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Wastewater treatment plants release complex mixtures of chemicals into the aquatic environment as wastewater effluent (WWE); however, the effects of these mixtures are still poorly understood. Chinook salmon (Oncorhynchus tshawytscha) are a culturally important species in the Pacific Northwest and are a vital food resource for southern resident killer whales (Orcinus orca) that are listed as 'critically endangered' under the U.S. Endangered Species Act (ESA). Chinook populations have declined drastically in this region and have failed to show significant recovery despite regional-to-federal efforts, resulting in many populations being listed as threatened under the ESA. One source of stress to juvenile Chinook is chemical pollution from WWE during their outmigration along river corridors and residency in estuaries. In this study, we investigated effects of WWE on juvenile Chinook health in a ten-day exposure to dilutions of WWE from 0.1% to 20%. At the end of the exposure, we measured endpoints associated with endocrine disruption, brain function, osmoregulation, stress, and metabolism. Exposure to WWE significantly (a = 0.1 for all analyses) induced vitellogenesis, indicating endocrine system disruption. We saw significant reductions in plasma glucose, an indication of stress, and brain Na+/K+-ATPase (NKA) activity, an enzyme essential for neuronal signaling. Lastly, metabolism was affected as evidenced by altered total protein, cholesterol, and albumin in plasma, a drastic decrease in whole body lipid content, and a significant increase in visible liver anomalies. We compared contaminant concentrations in exposure water with effects concentrations from the literature for chemicals known to induce vitellogenin or inhibit brain NKA. For most contaminants, concentrations in exposure waters were several orders of magnitude below effects concentrations in the literature. The exception was estrogenic hormones, which were detected at similar concentrations in this study compared to concentrations in other studies that induced vitellogenin. Based on comparisons to the literature, contaminants measured in this study could not explain the inhibition of brain NKA; however, WWE mixtures contain many quantified and undetected compounds that are likely acting together to cause harmful effects in Chinook. This research highlights the need for improved wastewater treatment to improve aquatic health and mitigate effects to threatened species like Puget Sound Chinook salmon. [ABSTRACT FROM AUTHOR]

Targeted metabolomic analysis was conducted on juvenile Chinook salmon exposed for 10 days to wastewater effluent (WWE) from a large urban treatment plant. Exposures included five dilutions of WWE (20%, 5.3%, 1.4%, 0.4%, and 0.1%) and a control with 7 replicates per treatment. Liver was extracted from fish and analyzed via liquid chromatography - mass spectrometry (LC-MS) for 361 endogenous metabolites, of which 185 were detected. Control-versus-treatment comparisons identified several metabolites that were associated with altered biochemical pathways observed for all treatments, including several that are important for energy generation and utilization. These altered pathways are crucial for fish health and may be an early indicator of potential adverse effects on growth, reproduction, behavior, and immune function. Juvenile ocean-type Chinook salmon spend several days to weeks in the nearshore estuary where they may encounter high concentrations of WWE contaminants. They are exposed to a wide range of potent pharmaceuticals, personal care products, and industrial compounds from WWE that have the potential to affect physiological homeostasis and disrupt their normal life cycle. [ABSTRACT FROM AUTHOR]

This study investigates the age and growth rates of juvenile Diplodus vulgaris in the Çanakkale Strait, utilizing Alizarin Red S (ARS) marking to analyze otoliths for daily growth increments. The research aimed to validate the daily deposition of growth rings in otoliths as a reliable method for age determination in young fish. A total of 65 specimens were subjected to ARS immersion at varying concentrations to identify the optimal marking conditions that would not adversely affect the survival rates of the juveniles. Post-treatment, the fish were released into controlled environments and monitored over a period to assess the incorporation and visibility of ARS marks in the otoliths. The results demonstrated a clear correlation between fish size and age, with a consistent daily growth rate that supports the hypothesis of daily increment formation in otoliths. The mortality rate associated with ARS treatment was within acceptable limits, confirming the method's viability for non-lethal age and growth studies. This research not only underscores the effectiveness of ARS marking in studying juvenile fish growth patterns but also contributes to a better understanding of the life history of D. vulgaris in the Çanakkale Strait, offering valuable insights for fisheries management and conservation efforts. [ABSTRACT FROM AUTHOR]

This study describes the advances in spotted rose snapper Lutjanus guttatus juveniles production. The broodstock (three groups, each of ten females, mean ± SD: 0.91 ± 0.2 kg and 20 males 1.2 ± 0.3 kg) with two years, were acclimated for 1.5 years in three communal cylindrical fiberglass tanks (18-m3). Fertilized eggs were obtained during natural spawning seasons. Floating eggs (average 90 ± 2%) were collected between 12 to 14 h after spawning. An average of 97% of them were transparent with live embryos. For the larval rearing process, initial stocking densities were 196 ± 70 embryos/l, incubated in twelve 6-m3 cylindrical fiberglass tanks with 3-m3 of water. The incubation period was 20 h at 26-28 °C. Hatching and survival at 48-h post-hatch (hph) were 90 ± 2% and 55 ± 10%, respectively, with an average of 281,258± 92,202 48-h larvae per tank and 105 ± 33 larvae/l at first feeding. A total of 338,812 juveniles with 45 days post-hatched (dph) were harvested, at an average of 28,234 ± 11,890 per larval rearing tank (2.4±1.0/l), and 180,000 juveniles (BW: Body weight of 5-8 g) from the nursery tanks with 90 dph. Average survival from first feeding to end of 45 dph rearing period was 12 ± 9%. The average harvest weight was 0.47 ± 0.10 g BW and the average final biomass per larval tank was 13 kg. An efficiency index at 45 days culture was 10 / 48-h larvae/juvenile, while at 90 dph the efficiency index was 19 / 48-h larvae/juvenile. The result showed that changes to the previous culture protocols of the CIAD-Mazatlan fish plant, ensure a higher production of juveniles. [ABSTRACT FROM AUTHOR]

This work examined diet composition of the juvenile orange-spotted grouper, Epinephelus coioides, and its trophic association with other juvenile fish species in tropical estuarine habitats during recruitment. From December 2015 to March 2016, juveniles were collected, their stomachs excised, preserved and analyzed. Small shrimps and amphipods, especially Grandidierella sp. and Elasmopus sp., were the most common food resources sharing among the most species. Epinephelus coioides predominantly ingested small shrimp, Grandidierella sp., Elasmopus sp. and fish larvae and had the greatest trophic overlap with Palatrus scapulopunctatus. Fish size, location and month significantly affected fullness indices and food items diversity in E. coioides. It is clear that the larger the size of E. coioides and its mouth opening, the larger the size of items ingested. This study confirms the ontogenetic dietary shift of juvenile E. coioides during recruitment season by starting as amphipod and small shrimp feeder and shifting to shrimp and fish larvae predator as they grow. This finding is fundamental to understanding how juvenile E. coioides cope with different conditions and its association with other co-existing species during the recruitment period. [ABSTRACT FROM AUTHOR]

Summary: This review is part of a series of annual updates summarizing the evidence base for atopic eczema (AE). It provides a summary of key findings from 28 systematic reviews that were published or indexed during 2016 with a focus on treatment and prevention of AE. There is reasonable evidence of benefit for topical corticosteroids, calcineurin inhibitors, a glycyrrhetinic acid‐containing preparation (Atopiclair®), oral ciclosporin, oral azathioprine, narrowband ultraviolet B radiation and education programmes. Overall, there is evidence that topical corticosteroids and calcineurin inhibitors have similar efficacy and that both can prevent AE flares when used twice weekly as maintenance therapy. However, topical calcineurin inhibitors are costlier and have more adverse reactions, thus topical corticosteroids should remain the standard of care for patients with AE. There is no evidence that multiple applications are better than once‐daily application of topical corticosteroid. There is inconsistent evidence to support omalizumab and specific allergen immunotherapy use in AE. There is some evidence that vitamin D supplementation and synbiotics reduce AE severity, although the margin of improvement may not be clinically meaningful. There is little evidence to support the use of wet wraps or of complementary/alternative medicine (including Chinese herbal medicine). There is some evidence to suggest that a diet high in fish in infancy may be preventative for AE, but other dietary interventions for the prevention of AE show little promise. This review provides a succinct guide for clinicians and patients wishing to remain up to date with the latest evidence for the treatment and prevention of AE. Click here for the corresponding questions to this CME article. [ABSTRACT FROM AUTHOR]

Pigfish, Orthopristis chrysoptera, is a candidate for aquaculture because it is a regionally popular marine baitfish and commercial production could increase its supply and reduce fishing pressure on wild populations. Identifying optimal conditions for pigfish growout is needed for efficient production. We investigated the effects of temperature on growth and survival from hatching to market size at five constant temperatures, ranging from 22 to 30 C. Larval survival was greatest at 22 C, but growth was slowest. Complete mortality of larvae at 30 C occurred by 6 d after hatch, suggesting an upper thermal limit between 28 and 30 C. For juveniles, growth in length and weight was greatest at 28 and 30 C, but there were no differences in survival among temperatures. The predicted upper thermal limit for juveniles is 35 C. Results indicate that maximum growth and survival would be achieved by rearing larvae at 24 C and juveniles at 28 C. Under this temperature schedule, pigfish would reach preferred market sizes of 7.6 cm (for bay fishing) and 15 cm (for offshore fishing) after 2.5 and 4 mo of culture, respectively. [ABSTRACT FROM AUTHOR]

Abstract We sampled the water chemistry and otolith chemistry and structure of juvenile Cutthroat Trout collected in the Marys River and adults collected in the Willamette River to evaluate the potential to identify life-history variation in this population. Differences in water chemistry between the Marys and the Willamette Rivers during the sampling period were reflected in otolith chemistry. We differentiated 2 life-history patterns: juveniles whose mothers appeared to be resident in the Marys River, and juveniles that likely had fluvial mothers from the Willamette River. Otolith elemental composition of both juveniles and adults showed maternal effects on core chemistry, movement, or changes in elemental incorporation related to changes in ontogeny, growth, or seasonal changes in temperature. Water and otolith edge 87Sr/86Sr were consistently lower in the Willamette River than in the Marys River. Mean otolith 87Sr/86Sr during early life provided evidence that some adults reared in tributaries and migrated into the Willamette River later in life, whereas core 87Sr/86Sr for some juveniles shows that they likely originated from outside of the Marys River or are offspring of mothers that migrated into the Marys River to spawn. Based on otolith annuli, growth rates during early life were generally higher for adults than juveniles; these differences could reflect inter-annual, habitat, or life-history differences. Otolith 87Sr/86Sr and structural analyses hold promise for elucidating origin and life-history patterns of Willamette River cutthroat populations. [ABSTRACT FROM AUTHOR]

Species identification is important in natural science and should be precise. Six specimens of juvenile Pseudoblennius were collected from the eastern coastal waters of the Korean Peninsula and Jeju Island in 2016-2017, and identified for the first time using DNA barcoding based on mitochondrial DNA cytochrome oxidase subunit I sequences. DNA barcoding analysis supported three adult species of genus Pseudoblennius (P. cottoides, P. marmoratus, and P. percoides) being quite distinct from each other. Six juvenile specimens were completely identified: two as P. cottoides; two more as P. marmoratus; and the final two as P. percoides. Mitochondrial DNA COI can be effective as a means of species identification method for the genus Pseudoblennius. [ABSTRACT FROM AUTHOR]

Size-selective mortality owing to lack of energy reserves during the first marine winter has been suggested to be a result of juvenile salmon failing to reach a critical size or condition by the end of their first marine summer and not surviving the following winter due to this presumed energy deficit. This hypothesis implies strong size dependency of mortality, and is subject to empirical data support for acceptance. Scale circulus spacing has been interpreted as an index for body size, and we reviewed the effect of size-selective mortality with a knife-edge mortality function on descriptive statistics for a scale circulus spacing index (SCSI). In order to invoke size selection as an important driver of mortality during the first year of ocean rearing, it is necessary to demonstrate not only that size-selective mortality is directed towards the smaller members of the population, but that the selective nature of the mortality can account for a substantial portion of the observed mortality. If the assumption is made that a random sample of a single juvenile population has been obtained, then studies that employ a SCSI to infer size-selective mortality coupled with a critical size limit must demonstrate a shift toward larger values of the SCSI, but also a concomitant reduction in the variance and range of the SCSI and an increase in the skewness and kurtosis of the SCSI values. Through simulation we found that the percentage of adults that displayed a SCSI value greater than the maximum observed in the juvenile sample was highly dependent on the initial juvenile sample size and size-selective mortality rate. Geographical distributions of juvenile Pacific salmon can be stratified by size, with larger individuals migrating earlier from local ocean entry locations than smaller individuals, and thus differential timing migration of juveniles based upon body size prior to the collection of the marine juvenile sample may be a more plausible explanation of published trends in the SCSI, rather than invoking substantial size-selective mortality and a critical size limit. [ABSTRACT FROM AUTHOR]

The environmental fate, persistence, and non-target animal impacts of traditional molluscicides for zebra, Dreissena polymorpha, and quagga, D. bugensis, mussel control led to the development of the biomolluscicide Zequanox. Although previous research has demonstrated the specificity of Zequanox, one study indicated sensitivity of salmonids and lake sturgeon, Acipenser fulvescens, following non-label compliant exposures to Zequanox. This study was conducted to evaluate sublethal and lethal impacts of Zequanox exposure on juvenile lake sturgeon and lake trout, Salvelinus namaycush, following applications that were conducted in a manner consistent with the Zequanox product label. Fish were exposed to 50 or 100 mg/L of Zequanox as active ingredient for 8 h and then held for 33 d to evaluate latent impacts. No acute mortality was observed in either species; however, significant latent mortality was observed in lake trout that were exposed to the highest dose of Zequanox. Statistically significant but biologically minimal differences were observed in the weight (range 20.17 to 21.49 g) of surviving lake sturgeon at the termination of the 33 d post-exposure observation period. Statistically significant and biologically considerable differences were observed in the weight (range 6.19 to 9.55 g) of surviving lake trout at the termination of the 33 d post-exposure observation period. Histologic evaluation of lake trout gastrointestinal tracts suggests that the mode of action in lake trout is different from the mode of action that induces zebra and quagga mussel mortality. Further research could determine the sensitivity of other salmonid species to Zequanox and determine if native fish will avoid Zequanox treated water. [ABSTRACT FROM AUTHOR]

Abstract: Stock assessments for anadromous river herring, collectively Alewife Alosa pseudoharengus and Blueback Herring A. aestivalis, lack adequate demographic information, particularly with respect to early life stages. Although sampling adult river herring is increasingly common throughout their range, currently no standardized, field‐based, analytical methods exist for estimating juvenile abundance in freshwater lakes. The objective of this research was to evaluate the relative effectiveness and sampling precision of a purse seine for estimating densities of age‐0 river herring in freshwater lakes. We used a purse seine to sample age‐0 river herring in June–September 2015 and June–July 2016 in 16 coastal freshwater lakes in the northeastern USA. Sampling effort varied from two seine hauls to more than 50 seine hauls per lake. Catch rates were highest in June and July, and sampling precision was maximized in July. Sampling at night (versus day) in open water (versus littoral areas) was most effective for capturing newly hatched larvae and juveniles up to ca. 100 mm TL. Bootstrap simulation results indicated that sampling precision of CPUE estimates increased with sampling effort, and there was a clear threshold beyond which increased effort resulted in negligible increases in precision. The effort required to produce precise CPUE estimates, as determined by the CV, was dependent on lake size; river herring densities could be estimated with up to 10 purse‐seine hauls (one‐two nights) in a small lake (<50 ha) and 15–20 hauls (two‐three nights) in a large lake (>50 ha). Fish collection techniques using a purse seine as described in this paper are likely to be effective for estimating recruit abundance of river herring in freshwater lakes across their range. [ABSTRACT FROM AUTHOR]

Abstract: Survival of juvenile fall‐run Chinook Salmon Oncorhynchus tshawytscha through the San Joaquin River Delta of California (hereafter, “Delta”) has been low for most estimates since 2002 and has been consistently low since 2010. From 2010 through 2015, annual estimates of the probability of surviving through the Delta (from Mossdale to Chipps Island, approximately 92 river kilometers) ranged from 0 to 0.05, based on acoustic‐telemetry data from smolt‐sized hatchery Chinook Salmon. River conditions were poor in most of these years; average daily river discharge into the Delta from the San Joaquin River was <40 m3/s in four of the six study years. In the high flow year of 2011 (average daily river discharge = 278–308 m3/s), the juvenile survival probability through the Delta was estimated at only 0.02 (SE < 0.01), suggesting increased flows alone will not be sufficient to resolve the low survival through the Delta. The low survival in this short portion of the salmon's life history makes achieving a minimal smolt‐to‐adult ratio of ≥2% nearly impossible for this fish stock. Over half of the fish surviving through the Delta during 6 years of study were salvaged at the Central Valley Project's water export facility and transported for release just upstream of Chipps Island. [ABSTRACT FROM AUTHOR]

Defending offspring provides fitness benefits to parents, but is costly. To moderate costs, parents should adjust aggressive responses to the threat posed by different species entering their territory. However, few studies have experimentally tested behavioral adjustments in response to the threat posed by different types of intruders, particularly in the field, and in environments with an array of heterospecific intruders. Here, using a biparental cichlid, the poor man's tropheus (Hypsophrys nematopus), we investigated whether males and females in the wild invest equally into offspring defense and what impact the absence of a partner might have on the quality of offspring defense provided by a solitary parent. In a separate experiment, we assessed responses of breeding pairs to 3 common heterospecific intruders that pose different levels of threat to the breeding pair and their brood. We found that both paired and unpaired females invested significantly more into territorial aggression than males. However, unpaired females were unable to fully compensate for the absence of their partner, with intruders left to venture closer to their offspring. Furthermore, we show that breeding pairs can readily discriminate between heterospecific intruders, with pairs responding quicker and more aggressively towards species that posed a greater potential threat. Our results demonstrate that biparental species can have extensive behavioral flexibility in their aggressive responses towards intruders, even in environments with a high frequency of territory incursion. The quality of territorial defense can nevertheless be compromised if one parent is left to defend the brood alone. [ABSTRACT FROM AUTHOR]

Identifying the scale of population processes is important for sustainable fisheries management. In the North Sea, the lesser sandeel, Ammodytes marinus, is now managed as seven stocks delineated on the basis of biophysical model predictions of the limited scale of larval mixing. This study used otolith chemistry to evaluate whether the stock units defined from these predictions actually reflect the degree of isolation of early life stages. Elemental composition near the core, settlement check and summer opaque zone were examined using laser ablation-inductively coupled plasma mass spectrometry in young of the year, sampled across 8 grounds within three of the main fished stocks in 2011. There were significant spatial differences in otolith chemistry enabling post-settled juveniles to be discriminated among stock areas and even between some grounds. Clustering of near core chemistry pointed to four natal sources, with dominant clusters in each of the three stocks studied and one unique to the Central Western North Sea (sandeel assessment area 4). Moreover, near core chemistry was similar to that of post-settled juveniles at the stock area level. Consistency in the scaling of early life mixing predicted by biophysical models and otolith chemistry supports the present stock units used in assessments. [ABSTRACT FROM AUTHOR]

Technological advances have led to smaller transmitters for telemetry studies involving small fishes, including juveniles, which minimize effects on fish performance and retention caused by tag burden. We evaluated three transmitter application procedures (external attachment and internal implantation with and without a trailing antenna) on the growth, survival, and tag retention of juvenile least cisco Coregonus sardinella over a 60-day laboratory experiment. For fish that received internal transmitters, we also examined the effects of suture type (absorbable versus non-absorbable) and suture knot adhesive (use versus non-use of 3M™ Vetbond™). In general, there were minimal to no effects of suture type or the use/non-use of knot adhesive on fish performance. Only least cisco in the control (no transmitter) and external transmitter groups exhibited positive growth over the experimental period. Despite growth differences among treatments, there were no significant differences in final mean total length and wet weight among treatment groups. Least cisco with internal transmitters exhibited significantly lower survival (trailing antenna: range, 53–73%; no trailing antenna: 80%) than fish in control (100%) and external transmitter (93%) groups. External transmitters were not shed by juvenile least cisco; however, transmitter shed rate ranged from 0% to 33% for fish in internal implant treatments. Our results showed that externally attached transmitters had a lower impact on fish growth, mortality, and tag retention than internal implants, which is an important consideration for telemetry evaluations involving fish that are susceptible to handling stress such as juvenile least cisco. [ABSTRACT FROM AUTHOR]

Distribution shifts of demersal fishes are important adaptive responses to warming oceans for species' persistence. Shifts are facilitated by factors such as adult movement and dispersal of pelagic larvae to normally cooler regions, where increasing ocean temperatures are now enhancing larval and juvenile survival. However, successful recruitment (i.e. larval settlement) at these new regions can be constrained by resource availability, specialisation (food, habitat) and ecological interactions (competition, predation). Evaluating the capacity or likelihood of a species to successfully shift or expand its range, provides information relevant to biodiversity conservation and fisheries management, and is particularly important for species with restricted ranges. Choerodon rubescens (Günther, 1862) is an exploited labrid endemic to ~ 1400 km of the west Australian coastline, encompassing 13° of latitude and a 6°C temperature gradient. This region recently experienced a rapid warming event of ~ 3°C, which lasted 3 months and mirrored ocean temperatures expected in the next 50 years. Following this event, high levels of recruitment of C . rubescens occurred towards its southern, cooler distribution limit. Juvenile abundances were surveyed in this study to evaluate: (1) the effect of elevated temperatures on recruitment success across shallow water habitats spanning the species' distribution, (2) temporal variation in recruitment success in the typically cooler, southern part of its range and (3) ecological characteristics important to recruit survival, including habitat preferences, diet and behaviour. Juvenile C . rubescens were significantly more abundant at the margin between reef and sand and towards the cooler southern range end. Reef margin habitat provides access to shelter from predators within the reef and to sand-associated invertebrate prey in adjacent soft sediments, where most feeding activity occurred. Juveniles were abundant (0.3 to 4 fish/40 m 2 ) in reef margin habitats of the southern cooler region for three consecutive years, with individuals represented by multiple cohorts, indicating suitable environmental conditions for ongoing recruitment and survival. Juveniles at this habitat were able to compete effectively with other co-occurring labrids for invertebrate prey. As oceans warm, the number of recruits arriving and surviving beyond the existing cooler range limit will be dependent on factors such as successful spawning, larval delivery and survival, and availability of reef margin habitat with associated prey; these factors will determine the successful range shift or expansion of C . rubescens . We present an example of how range-wide spatiotemporal ecological studies of juvenile fish can identify range shift capacity and inform management adaptive to climate change. [ABSTRACT FROM AUTHOR]

In present study the effect of feeding frequency on growth performance, food efficiency and survival rate of common carp fingerlings were investigated. Three groups of common carp fingerlings (average weight 22.88±1 gm) designed with three feeding frequencies one meal a day (D1), two meals a day (D2) and three meals a day (D3) with three replicates of each treatment. Fish in experimental treatments were fed by 4% of body weight. Feeding frequencies had significant effect on growth performance (P<0.05). The final body weight and specific growth rate (SGR) were significantly higher in group D3 (P<0.05) in this comparison. Similar responses were observed for body weight increased (BWI) and daily growth rate (DGR) and the best BWI and DGR were obtained in D3 group, that showed significantly different to other groups (P<0.05). The best feed conversion ratio (FCR) was obtained from three daily feeding (D3), however there were no significant different between D2 and D3 (P>0.05). Also feeding frequencies had positive effect on fish survival rate (P<0.05). The best results in growth performance and survival rate were obtained by feeding threemeals a day (D3). [ABSTRACT FROM AUTHOR]

Background. The silver therapon, Leiopotherapon plumbeus (Kner, 1864), is an endemic and economically important freshwater food fish in the Philippines. The natural populations of this species have been declining during the past years, mainly due to intense fishing pressure, habitat degradation, and introduction of invasive alien species. At present, it is considered a target species for domestication and conservation efforts. Despite several attempts of artificial reproduction and larval rearing, little is known on larval and early juvenile development of silver therapon. The presently reported study was therefore intended to fill this gap in the knowledge by determining the growth and describing body proportions, pigmentation, and fin formation of this fish. Materials and methods. Newly hatched larvae were reared in mesocosm tanks at a mean temperature of 29.5°C. Larvae up to 30 days after hatching were sampled at irregular intervals and preserved in 5% buffered formalin. Early development stages for 245 preserved specimens were described in detail with reference to changes in morphology, growth and body proportions, pigmentation, and fin formation. Results. Five developmental stages of silver therapon were identified: yolk sac larva (1.88 mm TL), preflexion (2.51 mm TL), notochord flexion (4.50-8.27 mm TL), postflexion larva (6.90-12.21 mm TL), and early juvenile (≥13.40 mm TL). Growth was isometric for eye diameter and gape size whereas positive allometry was observed for body depth, head length, and preanal length. Some body proportions showed abrupt changes from preflexion to postflexion larvae before it stabilized during the early juvenile stage. Pigmentation in the form of stellate and punctate melanophores increased with developmental stage, with larvae becoming heavily pigmented from postflexion to early juvenile stage. These morphological changes, together with the full complement of fin rays and squamation observed in specimens larger than 13.4 mm TL, suggest the attainment of the juvenile stage of this species. Conclusion. These morphological changes may explain the food and feeding habits during the early life stages of silver therapon which is critical to their survival and recruitment in the wild and in a mesocosm hatchery environment. [ABSTRACT FROM AUTHOR]

Archival tagging studies of southern bluefin tuna ( SBT , Thunnus maccoyii) have revealed that juveniles residing in the Great Australian Bight ( GAB) over the austral summer undertake seasonal cyclic migrations to the southeast Indian Ocean and the Tasman Sea during winter. However, there remains disagreement about the extent of mixing between juvenile SBT regularly caught by longline fleets south of Africa and those observed in the GAB. Some researchers have argued that archival tag recoveries indicate most juveniles reside in the GAB over the austral summer. Others have suggested that recoveries of conventional and archival tags are better explained by a juvenile population consisting of separate groups on the eastern and western sides of the Indian Ocean with limited intermixing. We present analyses of catch and tag recovery data and re-examine archival tagging studies. The evidence provided strongly favors the hypothesis of separate juvenile subgroups, or contingents, with limited intermixing. We draw some tentative conclusions about the nature of the putative contingents and discuss some implications of these findings for the interpretation of existing datasets and future research priorities. We also provide the first evidence that the migration choices of juveniles that summer in the GAB are influenced by fidelity to winter feeding grounds and suggest this helps explain the collapse of the surface fishery off New South Wales in the 1980s. [ABSTRACT FROM AUTHOR]

This study assesses seasonal variation in the morphology and diet of juveniles and adults of the Easter Island endemic goby Kelloggella disalvoi from intertidal pools during September-October 2015 (spring) and June-July 2016 (winter), utilizing geometric morphometric and gut-content analyses. A set of 16 landmarks was digitized in 128 individuals. Shape changes related to size changes ( i.e. allometry) were low (18·6%) and were seasonally similar. Body shape changes were mainly dorsoventral (44·2% of variance) and comprised posteroventral displacement of the premaxilla and bending of the body. The latter included vertical displacement of the anterior portion of the first and second dorsal fins and the entire base of the caudal fin. Diets mainly comprised developmental stages of harpacticoid copepods (from eggs to adults), ostracods, isopods, gastropods and bivalves. Also, trophic niche breadth remained constant throughout development and did not vary between seasons. Nonetheless, significant dietary differences were detected in specimens collected during spring (main prey items: harpacticoid copepods and copepod eggs) and winter (harpacticoid copepods and copepod nauplii). Finally, there was weak but significant covariation between diet and morphology: molluscivores were characterized by having an inferior mouth gape, whereas planktivores had an anteriorly directed premaxilla. [ABSTRACT FROM AUTHOR]

Key methodological assumptions regarding the degree of natural variability and influence of sample handling and storage of elasmobranch vertebral chemistry were assessed using laser-ablation inductively coupled plasma mass spectrometry. Vertebral chemistry of juvenile blacktip sharks Carcharhinus limbatus was examined to identify whether differences existed among different regions of the vertebral column, between thoracic vertebrae of individual fish or within individual vertebrae. Additionally, the effects of bleach exposure and storage in ethanol on vertebral chemistry were compared. No significant variation in vertebral chemistry was found among different regions of the vertebral column or between thoracic vertebrae, but significant differences among transect locations within individual vertebrae were observed. The variation at all three levels appears comparable with published data on sagittal otoliths of bilaterally symmetrical teleost fishes. The experimental assessment of potential treatment effects indicated vertebral chemistry was not significantly affected by bleach or exposure to ethanol. Taken together, these results support the idea that vertebrae taken from the same region of the vertebral column can be treated as equivalent and at least certain elements remain robust to exposure to bleach and ethanol. [ABSTRACT FROM AUTHOR]

This study compared the bioaccumulation of anthropogenic nuclides ( 65 Zn, 134 Cs, 60 Co and 241 Am) between the egg and juvenile life stages of a small shark ( Scyliorhinus canicula ), based on previously published experimental data. Rates of accumulation over 15 days were derived and summed for the transfer pathways which were specific to these two life stages. Radionuclide transfers to the egg and its embryo & yolk were quantified for i) the maternal pathway following her uptake of radionuclides via food and seawater and ii) from seawater following its oviposition. For the juvenile, the transfer of radionuclides were measured for aqueous & dietary pathways. The results show that, compared to juveniles, eggs have equivalent rates of accumulation of 65 Zn and 134 Cs but enhanced accumulation of 241 Am by a factor of five and of 60 Co by two orders of magnitude. The radiological exposure of the embryo due to radionuclides maternally transferred to the embryo & yolk is also enhanced for the alpha-emitting 241 Am. This enhanced accumulation of 241 Am and 60 Co, as well as the equivalent accumulation of 65 Zn and 134 Cs, suggest greater likely vulnerability to radiation damage in eggs as compared to juveniles. Radiological dose assessment confirmed highest doses to the egg which is predominantly due to accumulated 241 Am. [ABSTRACT FROM AUTHOR]

An 8-week feeding trial was conducted to investigate the effects of feeding rates on growth, feed utilization, and body composition of juvenile Pseudobagrus ussuriensis. Juvenile P. ussuriensis (initial body weight of 2.30 ± 0.01 g) were distributed into 15 tanks, and each tank was stocked with 30 fish. Satiation feeding (3.57% BW day) was determined by the point of cessation of voluntary feeding activity by fish. Five treatments that included triplicate groups were prepared for this study: 100% (satiation), 75, 50, and 25% of satiation groups and unfed group. The results indicated that weight gain (WG) and specific growth rate (SGR) increased with increasing feeding rates. WG and SGR of fish fed to satiation were significantly higher than that of fish fed to 50 and 25% of satiation and unfed fish ( P < 0.05), but not significantly different from that of fish fed to 75% of satiation ( P > 0.05). Feed efficiency (FE) and protein efficiency ratio (PER) of fish fed to 75% of satiation were significantly higher than that of fish fed other groups. There was a trend towards increased whole-body crude lipid and decreased whole-body moisture with increasing feeding rates, while whole-body protein content was not significantly affected by feeding rates. Condition factor and hepatosomatic index were increased with increasing feeding rates ( P < 0.05), while there was no significant difference in viscerosomatic index with increasing feeding rates. Considering these experimental results, it can be concluded that the optimum feeding rate for growth of juvenile P. ussuriensis could be lowered to 75% of satiation without growth suppression. [ABSTRACT FROM AUTHOR]

The aim of this study was to provide a reference value for the safe regulation and control of ammonia nitrogen in the aquaculture of Sepia pharaonis. The effects of acute and chronic toxicity of ammonia on the cuttlefish, S. pharaonis, were tested experimentally using juvenile S. pharaonis. The results showed that the half-lethal concentration ( LC50 ) values of ammonia nitrogen in juvenile S. pharaonis with a body weight of 6.52 ± 0. 23 g at 24, 48, 72, and 96 h were 31.72, 25.77, 23.33, and 18.33 mg/L, respectively, and the corresponding un-ionized ammonia nitrogen ( UIA-N) concentrations were 1.66, 1.35, 1.22, and 0.96 mg/L, respectively. Compared with the control, the survival rate, specific growth rate, and feed intake of juvenile S. pharaonis declined significantly, and the feed conversion ratio and hepatosomatic index increased significantly at 56 d after exposure to >1 mg/L ammonia nitrogen. Juvenile S. pharaonis should be maintained at a concentration of ammonia nitrogen of no more than 1 mg/L ( UIA-N is 0.056 mg/L) in culture, and removing harmful nitrogenous wastes from the seawater is critical in maintaining cuttlefish culture. [ABSTRACT FROM AUTHOR]

The influence of three different initial stocking densities (low stocking density [ LSD] = 1.5 kg/m2; medium stocking density [ MSD] = 3 kg/m2; and high stocking density [ HSD] = 6 kg/m2) in flow-through systems was evaluated on growth and welfare in beluga, Huso huso, and ship sturgeon, Acipenser nudiventris, juveniles for 2 mo. Fish were kept in 18 concrete square tanks (2.0 × 1.0 × 1.2 m3) at 22.3 ± 0.4 C and under a natural photoperiod. In both species, the growth performance in terms of final body weight, weight gain, specific growth rate, and feed intake significantly decreased with increasing stocking density ( P < 0.05). In both species, the percent of neutrophils increased after 60 d of trial ( P < 0.05). Moreover, hematocrit and white blood cell counts increased after 60 d of trial in ship sturgeon ( P < 0.05). Plasma immunoglobulin significantly decreased with increasing stocking density in both species. Plasma insulin-like growth factor I decreased with increasing stocking density in beluga; however, it was not affected in ship sturgeon. Overall, these results showed that the LSD group in both species demonstrated more homogeneous and higher growth rate than the MSD and HSD groups. [ABSTRACT FROM AUTHOR]

Coastal nursery habitats are essential for the renewal of adult fish populations. We quantified the availability of a coastal nursery habitat (shallow heterogeneous rocky bottoms) and the spatial variability of its juvenile fish populations along 250 km of the Catalan coastline (France and Spain). Nurseries were present in 27% of the coastline, but only 2% of them benefited from strict protection status. For nine taxa characteristic of this habitat, total juvenile densities varied significantly between nursery sites along the coastline, with the highest densities being found on the northern sites. Recruitment level (i.e. a proxy of nursery value) was not explained by protection level, but it was moderately and positively correlated with an anthropization index. Patterns of spatial variations were taxa-specific. Exceptional observations of four juveniles of the protected grouper Epinephelus marginatus were recorded. Our data on habitat availability and recruitment levels provides important informations which help to focus MPA management efforts. [ABSTRACT FROM AUTHOR]

Our lack of knowledge on the spatiotemporal drivers of the distribution of many freshwater fishes, particularly as they differ among life-history stages, is a challenge to conservation of these species. We used 2-stage hurdle models to investigate drivers of occurrence and abundance of locally threatened adult and juvenile Northern River Blackfish in the upper Condamine River, Queensland, Australia. Different processes drive occurrence and abundance between the 2 life-history stages. Both adult and juvenile occurrences were negatively associated with high-magnitude, extended warming events, suggesting Northern River Blackfish are thermally restricted to cooler headwaters. Juveniles had greater sensitivity than adults to high stream temperatures. In contrast, drivers of abundance differed between life-history stages. Adult fish were negatively associated with increased fine-sediment loads, whereas juveniles were negatively associated with a hydrologically active inverse-distance-weighted grazing metric that accounted for the greater influence of grazed land close to the stream or in areas of high overland flow. Teasing apart environmental drivers affecting multiple life-history stages of a locally threatened headwater species enabled us to provide direct management recommendations for conserving this species and ecologically similar headwater fishes and their associated habitats. [ABSTRACT FROM AUTHOR]

In response to a lack of data supporting (or otherwise) legally mandated escape gaps in an Australian recreational trap fishery for eastern rock lobster, Sagmariasus verreauxi , the effects of all prescribed options on catches were investigated. Round traps without escape gaps (control) were compared against those with either one (57 × 500 mm), two (both 57 × 250 mm) or three (all 57 × 200 mm) rectangular openings (i.e. all similar areas) evenly located around the base of the trap perimeter. All traps with escape gaps retained significantly fewer undersized (by 54–84%) but more legal-sized (by 1.6–2.8 times) S. verreauxi than the control. Irrespective of escape gaps, there was also a positive association between antennae loss by S. verreauxi and trap soak time, although only one undersized individual died (for a total associated discard mortality <2%). These observations are explained by possible density-dependant behavioural responses of trapped S. verreauxi , with legal-sized individuals replacing escaping juveniles and increased physical interactions among all catches the longer they remained in traps. Escape gaps could be promoted in the fishery, not only for their utility in reducing catches of undersized individuals, but via the potential for almost triple the fishing power for targeted catches. [ABSTRACT FROM AUTHOR]

Two diets with the same docosahexaenoic acid:eicosapentaenoic acid ratio (1.8:1), but with different n -3 long-chain polyunsaturated fatty acid ( n - 3 LC-PUFA) contents [29.5 g/kg (DH) and 17.9 g/kg (DL)], were designed and fed to two groups of 46 female and 30 male Siberian sturgeon ( Acipenser baerii ) broodstock for 11 months. Sperm and egg quality and reproductive performance indices were recorded during cross-breeding. Larval offspring resulting from cross-matings were divided into the following four groups for a 30-d feeding trial: D1 ( DH ♀ × DH ♂), D2 ( DH ♀ × DL ♂), D3 ( DL ♀ × DH ♂), and D4 ( DL ♀ × DL ♂). The results showed that egg size of the DH group was significantly larger than that of the DL group. With respect to sperm quality, there were no significant differences in wobble, amplitude of lateral head displacement, beat/cross frequency, and mean angular displacement between the two dietary groups; however, a high n -3 LC-PUFA diet increased sperm curvilinear, straight-line, and average path velocities in the DH group. The DH group had significantly lower levels of serum triglyceride, low-density lipoprotein cholesterol, and malonaldehyde, but higher superoxide dismutase level, and total antioxidant capacity compared with the DL group. At 7 and 32 days post hatching, the survival of larvae in groups D1 and D2 was significantly higher than that in groups D3 and D4. The specific growth rate of larvae in group D4 was the lowest among the four groups. The results suggest that n -3 LC-PUFA can improve the reproductive performance of male and female broodstock of Siberian sturgeon and the quality of their offspring, but that n -3 LC-PUFA enrichment of the diet is more critical for female broodstock than for males. [ABSTRACT FROM AUTHOR]

The nutritional value of whole wheat, corn, rye and barley was evaluated for European sea bass. Four isoproteic and isolipidic diets containg 30% of each whole cereal meal were formulated. A growth trial and a digestibility trial were conducted and fish performance was evaluated in terms of growth, feed intake, feed utilization, macronutrients digestibility, liver composition, glycaemia and cholesterolemia levels and gut histomorphology. Growth and feed utilization ranged from 1.43 to 1.46 and from 0.55 to 0.58, respectively, and were similar among experimental groups. Whole body and liver composition, hepatosomatic and visceral indexes were also not affected by dietary composition. Corn diet revealed the lower dry matter (62.9) and starch (55.5) apparent digestibility coefficients. Protein digestibility in fish fed the rye diet was the lowest of all groups (91.3) and differed from that of wheat diet group (93.2), which might be due to antinutritional factors present in this feedstuff. Plasmatic glucose levels suggested a slower absorption rate in fish fed barley and corn diets. No signs of enteropathy related to the whole cereal meals were observed. Among cereals tested, rye seemed to be the less tolerated by sea bass, although all diets were well accepted and sea bass performed equally well with all diets. [ABSTRACT FROM AUTHOR]

Regarding the practical farming of Litopenaeus vannamei, the deterioration of water quality from intensive culture systems and environmental pollution is a common but troublesome problem in the cultivation of this species. The toxicities that result from deteriorating water quality, such as that from ammonia stress, have lethal effects on juvenile shrimp and can increase their susceptibility to pathogens. The toxicity of ammonia plays an important role in the frequently high mortality during the early stage on shrimp farms. However, little information is available regarding the genetic parameters of the ammonia tolerance of juveniles in the early stage, but this information is necessary to understand the potential for the genetic improvement of this trait. Considering the euryhalinity of L. vannamei and the fact that low salinity can increase the toxicity of ammonia stress, we estimated the heritability of ammonia tolerance in juveniles in 30‰ (normal) and 5‰ (low) salinity in this study using the survival time (ST) at individual level and the survival status at the half-lethal time (SS50) at the family level. In the normal and low salinity conditions and for the merged data, the heritability estimates of the ST (0.784±0.070, 0.575±0.068, and 0.517±0.058, respectively) and SS50 (0.402±0.061, 0.216±0.050, and 0.264±0.050, respectively) were all significantly greater than zero, which indicates that the ammonia-tolerance of shrimp can be greatly improved. So it might provide an alternative method to reduce mortality, help to enhance resistance to pathogens and reduce the occurrence of infectious diseases. The significant positive genetic correlation between ST and body length suggested that ammonia is more toxic to shrimp in the early stage. The medium-strength genetic correlations of the ST and SS50 between the two environments (0.394±0.097 and 0.377±0.098, respectively) indicate a strong genotype-by-environment (G×E) interaction for ammonia tolerance between the different salinity levels. Therefore, salinity-specific breeding programs for ammonia tolerance in shrimp should be purposefully implemented. [ABSTRACT FROM AUTHOR]

We describe a process for evaluating proposed ecosystem restoration projects intended to improve survival of juvenile salmon in the Columbia River estuary (CRE). Changes in the Columbia River basin (northwestern USA), including hydropower development, have contributed to the listing of 13 salmon stocks as endangered or threatened under the U.S. Endangered Species Act. Habitat restoration in the CRE, from Bonneville Dam to the ocean, is part of a basin-wide, legally mandated effort to mitigate federal hydropower impacts on salmon survival. An Expert Regional Technical Group (ERTG) was established in 2009 to improve and implement a process for assessing and assigning “survival benefit units” (SBUs) to restoration actions. The SBU concept assumes site-specific restoration projects will increase juvenile salmon survival during migration through the 234 km CRE. Assigned SBUs are used to inform selection of restoration projects and gauge mitigation progress. The ERTG standardized the SBU assessment process to improve its scientific integrity, repeatability, and transparency. In lieu of experimental data to quantify the survival benefits of individual restoration actions, the ERTG adopted a conceptual model composed of three assessment criteria—certainty of success, fish opportunity improvements, and habitat capacity improvements—to evaluate restoration projects. Based on these criteria, an algorithm assigned SBUs by integrating potential fish density as an indicator of salmon performance. Between 2009 and 2014, the ERTG assessed SBUs for 55 proposed projects involving a total of 181 restoration actions located across 8 of 9 reaches of the CRE, largely relying on information provided in a project template based on the conceptual model, presentations, discussions with project sponsors, and site visits. Most projects restored tidal inundation to emergent wetlands, improved riparian function, and removed invasive vegetation. The scientific relationship of geomorphic and salmonid responses to restoration actions remains the foremost concern. Although not designed to establish a broad strategy for estuary restoration, the scoring process has adaptively influenced the types, designs, and locations of restoration proposals. The ERTG process may be a useful model for others who have unique ecosystem restoration goals and share some of our common challenges. [ABSTRACT FROM AUTHOR]

The impact of the great tsunami, which was generated by the Great East Japan Earthquake on 11 March 2011, on the quality of a nursery ground for juvenile Japanese flounder Paralichthys olivaceus with a sandy bottom of <15 m in depth in Sendai Bay, Japan, was evaluated. Growth rates of juveniles, as an index of the quality of the nursery ground, were compared between before and after the tsunami. Recent growth rates ( RGR; mm day−1) between 1 and 6 days before collection in 2011-2013, which were estimated from the width of otolith increments, ranged from 0.84 to 2.37 mm day−1 for juveniles of 24.8-146 mm in total length ( TL). These figures are comparable to the maximum RGR for juvenile Japanese flounder in the literature. A linear model for RGR selected TL and bottom temperature but rejected biomass of the mysid Orientomysis mitsukurii, the main prey item, as explanatory variables, indicating that the growth rates of juveniles after the tsunami were not controlled by food density, i.e., optimal food condition occurred in the nursery. A linear model for observed growth rate (mm day−1), which was calculated from the temporal changes in the juvenile size frequency distribution, suggested the growth rate did not change between before and after the tsunami. Additional information on prey abundance and sediment size distribution also support this conclusion. Therefore, we conclude that the quality of the nursery ground for juvenile Japanese flounder in the study site has not been damaged by the great tsunami. [ABSTRACT FROM AUTHOR]

Recent studies reported positive effects of taurine supplementation to plant protein-based diets on fish growth performance and feed conversion ratio but the mechanisms involved remain unclear. The objective of this work was to provide a first insight on the importance of taurine on dietary protein and lipid absorption and utilisation, in Senegalese sole ( Solea senegalensis ) juveniles fed plant-based diets. Seven practical diets were tested: a fishmeal-based diet (FM) and a plant protein-based formula (PP85) to which taurine was added in graded levels: 0.2% (TAU1), 0.3% (TAU2), 0.4% (TAU3), 0.7% (TAU4) and 1.5% (TAU5). Short-term metabolic trials were performed by tube-feeding the different experimental diets labelled with different tracers: 14 C-taurine, 14 C-triolein (as tracer of dietary triacylglycerol) and a mixture of 14 C-amino acids. Feeding sole juveniles with the PP85 diet affected taurine metabolism, since a higher proportion of dietary taurine was directed to gallbladder and probably used for bile salt synthesis. Consistent with this, fish receiving the plant-based low taurine-content diets (PP85 and TAU1) displayed a poor triacyglycerol digestion capacity. A higher proportion of 14 C-amino acids was retained in fish muscle when fed the TAU5 compared to the PP85 diet. These short-term trials suggested that taurine supplementation to a plant-based diet might be beneficial to sole performance by enhancing bile salt synthesis and triacylglycerol digestion as well as muscle amino acid retention. However, this dietary supplementation should be tested in long-term trials to verify the effect on fish growth and to assess the beneficial effects on protein and lipid metabolism suggested here. Statement of relevance in the general field of aquaculture (limited to 60 characters) Adding taurine to a plant-based diet is beneficial for sole [ABSTRACT FROM AUTHOR]

Based on the concept of nutritional programming in mammals, we tested whether a short term hyper or hypo vitamin stimulus during first-feeding could induce long-lasting changes in nutrient metabolism in rainbow trout. Trout alevins received during the 4 first weeks of exogenous feeding a diet either without supplemental vitamins (NOSUP), a diet supplemented with a vitamin premix to satisfy the minimal requirement in all the vitamins (NRC) or a diet with a vitamin premix corresponding to an optimal vitamin nutrition (OVN). Following a common rearing period on the control diet, all three groups were then evaluated in terms of metabolic marker gene expressions at the end of the feeding period (day 119). Whereas no gene modifications for proteins involved in energy and lipid metabolism were observed in whole alevins (short-term effect), some of these genes showed a long-term molecular adaptation in the muscle of juveniles (long-term effect). Indeed, muscle of juveniles subjected at an early feeding of the OVN diet displayed up-regulated expression of markers of lipid catabolism (3-hydroxyacyl-CoA dehydrogenase – HOAD - enzyme) and mitochondrial energy metabolism (Citrate synthase - cs , Ubiquitinol cytochrome c reductase core protein 2 - QCR2, cytochrome oxidase 4 - COX4, ATP synthase form 5 - ATP5A) compared to fish fed the NOSUP diet. Moreover, some key enzymes involved in glucose catabolism (Muscle Pyruvate kinase - PKM) and amino acid catabolism (Glutamate dehydrogenase - GDH3) were also up regulated in muscle of juvenile fish fed with the OVN diet at first-feeding compared to fish fed the NOSUP diet. We researched if these permanently modified gene expressions could be related to global modifications of epigenetic marks (global DNA methylation and global histone acetylation and methylation). There was no variation of the epigenetic marks in muscle. However, we found changes in hepatic DNA methylation, global H3 acetylation and H3K4 methylation, dependent on the vitamin intake at early life. In summary, our data show, for the first time in fish, that a short-term vitamin-stimulus during early life may durably influence muscle energy and lipid metabolism as well as some hepatic epigenetic marks in rainbow trout. Statement of relevance Programming at first feeding with different levels of vitamins was successfully tested in fish for the first time. These data proove one more time the importance of the early life on the fish metabolism in adults. [ABSTRACT FROM AUTHOR]

Modes and mechanisms of speciation are best studied in young species pairs. In older taxa, it is increasingly difficult to distinguish what happened during speciation from what happened after speciation. Lake Victoria cichlids in the genus Pundamilia encompass a complex of young species and polymorphic populations. One Pundamilia species pair, P. pundamilia and P. nyererei, is particularly well suited to study speciation because sympatric population pairs occur with different levels of phenotypic differentiation and reproductive isolation at different rocky islands within the lake. Genetic distances between allopatric island populations of the same nominal species often exceed those between the sympatric species. It thus remained unresolved whether speciation into P. nyererei and P. pundamilia occurred once, followed by geographical range expansion and interspecific gene flow in local sympatry, or if the species pair arose repeatedly by parallel speciation. Here, we use genomic data and demographic modelling to test these alternative evolutionary scenarios. We demonstrate that gene flow plays a strong role in shaping the observed patterns of genetic similarity, including both gene flow between sympatric species and gene flow between allopatric populations, as well as recent and early gene flow. The best supported model for the origin of P. pundamilia and P. nyererei population pairs at two different islands is one where speciation happened twice, whereby the second speciation event follows shortly after introgression from an allopatric P. nyererei population that arose earlier. Our findings support the hypothesis that very similar species may arise repeatedly, potentially facilitated by introgressed genetic variation. [ABSTRACT FROM AUTHOR]

The majority of organic marine fish farms currently begin the production cycle with nonorganic juveniles from conventional hatcheries, permitted by the European Regulation on organic fish origin (EC 710/2009) until the end of 2016. Wild juvenile gilthead seabream (Sparus aurata) from coastal lagoons and hatcheries were experimentally reared under organic conditions, in order (1) to investigate differences in fillet lipid content and fatty acids composition, and (2) to propose a possible future source of juveniles destined for organic aquaculture. Wild juveniles were readily distinguishable by their fatty acid signature, showing significantly higher ratio levels of n-3 polyunsaturated fatty acids and n-3/n-6. Fillet lipid composition of organically fed wild S. aurata juveniles was preferable to that from domesticated juveniles. These results seem promising for organic aquaculture, where fish feed is more environmentally sustainable but is of lower nutritional quality. [ABSTRACT FROM AUTHOR]

This study presents the results of the interviews with the fishermen, sightings records in the newspapers and electronic social networks and the details of eight sampled individuals of the lionfish, Pterois sp. in the eastern Mediterranean coast of Turkey. It is evident that the lionfish has established in the eastern Mediterranean coast of Turkey. However, there is still a lack of information about its abundance. The total length (TL) of the eight individuals was 8.5-29.3 cm and the wet-weight 7.09-398.77 g, that were sampled in nine SCUBA dives at 10-15 m depths between 20.01.2017 and 10.02.2017 in Kemer, Antalya. One of the large specimens was a male (29.3 cm TL) and the other was a female (28.6 cm TL) and the rest were juveniles. The stomachs of four individuals were empty; however, identifiable parts of Mullus surmuletus, an individual of Gobiidae sp., unidentifiable parts of a Teleost fish and an undistinguished content were found in the stomachs of the other four individuals. A total of twenty sightings were recorded in the newspapers and electronic social networks in the eastern Mediterranean coast of Turkey between 15.07.2014 and 17.01.2017, apart from the scientific records, and fifteen of them were evidenced by photo and video. The interviews showed that lionfish was not well-known by the fishermen around the Gulf of Iskenderun yet. The public perception about the lionfish is highly variable in Turkey, and this may affect our understanding of the rate of invasion. [ABSTRACT FROM AUTHOR]

Production efficiency, frequency of fin erosion, skeletal and gill covers deformities, proximal composition of fish body with special emphasis on fatty acid contents in liver and muscle, oxidative stress and antioxidant response in gill, liver, muscle and intestine were analyzed and compared in exclusively RAS- and POND-cultured juveniles and juveniles produced with the combination of POND and RAS aquaculture in pikeperch ( Sander lucioperca L.) with final body weight between 8.5 and 9.5 g. Higher production efficiency, lower fin erosion, no morphological deformities, higher level of essential fatty acids and lower oxidative stress were found in POND-RAS- and POND-cultured juveniles compared to exclusively RAS-produced pikeperch. This study showed that intensive pikeperch juvenile production still needs next technological innovations. On the other hand, the combination of POND-RAS aquaculture has provided a good potential to be an alternative production system producing high-quality juveniles for intensive or pond ongrowing culture mainly in countries with large pond area. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the effect of microalgae on the rearing of newborn juveniles of the longsnout seahorse, Hippocampus reidi. Two treatments in three replicates were tested over a 15-day period: with and without the addition of the microalgae Nannochloropsis oculata at a concentration of 2.02 ± 0.44 × 106 cells mL−1. At each replicate, beginning on the second day of life, 120 H. reidi juveniles (stocking density of 3 ind L−1) were fed the offspring of the benthic copepod Tisbe biminiensis (100 copepod cm−2) together with newly hatched Artemia nauplii (3.8 mL−1). From the sixth day of life, enriched Artemia metanauplii replaced newly hatched Artemia nauplii. After 15 days, the H. reidi individuals were counted, measured and weighed. Mean survival was significantly greater in the microalgae treatment (76.42 ± 5.07%) than in the treatment with no microalgae (25.44 ± 6.91%). Moreover, total length, height and dry weight were significantly larger in the microalgae treatment. Thus, the addition of microalgae increases the growth and survival of H. reidi juveniles fed T. biminiensis and Artemia. The higher growth and survival of H. reidi juveniles was not related to the larger ingestion rates but probably to the nutritional improvement of the live feeds or to the probiotic effect. The protocol developed for rearing H. reidi juveniles resulted in a high survival, and represents an advance in the farming of this species. [ABSTRACT FROM AUTHOR]

An 8-week feeding trial was conducted to evaluate the sparing effect of dietary phytase on decreasing supplement of dietary sodium dihydrogen phosphate (NaH2PO4) in the diets of juvenile yellow catfish Pelteobagrus fulvidraco. Seven diets were formulated: one reference group that contained only 2% NaH2PO4; one control group that consisted of neither NaH2PO4 nor phytase; and five treatment groups supplemented with 1000 IU kg−1 phytase and 2%, 1.5%, 1%, 0.5%, 0% concentrations of NaH2PO4. Thus, dietary NaH2PO4 was substituted with phytase at ratios of 0%, 25%, 50%, 75% and 100% respectively. Triplicate tanks were each filled with 50 juvenile fish (3.5 ± 0.1 g), which were fed one of the seven experimental diets. Substituting phytase for NaH2PO4 didn't diminish the growth performance, protein, dry matter, lipid and ash deposit and protein retention in the whole body and reduced feed conversion ratio compared to the reference diet. Moreover, phytase substitution at level of 0-50% enhanced P, Mg and Ca deposit. However, weigh gain had a tendendy of decreasing with increasing substituted level. Phytase substituted level exceeding 75% decreased serum P concentration compared to the control group. Apparent digestibility of P peaked when 1000 IU kg−1 phytase substituted 50% NaH2PO4. Phytase also increased apparent digestibility of protein. The improvement of digestibility of protein and P resulted in the decrease in N load by 25% and P load by 31% to environment. Therefore, 50% dietary NaH2PO4 can be substituted by 1000 IU kg−1 feed phytase for juvenile yellow catfish. [ABSTRACT FROM AUTHOR]

The effects of extracts from the fruits of Sponge plant (Luffa cylindrica) on the proximate composition of juveniles of Clarias gariepienus was investigated under laboratory conditions using static renewal bioassay for 56 days. The fish with average length and weight of 13.12±1.01cm and 14.72±3.63g respectively were exposed to sub-lethal concentrations of 883mg/L, 1766mg/L, 3532mg/L and 7063mg/L of extracts from the fruit of L. cylindrica. The physicochemical parameters of water contaminated with sub-lethal concentrations of Luffa cylindrica were examined. The pH of the test media was slightly acidic, which tend to increase as concentration of Luffa cylindrica extract increases. Dissolved Oxygen decreased while Conductivity and Total Dissolved Solids increased with increase in concentrations of Luffa cylindica extract. The changes in the physicochemical parameters were significant differences across the different concentrations (P<0.05). There were significant reductions (P<0.05) in protein, lipid, fiber and ash content (14.21±0.48% to 9.78±0.48%; 2.38±0.02% to 1.83±0.10%; 4.60±0.12% to 1.51±0.11% and 3.25±0.08% to 1.71±0.01 respectively) as the concentration of the extract increases. However, moisture content and carbohydrate content (74.67±0.61% to 82.55±0.43% and 1.44±0.48% to 2.62±0.48% respectively) significantly increased (P<0.05) from the control to the treated groups. The study revealed that the extract of Luffa cylindrical have adverse effects on the nutritional composition of Clarias gariepinus. Therefore, consumption of fish killed with piscicides should be discouraged because of the reduced nutritional values. [ABSTRACT FROM AUTHOR]

An 8-week feeding experiment was conducted in juvenile silvery-black porgy ( Sparidentex hasta) (initial mean weight 20.1 ± 0.1 g, mean ± SD) to estimate the optimum dietary docosahexaenoic to eicosapentaenoic acid (DHA/EPA) ratio. Triplicate groups of fish (12 fish in each replicate) were kept into 15 cylindrical polyethylene tanks (250 L) at 18.7 °C and handfed by one of the five diets which formulated with graded ratios of DHA/EPA (0.2, 0.4, 0.9, 2.0, 3.3) two times daily. In the fillet and liver, DHA and DHA/EPA ratios significantly increased with increasing dietary DHA concentrations ( P < 0.05). Fish fed the 0.2 DHA/EPA ratio diets had the highest hemolytic activity ( P < 0.05). Plasma thiobarbituric acid reactive substance concentration, catalase activity, total antioxidant capacity, total cholesterol, and triglyceride significantly decreased with increasing dietary DHA/EPA ratios ( P < 0.05). It is concluded that health status of silvery-black porgy juveniles were not influenced by dietary graded ratios of DHA/EPA. [ABSTRACT FROM AUTHOR]

Influence of waterborne butachlor (BUC), a commonly used pesticide, on morphometric, biochemical, and molecular biomarkers was evaluated in juvenile, full sibling, diploid and triploid African catfish ( Clarias gariepinus ). Fish were exposed for 21 days to one of three concentrations of BUC [mean measured µg/L: 22, 44 or 60]. Unexposed (control) triploids were heavier and longer and had higher visceral-somatic index (VSI) than diploids. Also, they had lighter liver weight (HSI) and showed lower transcript levels of brain gonadotropin-releasing hormone ( GnRH ), aromatase ( cyp191b) and fushi tarazu-factor ( ftz-f1 ), and plasma testosterone levels than diploids. Butachlor treatments had no effects, in either diploid or triploid fish, on VSI, HSI, weight or length changes, condition factor (CF), levels of plasma testosterone, 17-β estradiol (E2), cortisol, cholesterol, or mRNA levels of brain tryptophan hydroxylase ( tph2 ), forkhead box L2 ( foxl2 ), and 11 β -hydroxysteroid dehydrogenase type 2 ( 11β-hsd2 ). Expressions of cyp191b and ftz-f1 in triploids were upregulated by the two highest concentrations of BUC. In diploid fish, however, exposures to all BUC concentrations decreased GnRH transcription and the medium BUC concentration decreased ftz-f1 transcription. Substantial differences between ploidies in basal biomarker responses are consistent with the reported impaired reproductive axis in triploid C. gariepinus . Furthermore, the present study showed the low impact of short term exposure to BUC on reproductive axis in C. gariepinus . [ABSTRACT FROM AUTHOR]

This study evaluated the sensitivity of the wolfish Anarhichas denticulatus exposed to crude oil, comparing the effects of mechanically dispersed versus chemically dispersed oil using sub-lethal endpoints. To test the toxicity of this controversial technique, two experiments involving exposure of the organisms for 48 h were conducted. The first experiment assessed the effects of oil exposure on biomarker responses. The second experiment monitored the growth of juveniles over 5 weeks after exposure. Overall, this study demonstrated that polycyclic aromatic hydrocarbon (PAH) biliary metabolites, ethoxyresorufin- O-deethylase (EROD), and acetylcholinesterase (AChE) are appropriate biomarkers to assess exposure of A. denticulatus. Growth rate, both in length and weight, was significantly higher in control compared to oil exposure treatments. The lack of differences between chemically and mechanically dispersed oils in biomarker response and growth suggests that dispersant application is no more toxic than the natural oil dispersion. The results indicate the potential for population-level effects resulting from exposure to oil. [ABSTRACT FROM AUTHOR]

Life history variation in Pacific salmon (Oncorhynchus spp.) supports species resilience to natural disturbances and fishery exploitation. Within salmon species, life-history variation often manifests during freshwater and estuarine rearing, as variation in growth. To date, however, characterizing variability in growth patterns within and among individuals has been difficult via conventional sampling methods because of the inability to obtain repeated size measurements. In this study we related otolith microstructures to growth rates of individual juvenile Chinook salmon (O. tshawytscha) from the Columbia River estuary over a two-year period (2010–2012). We used dynamic factor analysis to determine whether there were common patterns in growth rates within juveniles based on their natal region, capture location habitat type, and whether they were wild or of hatchery origin. We identified up to five large-scale trends in juvenile growth rates depending on month and year of capture. We also found that hatchery fish had a narrower range of trend loadings for some capture groups, suggesting that hatchery fish do not express the same breadth of growth variability as wild fish. However, we were unable to resolve a relationship between specific growth patterns and habitat transitions. Our study exemplifies how a relatively new statistical analysis can be applied to dating or aging techniques to summarize individual variation, and characterize aspects of life history diversity. [ABSTRACT FROM AUTHOR]

The high loss of newly released hatchery-reared European lobster (Homarus gammarus) juveniles for stock enhancement is believed to be the result of maladaptive anti-predator behaviour connected to deprived stimuli in the hatchery environment. Our objective was to learn if an enriched hatchery environment enhances shelter-seeking behaviour and survival. In the “naïve” treatment, the juveniles were raised in single compartments without substrate and shelter whereas juveniles in the “exposed” treatment experienced substrate, shelter and interactions with conspecifics. Three experiments with increasing complexity were conducted. Few differences in shelter-seeking behaviour were found between treatments when one naïve or one exposed juvenile were observed alone. When observing interactions between one naïve and one exposed juvenile competing for shelter, naïve juveniles more often initiated the first aggressive encounter. The third experiment was set up to simulate a release for stock enhancement. Naïve and exposed juveniles were introduced to a semi-natural environment including substrate, a limited number of shelters and interactions with conspecifics. Shelter occupancy was recorded three times during a period of 35 days. Exposed juveniles occupied more shelters, grew larger and had higher survival compared with naïve juveniles. Our results demonstrate that experience of environmental complexity and social interactions increase shelter-seeking ability and survival in hatchery reared lobster juveniles. [ABSTRACT FROM AUTHOR]

Substantial declines of Pacific salmon populations have occurred over the past several decades related to large-scale anthropogenic and climatic changes in freshwater and marine environments. In the Columbia River Basin, migrating juvenile salmonids may pass as many as eight large-scale hydropower projects before reaching the ocean; however, the cumulative effects of multiple dam passages are largely unknown. Using acoustic transmitters and an extensive system of hydrophone arrays in the Lower Columbia River, we calculated the survival of yearling Chinook salmon ( Oncorhynchus tshawytscha) and steelhead ( O. mykiss) passing one, two, or three dams. We applied a unique index of biological characteristics and environmental exposures, experienced by each fish individually as it migrated downstream, in order to examine which factors most influence salmonid survival. High outflow volumes led to involuntary spill in 2011 and created an environment of supersaturated dissolved gas concentrations. In this environment, migrating smolt survival was strongly influenced by barometric pressure, fish velocity, and water temperature. The effect of these variables on survival was compounded by multiple dam passages compared to fish passing a single dam. Despite spatial isolation between dams in the Lower Columbia River hydrosystem, migrating smolt appear to experience cumulative effects akin to a press disturbance. In general, Chinook salmon and steelhead respond similarly in terms of survival rates and responses to altered environmental conditions. Management actions that limit dissolved gas concentrations in years of high flow will benefit migrating salmonids at this life stage. [ABSTRACT FROM AUTHOR]