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1.
Chlorophthalmus corniger is redescribed on the basis of recently collected specimens. The species is redefined as a species of Chlorophthalmus with the lower jaw terminating in a distinctly projecting horizontal plate with strong, spine‐like processes directed forward from the plate's corners; body silvery grey, with numerous minute black spots and traces of broad darker crossbars; base of anterior dorsal fin spines and distal parts of dorsal fins black; adipose fin tiny with numerous black spots; caudal fin black; 3·5 scales above lateral line; three rows of cheek scales; head very large, 34·3–40·1% standard length (LS); eye large, 29·8–40·8% head length (LH); pectoral fin long, extending to beyond dorsal fin base, 21·7–26·2% LS. Chlorophthalmus bicornis is a junior synonym of C. corniger based on the examination of the type series of both species. It is confined to the northern half of the Indian Ocean, reliably recorded from Somalia and the Gulf of Aden to southern Java, Indonesia, at depths between 200 and 500 m. A lectotype and three paralectotypes were designated for C. corniger. DNA barcodes for Indian species of Chlorophthalmus were generated.  相似文献   

2.
In wild ballan wrasse Labrus bergylta, mass–length relationships were not different between genders, and positive allometry was found in the mixed‐gender population. Male‐biased sexual size dimorphism was significant and the most effective morphometric method for sexing L. bergylta outside of the species spawning window used body mass (MB in g), total body length (LT in mm) and Fulton's condition factor (K) as discriminant variables to predict gender with 91% accuracy. The discriminant score (SD) of a specimen can be calculated as SD = 0·01 MB ? 0·016 LT ? 3·835 K + 6·252 to predict its gender as female or male if SD is < 1·459 or SD is > 1·504, respectively. There was a potential trend towards earlier sexual inversion compared to previous studies at comparable latitudes. Sex change is a phenotypically plastic trait under social control in haremic fishes and should be monitored in increasingly exploited L. bergylta.  相似文献   

3.
The effect of sampling with bongo (0·6 m diameter frame with 500 µm mesh) and Methot Isaac Kidd (MIK) (2 m diameter frame with 2 mm mesh finished with 500 µm codend) nets on standard length (LS) range and growth rate differences was tested for larval Sprattus sprattus (n = 906, LS range: 7·0–34·5 mm) collected during four cruises in the summer months of 2006, 2007, 2009 and 2010 in the southern Baltic Sea. Although the minimum size of larvae collected with the bongo and MIK nets was similar in each cruise (from c. 7 to 9 mm), the MIK nets permitted collecting larger specimens (up to c. 34 mm) than the bongo nets did (up to c. 27 mm). The growth rates of larvae collected with the bongo and MIK nets (specimens of the same size range were compared for three cruises) were not statistically different (mean = 0·55 mm day?1, n = 788, LS range: 7·0–27·4 mm), which means the material collected with these two nets can be combined and growth rate results between them were compared.  相似文献   

4.
5.
Juveniles of two Acentrogobius species collected in a mangrove estuary in Sikao Creek, southern Thailand, were identified by morphological and molecular methods. A total of 1315 Acentrogobius specimens were collected and grouped into types A (n = 1107, 4·4–12·0 mm standard length, LS) (melanophore absent or indistinct on posterodorsal contour of caudal peduncle; two rows of melanophore blotches on lateral midline) and B (n = 208, 4·8–12·6 mm LS) (distinct melanophore on posterodorsal contour of caudal peduncle; a single row of melanophore blotches on lateral midline). Based on the reverse series method, the melanophore patterns of larger juveniles were linked with the smallest specimens possessing adult characters. The homogeneities of mitochondrial cytochrome b region sequences between the two juvenile types and adult Acentrogobius species collected in the study area indicated type A to be A. kranjiensis (homogeneity between type A and A. kranjiensis: 99·3–100%), and type B to be A. malayanus (homogeneity between latter 98·1 and 99·7%). No Acentrogobius juveniles were collected from the surf zone outside the creek mouth, both species apparently spending most of their life histories within the estuarine habitat. During their pelagic phase, A. kranjiensis and A. malayanus dispersed in the upper, middle and lower reaches of the creek. On the other hand, occurrence patterns during the benthic phase of A. kranjiensis and A. malayanus differed, the former showing upstream movement and the latter downstream movement with growth. These results emphasize the necessity of analysing early fish life histories at the species level, and the collaboration between morphological and molecular methods should prove valuable in accurately identifying of larvae and juveniles.  相似文献   

6.
An expedition to the middle Rio Purus basin uncovered a remarkable new species of the genus Spinipterus. The new species has a very distinct and conspicuous colour pattern resembling a jaguar and it is almost four times larger than Spinipterus acsi, a small specimen (32 mm LS) from Caño Santa Rita, a right bank tributary of Río Nanay in Peru and a second specimen was reported from Rio Juruá, Amazonas State, Brazil. Although the new species is more similar in size and colour pattern to Liosomadoras, it shares the synapomorphies for Spinipterus. The new species differs from the congener by the following characters: (a) colour pattern with large black rosette-like spots over a light yellow to brown background (v. brown background with small dark blotches over the body); (b) adult body size reaching 104.5 mm LS (v. maximum known size 37.1 mm LS); (c) posterior process of cleithrum short, never reaching vertical through the dorsal-fin origin (v. posterior process long, surpassing vertical through the dorsal-fin origin); (d) seven soft pectoral-fin rays (v. six); (e) caudal fin truncated (v. caudal fin rounded).  相似文献   

7.
An opportunity arose to obtain humphead wrasse Cheilinus undulatus specimens between 2006 and 2009 from Indonesia, the major source and exporting country of this species, making study on its early gonad development possible for the first time. Protogynous hermaphroditism, previously proposed for this species, was confirmed in this study. Based on histological examination of 178 specimens, mainly <500 mm total length (LT) and ranging from 208 to 1290 mm LT (119·1 g to 43·0 kg whole body mass), the minimum body sizes for female and male sexual maturation were determined to be 650 and 845 mm LT, respectively. Primary male development through juvenile sexual differentiation was not detected. A unique blind pouch, with a possible sperm storage function and associated with the testis, was reported for the first time in the Labridae. In Hong Kong retail markets, the global trading centre for this valuable species, live C. undulatus on sale for food were dominated by body sizes <500 mm LT between 1995 and 2009, reflecting an international trade largely focused on juveniles. In consideration of these findings, and given the threatened status of this species, management for C. undulatus capture and trade nationally and internationally are discussed with recommendations for ensuring sufficient spawning biomass in exploited populations and for sustainable trade.  相似文献   

8.
A new cave‐dwelling fish Triplophysa luochengensis is described based on specimens collected from a karst cave in Guangxi Zhuang Autonomous Region, China, that is interconnected to the Hongshui River drainage. The species can be distinguished from its congeners by a combination of characters: eyes degenerated, anal fin with six branched rays, caudal fin with 16–17 branched rays, pectoral‐fin length 72·4–95·8% of the distance between pectoral‐fin origin and pelvic‐fin origin, lateral head length 26·2–28·2% of standard length (LS), eye diameter 7·5–8·6 of LS, body covered by sparse scales, lateral line complete and 7–8 pre‐operculo‐mandibular pores. Dark pigments irregularly present on dorsum of head, dorsum and flank.  相似文献   

9.
I. Parra    A. Almodóvar    G. G. Nicola    B. Elvira 《Journal of fish biology》2009,74(10):2355-2373
Spatial variation in growth of stream‐dwelling brown trout Salmo trutta was explored in 13 populations using a long‐term study (1993–2004) in the Bay of Biscay drainage, northern Spain. The high variability in fork length (LF) of S. trutta in the study area was similar to the body‐size range found in the entire European distribution of the species. Mean LF at age varied: 0+ years, 57·4–100·7 mm; 1+ years, 111·6–176·0 mm; 2+ years, 155·6–248·4 mm and 3+ years, 194·3–290·9 mm. Average LF at age was higher in main courses and lower reaches compared with small tributaries and upper reaches. Annual specific growth rates (GL) were: 0+ to 1+ years, 0·634–0·825 mm mm−1 year−1; 1+ to 2+ years, 0·243–0·342 mm mm−1 year−1; 2+ to 3+ years, 0·166–0·222 mm mm−1 year−1, showing a great homogeneity. Regression models showed that water temperature and altitude were the major determinants of LF at age variability within the study area. A broader spatial analysis using available data from stream‐dwelling S. trutta populations throughout Europe indicated a negative relationship between latitude and LF of individuals and a negative interaction between latitude and altitude. These findings support previous evidence of the pervasive role of water temperature on the LF of this species. Altitude appeared as the overall factor that includes the local variation of other variables, such as water temperature or food availability. At a larger scale, latitude was the factor that encompassed these environmental gradients and explained the differences in LF of S. trutta. In summary, LF at age in stream‐dwelling S. trutta decreases with latitude in Europe, the converse of Bergmann's rule.  相似文献   

10.
The growth and mortality rates of Myctophum affine larvae were analysed based on samples collected during the austral summer and winter of 2002 from south‐eastern Brazilian waters. The larvae ranged in size from 2·75 to 14·00 mm standard length (LS). Daily increment counts from 82 sagittal otoliths showed that the age of M. affine ranged from 2 to 28 days. Three models were applied to estimate the growth rate: linear regression, exponential model and Laird–Gompertz model. The exponential model best fitted the data, and L0 values from exponential and Laird–Gompertz models were close to the smallest larva reported in the literature (c. 2·5 mm LS). The average growth rate (0·33 mm day?1) was intermediate among lanternfishes. The mortality rate (12%) during the larval period was below average compared with other marine fish species but similar to some epipelagic fishes that occur in the area.  相似文献   

11.
The diet of Antarctic silverfish Pleuragramma antarcticum was evaluated by examining stomach contents of specimens collected in the Ross Sea (71°–77° S; 165°–180° E) in January to March 2008. Pleuragramma antarcticum (50–236 mm standard length, LS) and prey items were analysed for stable‐isotopic composition of carbon and nitrogen. According to index of relative importance (IRI), which incorporates frequency of occurrence, mass and number of prey items, the most important prey items were copepods (81%IRI over all specimens), predominantly Metridia gerlachei and Paraeuchaeta sp., with krill and fishes having low IRI (2·2 and 5·6%IRI overall). According to mass of prey (M) in stomachs, however, fishes (P. antarcticum and myctophids) and krill dominated overall diet (48 and 22%M, respectively), with copepods being a relatively minor constituent of overall diet by mass (9·9%M). Piscivory by P. antarcticum occurred mainly in the extreme south‐west of the region and near the continental slope. Krill identified to species level in P. antarcticum stomachs were predominantly Euphausia superba (14·1%M) with some Euphausia crystallophorias (4·8%M). Both DistLM modelling (PRIMER‐permanova+) on stomach contents (by IRI) and stepwise generalized linear modelling on stable isotopes showed that LS and location were significant predictors of P. antarcticum diet. Postlarval P. antarcticum (50–89 mm LS) consumed exclusively copepods. Juvenile P. antarcticum (90–151 mm LS) consumed predominantly krill and copepods by mass (46 and 30%M, respectively). Small adult P. antarcticum (152–178 mm LS) consumed krill, fishes and copepods (37, 36 and 15%M, respectively). Large adult P. antarcticum (179–236 mm LS) consumed predominantly fishes and krill (55 and 17%M, respectively), especially in the north (near the Ross Sea slope) and in the SW Ross Sea. Amphipods were occasionally important prey items for P. antarcticum (western Ross Sea, 39%M). General concordance between stomach contents and trophic level of P. antarcticum and prey based on δ15N was demonstrated. Pleuragramma antarcticum trophic level was estimated as 3·7 (postlarval fish) and 4·1 (fish aged 3+ years).  相似文献   

12.
Characteristics of the life history of the coral reef‐dwelling cardinalfish Siphamia tubifer, from Okinawa, Japan, were defined. A paternal mouthbrooder, S. tubifer, is unusual in forming a bioluminescent symbiosis with Photobacterium mandapamensis. The examined S. tubifer (n = 1273) ranged in size from 9·5 to 43·5 mm standard length (LS), and the minimum size at sexual maturity was 22 mm LS. The number of S. tubifer associated during the day among the spines of host urchins was 22·9 ± 16·1 (mean ± s.d .; Diadema setosum) and 3·6 ± 3·2 (Echinothrix calamaris). Diet consisted primarily of crustacean zooplankton. Batch fecundity (number of eggs; FB) was related to LS by the equations: males (fertilized eggs) FB = 27·5LS ? 189·46; females (eggs) FB = 31·3LS ? 392·63. Individual mass (M; g) as a function of LS was described by the equation: . Growth, determined from otolith microstructure analysis, was described with the von Bertalanffy growth function with the following coefficients: L = 40·8 mm LS, K = 0·026 day?1 and t0 = 23·25 days. Planktonic larval duration was estimated to be 30 days. The age of the oldest examined individual was 240 days. The light organ of S. tubifer, which harbours the symbiotic population of P. mandapamensis, increased linearly in diameter as S. tubifer LS increased, and the bacterial population increased logarithmically with S. tubifer LS. These characteristics indicate that once settled, S. tubifer grows quickly, reproduces early and typically survives much less than 1 year in Okinawa. These characteristics are generally similar to other small reef fishes but they indicate that S. tubifer experiences higher mortality.  相似文献   

13.
The main life‐history traits of the dorado Brachyplatystoma rousseauxii, a large Amazonian catfish undertaking the largest migration known for a freshwater fish species (from the nursery area in the estuary of the Amazon to the breeding zones in the head waters of the western Amazon basin close to the Andes), were determined from a 5 year sampling of >15 000 specimens in the Peruvian Amazon. The breeding season occurred during the falling and low‐water periods, which is hypothesized to be an adaptation to maximize the chances of young stages to reach the estuary. The size at first sexual maturity was slightly larger for females than males, c. 91 and 83 cm standard length (LS), respectively. Both males and females reproduce for the first time at >3 years old. The fecundity per spawning event ranged from 481 734 to 1 045 284 oocytes for females weighing 25 and 34 kg, respectively. Seasonal variations of body condition were similar among sexes, but differed between immature specimens that had a higher condition during the low‐water period and lower condition during rising waters, and mature individuals that showed the opposite pattern. The growth characteristics were estimated by LS frequency analysis. For females, the best fitting models gave a mean birth date in August, during the height of the breeding cycle, with the following von Bertalanffy growth function parameters: LS∞ = 153·3, K = 0·29 and t0 =– 0·37 years. For males, the best fitting model gave a mean birth date in July, also during the height of the breeding period, with LS∞ = 142, K = 0·30 and t0 =– 0·36 years. At a given age, females were systematically larger than males and the size difference increased with age. The largest females sampled (148 cm LS) was 11 years old and the largest male (134 cm LS) was 9 years old. The mortality estimates were higher for males total (Z) = 1·34, natural (M) = 0·52 and fishing (F) = 0·82 than for females (Z = 0·98, M = 0·50, F = 0·48). The life‐history patterns of B. rousseauxii are discussed in light of the available knowledge about this species and the understanding of its complex life cycle.  相似文献   

14.
The stable isotope values for a range of size classes of Hyporhamphus regularis ardelio from Moreton Bay, south‐east Australia were determined. There was a positive linear relationship between δ13C and standard length (LS)(δ13C = 0·034 LS ? 16·23; r2 = 0·78). δ13C ranged from ?8·48 to ?17·29‰ with the smallest size class (50 mm LS) being on average 1·04‰ enriched with respect to that of zooplankton (Temora turbinata) and 7·97‰ depleted compared to Zostera capricorni. δ13C was positively correlated with LS(P < 0·01)(more enriched with increasing LS) with those fish of the largest size class (225 mm LS) being 9·86 and 0·84‰ enriched than T. turbinata and Z. capricorni, respectively. There was no detectable trend in δ15N values with LS(P > 0·01) with δ15N, ranging from 9·18 to 11·00‰. Fish of all size classes were on average 2·32 and 7·63‰ more enriched than zooplankton and seagrass, respectively. Carbon isotope data indicate that H. r. ardelio commence life as carnivores and change to a diet in which seagrass is the primary carbon source. The dependence on animal matter, however, is always present. Due to the low percentage of nitrogen in Z. capricorni(2·5%) compared to zooplankton (9·1%) it appears that nitrogen from zooplankton is necessary throughout their life history with the carbon requirements for these fish coming chiefly from Z. capricorni.  相似文献   

15.
The structure and seasonal dynamics of larvae of the Gobiidae family in the Mucuri Estuary (Bahia, Brazil) were studied for nine consecutive years. Sampling was conducted at three stations in the lower estuary channel, between 2002 and 2010, in relation to season, day and night and tidal variations. A total of 5802 Gobiidae larvae, representing 15 taxa (12 species and three morphotypes), were collected in the Mucuri Estuary during this time. The highest mean ± s.d. density of fish larvae, 54·7 ± 79·8 larvae 100 m?3, was recorded during the flood tide and night sampling. Ctenogobius boleosoma was the most abundant species (68%), being dominant in the rainy and dry seasons and had a long reproductive period. This species was classed as a marine estuarine‐opportunist because it was observed at high frequencies and active larvae entering the estuary between 6·1 and 12·0 mm standard length (LS). Gobionellus oceanicus, second in abundance (12%), occurred only in later larval stages but did not use the estuary as a preferred location for spawning, being classed a marine estuarine dependent. Microgobius carri (11%) was represented in all LS classes and was resident in the estuary for spawning, remaining there throughout their life cycle. The other species were considered rare due to their low densities and could not be classified in any guild.  相似文献   

16.
The teeth of the oral jaws of two sympatric species of Argyrosomus, Argyrosomus japonicus and Argyrosomus inodorus, found along the South African coast developed first on the premaxilla and then on the dentary of the lower jaw. Teeth were observed on the premaxilla of A. inodorus [head length (LH) = 1·0 mm; notochord length (LN) = 2·7 mm] at a smaller size than in A. japonicus (LH = 1·2 mm; LN = 4·7 mm). The ventral elements of the gill arches (hypo‐ and basibranchials) were not ossified by the end of preflexion. The fifth ceratobranchial began ossifying and possessed pharyngeal teeth by 1·2 mm LH (LN = 4·7 mm) in A. japonicus and 1·1 mm LH (LN = 3·2 mm) in A. inodorus. To complement the osteological data, stomach contents were also analysed as a proxy for feeding apparatus functionality. Prey were first present in the stomach of A. japonicus at 1·2 mm LH (LN = 4·7 mm) and only 22% of the stomachs contained no prey suggesting that A. japonicus is already actively foraging by preflexion. In comparison, 83% of the stomachs of A. inodorus contained no prey and a single prey item was present in the largest examined specimen (LH = 1·6 mm; LN = 5·4 mm). Elements of the feeding apparatus begin to ossify early during ontogeny. While the overall pattern of ossification is similar between the two species, A. japonicus may be able to begin feeding at smaller head lengths relative to A. inodorus in their nursery habitats.  相似文献   

17.
Adult specimens of piabanha Brycon gouldingi were collected from Rio das Mortes (Mato Grosso, Brazil), adapted to captivity and induced to spawn at Buriti Fisheries (Nova Mutum, MT, Brazil). The early developmental stages of B. gouldingi were then characterized. Samples were collected at pre‐determined times from oocyte extrusion to total yolk absorption. Oocyte diameter, total larval length (LT) and yolk‐sac volume were measured. The mean ± s.d . duration of embryo developmental of B. gouldingi was 13·90 ± 0·06 h at 26·40 ± 1·13° C. The mean ± s.d . oocyte diameter was 1·13 ± 0·06 mm with 54% of oocytes ranging from 1·11 to 1·20 mm. Seven stages characterized the early developmental phase of this species: zygote, cleavage, morula, blastula, gastrula, histogenesis–organogenesis and hatching, with unique features related to each stage. At hatching, the larvae measured 3·40 ± 0·07 mm, presented an elongated shape with yolk‐sac volume of 0·46 ± 0·08 µl, non‐pigmented eyes and exhibited swimming ability. When the yolk was completely absorbed at 55 h post‐hatch, mean ± larval LT was 6·68 ± 0·65 mm, the eyes were highly pigmented and the teeth were visible. These are the first reported findings on the initial developmental stages of B. gouldingi and could be used to improve captive breeding management and conservation practices.  相似文献   

18.
The larval development of the dusky grouper Epinephelus marginatus up to the benthic juvenile stage is described in detail to establish a reference for their larval identification. Development is described in terms of ontogenetic changes in morphology, growth, pigmentation, fin structure and skeletal structure. Larvae were reared in mesocosms at a mean temperature of 24·3° C, salinity of 36·5, dissolved oxygen of 6·4 mg l?1 and pH of 8·2. Newly hatched larvae had an estimated total length (LT) of 2·3 mm. On the second day post hatching the yolk was almost fully absorbed with traces of the oil globule still present, the eyes were already pigmented and mouth and gut functional. At this stage the cranial skeletal elements for feeding and breathing (mouth and gills) and the pectoral‐fin support were already present. About 50% of the observed larvae had food in their guts. Pigmentation was very characteristic, consisting of two large chromatophores visible on the edge of the primordial fin, close to the midpoint of the post‐anal region of the body and over the midgut and hindgut and post‐anal portion of the body. At 2·9 mm LT the emergence of the second dorsal‐fin spine, characteristic of the Epinephilinae, was clearly visible. The pre‐flexion stage started in larva of 3·2 mm LT. At 5·5 mm LT the larvae possessed posterior preopercular angle spines, and the dorsal and pelvic spines presented serrated edges and were pigmented. The water surface‐tension‐related death of the yolk sac and pre‐flexion larvae described in the rearing of several other grouper species did not occur during E. marginatus culture. Notochord flexion, with initial ossification of the caudal‐fin supporting elements, started at 6·6 mm LT. At this stage the major melanophores, preopercular, dorsal and pelvic spines and mandibular teeth were already present. Transformation of larvae into juveniles occurred when larvae averaged 13·8 mm LT. Juveniles with a mean LT of 20·1 mm started to settle and most of them were benthic with a mean LT of 26·8 mm.  相似文献   

19.
Total length (LT) (range 24–1000 mm; mean ±s.e . = 170·21 ± 0·36 mm) and mass (W) (range 0·10–9590 g; mean ±s.e . = 76·03 ± 0·87 g) of 36 460 specimens of marble trout Salmo marmoratus were used to compute a standard mass (Ws) equation for this species by means of the empirical percentile (EmP) method. The EmP Ws equation calculated was: log10Ws = ?5·208 + 3·202 log10LT? 0·046 (log10LT)2 (LT range 90–570 mm) and it is valid throughout the species' area of distribution across Europe.  相似文献   

20.
The age, growth and maturity of bonnetheads Sphyrna tiburo inhabiting the estuarine and coastal waters of the western North Atlantic Ocean (WNA) from Onslow Bay, North Carolina, south to West Palm Beach, Florida, were examined. Vertebrae were collected and aged from 329 females and 217 males ranging in size from 262 to 1043 mm and 245 to 825 mm fork length, LF, respectively. Sex‐specific von Bertalanffy growth curves were fitted to length‐at‐age data. Female von Bertalanffy parameters were L = 1036 mm LF, k = 0·18, t0 = ?1·64 and L0 = 272 mm LF. Males reached a smaller theoretical asymptotic length and had a higher growth coefficient (L = 782 mm LF, k = 0·29, t0 = ?1·43 and L0 = 266 mm LF). Maximum observed age was 17·9 years for females and 16·0 years for males. Annual deposition of growth increments was verified by marginal increment analysis and validated for age classes 2·5+ to 10·5+ years through recapture of 13 oxytetracycline‐injected specimens at liberty in the wild for 1–4 years. Length (LF50) and age (A50) at 50% maturity were 819 mm and 6·7 years for females, and 618 mm and 3·9 years for males. Both female and male S. tiburo in the WNA had a significantly higher maximum observed age, LF50, A50 and L, and a significantly lower k and estimated L0 than evident in the Gulf of Mexico (GOM). These significant differences in life‐history parameters, as well as evidence from tagging and genetic studies, suggest that S. tiburo in the WNA and GOM should be considered separate stocks.  相似文献   

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