Early development of marine catfishes (Ariidae): from mouth brooding to the release of juveniles in nursery habitats

The development and allometric growth patterns of the ariid catfishes Cathorops spixii and Cathorops agassizii were studied from neurula embryos to juveniles. The ontogenetic sequence revealed that prior to hatching, embryos of both species are well developed, and their axial and appendicular skeletons are well ossified. Embryos of both species grow slowly longitudinally, but positively allometric growth (growth coefficient, β₁ > 1) was observed in head width and eye diameter. It is hypothesized that these growth patterns might be related to functional priorities for the development of sensory organs, such as the inner ears (otoliths), the Weberian apparatus, eyes and nostrils, during the embryonic period. The first appearance of vertebrae and otoliths, as well as the ossification of otoliths and the Weberian apparatus, occur earlier in embryos of C. agassizii than in embryos of C. spixii. After hatching, mouth‐brooded free embryos of both species grow isometrically. Negatively allometric growth was observed in head width and eye diameter during the yolk‐sac period, which is expected given that the sensory organs are already formed. Free embryos of C. agassizii are distinguishable from those of C. spixii by their larger eyes, longer snouts, longer heads and heavier yolk sacs. The end of the yolk‐sac period is characterized by a direct change from free embryo to juvenile, without a true larval period. The juveniles of the two species can also be distinguished from each other by the larger eyes of C. agassizii compared with C. spixii, as in adult fishes.     

Allometric growth and larval development in Pacific red snapper Lutjanus peru under culture conditions

Allometric growth is a common feature during fish larval development. It has been proposed as a growth strategy to prioritize the development of body segments related to primordial functions like feeding and swimming to increase the probability of survival during this critical period. In the present study we evaluated the allometric growth patterns of body segments associated to swimming and feeding during the larval stages of Pacific red snapper Lutjanus peru. The larvae were kept under intensive culture conditions and sampled every day from hatching until day 33 after hatching. Each larva was classified according to its developmental stage into yolk-sac larva, preflexion larva, flexion larva or postflexion larva, measured and the allometric growth coefficient of different body segments was evaluated using the potential model. Based on the results we can infer the presence of different ontogenetic priorities during the first developmental stages associated with vital functions like swimming during the yolk-sac stage [total length (TL) interval = 2.27–3.005 mm] and feeding during the preflexion stage (TL interval = 3.007–5.60 mm) by promoting the accelerated growth of tail (post anal) and head, respectively. In the flexion stage (TL interval = 5.61–7.62 mm) a change in growth coefficients of most body segments compared to the previous stage was detected, suggesting a shift in growth priorities. Finally, in the postflexion stage (TL interval = 7.60–15.48 mm) a clear tendency to isometry in most body segments was observed, suggesting that growth priorities have been fulfilled and the larvae will initiate with the transformation into a juvenile. These results provide a framework of the larval growth of L. peru in culture conditions which can be useful for comparative studies with other species or in aquaculture to evaluate the changes in larval growth due to new conditions or feeding protocols.     

Age and growth of the Giant Kelpfish,Heterostichus rostratus Girard 1854, in Southern California,USA

In order to update existing life history parameters, age and growth patterns were determined for Giant Kelpfish, Heterostichus rostratus sampled from nearshore kelp forest and estuary habitats in southern California (USA) from April 2012 through June 2015. Fish were collected by pole spear, beach seine, beam trawl, purse seine, and square enclosure. Using age‐at‐length data derived from otolith readings, Giant Kelpfish were found to have a relatively short life span with the largest examined fish reaching a maximum total length of 413 mm at an age of 5 years. Von Bertalanffy growth parameters estimated for this species were: L_∞ = 45.1 cm, k = 0.25, t₀ = ?0.66. Standard length (SL, cm)‐total length (TL, cm) and total length (TL, cm)‐weight (W, g) relationships were described by the equations: SL = 0.90 TL – 1 and W = 2.21 × 10^?3 TL^3.39, respectively. Wild juvenile Giant Kelpfish collected for this study had a higher growth rate than laboratory‐reared fish from a previous study.     

Early developmental and allometric patterns in the electric yellow cichlid Labidochromis caeruleus

The electric yellow cichlid Labidochromis caeruleus is a mouth‐brooding haplochromine cichlid from Lake Malawi and one of the most popular cichlids in the ornamental fish industry. To investigate the early development of L. caeruleus from hatching until the juvenile stage, we studied its morphological development and allometric growth patterns. In newly‐hatched larvae, most organs and body parts were not yet differentiated and continued to develop until 15 days post hatching (dph). The yolk sac was depleted at 13 dph. There was allometric growth, primarily in the anterior and posterior regions of the body, and inflection points when trajectories of allometric growth changed. Head and tail growth was prioritized, suggesting that body parts linked to feeding and swimming behaviour mature earlier than the rest of the body. Additionally, growth patterns revealed that development of organs related to vital functions such as branchial respiration, sensation, exogenous feeding and swimming was prioritized. Comparisons with other African and Neotropical cichlids revealed differences in ontogenetic processes and allometric growth along the anterior–posterior axis as well as variation in developmental timing. These results indicate how early morphological development and ontogenic processes might respond to the distinctive parental care observed in mouth‐brooding cichlids.     

Age,growth and maturity of tub gurnard (Chelidonichthys lucerna Linnaeus 1758; Triglidae) in the inshore coastal waters of Northwest Wales,UK

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 TL^3.10. 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 TL_t = 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.     

Age and growth of pearly razorfish,Xyrichtys novacula (Linnaeus 1758), in the central Mediterranean Sea

Age and growth of pearly razorfish Xyrichtys novacula (Labridae) were determined in specimens caught on sandy bottoms by surrounding nets and lines (depth range 5–30 m) between January 2000 and December 2002. The study location was in the central Mediterranean Sea. For this purpose the annual growth increments (annuli) in sagittae were analysed. A total of 470 individuals of X. novacula, ranging from 49 to 200 mm TL (total length), were examined. Conversion between total length and standard length was calculated and represented by the relationship: . Edge analysis on otoliths was carried out to validate seasonality deposition. Seven age‐classes were determined from 0+ to 6+. The linear relationship between maximum otolith length (OL) and TL was summarized in the equation . The estimated parameters of the von Bertalanffy growth function were L = 175.05 mm, k = 0.80 year^?1, t₀ =?0.73 years and the growth performance index calculated as (Φ = 2.39). The length–weight relationship W = 0.0139 TL^2.9326 described an isometric growth for the species in this area.     

Acute toxic effects of 8‐epidiosbulbin E,a 19‐norclerodane diterpene from yam Dioscorea antaly,on medaka Oryzias latipes embryos

The fractionation of an aqueous extract of yam Dioscorea antaly from Madagascar led to the isolation of terpenoids and flavonoids. Compounds were identified on the basis of modern mass spectrometry and two‐dimensional nuclear magnetic resonance (2D‐NMR). Toxicological effects of the most abundant isolated compound, 8‐epidiosbulbin E were studied on medaka Oryzias latipes embryo‐larval development. The lethal concentration (killing 50%; LC₅₀) to embryos treated 24 h before hatching and for 3 days after hatching was estimated to be 0·56 mg ml^?1 (P< 0·05). No mortality was observed with O. latipes larvae exposed after hatching until day 4. Anatomo‐pathological studies of embryos exposed to 0·56 mg ml^?1 showed development anomalies of the central nervous system, liver, muscle and intestine. The present data thus extend the model of O. latipes embryos as a useful animal model to analyse the effects of food toxins.     

Distribution and population structure of the Chlorophthalmus agassizi (Bonaparte, 1840) on an unexploited fishing ground in the Greek Ionian Sea

The distribution and population structure of the shortnose green eye, Chlorophthalmus agassizi, were studied in the Greek Ionian Sea using data collected during experimental trawl surveys carried out from December 1996 to November 1997. The length–frequency distribution ranged between 45 and 201 mm total length (TL). The significant increase in average size linked with depth has been observed, supporting the general ‘bigger‐deeper’ phenomenon. Specifically, 1528 individuals were measured in the 300–400 m depth zone with a mean TL = 101 mm, 2351 individuals in the 400–500 m depth zone with a mean TL = 132 mm and 1889 individuals in the 500–600 depth zone with a mean TL = 145 mm. Age and growth of the population were determined by otolith readings. Twelve age groups were identified. The von Bertalanffy growth function (VBGF) parameters were L_∞=202.22 mm, K=0.20 and t_o=?1.6 years. Natural mortality was estimated at 0.285 per year, while total mortality was estimated at 0.65. The reproductive period of C. agassizi extends from spring to autumn, with greater activity in the summer.     

Otolith formation,microstructure and daily increment validation in juvenile perch Perca fluviatilis

The otoliths of laboratory‐reared larval and juvenile perch Perca fluviatilis of known age were analysed to determine the age of otolith formation and validate the formation of daily increments. There was a linear relationship between number of increments and age in days post‐hatching, although by 82 days post‐hatching daily increment counts underestimated actual age by an average of 5 days. Otolith dimensions in relation to standard length indicated allometric growth of otoliths until completion of yolk absorption, and isometric growth thereafter, up to 82 days post‐hatching.     

Length‐weight relationships,condition factor,gonadosomatic index‐based size at first sexual maturity,spawning season and fecundity of Aspidoparia morar (Cyprinidae) in the Jamuna River (Brahmaputra River distributary), northern Bangladesh

The present study describes the length‐weight relationships (LWRs), length‐length relationships (LLRs), Fulton's condition factor (K_F), size at first sexual maturity, spawning season, sex ratio and fecundity of the Morari Aspidoparia morar (Hamilton, 1822) (Cyprinidae). Sampling was done using traditional fishing gear jhaki jal (cast net) from July 2010 to June 2011. Total length (TL), fork length (FL) and standard length (SL) were measured with digital slide calipers. Individual body weight (BW) and gonad weight (GW) were determined to an accuracy of 0.01 g for all specimens. The gonadosomatic index (GSI) was calculated and size at first maturity for males and females estimated using GSI and TL as indicators. Female ≥ size at first maturity was used to determine fecundity. A total of 1200 specimens (males = 552, females = 648) ranging from 4.06–12.84 cm TL and 0.53–16.75 g BW were analyzed. The overall coefficient b for the LWR indicated positive allometric growth (>3.00) in males and isometric growth in females (~ 3.00). ancova (analysis of covariance) revealed significant differences between males and females (P < 0.001). All LLRs were highly correlated (r² > 0.973, P < 0.001). Sizes at first sexual maturity for males and females were 6.0 and 7.0 cm TL, respectively. K_F changed little throughout the year and GSI peaked in November to April, indicating the spawning season (GSImax = 15.0 in females, 2.0 in males). Mature females were dominant during the entire spawning season except in April. Mean total fecundity was 6700 ± 3500, ranging from 1860 to 19680. In addition, relative fecundity ranged from 190 to 1200 (mean 560 ± 235) in the Jamuna River. To ensure sustainable management of this species, the protection of mature individuals during the peak spawning season is highly recommended.     

Growth and mortality of two small fishes,Toxabramis swinhonis Günther, 1873 and Hyporhamphus intermedius (Cantor, 1842), in a Yangtze shallow lake (China) assessed by length frequency analysis

This study examined the growth and mortality of two widespread small fish species, Toxabramis swinhonis (Cyprinidae) and Hyporhamphus intermedius (Hemiramphidae), from a shallow lake (Niushan Lake, China) along the Yangtze River, by analyzing monthly length frequency data (July 2005 to June 2006) with the FAO‐ICLARM stock assessment tool (FiSAT). Estimated von Bertalanffy growth equation parameters were: L_∞ (asymptotic length) = 145 mm TL, and K (growth coefficient) = 0.66 year^?1 for T. swinhonis; L_∞ = 189 mm TL, and K = 0.68 year^?1 for H. intermedius. The instantaneous rates of natural mortality (M) calculated for T. swinhonis and H. intermedius were 1.35 and 1.28 year^?1, respectively. The length‐converted catch curve method gave the total annual instantaneous mortality rate (Z) of 2.92 year^?1 for T. swinhonis and 1.53 year^?1 for H. intermedius. Recruitment patterns of both species were continuous, displaying a single major peak event per year. Despite not being of direct fishing interest, T. swinhonis, with high abundance and productivity as indicated by a high Z‐value, can be an important species in fisheries management as an excellent food source for aquatic organisms, especially for larger fishes of economic value. These results represent the first information on population characteristics of T. swinhonis and H. intermedius, and constitute a comparison base for future growth studies in other lake environments.     

Development of sexual dimorphism in two sympatric skinks with different growth rates

Sexual size dimorphism (SSD) is widespread in animals, especially in lizards (Reptilia: Squamata), and is driven by fecundity selection, male–male competition, or other adaptive hypotheses. However, these selective pressures may vary through different life history periods; thus, it is essential to assess the relationship between growth and SSD. In this study, we tracked SSD dynamics between a “fading‐tail color skink” (blue tail skink whose tail is only blue during its juvenile stage: Plestiodon elegans) and a “nonfade color” tail skink (retains a blue tail throughout life: Plestiodon quadrilineatus) under a controlled experimental environment. We fitted growth curves of morphological traits (body mass, SVL, and TL) using three growth models (Logistic, Gompertz, and von Bertalanffy). We found that both skinks have male‐biased SSD as adults. Body mass has a higher goodness of fit (as represented by very high R² values) using the von Bertalanffy model than the other two models. In contrast, SVL and TL for both skinks had higher goodness of fit when using the Gompertz model. Two lizards displayed divergent life history tactics: P. elegans grows faster, matures earlier (at 65 weeks), and presents an allometric growth rate, whereas P. quadrilineatus grows slower, matures later (at 106 weeks), and presents an isometric growth rate. Our findings imply that species‐ and sex‐specific trade‐offs in the allocation of energy to growth and reproduction may cause the growth patterns to diverge, ultimately resulting in the dissimilar patterns of SSD.     

The actions of in ovo cortisol on egg fertility,embryo development and the expression of growth‐related genes in rainbow trout embryos,and the growth performance of juveniles

Rainbow trout (Oncorhynchus mykiss) oocytes were incubated for 3 hr in ovarian fluid alone (CC), or cortisol‐enriched ovarian fluid [100 or 1,000 ng ml^?1 (CL and CH, respectively)], after which they were fertilized; the growth and development of the embryos reared from these oocytes was monitored until first feed, and the juveniles were monitored for 9 months. The hatching rates of the CH group were significantly reduced, but the overall survival as measured at 40‐week post‐fertilization was similar in the three treatment groups. In addition, significant apparently biphasic changes relative to the CC group were found in the expression of some key growth‐related genes in the CL and CH treatment groups, particularly IGF‐1, IGF‐2, GH1, GH2, GH receptors, and thyroid hormone receptors (TRα and TRβ). Moreover, the juveniles of the CL (but not the CH treatment group) exhibited enhanced growth; the enhanced growth could not be explained on the basis of increased feed conversion efficiency or changes in serum GH levels at the juvenile stage. Additionally, relative growth rates from the three treatment groups were similar, suggesting that the biphasic growth‐enhancing effects of cortisol occurred very early in embryogenesis. Mol. Reprod. Dev. 77:922–931, 2010. © 2010 Wiley‐Liss, Inc.     

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.     

Sex,growth rate,rank order after brood reduction,and hatching date affect first‐year survival of long‐lived Herring Gulls

Among most species of birds, survival from hatching throughout the first year of life is generally lower than subsequent survival rates. Survival of young birds during their first year may depend on a combination of selection, learning, unpredictable resources, and environmental events (i.e., post‐fledging factors). However, knowledge about post‐fledging development in long‐lived species is usually limited due to a lengthy immature stage when individuals are generally unobservable. Therefore, pre‐fledging characteristics are often used to predict the survival of young birds. We assessed effects of nestling growth rates, hatching date, hatching asynchrony, brood size and rank order after brood reduction, and sex on first‐year survival of 137 fledglings using a mark‐resighting analysis. We found that the survival probability (Φ_1yr = 0.39) of first‐year Herring Gulls (Larus argentatus) in our study colony located at the outer port of Zeebrugge (Belgium) was lower than that of older individuals (Φ_>1yr = 0.75). All 10 models best supported by our data included nestling growth rate, suggesting that variability in first‐year survival may be linked primarily to individual variation in growth. First‐year survival was negatively correlated with hatching date and rank order after brood reduction. Hence, carry‐over effects of breeding season events such as timing of breeding, early development, and social status had an influence on survival of Herring Gulls after fledging. Furthermore, we found sex‐biased mortality in first‐year Herring Gulls, with females (Φ_1yr = 0.45) surviving better than males (Φ_1yr = 0.38). Although adult survival is generally regarded as the key parameter driving population trajectories in long‐lived species, juvenile survival has recently been acknowledged as an important source of variability in population growth rates. Thus, increasing our knowledge of factors affecting age‐specific survival rates is necessary to improve our understanding of population dynamics and ultimately life‐history variation.     

Development of eggs,larvae and juveniles of the puffer,Takifugu chrysops,reared in the laboratory

The artificial fertilization of the puffer,Takifugu chrysops (Hilgendorf), was carried out at Sajima in Yokosuka City on May 22, 1984. Hatched larvae were reared for a period of about 150 days. The spawning period seems to extend from mid to late May in the eastern part of Sagami Bay. The eggs were spherical, pale milky white and semitransparent, demersal and adhesive in nature, measuring 1.32±0.04 mm in diamter, and with a cluster of small oil-globules. The incubation period was about 162 hours at a water temperature of 17.4 to 21.8°C. During embryonic development, the only pigment cells that appeared on the embryo were the black chromatophores. The newly hatched larvae measured from 2.72 to 3.06 mm TL, averaging 2.87±0.1 mm TL, and 22–23 (9 + 13?14) myomeres. At yolk absorption, 4 days after hatching, the larvae attained 3.64–3.79 mm TL. On the 11th day, postlarvae averaged 4.69±0.24 mm TL. Larval finfolds disappeared and rudimental dorsal, anal and caudal fins were formed. There were two large clusters of melanophores, one on the back, exteding from the mid-base of the dorsal fin to the caudal peduncle region, the other along the anal fin base. The color of the body began to turn pale green to brownish-orange and spinelike scales appeared on the belly. Eighteen days after hatching (7.02±0.27 mm TL), the caudal notochord began to turn up and a “constriction” appeared on the posterior margin of the caudal fin membrane. This notch moved upwards as the notochord upturning advances. The larvae attained full fin ray counts and reached the juvenile stage at 9.1-9.5 mm TL, 24 days after hatching. Characteristic black blotches on the back and specific brownish orange body color appeared at the stage of 20 mm TL, 24 days after hatching. The growth during the larval stage and early juvenile stage (24 to 51 days after hatching) were expressed by the following equations, wherey is total length (mm) andx is days after hatching.y ₁=2.8424× 1.0509⁹ (0≦x≦24)y ₂ = 3.7872×1.0372^x (24≦x≦51)     

Thermal effects in rainbow trout (Oncorhynchus mykiss) F1 embryos (farmed female × wild thermal-resistant male)

The aim of this work was to investigate the response of rainbow trout embryos (Oncorhynchus mykiss) (i.e., survival, size at hatching, time to hatching, malformations) to four incubation temperatures (5.8, 8.9, 14.0 and 16.8°C), taking into account the origin of the male parental genome and comparing pure farmed and F1 embryos (farmed female × wild thermal-resistant male). Several consequences of thermal stress were observed: lower accumulated thermal units (ATU) at hatching at high temperatures, and lower survival, shorter hatched free embryos and less-consumed yolk sac at extreme temperatures. The effect of the thermal-adapted male parental genome was shown only in the lower percentage of incompletely hatched free embryos in the F1 families. It appears that to obtain greater modification of thermal performance during early development, the adapted genome of the wild thermal-resistant population has to be included through maternal inheritance, thus producing a stabilized strain selected for domesticity, growth and thermal adaptation.     

Ontogenetic shift in geotaxis for walleye pollock,Theragra chalcogramma free embryos and larvae: potential role in controlling vertical distribution

Synopsis The behavioral capability of walleye pollock,Theragra chalcogramma free embryos and larvae to control vertical distribution was assessed by examining buoyancy during resting and swimming orientation and activity as they developed in complete darkness from hatching to first feeding readiness (1 to 7 d post hatching at 6° C). Free embryos exhibited positive geotaxis 1 d post hatching, actively swimming through a density gradient to remain in the lower water column. Activity increased with free embryo development and by 7 d post hatching, feeding-ready larvae reversed their vertical orientation, now exhibiting negative geotaxis as they migrated to the upper water column. The results indicate that even at the earliest developmental stages, walleye pollock possess the capability to control vertical distribution. Laboratory results are compared with patterns of vertical distribution observed in the sea.     

Larval ontogeny and morphology of giant trahira Hoplias lacerdae

In the present study, the morphology and behaviour of giant trahira Hoplias lacerdae larvae were investigated, from hatching to complete absorption of the yolk sac, under laboratory conditions. In the first day post‐hatching (dph), the larvae presented a big ovoid‐shaped yolk sac that underwent regression during larval ontogeny. The mouth opened 3 dph, when the pectoral fins were evident. From this day, the larvae were able to perform sudden bursts of activity and appear to be able to swim a few centimetres before sinking again. The branchial apparatus was defined at 5 dph, and by 6 dph the operculum was formed. The internal organs such as intestine, liver, kidney and external sensorial structures were present at 7 dph. The yolk sac remained until 7 dph.