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1.
The present study shows that small non‐territorial terminal‐phase males of the rusty parrotfish Scarus ferrugineus are reproductively active and are comparable with initial‐phase males in behaviour, rates of participation during group‐spawning and success in streaking into pair spawning. Large territorial terminal‐phase males defend contiguous territories for several hours during the morning where they pair spawn with initial‐phase females.  相似文献   

2.
Age, growth, and age at sexual maturity of the polkadot skate Dipturus chinensis, in the northern East China Sea were determined for a total of 614 specimens collected from April 2009 to December 2014. Vertebral centrum analysis was used to calculate the age of the skates. Annual band deposition was determined by marginal increment analysis. The von Bertalanffy growth model was fitted to the observed length‐at‐age data for each sex (males, L = 76.8, k = 0.109, t0 = ?1.28; females, L = 83.1, k = 0.103, t0 = ?1.20). Growth patterns of females and males were similar until the age of 6; thereafter, females grew larger than males. Maximum age recorded was 13 years for males and 15 years for females. Age at 50% sexual maturity was 8.22 years for males and 9.39 years for females. These results indicate that Dchinensis is slow growing, relatively long‐lived, and late maturing, and therefore vulnerable to exploitation.  相似文献   

3.
Temporal trends in growth of the rusty parrotfish Scarus ferrugineus were studied on a southern Red Sea fringing reef that experiences seasonal changes in environmental conditions and benthic algal resources. Length increment data from tagging and recapture were compared among periods and sexes and modelled using GROTAG, a von Bertalanffy growth model. The growth pattern of S. ferrugineus was highly seasonal with a maximum occurring between April and June and a minimum between December and March. Body condition followed the seasonal variation in growth, increasing from April to June and decreasing from December to March. The season of maximum growth coincided with high irradiation, temperature increases and peak abundance of the primary food source, the epilithic algal community. There was a decline in growth rate during summer (July to October) associated with a combination of extreme temperatures and lowered food availability. There were strong sexual size dimorphism (SSD) and life‐history traits. Terminal‐phase (TP) males achieved larger asymptotic lengths than initial‐phase individuals (IP) (L 34·55 v. 25·12 cm) with growth coefficients (K) of 0·26 and 0·38. The TPs were growing four times as fast as IPs of similar size. Three individuals changed from IP to TP while at liberty and grew eight times faster than IPs of similar size, suggesting that sex change in S. ferrugineus is accompanied by a surge in growth rate. The SSD in S. ferrugineus thus coincided with fast growth that started during sex change and continued into the TP. Faster growth during sex change suggests that the cost associated with sex change is limited.  相似文献   

4.
The sharpbelly Hemiculter leucisculus, an invasive species, has expanded its range throughout much of Asia and into the Middle East. However, little is known of its adaptive changes regarding life history traits such as age, growth and mortality that could possibly explain its success as an invasive species. A detailed study of the invasive sharpbelly was conducted based on 4539 samples collected from July 2009 to June 2011 in Erhai Lake, China. Standard length ranged from 4.3–19.1 cm for females and 4.6–12.3 cm for males. Length–weight relationships for females and males were significantly different and described as W = 0.0076SL3.2608 and W = 0.0084SL3.1901, respectively. Otoliths are ideal for age determination because of the single annulus formed each year. Based on marginal increment analysis, the total mean CV for age estimate between two readings was 3.55%. The von Bertalanffy growth curves computed by observed length‐at‐age data were expressed as Lt = 25.6 (1 ? e?0.176 (t + 1.347)) for females and Lt = 16.4 (1 ? e?0.354 (t + 0.819)) for males. According to the age, growth and mortality data, there are three possible reasons for H. leucisculus attaining such dominance within a short time in Erhai Lake. First, because of the simple age structure of this species: 97.58% of males were 1–2 years old with a maximum age of only 3 years; 93.14% of females were 1–3 years old, with a maximum age of 6 years. Second, females grew larger than males at any age. Third, instantaneous mortality rates were much higher for males (4.22 year?1) than for females (1.17 year?1).  相似文献   

5.
We describe the isolation and characterization of 17 polymorphic microsatellite loci for the ember parrotfish Scarus rubrioviolaceus. In a Hawaiian sample of 69 fish, we found between three and 20 alleles per locus, and observed heterozygosity ranging from 0.283 to 0.896. Four of these loci consistently cross‐amplified in the stareye parrotfish Calotomus carolinus, the spectacled parrotfish Chlorurus perspicillatus, the palenose parrotfish Scarus psittacus, and the bullethead parrotfish Chlorurus sordidus, but others gave mixed results. These loci will be useful for describing mating systems and population structure in marine species with broad dispersal potential that play key ecological roles in tropical environments.  相似文献   

6.
The age, growth, reproduction, sexual maturity and stomach content of John Dory (Zeus faber), caught in the Bay of Saros (North Aegean Sea) between September 2006 and September 2008, were investigated. The female‐male ratio was 1.6 : 1. The total length of females ranged from 13.8 cm to 52.8 cm, and of males from 12.2 cm to 42.9 cm. The length‐weight relationship was W = 0.0174*L2.936. Age data derived from vertebral centra readings were used to estimate the growth parameters of the von Bertalanffy equation. Growth parameters for females were L = 58.50 cm K = 0.11 year?1, t0 = ?0.99 year and for males L = 45.01 cm, K = 0.13 year?1, t0 = ?1.17 year. Maximum age was 18 years for females and 17 years for males. Length at first maturity for both females and males was 25.4 cm. Monthly values of the gonadosomatic index indicated that spawning occurred mainly in two peaks: one between January and June, and the other from August to September. Stomach content analysis showed the most‐preferred prey to be Pisces (IRI% 97.3).  相似文献   

7.
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 L3.077 (r2 = 0.935) for males and W = 0.0047 L3.176 (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 (Φscales = 3.34, Φotoliths = 3.33) grew at the same rate as females (Φscales = 3.19, Φotoliths = 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.  相似文献   

8.
This work contributes to the knowledge of the reproduction, growth parameters and mortality rates of Iheringichthys labrosus in a newly‐formed reservoir. A total of 554 males and 1227 females were collected over 12 consecutive months, 1998–1999, from sites in the Corumbá Reservoir, Brazil, using gillnets (meshes: 2.4–16 cm). Information on each individual, i.e. standard length (cm), weight (g), sex, and gonadal development phase was recorded. The pectoral spines were removed to estimate age. The number of juveniles and adults, males and females, reproductive sites and seasons were estimated. First maturation length was estimated using a likelihood function fitted by binomial distribution. Growth parameters were estimated using the von Bertalanffy equation. Total instantaneous mortality was obtained through a linearized catch curve method. Standard length varied from 6.0 to 20.5 cm. Growth showed negative allometry for both sexes. The reproduction period was August to December in all environments sampled and first maturation length was 11.5 cm. All individuals were adults with 17.0 cm standard length. Ages varied from zero to 7 years. Asymptotic length, growth coefficient and t0 for the entire population were 27.79 cm, 0.12 and ?2.64, respectively. Instantaneous and annual mortality rates were 0.90 and 0.59, respectively.  相似文献   

9.
Spawning time and male mating tactics of parrotfishes (family Scaridae) were investigated on a fringing coral reef at Iriomote Island, Okinawa. Spawning was observed in 14 species, and more frequently in more abundant species such as Chlorurus sordidus, Scarus rivulatus and Chlorurus bowersi. At the reef-edge spawning site, C. bowersi spawned at high tide, C. sordidus spawned both at high tide and in the early morning, whereas Calotomus carolinus and most of the Scarus species such as S. rivulatus spawned only in the early morning, mostly 0630–0830 h. Spawning only in the early morning irrespective of tide phase and moon age has seldom been reported from the scarid species of other localities. It is suggested that spawning in the early morning would be adaptive in species such as S. rivulatus, which migrated considerable distances (ca. 500 m) to the inshore feeding sites, in order to minimize feeding losses due to migration. For male mating tactics, pair spawning by territorial TP (terminal phase) males occurred in all 14 species, and streaking and group spawning by nonterritorial small IP (initial phase) males were seen more frequently in more abundant species. Moreover, group spawning by nonterritorial TP males, which were larger than the IP males but smaller than the territorial TP males, frequently occurred in S. rivulatus. Such mating tactics of TP males have not been reported from Scaridae.  相似文献   

10.
In this study, we examined the life history characteristics of the parrotfish Calotomus japonicus, using individuals collected between May 2003 and May 2008 off the Nagasaki Peninsula in northwest Kyushu, Japan. Age determinations were performed using scales. Marginal increment analysis revealed that growth rings were formed annually around July. Growth in both sexes was fitted to the von Bertalanffy growth function (L  = 513, k = 0.28, t 0 = 0.03, where L is the theoretical asymptotic total length in mm, k is the growth rate coefficient and t 0 is the theoretical time at zero length). Observed maximum age for both sexes was 8 years. We also characterized the reproductive biology of this species based on a gonadosomatic index and histological examinations of the gonads. The spawning season extends from July to October, with peak spawning activity occurring during July and August. Fish reach sexual maturity by the second year of life. Females are assumed to be multiple spawners, since we observed specimens with postovulatory follicles in ovaries containing either yolk globule oocytes or migratory nucleus oocytes. All males had secondary testes, which were characterized by the presence of an ovarian lumen structure and sperm sinuses in the gonadal wall. This indicates that all males, irrespective of whether they were initial or terminal phase males, had undergone a sexual transition. Sex change appears to occur during the spawning season, and thereafter sex-changed males are able to fertilize female eggs throughout the remainder of the current spawning season.  相似文献   

11.
Growth parameters in pikeperch may be affected by several factors. The purpose of this study was to investigate the growth and length–weight of pikeperch in a reservoir in south‐western Spain and compare the results with previous published data. Age and growth are described for Sander lucioperca from the Alcántara Reservoir (south‐western Spain) from March to October 2009. A total of 285 fish were examined; the ratio of males to females was estimated as 0.78:1 and age ranges as 1–5 years. Total lengths ranged from 16.1 to 52.5 cm. The length–weight relationships were described as W = 0.00 462 TL3.09 (r = 0.9865) for males and W = 0.00279 TL3.16 (r = 0.9921) for females. Growth was expressed in length and the von Bertalanffy growth parameters were estimated as L∞ = 92.14 cm, k = 0.09, t0 = ?1.05 for males and L∞ = 107.72 cm, k = 0.08, t0 = ?1.16 for females. Growth performance indexes were also estimated as Φ’ = 2.88 for males and Φ’ = 2.96 for females. Differences in growth and length–weight relationships between sexes were not found.  相似文献   

12.
To aid in species' conservation, the aim of this study was to provide initial findings on age, growth and reproduction of an endemic species, Aegean chub Squalius fellowesii (Günther, 1868) populations from streams in the Aegean region of Mu?la Province, Turkey. The species is relatively short‐lived (maximum 6 years), attaining a size of about 200 mm total length with a rapid growth to first maturity (≈60 mm TL), and relatively little growth thereafter. The male:female ratio was 1.0 : 0.6, males significantly outnumbering females in the majority of the streams. General condition values of individual fish varied between 2.9 and 3.4. Sexual maturity was usually achieved later and at larger sizes in females than in males. Sexual maturation in most populations was at the age of 2 years in females and 1 year in males. The species spawns between early April and late May. Mean absolute and relative fecundity were about 4440 eggs and 57 eggs·g?1, respectively. Mean egg diameter was 1.00 ± 0.03 mm, ranging from 0.70 to 1.20 mm. Suggestions for the conservation of Aegean chub are discussed.  相似文献   

13.
The study purpose was to investigate the reproductive biology, growth and length‐weight of the Turkmenian crested loach, Metaschistura cristata, in the Radkan River of northeastern Iran. Age and growth are described for 1029 specimens from January 2009 to December 2010. The sex ratio was 1:1. Maximum age, based on opercula readings, was 6+ years for both sexes. Specimens ranged in size from 24 to 98 mm total length and weighed from 0.08 to 7.32 g. The length‐weight relationships were described as W = 0.005166 TL3.225 (R2 = 0.97) for males and W = 0.006192 TL3.125 (R2 = 0.97) for females. Growth was expressed in length and the von Bertalanffy growth parameters were estimated as L = 354.9 mm, k = 0.0038, t0 = ?26.82 for males and L = 339.0 mm, k = 0.0043, t0 = ?24.88 for females. Growth performance indexes were also estimated as Φ′ = 6.17 for males and Φ′ = 6.20 for females. The gonadosomatic index showed that peak reproduction occurred during April and June, with highest average values of 2.1% for males and 25.3% for females in May. Oocyte diameter ranged from 0.09 to 1.58 mm, with a mean value of 0.54 ± 0.42 mm.  相似文献   

14.
Demographic parameters and status assessments for L. ehrenbergii, L. lentjan, P. sordidus and R. sarba in the southern Arabian Gulf were established using a combination of size frequency, biological and size‐at‐age data. Defined structural increments consisting of alternating translucent and opaque bands in transverse sections of sagittal otoliths were validated as annuli. The maximum age estimates ranged from 5 years for R. sarba to 14 years for P. sordidus. Growth trajectories were significantly different between sexes for L. ehrenbergii and L. lentjan with females achieving a larger asymptotic size than males. Estimates of fishing mortality rates were less than the target (FSB40) and limit (FSB30) biological reference points for L. ehrenbergii, L. lentjan and P. sordidus indicating that these species were exploited within sustainable limits. Conversely, R. sarba was found to be heavily overexploited and recruitment overfishing may have occurred as the fishing mortality rate was considerably greater than the limit reference point and the relative spawner biomass per recruit was 6.4% of the theoretical unexploited level. Due to restrictions in the available data set, the presented results require confirmation from specific studies on natural mortalities and from growth estimates based on more extended size spectra, avoiding any size selective sampling method.  相似文献   

15.
This study tested the suitability of several staining methods to determine the age of common stingray (Dasyatis pastinaca) from Iskenderun Bay, Turkey. A total of 384 specimens (16.6 cm–69.3 cm disc width) were obtained by trawling between September 2010 and December 2011. Sex ratio of the samples was 53% males and 47% females. Appropriate age determination was firstly demonstrated using Safranin‐O staining. Age readings were made by two independent readers and the index of average percent error (IAPE) determined as 6.3% for Safranin‐O, 6.8% for Crystal Violet, 7.9% for Alcian Blue, and 9.3% for Silver Nitrate. Safranin‐O and Crystal Violet staining methods provided the best results. Verification of temporal growth ring formation was by marginal increment analysis. Disc width–weight relationships were determined by W = 0.0272*DW3.06 for females and W = 0.0247*DW3.08 for males. Estimates of the von Bertalanffy growth parameters indicated a larger asymptotic disc width (DW = 127.06 cm) for females than for males (DW∞ = 114.54 cm); growth parameters were = 0.058 year?1, to = ?1.508 and = 0.041 year?1, to = ?3.632 for females and males, respectively.  相似文献   

16.
The age and growth parameters of Dipturus chilensis were estimated by counting growth rings from thin sections of vertebral centra from 400 fish (246 females and 154 males), ranging from 23 to 124 cm total length (LT), and backcalculating fish lengths at previous ages. Marginal increment analysis lent support to the hypothesis of annual deposition of band‐pairs, which formed during the winter months. The oldest female D. chilensis aged in this study was 21 years and 117 cm LT, whereas the oldest male was 18 years and 93 cm LT. A 4·7% index of average per cent error (IAPE) suggested that this is a precise method for calculating the age of D. chilensis. Observed LT were lower than backcalculated LT, which implies the influence of Lee's phenomenon. The von Bertalanffy growth equations, based on mean length‐at‐age data, were estimated as Lt = 128·3 (1 ? e?0·112 (t + 0·514)) for females and Lt = 107·8 (1 ? e?0·134 (t + 0·862)) for males where t is age (years). Growth was significantly different between sexes: females reached a larger adult size. Ages and lengths at 50% maturity were estimated at 14 years of age and 106 cm LT for females and 11 years of age and 86 cm LT for males. At c. 14 years, there was a decline in growth rates in females. The factor most likely responsible for this was sexual maturity, which caused a discontinuity in growth of female fish. These results show that this species is slow‐growing, long‐lived, relatively large and of delayed maturity, characteristics that make it vulnerable to exploitation.  相似文献   

17.
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 = 0.0125TL3.1631 for females, and WW = 0.0091TL3.2769 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 Lt = 19.93 [1 ? exp?0.21 (t + 0.811)] total length and wet weight was females, and Lt = 16.47 [1 ? exp?0.32 (t + 0.499)] for males.  相似文献   

18.
The tub gurnard Chelidonichthys lucerna has been identified by ICES as a potential commercial species in the northeast Atlantic with recommendations made to monitor landings and discards and to derive information on population biology for stock assessment purposes, however, data are lacking for the species in the northeast Atlantic. Therefore, aims of this study were to provide data on the size/age‐structure and patterns of growth, maturity and mortality of C. lucerna in Northwest Wales, UK, and in doing so to provide data on the biological characteristics of the most northerly population studied to date for comparison with the existing data for southerly Mediterranean populations. Data on the age, growth and maturity of C. lucerna were collected by otter trawling (73 mm cod‐end stretched mesh size) in the coastal waters of Northwest Wales, UK in October (2000–2011, excluding 2006). Total length (TL) of fish sampled ranged between 10.5–41.0 cm (males) and 10.4–57.5 cm (females). The majority of the female fish were between 20–30 cm TL (60.2%) and the majority of the male fish between 20–30 cm TL (58.3%) respectively. TL/weight (W) relations for male and female fish were similar and the combined data was described by W = 0.0067 TL3.10. Age of fish ranged between 1–7 years old for female fish and 1–5 years old for male fish respectively with the majority of female fish 3 years old (40%) and the majority of male fish 3 years old (37%). The age structures of female and male tub gurnards were not significantly different with the older age classes consisting predominantly of female fish. Both males and females exhibited similar asymptotic growth patterns and the combined von Bertalanffy growth function was TLt = 51.6 (1 ? e [?0.25(t + 0.41)]). Instantaneous rates of total mortality were calculated as 1.04 year?1 for males and 1.11 year?1 for females. The size (L50) and age at first maturity (A50) were estimated to be 29.1 cm TL and 2.8 years for males, 27.7 cm TL and 2.7 years for females and 28.0 cm TL and 2.8 years for both sexes combined. The results of this study provide the first information on the biology and population dynamics of C. lucerna in the Irish Sea, the first data collected in the northeast Atlantic since 1985 and the most northerly population studied to date.  相似文献   

19.
Population structure and reproductive biology of an important and less studied freshwater carp, Labeo boggut (Sykes, 1839), from two perennial rivers of Central India were studied between January 2008 and December 2009. Maximum three annual rings were found and used to assess growth data in samples representing 0 to 3+ year classes. LWR indicated positive allometric growth in males and females of both rivers. Asymptotic length (L) and growth co‐efficient (K) were 22.5 cm and 0.5 year?1 for the Betwa River; and 23.6 cm and 0.6 year?1 for the Ken River. Growth performance index (ø’) was higher in the Ken than in the Betwa. Reproduction was between June and September and GSI of both sexes were maximal in mid‐June, thereafter declining until September. Mean size at first sexual maturity was 12.2 cm (n = 12) for females and 13.2 cm (n = 8) for males in the Betwa, and 12.5 cm (n = 13) TL for females and 13.1 cm (n = 9) TL for males in the Ken. The exploitation level (E) and maximum allowable exploitation (Emax) limit of L. boggut was 0.23 and 0.36 in the Betwa, whereas it was 0.33 and 0.37 in the Ken. These presented biological traits and population characters of L. boggut from both rivers provide first basic information for use in future assessment and conservation planning.  相似文献   

20.
The smooth hammerhead Sphyrna zygaena (Sphyrnidae) is a pelagic shark occasionally caught as bycatch in pelagic longline fisheries, but is one of the least studied of all pelagic sharks. Age and growth of S. zygaena was studied along a wide Atlantic region covering both the northern and southern hemispheres. Data from 304 specimens, caught between October 2009 and September 2014, ranging in size from 126 to 253?cm fork length (FL), were analysed. Growth models were fitted using the three-parameter von Bertalanffy growth function (VBGF) re-parameterized to calculate L0 (size at birth). Growth models were fitted to the sample data and data from several back-calculation models. The model fit to the quadratic modified Dahl-Lea back-calculated data seems to be the most appropriate to describe growth in this species, with resulting growth parameters of Linf?=?285?cm FL, k?=?0.09 year?1 for males and Linf?=?293?cm FL, k?=?0.09 year?1 for females. Compared with other species of the same genus, estimated growth coefficients for S. zygaena seem to fall in the low to middle range. Although further work is still needed, this study adds to knowledge of the vital life-history parameters of smooth hammerheads in the Atlantic Ocean, which can be used in the management and conservation of this species.  相似文献   

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