Figure 6 - uploaded by Glenn Schipp
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1. Example growth rate of marine pond raised barramundi in the NT. The plot shows the mean weight in grams (♦). The vertical bars show the standard deviation
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Foreword This booklet represents the third revision of the NT Barramundi Farming Handbook. The first edton appeared n 1993 and the second revson was completed n 1996. In the last ten years there have been some dramatc mprovements n the way barramund have been produced n the Northern Terrtory. The establshment of a large sea cage farm by Marne Harve...
Citations
... Research was conducted under James Cook University animal ethics approval Permit Number A2014. Spawning procedures, handling methods and rearing conditions followed standard intensive barramundi hatchery practices in Australia (Schipp et al., 2007), including artificial diets of Otohime A (BMAqua), O-range Wean S or L (INVE), and/or Nutraguard Start (Ridley Aquafeeds) fed up to 4 times per day, according to their age and size. A 12 h light and 12 h dark photoperiod was maintained from 0 to 100 dph (followed by natural light conditions), and periodic grading was performed after 18 dph to avoid cannibalism (Dhert et al., 1992). ...
Sex differentiation in many gonochoristic fish is highly responsive to temperature treatment. In some species, exposure to high or low temperatures during primary gonadal development induces phenotypic reversal of an otherwise genetically encoded sex. These changes in sexual phenotype occur in the absence of changes in genotype and are often accompanied by epigenetic modifications, such as DNA methylation. It is unknown if sequentially hermaphroditic fish exhibit similar temperature sensitivity to what has been shown in gonochoristic species; however, sex-specific differences in DNA methylation have been observed. The barramundi (Lates calcarifer) is a protandrous (male-first) sequential hermaphrodite that exhibits sex-specific DNA methylation patterns. To examine the effect of temperature on DNA methylation and primary gonadal differentiation in a sequential hermaphrodite, sexually immature barramundi were exposed to high (34 °C), control (29 °C) low (24 °C) and fluctuating (25–33 °C) temperatures from 10 to 90 days post hatch, and then on-reared at 29 °C for 12 months. At 6 months and 12 months, individuals were sampled, and their gonads examined for evidence of changes in DNA methylation and/or gonadal differentiation. Male-specific DNA methylation patterns and advanced testis development were observed at 12 months but were absent at 6 months, suggesting that low temperature treatment had a delayed effect on the gonads of juvenile barramundi. Additionally, there was an initial, but not lasting, negative effect of low temperature treatment on fish length and weight, indicating that compensatory growth may have occurred. This research provides the first evidence for an effect of temperature on gonadal DNA methylation and primary sexual development in a sequential hermaphrodite. A refinement of treatment timing and intensity could lead to the development of a hormone-free method of sex control for this widely cultured species.
... calcarifer) is a farmed tropical finfish species with high-value white flesh and desirable firm texture. Barramundi can be cultured under a diverse range of environmental conditions, from freshwater to full marine salinities, and are well suited to numerous production systems, including recirculating aquaculture systems (RAS), pond and cage culture (Schipp et al., 2007). Based on its high market value and adaptability, barramundi is cultured in numerous countries across Southeast Asia, North America, the Middle East, Europe and Oceania. ...
... Key water quality parameters were monitored daily and maintained within acceptable limits for barramundi (TAN <1 mg/L; NO2 < 1 mg/L; pH 7.8-8.0; (Schipp et al., 2007)). ...
... To assess the occurrence and progression of maturation, the fish were weighed (kg, ± 0.01 kg, measured (cm, ± 0.1 cm) and cannulated at five time points: 6 (T1), 8 (T2), 10 (T3), 11.5 (T4), and 13 (T5) months after sex change. Each cannulation time point involved anaesthetizing the fish in a bath containing isoeugenol at 40 mg/L (AQUI-S®, New Zealand Ltd) before introducing a cannula tube (PE-90 polyethylene tubing, Becton Dickinson, Sparks, MD, USA) into the gonopore (Schipp et al., 2007). Retrieved oocyte samples were held in 2 mL Eppendorf tubes on ice during collection. ...
Breeding programs for barramundi (Lates calcarifer) are impeded by the lack of control over the sexual development of broodstock. As a protandrous hermaphrodite, barramundi initially sexually mature as male at 2–3 years (2–4 kg body weight; BW), before changing sex to female at 4–6 years (>6–8 kg BW). Recently, precocious female barramundi have been generated using a single intramuscular estrogen implant, providing the potential to speed up the sex change process and implement same-age mating of male and female broodfish. However, the functional maturation of hormonally-induced precocious females and their ability to spawn and produce viable progeny remains untested.
Male barramundi (~2.2 kg BW, 57.8 cm total length; TL) were hormonally induced to sex change using an estrogen implant. The precocious female barramundi were cannulated at 6 (T1), 8 (T2), 10 (T3), 11.5 (T4) and 13 (T5) months after sex change, with oocytes measured and staged to determine reproductive condition. At T3, four females (~4.2 kg BW, 67.8 cm TL) with oocytes >350 μm in size were transferred to a spawning tank along with four males to assess their spawning performances. Mass spawning events were induced at T3, T4 and T5, and eggs released on the first and second spawning nights were collected to determine rates of fertilization, hatching and larval survival at 24 and 48 h post-hatch.
At each cannulation event (T1 - T5), several precocious females were confirmed to have mature oocytes and were considered ready for induced spawning. Conversely, in some individuals, only immature oocytes were during each cannulation event. The four precocious females induced to spawn generated large numbers of eggs, with 7.7 million (T3), 10.9 million (T4) and 9.1 million (T5) eggs obtained across the two nights of each mass spawning event. Fertilization of oocytes was not observed at T3 and was likely due to male inactivity. Spawning performance improved considerably for T4 and T5 spawns, with the highest fertilization rate (64%) and hatching rate (72%) observed during T5 - Night 1. Furthermore, larval survival at 24 and 48 h after hatching was 99% and 94%, respectively. Total larval production across both nights of the T5 spawn exceeded 3 million individuals. Spawning performances of precocious females were comparable to routine commercial stocks of large females (8–15 kg), and confirmed that precociously induced female barramundi can produce the quantity of seedstock required in existing selective breeding programs. Further research examining the factors involved in promoting oocyte growth and maturation is needed to enhance the rate at which mature precocious females are available for spawning.
... The recorded water temperature, DO, pH, NH 3 , NO 2 and Alkalinity, was within the suitable range in all treatments required for Asian seabass (Schipp et al., 2007;Kungvankij et al., 1985;Rimmer and Russell, 1998;Saraswathy et al., 2015). During the experiment, the water temperature was dominated by room temperature. ...
The effect of stocking density on the growth performance, cannibalism and survival of Asian seabass Lates calcarifer fry in the static water system (SWS), and recirculating aquaculture system (RAS) was investigated. Three stocking densities 0.03, 0.04 and 0.05 ind/L were used, where the initial length and weight of the fry were 2.5 ± 0.0 cm and 0.27 ± 0.0 g respectively. At the end of the trial, no significant effect of stocking density was observed on the growth performance of Asian seabass fry (p > 0.05). After 45 days, the total body length and wet body weight were 11.63±0.18cm and 20.06 ± 0.98 g respectively obtained from the RAS were significantly higher than the SWS (p < 0.001). The maximum weight gain (WG) and specific growth rate (SGR) were 19.79 ± 0.98 g and 9.56 ± 0.10% day−1 respectively were found in the RAS significantly higher than the results obtained in the SWS (p < 0.001). A considerably lower FCR (0.67±0.03) in RAS indicated better feed utilization by fish than SWS (p < 0.01). In the present study, cannibalism was highly influenced by the stocking density and culture system and positively correlated with the stocking density. Lower cannibalism was observed at 0.03 ind/L stocking density (27.78 ± 5.56%), and the cannibalism was (35.97 ± 6.28%) in the RAS. There was no natural mortality occurred during the experimental period. The present study suggests that Asian seabass fry reared in the RAS with a lower stocking density can significantly reduce cannibalism and increase the survival rate with better growth performance.
... Water quality parameters were checked daily and maintained within acceptable limits for barramundi (TAN < 1 mg/L; NO 2 -< 2 mg/L; pH 7.8-8.0) (Schipp et al., 2007). Fish were fed a commercial barramundi diet (Ridley Corporation) twice daily at 3% BW per day. ...
Sex control is vital for the efficient breeding of aquaculture species. Barramundi (Lates calcarifer) is a protandrous sequential hermaphrodite that naturally sex change from male to female over its lifespan. The induction of precocious female barramundi will permit breeding of males and females of the same-generation individuals in selective breeding programs, increasing the rates of genetic gain, while reducing infrastructure costs. Accordingly, the efficacy of two dosages of 17β-estradiol (E2) delivered via implants to induce the precocious female barramundi were evaluated. Six-month-old male barramundi (405 ± 50 g body weight (BW)) were given a single cholesterol-based pellet implant containing either 0 mg E2 kg⁻¹ BW (untreated control), 4 mg E2 kg⁻¹ BW (‘low dose’), or 8 mg E2 kg⁻¹ BW (‘high dose’). Changes in gonadal morphology and liver condition of implanted males, along with RT-qPCR and bisulfite amplicon sequencing to quantify expression profiles and DNA methylation of key male-female sex-related genes were then examined after 9 weeks post-implantation. Results showed that at 9 weeks post-implantation, in the ‘high dose’ E2 treatment group, 78% (7/9) of fish sex-changed completely to female, signified by gonads containing oocytes (20–30 μm) and no observed residual sperm. Comparably, 44% (4/9) of fish in the ‘low dose’ E2 treatment group had sex-changed, while remaining fish showed complete testicular regression with gonads containing only undifferentiated germ cells. In the ‘high dose’ E2 treatment, upregulation of female-biased genes (cyp19a1a and foxl2) and downregulation of male-biased genes (dmrt1, cyp11b and esr1) were observed. Increased gene expression was accompanied by decreased DNA methylation in cyp19a1a, but no significant changes in DNA methylation of foxl2 or esr1 were observed. The success of artificially-induced sex change in barramundi provides an important tool that is critical to improving selective breeding of this species.
... Fish were reared in recirculated seawater (30-35 ppt) at 28-30°C, with a stable 12-hr light:12-hr dark photoperiod (Schipp et al., 2007). ...
This study investigated the effect of 17 β‐oestradiol (E2) and 17 α‐ethinyloestradiol (EE2) on the feminization of barramundi (Lates calcarifer). Fish were fed pellets containing 10 mg E2/kg food, 20 mg E2/kg food, 5 mg EE2/kg food and 10 mg EE2/kg food from 30 to 160 days post hatch (dph), which covers the period of initial male gonad differentiation. The effect of E2 and EE2 treatment on gonadal morphology and dmrt1 and cyp19a1a gene expression was analysed by histology and RT‐qPCR. Orally delivered E2 and EE2 induced observable changes in gonad morphology. Previtellogenic oocytes (PO) were observed in 33% and 50% of the fish fed with 20 mg E2/kg at 160 dph and 12 months post hatch (mph), respectively, while PO were not observed in control fish. 10 mg E2/kg treatment did not induce feminization, but significantly suppressed testicular development. Treatment with EE2 resulted in fibrosis within gonad tissues at a dose‐dependent rate. E2 administration resulted in upregulation of the gene cyp19a1a and downregulation of dmrt1. EE2 significantly suppressed expression of dmrt1 at 160 dph and 12 mph, while cyp19a1a was not significantly different at 160 dph and was significantly downregulated at 12 mph. The result of this study showed that E2 is a more suitable hormone than EE2 to induce precocious feminization of barramundi, and when delivered through the feed it has a dose‐dependent feminizing effect.
... Milt was collected from males in spawning condition. Selected broodstock were sedated in an anaesthetic bath containing isoeugenol at 40 mg/L (AQUI-S®, New Zealand) prior to sperm collection (Schipp et al., 2007). The gonopore of males was rinsed with distilled water and dried to prevent saltwater prematurely activating spermatozoa during collection. ...
Barramundi (Lates calcarifer) is a tropical finfish species rapidly growing in popularity for aquaculture production. However, sperm quality tests have yet to be adapted to enable selection of highly fertile male broodstock in this species. Accordingly, in this study advanced tools were optimized to evaluate barramundi sperm function to facilitate the future study of male fertility and address some of the reproductive constraints currently observed in captive-bred broodstock. Sperm morphology data were used to calibrate and validate automated sperm counting and motility detection by computer-assisted sperm analysis (CASA; AndroVision, Minitube). Several parameters were examined to determine the optimum settings for accurate CASA sperm counting and were compared to manual haemocytometer methods including: sample dilution (1:1000, r = 0.87), minimum number of fields (n = 4, CV = 7.5%), and the effect of motile vs. immotile spermatozoa on automated counting (no effect, r = 0.99, P < .001). Assays for cell viability and DNA damage were also validated for barramundi spermatozoa using 70 °C heat-treated controls and a 5-point intact:damaged dilution curve (r = 0.98, P < .001), and DNase-treated sperm controls, respectively. Data from these optimized assessments indicated high variation between individuals for each parameter assessed and the presence of high rates of DNA and membrane damage in sperm samples tested. Further research building upon this preliminary sperm quality data, is required to identify the cause of DNA and membrane damage in barramundi spermatozoa and understand any potential relationships with paternal performance in commercial spawns.
... Asian seabass Lates calcarifer also known as barramundi is an important fish species for aquaculture in Australasia since 1980s (Tucker, 2002) due to its popularity as a plate-size fish (500 g) after 9 monthgrowth in intensive aquaculture (Schipp et al., 2007). Previous studies indicate that Asian seabass require 400-600 g kg −1 crude protein (Glencross, 2006) and solvent-extracted soybean meal to support good growth up to a level of 300 g kg −1 in feed (Williams, 1998). ...
This study explored the impact of fishmeal replacement by commercial soybean meal (SM) and EnzoMeal (EZM) on Asian seabass Lates calcarifer growth performance using six diets. The six diets comprised two sources of plant proteins with three levels each, including 300 g kg⁻¹ soybean meal (SM30), 300 g kg⁻¹ EnzoMeal (EZM30), 400 g kg⁻¹ soybean meal (SM40), 400 g kg⁻¹ EnzoMeal (EZM40), 500 g kg⁻¹ soybean meal (SM50), and 500 g kg⁻¹ EnzoMeal (EZM50). The soybean level was shown to significantly affect the final fish weight, weight gain, specific growth rate (SGR), survival, feed intake, feed conversion ratio (FCR), and apparent digestibility coefficient (ADC). Further, the plant meal type significantly affected the final weight, weight gain, feed intake, ADC, and body lipid content. The highest final weight was observed in the SM30 group, and the lowest final weight was in the EZM50 group. Fish fed EZM had lower body weight than those fed soybean meal at the same inclusion level. However, once the fish had adapted to the EZM diet the fish weight variation was low. At the 300 g kg⁻¹ and 400 g kg⁻¹ inclusion levels the fish fed EZM showed significantly higher ADC than those fed soybean. The pepsin activity of fish fed EZM at 300 g kg⁻¹ and 400 g kg⁻¹ was higher than those fed soybean meal at the same levels. The enterocyte height in the hindgut of fish fed SM40 and SM50 was significantly higher than those fed EZM40 and EZM50, respectively. This study indicates that EZM could be a potential source of plant protein to replace fishmeal in fish feed as it contains high protein and low anti-nutritional factors. However, the major endpoint measurements on fish performance suggest that low feed intake constrains further EZM inclusion beyond 300 g kg⁻¹ in the diet.
... The DM-domain from dmrt1 mRNA was completely spliced out in female gonads and contrarily, aromatase exons 1 and 2 were partially spliced out from male gonads, as validated through two novel sex-specific RT-PCR assays. Transitional gonads were not found in 122 individuals sampled, likely due to the rapid transition phase reported from male-to-female [35,36]. Whether promoter methylation of dmrt1 (and nr5a2) and demethylation of cyp19a1 (and amh) during barramundi sex inversion is a progressive phenomenon like it has previously been reported for the protogynous ricefield eel [16] and for the protandrous black porgy [17], still remains to be elucidated. ...
Epigenetics is involved in sex differentiation of gonochoristic and hermaphroditic fish species, whereby two genes dmrt1 (pro-male) and cyp19a1 (pro-female) are known to play major roles. Barramundi, Lates calcarifer, is an important tropical aquaculture species that undergo natural and permanent male to female sex change, a process for which the exact underlying molecular mechanisms are still unknown. To elucidate whether DNA methylation is involved in sex control of barramundi, a next-generation bisulfite amplicon sequencing approach was used to target 146 CpG sites within proximal promoters and first exons of seven sex-related genes (dmrt1, cyp19a1, amh, foxl2, nr5a2, sox8 and sox9) of 24 testis and 18 ovaries of captive and wild adult barramundi. Moreover, comparative expression profiles of the key dmrt1 and cyp19a1 genes were further investigated using RT-qPCR and Sanger sequencing approaches, whereas expression levels of remaining targeted genes were based on available literature for the species. Results showed that cyp19a1 and amh were more methylated in males, whereas dmrt1 and nr5a2 were more methylated in females (P < 0.001), with no gender differences found for foxl2, sox8 or sox9 genes (P > 0.05). Sex-biased promoter DNA methylation was inversely related to gene expression only for dmrt1 and nr5a2, and directly related to amh expression, whereas no differences in cyp19a1 expression were found between testes and ovaries. Notably, unique sex-specific alternative splicing of dmrt1 and cyp19a1 were discovered, whereby males lacked the full-length aromatase coding cyp19a1 mRNA due to partial or total exon splicing, and females lacked the dmrt1 exon containing the DM-domain sequence. This study advances the current knowledge aiming to elucidate the genetic mechanisms within male and female gonads of this large protandrous hermaphrodite by providing the first evidence of epigenetics and alternative splicing simultaneously affecting key genes (cyp19a1 and dmrt1) central to sex differentiation pathways.
... Other variations in nomenclature includes anama in Papua New Guinea, kakap in Indonesia, bulgan in Philippines, bhakti in India (Schipp et al., 2007). It is the most commonly eaten and popular fish therefore among the most commercially valuable. ...
... Barramundi is known to survive in water with a salinity over 50 ppt and at temperature 16°C to 35°C. Yet, juvenile barramundi tend to grow faster in lower salinities (Schipp et al., 2007). They are widely known for their good taste and firm texture including tender, mild tasting as well as boneless fillets (Schipp et al., 2007;Peet, 2006). ...
... Yet, juvenile barramundi tend to grow faster in lower salinities (Schipp et al., 2007). They are widely known for their good taste and firm texture including tender, mild tasting as well as boneless fillets (Schipp et al., 2007;Peet, 2006). Barramundi are suited to aquaculture as they are hardy, fast-growing, feed well on pelleted diets and universally regarded as a fine table fish (FIGIS, 2013;Peet, 2006). ...
In carnivorous fish farming industry, there are progressive increase demands for the finite resource of fish meal. A potential alternative to fish meal is to use legume meals which are free of enzyme inhibitors. In selected underutilised legumes the most effective processing method for eliminating trypsin (TIA), chymotrypsin (CIA) and alpha-amylase (AIA) inhibitors, without affecting the crude protein content, was investigated. These methods included soaking (S), wet heating (W), autoclaving (A) and dry freezing (D). No single method was effective at removing all the inhibitors. In all legumes tested, the combined processing methods which involved A were most effective in reducing CIA and AIA (p<0.05), but not TIA. However, in adzuki bean both TIA and CIA were reduced by the D+A combined method (p<0.05), whereas AIA of soybean and adzuki bean was decreased by combined methods of S+A (84.7 % and 99.3 % reduction respectively, p<0.05) or A+D (99.1 % and 72.6 % reduction respectively, p<0.05). All the processing methods retained 86.5 – 90.5 % of crude protein. Replacement of 10 % (w/w) of fish meal with D+A treated legume meal (either bambara groundnut or adzuki bean) for 28 days showed no significant difference in growth performance or inflammatory effects in Danio rerio or Lates calcarifer. Compared to Lates calcarifer given feed containing unprocessed adzuki bean meal, those on feed containing processed adzuki bean meal had increased hepatic gene expression of alanine aminotransferase (p<0.01), indicating an enhanced ability to utilise amino acids. The project identified specific food processing methods which are effective at removing enzyme inhibitors in legumes, thereby facilitating the application of legumes as aquafeed ingredients. Future studies are required to examine what inclusion level of treated legume meal can promote growth performance in specific commercial fish species.
... Fertilized eggs (~20,000) obtained from a commercial barramundi hatchery were placed in 600 l tanks (5 replicates). Fish were cultured following common hatchery practices in Australia (Schipp et al., 2007), whereby they were kept in seawater at 28-31°C and 12 h light and 12 h dark photoperiod. Fish were weaned at 18 days post-hatch (dph) and fed ad libitum with formulated pellets (Ridley Corporation, Australia). ...
Elucidating teleost sex differentiation is not only important for a broad understanding of vertebrate sexual development, but also to aid sex control in aquaculture. Barramundi, Lates calcarifer, is an important aquaculture species which exhibits protandry, whereby fish mature initially as male and subsequently sex change to the female gonadal state several years later. This late female sex change impedes efficient breeding programs, as males and females of the same generation cannot be mated. In order to further understand how sex development is controlled and possibly manipulated in barramundi, the timing and process of testicular differentiation from hatching through to spermatogenesis was morphologically described by histological analyses. Furthermore, expression of two key male genes, dmrt1 and cyp11b were also examined using RT-qPCR.
