for the east-central Aegean Sea. The aim of the presently reported study was to expand our knowledge on the biology of A. laterna. Materials and methods. Specimens of A. laterna were collected at monthly intervals by bottom trawl hauls between July 2004 and June 2007 from İzmir Bay (Turkey). The total length (L, cm), total weight (W, g), gonad weight (W G , g), and the sex were determined and the sagittal otolith pairs were removed for age reading. The length-weight relations were estimated by linear regression analysis on log-transformed data by equation: W = aL b. The growth was analysed by fitting the VBGF to size-at-age data using standard nonlinear optimization methods. Spawning period was established with monthly variations of the GSI values. Length at first maturity was estimating by the logit function. Results. A total of 2469 A. laterna individuals were sampled and the sex ratio was calculated as 1 ÷ 1.57 (F ÷ M). The length range of the sample was from 4.4 to 19.8 cm and the mean length was calculated as 9.4 ± 0.05 cm. For all samples, the length-weight relation was W = 0.0074L 3.04 and the growt type was deterined as positive allometic. The age distribution of individuals varied from 1 to 8 years and the growth equation was determined as L t = 20.62[1-e-0.245(t + 1.071) ]. The first maturity lengths were estimated as 11.88 cm for females and 11.41 cm for males. Conclusion. The presently reported study provides the age, growth, and reproduction parameters for A. laterna and the first information on the mortality rates, spawning period, first maturity size, and age parameters for the east-central Aegean Sea. These parameters can be useful for managers in the management and conservation of the stock.

Acta Ichthyologica et Piscatoria, 2018

Background. Shark populations within the eastern Mediterranean are declining due to overfishing. Unfortunately, our knowledge on the biology of sharks and specifically dogfishes within eastern Mediterranean is extremely limited due to the lack of landings. Mustelus mustelus (Linnaeus, 1758) is one of such deficiently known cartilaginous fishes and the relevant information on its age and growth in the eastern Mediterranean is missing. The understanding of growth and reproductive behaviour is important for management and conservation of this species. The presently reported study was intended to determine age, growth, and some reproductive parameters of Mustelus mustelus collected in the Gulf of Iskenderun, the northeastern Mediterranean Sea. Materials and methods. In this study, a total of 155 Mustelus mustelus were caught in the northeastern Mediterranean Sea between March 2012 and October 2015. Fish age was determined based on band counts of sectioned vertebrae. The periodicity of band pair formation was examined using the marginal increment analysis. Growth parameters for all specimens were then determined by fitting the observed and the length-at-age data using the von Bertalanffy Growth Equation. The size and age at which 50% of both sexes reached maturity was estimated by a logistic model for maximum likelihood process and the gonadosomatic index was determined. Results. The total length and weight of the specimens examined ranged from 44.3 to 162.6 cm and from 241.3 to 12 060 g, respectively. The presently reported study provides new maximum lengths (162.6 cm) for M. mustelus from the northeastern Mediterranean. The fish studied represented age groups from 0 through 25. The observed sex ratio was 1 ÷ 1.04 (females ÷ males). Von Bertalanffy growth parameters were estimated to be L ∞ = 195.13 cm, W ∞ = 20 060 g, K = 0.06, and t 0 = −4.27 for all specimens. Length-weight relation was found to be W = 0.0027L 3.0054 (R 2 = 0.98) and 95% confidence intervals of b = 2.936-3.075, t-test P < 0.05. All studied specimens of M. mustelus represented isometric growth (b = 3). Condition factor ranged from 0.148 to 2.87 for females and from 0.103 to 1.024 for males. The length at 50% maturity and the age at 50% maturity were 109 cm and 8 in females and 92 cm and 7 in males, respectively. It was observed that mean GSI values were low in September and July, reaching a maximum in January to February. Conclusion. The results of this study could give useful insight for management plans and conservation of M. mustelus in the Mediterranean coast of Turkey.