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The effects of gonadotropin-releasing hormone agonist (GnRHa) on plasma levels of follicle-stimulating hormone (Fsh) and luteinising hormone (Lh) are reported for female greater amberjack Seriola dumerili with post-vitellogenic ovarian oocytes. Five females were implanted with pellets containing GnRHa (600 μg kg-1 body weight), while five other females were injected with saline. All females implanted with GnRHa-containing pellets ovulated 36-42 h post-implantation. The GnRHa implants elevated Lh, but not Fsh plasma levels within 42 h of GnRHa administration.

[EN] The apparent digestibility coefficients (ADCs) of dry matter, crude protein, crude lipid, and amino acids in fish, krill, squid, meat, defatted krill, soybean, wheat gluten, wheat, camilina, pea, sunflower, and fava bean meals were determined for juvenile Seriola dumerili. The results showed that the ADC of dry matter for yellowtail ranged from 57.7 to 87.2% for animal ingredients and from 42.2 to 82.2% for plant ingredients. An ADC of protein exceeding 90% was observed in fishmeal, while camilina meal and fava bean meal presented the lowest values. Pea meal presented the lowest lipid ADC (83.5%). The availabilities were generally higher in animal ingredients than those in vegetal ones. Except camilina and fava bean meal, the other ingredients appear to be favorable for S. dumerili diets, especially the ones from animal sources. Lower case chemical score values (minimum value from amino acid ratios [AARs]) were obtained in some vegetal ingredients (14¿18%), while the highest ones were observed in marine ingredients (69¿88%). According to Oser's Index, the most balanced protein for yellowtail with regard to essential amino acids was in krill, defatted krill, and fishmeal (92¿96%). So, animal sources are suitable as protein ingredients, but they could be enhanced through some essential amino acid supplementation., This project was financed by the “Ministerio de Ciencia e Innovación” (reference AGL2011-30547-C03).

Fish mariculture from the genus Seriola spp. can present high mortalities due to parasites. In Mexico, the mortality yellowtail Seriola dorsalis caused by parasites is low, and there are no reports of massive mortality events. However, as the aquaculture activity of yellowtail intensifies, parasites will be increasingly conspicuous. Therefore, the present study is an aim to know S. dorsalis ’s susceptibility to a monogenean infection mixed under RAS experimental conditions and their intensity and spatial distribution on the skin and gills. In this study, a parasitic mix induction was performed using two monogenean species such as Zeuxapta seriolae and Benedenia seriolae besides the Amyloodinium ocellatum , a dinoflagellate that was naturally presented. At the end of the experiment after 45 days, B. seriolae prevalence was 100% with a mean intensity of 122 parasites and showed a preference for the head and body of the fish. Zeuxapta seriolae prevalence was 100% with a mean intensity of 40 parasites preferentially found in the second branchial arch. In the case of A. ocellatum prevalence was of 100% with a mean intensity greater than 200 trophozoites per fish. The fish mortality reached 90% at the end of the experiment. During the infection, the fish weight decreased a 14% at the end of the experiment. Therefore, it will be necessary to carry out prophylactic and control strategies, to reduce the impact of these parasites under culture conditions.

Nocardia seriolae infection is one of the most serious bacterial diseases in Seriola species in Japanese aquaculture. In this study, the absorption-enhancing effect of citric acid on oral oxytetracycline (OTC) treatment against nocardiosis was evaluated with experimentally infected juvenile yellowtail, Seriola quinqueradiata, followed by serum, kidney and spleen OTC level analysis. When 50 mg/kg body weight (BW) of OTC was administered orally in combination with 1250 mg/kg BW of citric acid, the serum OTC level increased 3-fold at 6 h post single-dose administration, while no effect was observed when the dose of citric acid was set at 50 mg/kg BW. OTC levels in the kidney and spleen were increased 2-fold when 50 mg/kg BW of OTC and 1250 mg/kg BW of citric acid were administered for 5 consecutive days. This coadministration improved the clinical efficacy of oral OTC treatment against nocardiosis by significantly reducing the mortality rate compared to that of the group that received OTC alone and the untreated control group. These results suggest that coadministration of 1250 mg/kg BW of citric acid enhanced OTC absorption and therefore improved the clinical efficacy of oral OTC treatment against nocardiosis.

Neobenedenia spp. are harmful ectoparasites that can cause disease and mortality in aquaculture systems. The identification of Neobenedenia spp. is difficult using only morphological characteristics; therefore, molecular techniques represent a very useful tool to differentiate species, as recently demonstrated for Neobenedenia melleni and Neobenedenia girellae. In line with this, DNA barcoding (a region of the mitochondrial cytochrome c oxidase subunit I (COI)) can provide strong resolution at the species level for different parasite groups. Neobenedenia spp. have been reported in captive Seriola species along the western Pacific Ocean and in several wild fish species from the Chilean coast (South-Eastern Pacific, SEP) but has never been previously reported in wild and farmed Seriola lalandi from SEP. During routine sampling in 2015 and 2017, specimens of Neobenedenia sp. were recorded, for the first time, in S. lalandi cultured in a hatchery. In the present study, we used mitochondrial DNA (the COI gene) and nuclear DNA (28S LSU rDNA) to support the specific identification of these monogeneans. Then, we evaluated the potential source of infestation of Neobenedenia sp. by comparing COI sequences and morphometry of monogenean specimens from five abundant wild littoral fish species collected by local fishermen from the SEP. Parasites were sorted and fixed in 70% and absolute ethanol for taxonomic identification, morphometric measurements and molecular analysis. In total, 58 COI sequences of Neobenedenia sp. were identified; each of these was 641 bp in length. The least genetic distance of Neobenedenia spp. was recorded between Neobenedenia sp. from S. lalandi and Cheilodactylus variegatus (0.2%–1.2%) and between sequences from S. lalandi and Aplodactylus punctatus (0.4%–1.4%). Neobenedenia specimens from Paralabrax humeralis were the most genetically distant with respect to the other specimens used for comparison. Molecular analysis determined that Neobenedenia species from cultured S. lalandi and littoral fish species from the SEP are genetically distinct from N. melleni and N. girellae. In addition, our results suggest that there are at least two species of Neobenedenia in wild fish from the Chilean coast. Furthermore, the morphometry of Neobenedenia specimens differed among different host species. Finally, given the higher genetic similarity between Neobenedenia sp. from the most abundant littoral fish species (C. variegatus and A. punctatus) and those parasites from S. lalandi, we suggest that these wild host fishes were important in transmitting Neobenedenia sp. to cultured S. lalandi in a hatchery.

This study examines the effects of swim bladder inflation failure, a common developmental abnormality in finfish aquaculture, on the energy allocation, growth, and development of California Yellowtail (Seriola dorsalis). Health and fitness metrics including oxygen consumption, aerobic scope, critical swimming speed, feed conversion ratio, and growth rate, were monitored over a 32-week growout period in three groups of S. dorsalis: aquaculture-reared fish that failed to inflate their swim bladders (uninflated), aquaculture-reared fish with properly inflated swim bladders (inflated), and wild-caught individuals (wild). After the growout period, the uninflated fish had significantly lower body mass (636.1 ± 80.4 g vs. 758.6 ± 92.7 g inflated), shorter body length (36.5 ± 1.9 cm vs. 39.6 ± 2.0 cm inflated), and smaller girth (21.5 ± 1.2 cm vs. 23.2 ± 1.1 cm inflated) than the inflated fish. In addition, the uninflated fish had the least efficient feed conversion ratio (2.08 uninflated vs. 1.49 inflated, 1.41 wild), needing 39.8% more feed than the inflated fish, and 47.8% more feed than the wild fish to gain equivalent mass. These differences in growth and feed conversion appear to be primarily attributed to differences in energy allocation. Measures of oxygen consumption using a swim tunnel respirometer at two time points during the growout period showed that uninflated fish had significantly higher metabolic costs than both the inflated and wild groups over a large range of the swimming speeds tested. In addition, the uninflated fish were often observed swimming faster in their growout tank, likely to generate enough lift to compensate for the lack of a buoyant swim bladder. The wild-caught fish had the lowest feed conversion ratios and had significantly lower metabolic costs than both the inflated and uninflated aquaculture-reared fish at the beginning of the growout period (shortly after capture from the wild). The results of this study show that rearing S. dorsalis without a functional swim bladder is not economically feasible based on their poor growth and feed conversion ratios, and suggest that there is room for improvement in the metabolic efficiency of cultured S. dorsalis with properly inflated swim bladders.

This study was carried out to estimate total catches extracted from the offshore areas of northeastern Brazil by recreational fishers from offshore operations, daily activities, and fishing competitions. It also aimed at providing a first estimate of expenditure by anglers in the region. The basis for this analysis was the data supplied by the only offshore fishing operator established in Paraiba State. The available logbooks allowed for the first estimate of total catches by anglers in Paraiba State, which was extrapolated to the entire region using information provided in a database of recreational fishers’ licenses. By combining these data with catch data from fishing competitions, we were able to estimate that a peak of about 90 t was extracted in 2011. This catch is low when compared with commercial catches, but the associated economic impacts, assessed via the expenditure by recreational fishers at US$1.5 million in 2014, is high. Moreover, catches are concentrated mainly on a small number of species, mostly Thunnus spp. and Seriola spp. in waters off Paraiba State. No information is available on the current status of these amberjacks ( Seriola spp.). However, some of the snappers (Fam. Lutjanidae) included in the top species caught by recreational fishers are considered overexploited in the region. Normal 0 21 false false false PT-BR X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Tabela normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-fareast-language:EN-US;}

Aspects of swimming and metabolic physiology were measured in aquaculture-reared California Yellowtail (Seriola dorsalis) in comparison to wild-caught individuals in order to examine potential differences in health and fitness associated with captive rearing, and to help identify areas for targeted improvement in Seriola aquaculture. Incremental swimming velocity trials using a swim tunnel respirometer on small yellowtail (mean body length = 18.9 cm, mass = 80.1 g) showed that aquaculture-reared fish had a significantly slower mean maximum sustainable swimming speed (Ucrit) (4.16 ± 0.62 BL s−1) in comparison to that of wild-caught fish (4.80 ± 0.52 BL s−1). In addition, oxygen consumption (ṀO2) measurements at varying swimming speeds allowed for estimation of standard metabolic rate, which was significantly higher in aquaculture-reared yellowtail (7.31 ± 2.32 vs. 3.94 ± 1.60 mg O2 kg−1 min−1 at 18 °C). Aquaculture fish also had a lower aerobic scope (9.20 ± 3.44 mg O2 kg−1 min−1) in comparison to wild-caught yellowtail (15.80 ± 5.78 mg O2 kg−1 min−1), which likely contributed to their reduced capacity for fast sustainable swimming. Reduced physical fitness is commonplace in aquaculture-reared fishes, and the examination of wild-caught yellowtail in this study provides baseline metrics that can be used to gauge the health and fitness of future S. dorsalis production. In particular, the lower standard metabolic rate and higher aerobic scope of wild-caught fish represent desirable metabolic characteristics that if achievable in aquaculture through better-rearing practices could allow for increased feed conversion efficiencies and potentially faster growth. At a minimum, a 35–40% reduction in metabolic costs at low swimming speeds (to those observed for wild-caught yellowtail) should result in substantial cost savings for feed in aquaculture operations.

Lipids rich in saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA) are among the alternative sources reported to maintain growth and tissue fatty acid composition and, in some cases, reducing the long-chain polyunsaturated fatty acids (LC-PUFA) requirements. The present works aims to investigate the effects of different SFA:MUFA ratios on growth performance, tissue fatty acid composition, and the expression of crucial genes involved in the lipid metabolism of juvenile California Yellowtail (Seriola lalandi) fed diets with increasing SFA:MUFA ratios (1.6, 1.8, and 2.0) with low LC-PUFA levels. After eight weeks, fish fed the control diet outperformed the experimental feeds with increasing SFA:MUFA ratio in terms of final weight, specific growth rate, and liver index. No differences were observed in survival, viscerosomatic index, and condition factor across dietary treatments. Whole-body, liver, and muscle tissues proximate composition was slightly affected by increasing the dietary SFA:MUFA ratio. In terms of fatty acid composition, whole-body, liver, and muscle tissues reflected the dietary fatty acid composition to most extent, except SFA (mainly 16:0) that was not proportionally deposited. LC-PUFA sparing effect was demonstrated at a low degree in this study, likely due to the low SFA:MUFA ratio or high content of dietary MUFA. Significant changes were observed in the expression of genes related to lipid metabolism. The ppara and igf1 expression were higher in fish fed the Control diet than those fed SFA:MUFA 1.6 diet. Whereas the fish from SFA:MUFA 1.6 group displayed higher cptla expression compared to fish from SFA:MUFA 2.0.

Five cohorts of cultured California Yellowtail (Seriola dorsalis) were used in exercise training experiments to assess the duration of exercise necessary to induce a positive growth and fitness response, quantify the variability and replicability of this response between cohorts, and track the longevity (persistence) of exercise-induced benefits following removal from the exercise stimulus. Custom-designed raceways were used to continuously exercise juvenile yellowtail at their optimal swimming speed for two, three, or four weeks following which several fitness metrics including measures of somatic growth, white muscle fiber area, metabolic rate, and feed conversion were tracked for up to 20 weeks post exercise in comparison to non-exercised controls. Within a cohort, the longest duration of exercise (4 weeks) generally had the largest and longest-lasting impact on growth, followed by the 3-week, and then the 2-week exercise regimes. However, all exercise treatments showed substantial variability in the magnitude and longevity of the response between cohorts. For example, the positive growth response (increase in mass above that of controls) of the 4-week swimming group ranged from 9.8% to 37.8% between cohorts. This variability in the exercise response between cohorts is similar in magnitude to that associated with other experimentally manipulated variables in the exercise regimes of previous studies, and thus highlights the need for additional species-specific experiments to quantify replicability of positive exercise results. In addition, the longevity of exercise-induced benefits was highly variable between cohorts and generally not retained for prolonged periods post exercise. Most notably, the exercise-induced growth response which may result from muscle hypertrophy (increase in white muscle fiber size) during exercise, subsided within weeks. Taken together, these results indicate that exercise can play an important role in the growth and fitness of S. dorsalis and other species, however the duration of the exercise, as well as the timing of exercise in the rearing process likely have important implications for optimizing exercise training for aquaculture enhancement.

Amberjack Seriola dumerili (Carangidae) and yellowtail S. quinqueradiata are important commercial fish species in Japan; however, they are susceptible to skin and gill monogeneans. Recently, a treatment of 75 ppm hydrogen peroxide (H2O2) for 30 min was found to effectively eliminate these monogeneans. However, histological analyses of the host fish subjected to treatments with lower H2O2 concentrations have not been performed to determine the influence of these treatments on fish. Therefore, we investigated the influence of a 100 ppm H2O2 treatment at 25 °C on the survival, swimming behavior, feeding behavior and the histopathology of S. dumerili and S. quinqueradiata compared with the 300 ppm treatment at 25 °C, which is the conventional concentration. We then evaluated the susceptibility of both species to infestations of the skin monogenean Neobenedenia girellae after the administration of a 75 ppm H2O2 bath treatment relative to the susceptibility after the administration of the conventional procedure (300 ppm for 3 or 4 min) at 25 °C. Both species suffered severe effects when exposed to 300 ppm H2O2; however, when exposed to 100 ppm H2O2 for 60 min, the survival, appetite, and swimming behavior were unaffected. Histopathological changes were not observed during the examination of the skin, gills, and internal organs of the fish in the control group and the group treated with 100 ppm H2O2 for 60 min, whereas histopathological changes were observed in the skin, gills and liver of the fish treated with 300 ppm H2O2 for 60 min, and the changes in S. dumerili became more pronounced with increasing exposure time. Furthermore, the fish treated with 75 ppm H2O2 baths for 30 or 40 min did not show increased N. girellae infestation levels relative to the untreated controls; however, the fish treated with the 300 ppm H2O2 baths for 4 min showed significantly increased N. girellae infestation levels relative to the untreated controls (P Statement of relevance To eliminate B. seriolae and N. girellae, Z. japonica, fish may be fed praziquantel-supplemented feed, submerged in a freshwater bath for 2- to 5- min, or placed in a hydrogen peroxide bath. However, none of these measures simultaneously dislodge B. seriolae, N. girellae, and Z. japonica. Orally administered praziquantel is ineffective against N. girellae infestations in Seriola species, and the freshwater treatment is not effective when the fish are infected with Z. japonica. Additionally, H2O2 treatment at a concentration of 300 ppm (conventional concentration in Japan) negatively affects fish health and viability, especially in the summer when water temperatures are higher and the parasite doubling and maturation rates are increase. Thus, any parasite control measure must be performed frequently during the summer. A bath treatment with 75 ppm H2O2 for 30 min effectively eliminates these parasites and the fish survival, appetite and swimming behavior were unaffected when exposed to 75 ppm H2O2 for 6 h at 25 °C. Therefore, treatment with 75 ppm H2O2 for 30 min is not expected to adversely affect S. dumerili. However, histological analyses of lower H2O2 concentrations have not been performed to determine the effects on the host fish, and experimental proof of the safety of different concentrations is important for the use of this treatment in aquaculture.

In aquaculture of species with a large body size such as tuna and yellowtail, a major problem still is that broodstock management for egg collection requires high feeding cost and labor. In order to reduce feeding costs, development of restricted feeding techniques without affecting the reproductive performance may be useful. To gain a better understanding of reproductive responses to food supply, we examined the effect of restricted feeding during the previtellogenic and vitellogenic phases on sexual maturation in female yellowtail, Seriola quinqueradiata. Restricted feeding during the vitellogenic phase tended to reduce ovary weight relative to normally fed controls at the end of the experiment. Histological observations revealed that both restricted feeding regimes do not affect the percentage of atretic follicles as compared to the control group. Nevertheless, the mean diameter of the most advanced follicles of the females subjected to restricted feeding during the vitellogenic phase was significantly smaller to normally fed controls. These results suggest that reduced food intake during the vitellogenic phase is likely to delay oocyte growth, and lead to low ovarian weight. Endocrine analyses showed that restricted feeding during the vitellogenic phase reduced plasma 17β-estradiol levels, but not plasma and pituitary gene expression levels of gonadotropins (follicle-stimulating hormone and luteinizing hormone) at the end of the experiment. Transcripts for ovarian steroidogenesis-related genes, such as P450 side-chain cleavage (cyp11a1) and 3β-hydroxysteroid dehydrogenase (hsd3b) after food restriction during the vitellogenic phase tended to be high. Therefore, the effects of restricted feeding on reproduction would not be mediated by alterations in circulating gonadotropin levels, but rather through direct effects on the ovarian steroid production in yellowtail females.

This work contributes basic knowledge on larval development of Seriola rivoliana. A histological study describes the development of the digestive tract and accessory glands in S. rivoliana larvae reared under laboratory conditions at 24 °C from hatching to 30 days post-hatching (DPH). At hatching (2.6 ± 0.12 mm), larvae had an undifferentiated digestive tract with a closed straight tube and a large yolk sac with an oil globule. The liver and pancreas were observed at 1 and 2 days, and the mouth and anus opened at day 2. Enriched rotifers were visible in their digestive tract. At the beginning of the pre-flexion stage, a mixed nutritional period was observed. At day 3, exogenous feeding began; the digestive tract became differentiated into the buccopharynx, esophagus, an undifferentiated stomach, and the intestines. Zymogen granules were visible in the exocrine pancreas. At day 4, supranuclear vacuoles were present in the posterior intestine, indicating the beginning of intracellular digestion. At day 5, goblet cells were present in the esophagus and became functional at day 7 in the esophagus and intestine. The buccopharynx goblet cells developed at day 15. The presence of gastric glands and differentiation of the stomach in the fundic, cardiac, and pyloric regions during the post-flexion stage occurred at day 20. This was the onset of the juvenile period and the beginning of weaning; however, a long co-feeding phase is recommended. Pyloric caeca were observed at day 30 (13.6 ± 1.6 mm). These results provide valuable information on S. rivoliana larvae biology and digestive physiology, which should be useful to improve cultivation techniques and identify ecological features involved in ontogeny.

A large number of fish species are associated with drifting seaweeds; however, the ecological significance of such seaweeds for fishes remains unclear. Here, we developed a raft equipped with a seaweed clump, interval still/video cameras, and a GPS satellite buoy. This novel monitoring system was used to monitor the schooling and associative behavior of Seriola spp. juveniles with seaweed for up to 1 wk in the East China Sea. We observed diel behavioral patterns of the fish, which swam around the seaweeds during the day and remained ‘attached’ to the seaweed or to conspecifics at night. This nighttime behavioral pattern suggests that the fish may use drifting seaweed to maintain schools at night when vision is less effective. Solitary individuals and those in smaller schools tended to remain close to the seaweed, whereas fish in larger schools were observed swimming actively around the seaweed. Additionally, some of the solitary fish and small schools escaped into the seaweed when potential predators appeared. As the school size of the fish increased over time, solitary individuals and small schools may have used drifting seaweeds as a shelter from predators until the fish could gather to form larger schools. We suggest that drifting seaweeds have multiple ecological functions for Seriola spp. and other seaweed-associated fishes, and the knowledge of these functions will be useful in designing conservation and management measures for the associated fishes., Marine Ecology Progress Series, 573, pp.101-115; 2017

The visual environment of several aquaculture species has been shown to be crucial for increased survival and growth. However, very little is known about the visual system of the increasingly popular Seriola genus and its developmental changes. We investigated the ontogenetic changes in colour vision and spatial resolution in the yellowtail kingfish, S. lalandi and discuss them in relation to past behavioural feeding experiments. Microspectrophotometry was used to measure the spectral sensitivities of photoreceptor visual pigments in larvae and sub-adults. The yellowtail kingfish larva has a broad spectral range including ultraviolet-sensitive (UVS) single cones, middle-wavelength-sensitive (MWS) single cones, MWS twin cones and long-wavelength-sensitive (LWS) twin cones. The overall spectral range narrows during development through the loss of the LWS twin cones and a general short-wavelength shift in the spectral sensitivities of the other photoreceptor types. As a sub-adult the yellowtail kingfish also gains a short-wave-sensitive (SWS) single cone. This suggests that different lighting conditions will be optimal for larvae and sub-adults. No changes are observed in retinal ganglion cell (RGC) distribution between juveniles and sub-adults. A temporal concentric increase in RGC density and a weak horizontal band of medium RGC density (30% of the peak density) are present at both stages. This suggests that no changes in the feeding behaviour will occur throughout growth although the sub-adult possesses 1.6 times higher spatial resolution which would increase feeding accuracy at higher pellet densities. Research into the spectral properties of feed types combined with the data obtained here will allow for better contrast between prey and background by optimising lighting conditions.

Taurine is an important amino acid derivative for marine and freshwater fish, especially during early development. We investigated the range of taurine concentrations that influence the growth and survival rates of California yellowtail (CYT; Seriola dorsalis) during transition from live feeds to microparticulate diets, as well as the extent to which nutrient leaching from the microparticulate diets affects these ranges. We tested particle-assisted rotationally agglomerated (PARA) particles with four levels of taurine: 4 (low taurine; LT), 45 (medium taurine; MT), 93 (high taurine; HT) and 122 g/kg (very high taurine; VHT). Our results showed that CYT postlarvae had no significant differences in growth, survival and feed consumption rates between the MT, HT and VHT treatments. However, it should be noted that the PARA particles containing 122 g/kg (VHT) taurine were especially prone to leaching and may have had taurine concentrations as low as 34.9 g/kg before they settled on the bottom of the tank. Therefore, the actual dietary taurine concentrations experienced by the larvae were likely lower than the initial dietary concentrations. More research is needed to evaluate the potential nutrient toxicity of elevated dietary taurine concentrations for marine fish larvae and juveniles.

espanolEl cultivo de peces marinos, tanto en el criadero como en el cultivo para engorda, es vulnerable a la incidencia de parasitos, lo que afecta la salud de los peces y, en general, conduce a altas tasas de mortalidad. La enfermedad mas frecuente en estos cultivos, la amiloodiniosis, es causada por el dinoflagelado Amyloodinium ocellatum, considerado el parasito que inflige el dano mas considerable a las empresas comerciales de peces marinos. En los ultimos anos, el jurel Seriola dorsalis cultivado en Baja California ha padecido infestaciones parasitarias recurrentes. Por lo tanto, el objetivo del presente trabajo fue evaluar los efectos de una infestacion parasi-taria (A. ocellatum) en juveniles de jurel en terminos de mortalidad, histologia de las branquias y parametros sanguineos. Los peces expuestos a la infestacion parasitaria exhibieron una prevalencia del 100% con una intensidad media de 766 ± 500 parasitos por pez (gran promedio ± desviacion estandar). El analisis histologico de las branquias indico dano caracterizado por inflamacion, desprendi-miento epitelial, hiperplasia, fusion de las lamelas secundarias, telangiectasia y proliferacion de celulas del mucus. Con respecto a los parametros sanguineos, el recuento de globulos rojos, la concentracion de la hemoglobina corpuscular media, y las concentraciones de hemoglobina, glucosa y trigliceridos fueron significativamente mayores (P 0.05). Este estudio demostro que la infestacion por A. ocellatum causo danos severos en las branquias que afectaron la eficiencia del intercambio de gases, lo que resulto en cambios en los parametros sanguineos y, en consecuencia, altas tasas de mortalidad en un corto periodo de tiempo. EnglishMarine fish culture, both in hatchery and grow-out systems, is prone to parasitic infestations, which lead to fish health impairment and generally high mortality rates. The most frequent disease in these cultures, amyloodiniosis, is caused by the dinoflagellate Amyloodiniumocellatum, the parasite considered to inflict the most considerable damage on commercial marine fish ventures. In recent years, the yellowtail Seriola dorsalis cultured in Baja California has undergone recurrent parasitic infections. Thus, the objective of the present work was to evaluate the effects of a parasitic infection (A. ocellatum) in juvenile yellowtail in terms of mortality, gill histology,and blood parameters. Fish exposed to parasitic infection exhibited 100% prevalence, with mean intensity of 766 ± 500 parasites per fish (grand mean ± SD). Gill histological analyses indicated damage characterized by inflammation, epithelial detachment, hyperplasia, fusion of secondary lamellae, telangiectasia, and proliferation of mucous cells. Regarding blood parameters, red blood cell count, mean corpus-cular hemoglobin concentration, and hemoglobin, glucose, and triglyceride concentrations were significantly higher (P 0.05). This study demonstrated that A. ocellatuminfection caused severe gill damage, affecting gas exchange efficiency, which resulted in blood parameter changes and, consequently, high mortality rates in a short-term period.

The main objective of this study was to determine the effect of two feeding additives (cMOS: Actigen®, Alltech Inc., USA) and a phytogenic specifically designed for reducing ectoparasite incidence, combining garlic and labiatae herbal extracts (HERB; Delacon, Austria) on growth performance, stress and immune response of greater amberjack (Seriola dumerili) before and after an experimental parasitization with the skin ectoparasite Neobenedenia girellae, a monogenean with high incidence on Seriola cultured in sea cages. Two parallel trials were conducted in order to determine the effect of 70 days of functional diets supplementation (0.2% cMOS and 200 ppm HERB) on greater amberjack: a) Growth performance and stress resistance and b) disease resistance against N. girellae. Additionally, in order to evaluate the effects of the dietary supplements pre- and post- parasitization challenge against N. girellae, the expression of some immune-related genes was evaluated. The relative expression of Il-1β, piscidin, hepcidin, IgT, tnf-α, muc-2, cathelicidin, complement c3, cd8, and caspase-3 was determined in skin. The activity of protease and lysozyme in serum and skin mucus were also evaluated, as well as parasite load and parasite total size. The use of both functional additives did not affect fish growth performance. However, the dietary supplementation of HERB significantly (p In general, greater amberjack supplementation with cMOS and HERB at the dose used in the present study was effective for reducing stress and for increasing the skin associated lymphoid tissue (SALT) immune response against N. girellae during the infection process.

The present work aimed to evaluate the effects of different levels of Ulva fasciata obtained from an Integration Multi-Trophic Aquaculture (IMTA) culture and added at different levels (0, 5, 10, and 20 g kg−1) to formulated isoproteic and isolipidic diets (45% crude protein and 12.5% crude fat) for Seriola dorsalis on growth, hematology, and fatty acid profile content in muscle tissue. One hundred and twenty juveniles (7.93 ± 0.24 g) were randomly distributed into 12, 500 L tanks connected to a recirculating system (four treatments in triplicate groups). After 48 days that fish were fed at 5% of the initial fish biomass, no effects on growth performance and somatic parameters were found. However, concerning the hematological parameters, the hematocrit showed statistical differences among the treatments, being higher in fish fed the U-20 diet than the control (U-0). Moreover, U. fasciata supplementation at 10 g kg−1 resulted in a decrease of approximately 20% in linoleic acid and an increase of approximately 49% in DHA of muscle tissue, most likely associated with LC-PUFA sparing effect. Therefore, the addition of U. fasciata from IMTA culture improves the fish muscle tissue quality.

The culture of Seriola species is well established in Japan and is an emerging industry in many other temperate regions around the world. Despite many studies on the growth, physiology and nutritional requirements of yellowtail kingfish, the complex interactions between nutrition and environmental impacts are still being investigated. Here, we present a theoretical bioenergetic model for yellowtail kingfish bringing together the current knowledge of this species growth, metabolism and other aspects of its physiology. We solve the energy budget of yellowtail kingfish using existing theoretical equations to represent all energy gains and all metabolic costs and parameterising them with published data obtained when rearing yellowtail kingfish. Our model predicts growth as a function of suitable temperatures for yellowtail kingfish (18–27 °C) and estimates the rate of feed ingestion as well as the effect of diet on feed conversion ratio (FCR). Our model can be used to estimate energy and protein retention, nutrients loads into the ecosystem, and how these outputs change through diet manipulation at specified weight classes. We demonstrate how to use our model to predict improvements to FCR and include a simulation example showing results from shifting from a high protein-low fat diet for juveniles (0 to 500 g) to a low protein-high fat diet for adult fish (500–1000 g). Excretion of dissolved nitrogen and the consumption of oxygen through fish respiration are highest at the optimum temperature for growth. When fed a diet of 45% protein and 20% fat, our simulation shows that a constant biomass of 1000 kg of fish at a constant optimum temperature of 22.8 °C, excretes 153.1 kg of nitrogen year -1. For the same diet composition and temperature, oxygen consumption decreases from 19.9 to 10.2 kg day−1 for 1000 kg of fish weighing 50 g and 1.5 kg, respectively. Our model is useful to investigate complex interactions of metabolism for the culture of yellowtail kingfish in a commercial setting and allows predictions for changes that could improve production.

Communal spawning behaviour in marine aquaculture species often results in a few individuals contributing disproportionate amounts of gametes. This can lead to a reduction in genetic variability and increases the risk of inbreeding among successive generations. Therefore, long term sustainability of captive breeding programmes for such species partly depends upon maintaining a sufficiently high proportion of parents contributing high quality gametes during spawning. The current study was conducted to evaluate if the use of slow-release gonadotropin-releasing hormone analog (GnRHa) implants could increase the number of females spawning high quality gametes, and thus increase genetic variation in a captive population of yellowtail kingfish Seriola lalandi (Valenciennes, 1833). Broodstock fish received implants with or without 500 μg of GnRHa during the spawning season. GnRHa treatment was associated with a higher proportion of females contributing to spawning. However, compared to eggs from non-GnRHa-treated broodstock, GnRHa significantly decreased the floating rate, fertilisation rate, number of viable eggs and egg oil globule diameter. Overall, the use of slow-release GnRHa implants is a useful tool to increase parental contribution to spawning, but this benefit must be carefully balanced against lower egg quality.

Praziquantel (PZQ) is registered for oral use against Benedenia seriolae infecting Seriola spp. in Japan, but its bitter taste causes poor palatability. Incorporating PZQ in a moist pellet may help mask the flavor to improve intake. Altering delivery, however, may influence efficacy. We assessed the minimum effective concentrations of PZQ in moist pellets delivered by intubation for the monogeneans Zeuxapta seriolae and B. seriolae infecting yellowtail kingfish Seriola lalandi in flow-through tanks. The optimised dose was then evaluated in a sea-cage of S. lalandi to assess feed acceptance and efficacy. During intubation trials, efficacy was assessed as a percent reduction compared to control groups; in the field trial, efficacy was assessed by a percent reduction after treatment. PZQ delivered by intubation at 70 mg kg-1 body weight (BW) for 3 d was 99.7 and 81.7% effective against Z. seriolae and B. seriolae, respectively. Increasing the dose to 120 mg kg-1 BW for 3 d had a similar efficacy against Z. seriolae (98.4%) and increased efficacy against B. seriolae to 89.2%, but partial emesis of the medicated feed was sometimes noted. S. lalandi in a sea-cage at 17°C readily consumed PZQ administered daily in moist pellets at 70 mg kg-1 BW for 3 d (inclusion rate: 5.15 g kg-1), which significantly reduced Z. seriolae and B. seriolae abundance with 99.4 and 81.6% efficacy, respectively. Juvenile B. seriolae were common on the eyes of fish post-treatment which indicates a strategically timed repeat treatment is necessary.

Changes in marine species distributions in response to climate warming are being observed globally. However, there is great variation in the magnitude and rate of species responses. South-eastern Australia represents a global hotspot for ocean warming and, subsequently, numerous poleward extensions in marine species distributions are evident within the region. We report on two species of Carangid not previously found in this region, recorded through photo-verified observations by citizen scientists. This includes the first record of Amberjack (Seriola dumerili) in eastern Tasmania and an extension of the previously most southern reported observation of a similarly mobile congener, the Yellowtail kingfish (Seriola lalandi) along south-eastern Tasmania. Out-of-range observations may simply represent vagrant individuals; however, there is also evidence that they are often indicators of future colonisation potential. Moreover, the observations presented here are potentially representative of a range of climate-driven changes to marine biodiversity in this region and highlight the utility of community observations in acting as an effective early-warning system for reporting changes in the marine environment. Early detection and reporting of distributional changes are important for proactive environmental management, and is enhanced by establishing an informed community and mechanisms for conveying these observations to science and management authorities.

It is likely that Seriola spp. have nutritional requirements for long-chain polyunsaturated fatty acids (LC-PUFAs) and are unable to meet physiological demand for these nutrients via biotransformation of C18 polyunsaturated fatty acids (C18 PUFAs). However, it is unclear whether 20:4n-6 (arachidonic acid, ARA), 20:5n-3 (eicosapentaenoic acid, EPA), and 22:6n-3 (docosahexaenoic acid, DHA) are each required or, as in other fish, EPA is comparatively unimportant in maintaining performance of Seriola spp. Accordingly, we assessed growth performance and tissue fatty acid composition of juvenile California Yellowtail Seriola dorsalis (formerly Seriola lalandi) fed a fish oil-based positive control diet (FISH), a soybean oil-based negative control diet (SOY), or experimental diets based on soybean oil supplemented with ARA, EPA, DHA, ARA and DHA, or all three of these fatty acids combined to achieve 50% or 100% of the concentrations typically observed in fish oil (SOY + 50% ARA, SOY + 100% ARA, SOY + 50% EPA, SOY + 100% EPA, SOY + 50% DHA, SOY + 100% DHA, SOY + 50% ARA and DHA, SOY + 100% ARA and DHA, SOY + 50% ALL, SOY + 100% ALL). As expected, fish fed the SOY diet exhibited significantly reduced growth relative to those fed the FISH diet. Supplementing with ARA alone had no effect on growth performance, and independent supplementation with EPA or DHA did not yield predictably positive effects on growth. However, fish fed the SOY + 100% ARA and DHA feed grew as well as those fed the FISH diet, and those raised on the SOY + 50% ALL and SOY + 100% ALL diets outperformed all others. Fatty acid composition of the fillet, liver, eye, and brain tissues was significantly affected by dietary treatment. As expected peripheral tissues were more modified than central tissues, and tissues of fish fed the soybean oil-based feeds exhibited higher levels of 18:2n-6 and lower levels of LC-PUFAs than those fed the rest of the experimental feeds. This effect was less overt among feeds supplemented with ARA and DHA or all three fatty acids. Results indicate that soybean oil can completely replace fish oil in California Yellowtail diets, assuming adequate levels of DHA and ARA are provided. Furthermore results illustrate the value of supplementing fish oil-free feeds with ARA, EPA, and DHA, but suggest that ARA and DHA are the primary drivers of LC-PUFA essentiality in this species. Statement of relevance The current manuscript provides valuable insights for fish nutritionists, for the aquafeed and aquaculture industries regarding fatty acid essentiality for marine carnivorous finfish. Our study supports the hypothesis that some LC-PUFAs are more physiologically important than others, with DHA and ARA being the primary drivers of fatty acid essentiality for juvenile California Yellowtail.

We investigated the influence of infection with the flatworm Neobenedenia girellae (Capsalidae) on the growth of the amberjack Seriola dumerili (Carangidae) in a 14-day rearing experiment. We assessed both hematological parameters and abnormalities present in histopathological sections of the skin and internal organs of infected fish compared with uninfected fish. Uninfected fish grew significantly larger than fish in the infected groups, and mortality was observed only in the severely infected groups, as defined by an infection level > 1 parasite/cm2 fish surface. Hematological parameters, hematocrit, blood urea nitrogen, and total protein and globulin values were significantly lower in the severely infected groups than in the control groups; conversely, the mean Na+ concentration recorded in the severely infected groups was significantly higher than that detected in the control groups. The epidermis of the severely infected fish was significantly thinner than that in the uninfected fish. Most hepatocytes in the livers of the uninfected fish showed glycogen deposition, whereas this was not the case for the severely infected fish. Additionally, we observed hepatocyte vacuolar degeneration and cell necrosis and liver congestion in 40% of the infected fish, and many tubular epithelial cells from the severely infected fish were necrotic and fragmented. These hematological and histopathological symptoms indicated that N. girellae infection disrupts the osmotic balance of the host fish and impairs liver and kidney function. Statement of relevance As background, Seriola species are the major commercially cultured fish in Japan and are cultured in floating net pens and cages. The parasite N. girellae (Capsalidae), a capsalid monogenean that infects the skin of host fishes, is problematic in these conditions. In S. dumerili (Carangidae), N. girellae feeds primarily on epithelial cells, and indeed at high numbers it causes not only hemorrhaging of the S. dumerili skin surface but also mortality. However, physiological impairment of the host by N. girellae infections has not been investigated. In this study, we provide a detailed analysis of several relevant biological parameters. Specifically, after infection by N. girellae, we examined not only growth of S. dumerili but also a wide range of hematological parameters and characterized distinctive histopathological features of the liver, kidney, spleen, and intestine. The results of these analyses are consistent with the hypothesis that N. girellae infection disrupts osmotic balance in S. dumerili. The resulting ionic disequilibrium provokes liver and kidney dysfunction that ultimately affects fish growth, and in severely infected fish this dysfunction can lead to death.

The larval rearing performance of California yellowtail (Seriola lalandi) and white seabass (Atractoscion nobilis) was compared between larvae fed taurine-supplemented rotifers (Brachionus plicatilis) and Artemia (Artemia franciscana) and control groups fed live feeds with no taurine enhancement. Results from the S. lalandi trial demonstrated that when fed taurine-supplemented rotifers, survival was significantly higher than the control group (20.1% vs. 9.1%, P

The advent of molecular technologies allow for identification of organisms that were previously challenging or not possible. Conventional polymerase chain reaction analyses of a segment of the small subunit ribosomal RNA gene from trypanorhynch plerocerci obtained from cultured and wild caught amberjacks, Seriola dumerili, and Seriola rivoliana of the family Carangidae from Hawai‘i and Japan were found to be 100% identical, indicating that the cestodes from Japan and Hawai‘i are the same species, Protogrillotia zerbiae. The prevalence of the trypanorhynch plerocerci found in the musculature of Hawai‘i wild-caught S. dumerili and S. rivoliana was 86.9 and 72.7%, respectively. In stark contrast, no trypanorhynch plerocerci have been detected in S. rivoliana cultured in Hawai‘i and they are only rarely seen in S. dumerili cultured in Japan. Trypanorhynch plerocerci are part of a complex life cycle that involves the transmission in at least two intermediate hosts before finally residing in a host shark species. The results of this study indicate that artificial propagation of the amberjacks using manipulated diets has most likely disrupted the life cycle of this tapeworm, thus reducing the prevalence of this parasite in farmed amberjacks and enhancing the marketability of cultured amberjack.

Taurine, a β-sulphonic amino acid, is a growth and health promoting dietary supplement in commercial finfish aquaculture. Reported recommendations for taurine supplementation in Seriola spp. feeds broadly range from 2.6 to 10.2 g kg−1 diet. Methionine is an essential amino acid and substrate for various metabolic compounds and acts as a methyl and sulfur donor, potentially sparing taurine. Dietary methionine requirements are currently unknown for Yellowtail Kingfish (Seriola lalandi); however, recommendations for the closely related Japanese Yellowtail (Seriola quinqueradiata) indicate that 11.1 g kg−1 diet is adequate. The taurine requirement and sparing effect of methionine of juvenile Yellowtail Kingfish was quantified by conducting a feeding experiment and applying a factorial, orthogonal dose-response design. Fourteen isonitrogenous and isoenergetic diets were prepared using practical raw ingredients with either one of two levels of methionine (10.9 ± 0.2 g kg−1 or 17.2 ± 0.6 g kg−1) and either one of seven levels of taurine, increasing from 1.6 to 20.4 g kg−1, respectively. Triplicate groups of 14 fish (53.3 ± 0.4 g fish−1) were fed one of the 14 diets over seven weeks. Based on growth and feeding results, juvenile Yellowtail Kingfish do not require dietary taurine supplementations when the basal taurine diets content is at least 1.6 g taurine kg−1 at a dietary methionine content of 17.2 ± 0.6 g kg−1 diet. This demonstrates that dietary methionine has a sparing effect on taurine supplementation. Yellowtail Kingfish fed dietary methionine exceeding the current minimum industry standard (~11.1 g kg−1), grew more rapidly than those fed high dietary taurine contents at dietary methionine levels approximating that of current industry practice, indicating the indispensability of adequate methionine supply. Breakpoint analysis on the specific growth rate in Yellowtail Kingfish fed a methionine level of current industry practice, estimated a digestible taurine requirement of 1.98 g kgBW−1 d−1 at an average digestible methionine intake of 3.4 g kgBW−1 d−1 This equates to a dietary taurine content of 7.7 g kg−1 diet at a dietary methionine content of 10.9 g kg−1 diet. Our results indicate that in juvenile Yellowtail Kingfish: adequate dietary methionine spares dietary taurine supplementation; insufficient dietary methionine provokes a taurine requirement; and current industry specifications for dietary methionine for Yellowtail Kingfish aquafeed require reassessment.

The lack of knowledge in what optimizes egg and larval quality is an important limiting factor in developing culture techniques for any species. Inconsistent or poor egg quality significantly affects the production of larval and juvenile fish. Egg quality is a known predictor of subsequent larval viability, quality, and stress resistance. Without high quality eggs, it is not possible to optimize husbandry practices. Here we tracked egg quality in a population of California yellowtail (Seriola dorsalis), CYT. We used spawn events from three consecutive years and monitored basic egg quality metrics such as: spawn viability, egg diameter, oil diameter, hatch rates, larval size at hatch, and larval survival to first feeding. Along with these metrics we also ran proximate composition and fatty acid analysis of these spawn events on the viable portion of the eggs collected. During this study we demonstrated that egg diameters for S. dorsalis decreased as the spawning season progressed and water temperature increased. We showed that larger eggs lead to higher quality hatched larvae, and that using eggs earlier in the season would lead to better overall larval and juvenile production. Our fatty acid analyses suggest that both arachidonic acid (ARA) and linoleic acid (LA) were limiting fatty acids in eggs produced, and there is potential to improve the quality of cultured CYT eggs with the addition of these fatty acids to the broodstock diet.

Members of the genus Seriola have been notable species for aquaculture production worldwide, with the greater amberjack Seriola dumerili being a prominent species, partly due to its cosmopolitan distribution. A prerequisite to sustainable aquaculture production is controlling reproduction in captivity, which has been lacking for greater amberjack. The objective of the present study was to develop broodstock management and spawning induction methods using gonadotropin releasing hormone agonist (GnRHa) implants for greater amberjack reared in tanks and sea cages, and evaluate spawning performance. The advantages of sea cage rearing and spawning include optimal environmental conditions and welfare, and low cost of fish maintenance; while the advantages of tank rearing and spawning include biosecurity, ease of management and handling operations, and control of egg collection. Females reared in tanks supplied with well seawater throughout the year exhibited a significant reproductive dysfunction, such as limited gametogenesis, lower oocyte diameter at the peak of the reproductive season, low female eligibility for spawning induction and almost 0% fertilization success. On the contrary, females in three different broodstocks reared in sea cages for three consecutive years underwent vitellogenesis completely, and almost all females were eligible for spawning induction. Males reared under both conditions exhibited reduced sperm production compared to the wild, but unlike the situation in the females, tank rearing did not seem to have any negative effects on sperm quality parameters compared to rearing in sea cages. Spawning performance (eggs collected and fertilization) was best when fish were reared in sea cages during the year and then moved to land-based tanks for spawning after GnRHa treatment, resulting in the production of large numbers of eggs of adequate quality for commercial larval rearing of the species.

Feed is one of the largest costs in most aquaculture operations, and as such, aquaculturists are continually striving to improve on ingredient sourcing and formulations to increase growth and performance while reducing costs. Analysis of the energy expended in digestion of different feeds can be a valuable early indicator of the suitability of a new ingredient or formulation. We use respirometry, an activity level analysis, and proximate analysis of fecal samples to compare the metabolic cost of digestion in California yellowtail (Seriola dorsalis) fed two different diets – a meal of whole sardine fillets representing a whole fish diet and a commercial pelleted feed designed specifically for Seriola aquaculture. Respiration trials reveal that the specific dynamic action coefficient (SDACoefficient), SDA coefficient (SDACoefficient), or percent of energy expended on digestion in relation to the total energy available in a meal, was more than double for a whole-fish type meal (20.8 ± 0.1%) than for the pelleted meal (10.2 ± 0.8%). Analysis of fish activities indicated 12.3% greater activity during the whole-fish type meal, as compared with the pelleted meal. After 24 h, the total amount of protein and lipid remaining in the feces from the whole-fish type meal (4.2 ± 0.7 kJ, 2.2 ± 0.4 kJ respectively) was significantly higher than the pelleted meal (1.8 ± 0.2 kJ, 0.9 ± 0.2 kJ respectively). Digestibility of the whole-fish type meal was slightly lower than the pelleted meal at 95.3 ± 0.5% and 97.7 ± 0.2%, respectively. The reduction in the energetic cost of digestion observed in fish fed the commercial pellet diet is likely attributed to the additional processing during manufacture, which liberates a significant portion of the energy normally allotted towards digestion. The results of this work reveal and quantify the benefits of switching from whole-fish feed to a commercial compound feed, as the reduced energetic costs of digestion allow for greater amounts of energy to be available for somatic growth.

Genetic data are increasingly being applied to re-evaluate past taxonomic hypotheses and better understand the evolutionary patterns and connectivity among regional populations of cosmopolitan species. This is of particular importance for heavily exploited, commercially important species. The phylogenetic structure of the Yellowtail Jack, Seriola lalandi Valenciennes, 1833, was investigated using genetic data from 42 individuals collected from California, the Pacific coast of Baja California (Mexico), the Gulf of California (Mexico), New Zealand, Japan, South Africa, and Chile. An analysis using S. dumerili as an outgroup and combining the sequences of two mitochondrial genes (CR and COI) and four nuclear genes (RAG2, EHHADH, UBE3A, MLL) was used to determine the level of genetic divergence among samples from different geographic regions. Bayesian and Maximum Likelihood analyses utilizing combined mitochondrial gene (mtDNA) or nuclear gene (nucDNA) data supported the existence of multiple regionally restricted clades with mtDNA analysis identifying four major clades and nucDNA supporting three. Both mtDNA and nucDNA trees were very similar in topology, which was reflected in the combined total evidence phylogram. These clades were highly supported with Bayesian posterior and bootstrap probabilities ranging from 90 to 100 percent for the three major clades that were recovered in both mtDNA and nucDNA trees. These clades represent regionally specific specimens collected from the 1) Northeast Pacific, 2) Northwest Pacific, and 3) Southern Hemisphere. Morphometric analysis (MDS and ANOSIM) of available meristic data on the number of soft dorsal-fin rays, anal-fin rays, and total number of gill rakers separated specimens among the three regions identified by genetic analysis (P = 0.05). Based on the phylogenetic structure within this taxonomic unit as evidenced by genetic data and significant meristic differences among these regional lineages, we conclude that three cryptic species currently bear the name Seriola lalandi Valenciennes, 1833. We propose the resurrection of two currently available names based on nomenclatural priority. The Northwest Pacific species name should revert to Seriola aureovittata Temminck and Schlegel (1845) (type locality Japan), and the Northeast Pacific species to Seriola dorsalis Gill (1863) (type locality Cabo San Lucas, Mexico). Seriola lalandi Valenciennes, 1833 (type locality Brazil) should apply only to the species in the Southern Hemisphere.

Marine finfish require long-chain polyunsaturated fatty acids (LC-PUFAs) for normal physiological function, and because these LC-PUFAs cannot be synthesized by the fish they must be obtained from the diet. Three LC-PUFAs—arachidonic acid (ARA; c20:4 n-6), eicosapentaenoic acid (c20:5 n-3) and docosahexaenoic acid (c22:6 n-3) are especially important for growth and development of marine fish embryos and larvae. Here we supplemented ARA in the diet of California yellowtail (CYT; Seriola dorsalis), to determine whether ARA levels have an effect on egg and larval quality.Two experimental diets were offered to replicate groups of CYT held in 10 m3 tanks under ambient water temperature and photoperiod conditions. The reference diet (REF-D; 1.4 g ARA 100 g−1 total fatty acids) was a commercial premix (Bio Vita Starter Mash; Bio-Oregon) without ARA supplementation, the ARA diet (ARA-D; 4.7 g 100 g−1 total fatty acids) was the commercial premix with 1.0% concentrated ARA oil (40% ARA, w/w) added.Fish in th...

Morphological development and allometric growth patterns of Seriola lalandi larvae were assessed to characterize normal growth patterns under culture conditions. Early ontogenetic stages of yellowtail kingfish exhibited an exponential growth in terms of standard length as a function of age. Five development stages were characterized from hatching to the juvenile stage: larval stage I (0–2 days post hatch, dph) with endogenous feeding, characterized by a small yolk sac, unpigmented eyes, primordial finfold surrounding the body and a closed mouth; larval stage II (2–15 dph) characterized by mouth opening, complete pigmentation of eyes and the beginning of the exogenous feeding; subsequently, in the larval stage III (15–25 dph) the posterior tip of notochord of the larvae bended upward and the first rays appeared in fins, concomitant with a change in swimming behaviour; thereafter, larval stage IV (post-flexion stage; 25–30 dph) began when larvae resembled in morphology to a juvenile organism; however, caudal and dorsal fins were not completely development. Lastly, the juvenile stage was reached 30 dph characterized by a morphology and fin structures similar to those of the adults. Growth and development of structures and organs associated with vital functions such as feeding, sensorial and breathing systems seemed to be more critical previous to 23 dph, which was reflected with a positive allometric growth of head and eyes during this period. The results from this study can be used as a tool-guide to assess normal development in larval research with S. lalandi to improve existing rearing protocols in hatchery production.

To optimize broodstock management for Seriola rivoliana, a survey over 5 years was performed to evaluate the effects of successive hormonal inductions with GnRHa or dietary regime on spawning quality. Running males and females with an oocyte diameter > 500 μm were injected with GnRHa. The spawning quality was compared among consecutive years and different moments along the spawning season. Besides, three different feeding regimes were tested. Spawning quality parameters were not significantly affected by time along the spawning season, whereas they were clearly influenced by diet. Particularly, broodfish fed the mackerel regime (M) showed a significantly higher number of eggs than other treatments. Besides, dietary protein content significantly improved broodstock fecundity of S. rivoliana. Moreover, hatching rates were also higher in broodfish fed mackerel and the dietary docosahexaenoic acid (DHA) levels significantly increased this parameter. Despite polar lipids were not significantly affected, neutral lipids fatty acid composition of S. rivoliana eggs showed higher 18:2n-6 in eggs, whereas ARA content was not affected. The results of this study denoted the high fecundity and good spawning quality of S. rivoliana broodfish and suggested the importance of high protein, energy and DHA levels in broodstock diets.

The soybean meal as a possible anti-nutritional factor to result in intestinal damage in the California yellowtail, Seriola dorsalis, was study. Four diets were formulated to contain increasing amounts of soybean meal (SBM; 0, 10, 15, and 20%) at the expense of fishmeal. The diets contained similar protein and lipid levels (54 and 15%). After a 30-day feeding trial, coexistent damage in the intestinal epithelium was revealed. While the overall performance showed no significant differences among treatments; blood parameters, histology and molecular expression of functional, immunological and antioxidant enzymes, of the distal intestine (DI) displayed significant differences. The histology snits exhibited a reduction in the DI mucosal folds number, and height. The expression patterns of il1b, hsp70, hsp90, and bcl-2 genes revealed an impaired immunological response at higher levels of SBM (15% and 20%). The digestive functions estimated by the expression patterns of mga, apn, and ATPase also showed significant differences among treatments. The expression of antioxidant enzymes (sod and gpx1) as an indicator of oxidative stress was drastically modified following the increasing levels of dietary SBM. In conclusion, the results indicate a detrimental status of the intestinal physiology of S. dorsalis fed SBM-based diets at inclusion levels above 10%, suggesting that SBM should be used with caution.

One of the key limitations in the use of artificial microdiets for the culture of marine fish larvae and post-larvae is their poor acceptability. The chemosensory systems of adult and juvenile fish are known to serve important roles in the detection and selection of food items; however, the relative importance and functionality of chemosensory detection and responses are less well understood for the larval stages. Many chemical compounds previously found to promote feeding in fish are low molecular weight, water-soluble compounds that are prone to rapid leaching from artificial microdiets. Particle taste, which requires retention of these low molecular weight water-soluble compounds, is difficult to manipulate in currently available larval diets. In the present study, we used liposomes embedded in alginate particles (alginate complex particles), that showed high retention of low-molecular weight water-soluble compounds, as a tool to evaluate the impacts of several water-soluble organic compounds on the feeding of California yellowtail (Seriola dorsalis) and white seabass (Atractoscion nobilis). We also compared the relative importance of including (and retaining) these compounds within the particles (enhanced taste) as opposed to dissolving these compounds in the culture water (enhanced smell). The results of this study showed that alginate complex particles retained >50% of sodium fluorescein and >70% of amino acids after 1 h suspension in seawater. Moreover, we found that feed consumption rates (feeding incidence and fullness) were greatest when a mixture of glycine, betaine and alanine were included in the complex particles suggesting that particle taste was an important factor for influencing the feeding of white seabass and California yellowtail post-larvae.