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REPRODUCTION OF PENAEUS SPECIES IN CAPTIVITY
... Ablation leads to predictable peaks of maturation and spawning that facilitate the establishment of production schedules, in contrast to scattered spawns from unablated females (Primavera1985; Browdy 1992). Several studies have demonstrated the advantage of unilateral eyestalk ablation because of the increased production of a greater quantity of spawns and total nauplii per female (Primavera 1985;Browdy 1992;Bray and Lawrence 1992). Ablated females have a faster rematuration, which can increase the bioenergetic demands of the spawner (Browdy 1992) and thus have an effect on the quality or survival of the spawner. ...
... Ablated females have a faster rematuration, which can increase the bioenergetic demands of the spawner (Browdy 1992) and thus have an effect on the quality or survival of the spawner. Spawn quality and subsequent survival of the larvae have been reported to be negatively affected when these are obtained from ablated females (Emmerson 1980;Bray and Lawrence 1992;Redan and San-Feliu 1993;Yano~ 1993). These results are still controversial, and similar spawn quality from ablated and unablated broodstock has been reported (Browdy and Samocha 1985;Rothlisberg et al. 1991). ...
... Shrimp eyestalk ablation can affect the quality of the spawns produced at two points: immediately after ablation, females can produce abortive or low viability spawn; ablated females may produce spawns of decreasing quality over time or in successive spawns. Increased mortality immediately after the ablation procedure has been reported, which seems to depend on the molting stage of the shrimp, the procedure used for ablation, and the stress (i.e., handling, infection, hemolymph loss) that is involved during the ablation procedure (Primavera 1985;Bray and Lawrence 1992;Browdy 1992). Decreased spawn viability or abortive spawns that have been reported to occur immediately after ablation (Primavera 1985) are probably not a consequence of decreased hormone levels, but a result of the stress involved in the ablation procedure. ...
... Number of eggs per spawn and fertilization rate were not affected by multiple spawns in the present study. Egg diameter is easily measured and is one of the most reported quality criteria in studies of marine invertebrate reproductive biology (Bray and Lawrence, 1992;Clarke, 1993;Racotta et al., 2003). The prevailing view is that large eggs show greater viability than small eggs, probably because of higher yolk content in large eggs (Clarke, 1993). ...
... Stress tests are based on the principle that the physiological condition of the organism, determines its ability to survive to adverse environmental conditions, and several methods to estimate larval quality of penaeid shrimp have been proposed (for reviews see Racotta et al., 2003). These methods include exposure of the larvae to a short but extreme environmental stress, such as low salinity, low temperature, formalin, high ammonia concentrations, low dissolved oxygen, and others (Bray and Lawrence, 1992;Samocha, 1998;. The salinity stress test applied to postlarvae is by far the most commonly used test (Tackaert et al., 1989;AQUACOP, 1991;Dhert, et al., 1992;De la Cruz, 1992;Samocha, et al., 1998;. ...
... cit.) egg diameter was also measured digitally (image analysis). An explanation for the low observed genetic variance in egg diameter at spawning age could be associated with the artificial method used to induce spawning in penaeid shrimp by means of removing one eyestalk Bray and Lawrence 1992). This would result in a lack of correlation between egg size and number, another result of that study (Arcos et al., 2003b), and one that also contrasted with the results of a significant negative correlation between total number of oocytes and oocyte mean diameter in the present study, a correlation commonly seen in fish . ...
El factor más limitante del crecimiento de la camaronicultura es la
insuficiencia en cantidad y calidad de postlarvas, por lo cual las
investigaciones sobre la reproducción en cautiverio se ha enfocado hacia la
identificación/optimización de técnicas y factores (ambientales,
nutricionales bioquímicos-fisiológicos y endocrinos) que están
involucrados en el proceso de maduración apareamiento y desove, con el
fin de lograr un optimo desempeño de los reproductores con la obtención
de larvas de calidad. Con base en los resultados obtenidos en algunas
especies de peces como la trucha, recientemente se ha enfatizado que la
aplicación de programas de mejoramiento genético en camarón, basados
sobre conocimientos fisiológicos y genéticos de caracteres productivos y
reproductivos que contribuirán a incrementar la producción con la
obtención de larvas de calidad. Sin embargo actualmente los programas de
mejoramiento genético que existen están basados principalmente en
caracteres del crecimiento y no en caracteres reproductivos, esto se debe
principalmente a que la base genética y la existencia de variabilidad
genética para esos caracteres no ha sido evaluada en camarón, a pesar de
que la optimización de la reproducción es tan importante como el
crecimiento.
... Although several reviews on the maturation of penaeids have published over the past few years (Alfaro-Montoya et al., 2016;Arcos, Racotta, and Ibarra, 2004;Bray and Lawrence, 1992;Browdy, 1998;Diwan, Harke, and Panche, 2018), information available on the reproduction of closed thelycum shrimps are highly dispersed (Coman et al., 2013). There is a scarcity of data on reproductive performance of wild P. indicus broodstocks in a near commercial system following two decades of WSSV prevalence. ...
... During ecdysis, resorption of the ovary was also noticed which corroborate with earlier reports (Emmerson, 1980). It is widely documented that ovaries of many induced female populations either never mature or have prolonged latency period (Arcos, Racotta, and Ibarra, 2004;Bray, and Lawrence, 1992;Palacios, Ibarra, and Racotta, 2000) and eventually leads to deterioration of spawn quality (Emmerson, 1980;Harison, 1990;Palacios and Racotta, 2003). These type of inherent reproductive constraints such as poor mating is reported both in open and closed thelycum penaeid breeding population (Arcos, Racotta, and Ibarra, 2004). ...
... Reproductive performance of hatchery broodstock is also affected by photoperiod, water quality parameters such as temperature, salinity apart from broodstocks age (Browdy and Samocha, 1985;FAO, 2007;Harison, 1999). Though 100-400% water exchange is recommended in maturation tanks (Bray and Lawrence, 1992), flow through the model with 100% water exchange was followed in the present study as nitrogenous compounds are were below the critical level (Cavalli, Scardua, and Wasielesky, 1997). Compared to flow through the system, recirculatory maturation models have better water quality maintenance and retention of pheromones within the system, which in turn can enhance the broodstock performance (Otoshi et al., 2003). ...
... In crustaceans, the hepatopancreas is not only the main digestive gland, but also the main storage depot for energy reserves (Mikami and Greenwood 1994;Cheng et al. 1998). In the wild, nutrients are first used for metabolism and then for growth and reproduction (Bray and Lawrence 1992). Once the nutrient or energy requirement for metabolism and growth is met, surplus nutrients or energy are then stored in the hepatopancreas. ...
... The energy requirements for the growth and reproduction of crustaceans are considered to compete with each other (Charmantier et al. 1997). In general, nutrients must be available first for metabolism, then for growth, and third for reproduction in nature (Bray and Lawrence 1992;Yuan et al. 2016). In other words, once the nutrients or energy needed for metabolism and growth is met, the surplus nutrients or energy will be stored or used for reproduction. ...
The effects of intermittent starvation on the growth, precocity, digestive enzyme activity, feeding, and body chemical composition of the juvenile Chinese mitten crab Eriocheir sinensis were investigated in two independent experiments. Crabs were reared individually during Experiment I and cultured in aggregate during Experiment II. Five treatments were tested in both experiments. Crabs in the control group (Group C) were fed continuously and, in Groups S3, S6, S10, and S15, were starved and then re-fed for 3, 6, 10, and 15 days, respectively. The precocity rate of Group C was significantly higher than that of the other groups. In Experiment I, the final mean body weight and the mean specific growth rate in dry matter of Groups C and S3 were significantly higher than those of the other groups. In Experiment II, the mean specific growth rate in body weight in Group C was similar to that of Groups S3, S6, and S10 but significantly higher than that of Group S15. Crabs in Groups S3, S6, and S10 compensated for starvation-induced growth depression after being re-fed, and compensatory growth was achieved via both higher feeding rate and improved feed efficiency. There was no significant difference in trypsin and alkaline phosphatase activity, while steapsin and amylase activity were significantly affected by the starvation period. There was no significant difference in dry matter, ash, and protein content among Groups C, S3, S6, and S10 in Experiment I. The results demonstrated that proper intermittent starvation was sufficient for reducing the precocity rate of cultured juvenile E. sinensis, and it is recommended that juvenile crabs be subjected to intermittent fasting for 6 to 10 days to maintain precocity rates at acceptable levels without inhibiting growth and yield.
... The broodstock used were from a single batch of postlarvae that were initially reared in seven-ton tanks for three months until secondary sexual organs were identifiable, such as developed petasma for the males (Bray and Lawrence, 1992). Test animals were then grouped into communally reared (CR) and separately reared (SR) groups. ...
... High maturation rates were recorded for this study despite the small size of broodstock used. This result is likely because P. indicus at a size age of 10 g or less are considered reproductively active (Bray and Lawrence, 1992). Furthermore, an ablated female (6.9 g) paired with a 5.6 g male successfully produced 6.6 million eggs after two months (Primavera et al., 1979). ...
Monosex culture was proven to be an effective rearing method for grow-out, but in a closed-cycle hatchery, males and females are usually reared communally in tanks until maturation. This study determined the effect of communal rearing (CR) and separate rearing (SR) on male and female Penaeus indicus broodstock gonad maturation. This study also evaluated the influence of the rearing method on reproductive behavior and mating success. The results showed that CR female broodstock had higher maturation rates at 77.78 ± 5.31% (p = 0.061) and a shorter latency period at 6.71 ± 2.54% than SR females (p = 0.211), but the differences were not statistically significant. Similarly, maturation rates for both male groups were 40.62 ± 3.12% and were not significantly different (p = 1.00). The interspermatophore period (p = 0.044), spermatophore weight (p = 0.878), count (p = 0.780), viability (p = 0.257), and percent abnormality (p = 0.257) did not vary between males. In terms of the effect of rearing method on reproductive behavior, males from the SR group initiated more chase (p = 0.018) and fight with other males (p = 0.022) than CR males did, and the differences were significant. SR males also touched the discarded molt (p = 0.167) and advanced to the probe position (p = 0.525) more times than CR males, but the differences were not significant. The sum of all the reproductive behaviors was also significantly higher in the SR (54.00 ± 1.20) than in the CR (24.20 ± 0.86) groups (p = 0.017). Initial results showed that successful mating in the SR (80%) was higher than that recorded in the CR group (20%). These findings suggest that monosex rearing of male and female P. indicus will not negatively affect gonad maturation and will enable sex-specific nutritional manipulations, which can even possibly promote higher mating success.
... They also reduce tank fouling and the risk of disease introduction. And above all, they allow controlling diet composition and nutritional value (Bray & Lawrence, 1992;Calado, 2008;Harrison, 1990). Despite its numerous advantages, commercial diets are usually more expensive than fresh ones (Calado, 2008). ...
... The recommended protein content in food varies between 30% and 45% for this group, depending on the species(Alava & Lim, 1983; Córdova-Murueta & García-Carreño, 2002). Penaeid broodstock diets have even higher protein contents, in the range of 45%-60%(Bray & Lawrence, 1992). Another important factor in diet formulation is the source of proteins. ...
The red cherry shrimp Neocaridina davidi is a popular freshwater ornamental species traded worldwide for aquarium keeping. Its aquaculture generally relies on commercially available feeds. This study evaluated the effect of three commercial diets (A, B and C) on its female reproductive performance and offspring quality. Relative
realized fecundity and egg size did not differ among treatments. However, egg carotenoid content was 40% and 52% lower in eggs from brooders fed B and C, respectively, than in those from brooders fed A, which had the highest carotenoid content.
This suggests that dietary carotenoids directly affected egg carotenoid content. They
also appeared to influence embryo survival, as relative actual fecundity was 59% and
47% lower for B and C compared to A, although this difference was not statistically significant. Although juvenile I weight was similar for all diets, the amount of lipid
droplets in the perigastric organ region in juveniles I from brooders fed B, was about
20% lower than in the others. Offspring survival to the food restriction test was similar for all diets. However, the weight of 32-day-old juveniles was lower when brooders were fed C which had the lowest n-3 PUFAs content, but the highest content of
linoleic acid.
... The availability of an optimal diet is a crucial factor for the maturation and reproduction of shrimps. It has been reported that an unbalanced or incomplete diet causes poor reproductive performance or may even stop animals from reproduction [8] . Feed contributes 60-80% of the total operational cost in aquaculture system which is a major challenge for aquaculture industry. ...
... The availability of an optimal diet is a crucial factor for the maturation and reproduction of shrimps. It has been reported that an unbalanced or incomplete diet causes poor reproductive performance or may even stop animals from reproduction [8] . ...
The marine ornamental fish trade moves nearly 20-25 million live fish worldwide per year. Nearly 90% of these are wild caught from the pristine coral reef environments. The demand for fishes is on the rise and it has led to depletion of natural fish stocks around the globe. Clown fishes (Amphipirion sp.) are among the most popular marine ornamental fish, and reliance on the natural reefs has led to depletion of stocks. The efforts to reduce dependence of wild stocks as well as to ensure market sustainability spurred research into captive breeding and several researchers have successfully bred many species of clown fish. Breeding of clown fish is important to reduce the dependence on wild caught. Broodstock nutrition is one of the major hurdles faced by breeders, an improvement in broodstock nutrition improve the brood quality. Traditionally fresh natural diets are used for feed broodstock development. The fresh diets such as squid (38%), cuttlefish (50%), bivalve meat, krill (10%) and other small crustaceans, fish gonads, polychaetes, other worms are popular maturation diets. In this study conducted at Mandapam Centre for Sustainable Aquaculture (TNJFU). With several diets, a combination fresh fish with clam was observed to be the best for gonadal maturation of A. sebae.
... Spermatophores used for artificial insemination and sperm quality analysis are usually obtained from these animals. Extrusion is the technique employed to obtain the sperm mass from the terminal ampoules and may be successively applied to the males (Bray and Lawrence 1992;Peixoto et al. 2011). ...
... Penaeid broodstock is routinely maintained in captivity at a temperature range higher than in their natural environment as a strategy to accelerate gonad maturation and spawning after unilateral eyestalk ablation is carried out (Bray and Lawrence 1992). Although eyestalk ablation is not performed in males, they are also maintained at higher temperature levels and respond to it with constant spermatophore regenerations (Chamberlain et al. 1983). ...
Spermatophore successive manual extrusions are often employed in hatcheries, but it causes melanin deposition, decreasing sperm quality via cell degeneration. Melanization (brown or black spots) is an indicator of the moment to discard males. The evaluation of more efficient strategies is required to avoid it, increasing males’ lifespan. The effects of two temperatures (26 and 30 °C) on closed thelycum Farfantepenaeus paulensis spermatophore melanization and sperm quality after successive manual extrusions were evaluated. Wild-caught males were acclimated to laboratory conditions for 1 week and fed commercial broodstock feed and fresh-frozen food items ad libitum four times a day. Later, a 35-day trial was conducted with 24 males (26.05 ± 2.4 g) randomly distributed into eight 200-L tanks (4.3 shrimps m−2). Temperature was gradually increased from 23 to 26 °C or 30 °C. Only males showing a formed spermatophore and in the intermolt period were submitted to four consecutive manual extrusions every 11 days. Melanization was visually examined in extruded spermatophores, which were weighed. Spermatozoa were released in saline solution and observed in a hemacytometer under a light microscope. Morphological abnormalities (main body or spike malformations) were identified. Total and abnormal spermatozoa were counted in five fields of the hemacytometer to calculate sperm count and abnormal sperm rate. No significant differences were found on sperm quality among extrusions, but from the second extrusion onwards, an increase of melanization was evident. On the other hand, temperature did not affect the occurrence of spermatophore melanization related to successive extrusions.
... Several studies have demonstrated that spermatophore quality can be a powerful tool to evaluate the effectiveness of a diet on the reproductive male performance (Coman, Arnold, Callaghan, & Preston, 2007;Pérez-Rodríguez, Gómez-Gutiérrez, López Greco, & Cortés-Jacinto, 2019;Perez-Velazquez, Lawrence, Gatlin, González-Félix, & Bray, 2002). Shrimps fed unbalanced diets have deficient reproductive performance or may even stop the reproduction process (Bray & Lawrence, 1992;Wouters, Lavens, Nieto, & Sorgeloos, 2001). ...
... Yet, the exact composition and ingredients of commercial foods are not completely known. Nevertheless, they provide several advantages such as reducing disease transmission, decreasing tank fouling and having a controlled nutritional value and longer storage (Bray & Lawrence, 1992;Tziouveli, Hall, & Smith, 2011), and they can be very effective in terms of growth, survival and reproductive performance. Additionally, commercial diets can provide valuable information to establish an approximation to the nutritional requirements of a particular species. ...
In aquarium industry trade markets, Neocaridina davidi, the “red cherry” shrimp, is one of the most attractive ornamental shrimps due to the striking reddish coloration of females. Five commercial diets formulated for ornamental species were evaluated over a 90-day period in N. davidi males and females, based on survival, biochemical composition, body weight, carotenoid content and body coloration. Furthermore, histological and histochemical analyses of the male reproductive system were performed to evaluate the spermatophore quality. In all treatments, survival was >80%, and protein content was similar in both female and male shrimps. Lipid content was
higher in females and males fed on a diet having the highest lipid level. Carotenoid content was higher and body coloration was brighter in females and males fed on a diet containing the highest carotenoid level. Histological and histochemical analyses of the spermatophore structure and composition showed no differences among diets, suggesting that the five commercial diets are adequate for satisfactory growth and spermatophore quality of N. davidi. The diverse sources and quantities of carotenoids in the highest carotenoid level diet render it more suitable for colour enhancement of this species.
... Cultivation of native species has been developed for the oriental river prawn Macrobrachium nipponense (De Haan, 1849) Therefore, any attempt at cultivation would depend on the collection of wild specimens and the success of reproduction in aquaculture is closely related to the nutritional status of broodstock as an initial condition for reproduction (Bray & Lawrence, 1992;Racotta, Palacios, & Ibarra, 2003). ...
... Nutrition is one of the main factors that influences the status of crustacean sexual output, because it promotes gonad development and influences the morphological and physiological state of the gametes (Bray & Lawrence, 1992;Harlioğlu et al., 2013;Harrison, 1990;Wouters, Lavens, Nieto, & Sorgeloos, 2001;Yamasaki-Granados et al., 2013). The study of the effect of the reproductive condition of both parents on egg production and early survival of larvae is one of the most influential aspects for achieving commercial profits from river prawn aquaculture. ...
The effects of different diets on spermatophore production and sperm quality were investigated in the river prawn Macrobrachium americanum. River prawns were cultured and fed with three diets for 244 days: fresh food (50% squid meat, Dosidicus gigas and 50% sardine muscle, Sardinops sagax); commercial pellets (35 Purina®); and a 50:50 mixture of both diets. Spermatophore production was recorded every 24 days on average as the percentage of spermatophores produced per extraction per diet, weight and biochemical composition. Sperm quality was measured as the total number of sperm, the proportion of live/dead sperm and normal/abnormal sperm morphology. There were no significant differences in the mean biochemical composition of M. americanum spermatophores for any of the diets. Biochemical composition was 36.3% protein, 25.8% carbohydrate and 4.6% lipids for all data pooled. The weight of spermatophores and sperm counts was not significantly different among diets, nor were there any differences as a function of the male initial total length (p > .05). Male river prawn reproductive exhaustion was observed as a decline in spermatophore production, weight of the spermatophores and the number of sperm cells per spermatophore, with an increasing proportion of dead and abnormal sperm seen throughout the experiment. The recommended period of maintenance in captivity for male broodstock is less than 115 days. It is recommended to feed broodstock males of M. americanum with commercial pellets because no significant differences were detected with the diets tested; pellets are easier to use, ensuring the same spermatophore production and sperm quality that was obtained with fresh food.
... Various researchers conducted successful researches on the maturation of penaeid shrimp in captivity through unilateral eyestalk ablation (Santiago, 1977;Aquacop, 1979;Beard and Wickins, 1980;Emmerson, 1983). Noble literature reviews of maturation and reproduction in penaeid shrimp was done by Primavera (1984), Harrison (1990), Bray and Lawrence (1992). Emmerson (1980) and Primavera et al., (1980) successfully achieved the reproduction of penaeid shrimps without ablation, through the control of nutrition, temperature, salinity, pH, light and density. ...
... Eyestalk ablation leads to expectable maturation and spawning in penaeids. However, it is generally accepted that over-stimulation of reproduction in the broodstock ablated in captivity reduces the reproductive performance (low fecundity, low fertility and hatching rate) of the females of various penaeid species (Lumare, 1979;Bray and Lawrence, 1992). The present results show a decline in the reproductive performance in the broodstock of ablated P. monodon, confirming the results of Browdy and Samocha (1985) for the same species. ...
p>In this study, the effects of eyestalk ablation on maturation, moulting, spawning and hatching rate of wild caught Penaeus monodon were investigated. Twenty males (M) and 30 eyestalk–ablated and 30 non–ablated females (F), all individually marked (M: F=1:3) were stocked into two 15–ton capacity (each) maturation tank. All the ablated females moulted in 7.92±0.24 (mean±standard error) days, and first spawning occurred 3.2±0.20 days following eyestalk ablation. While twenty-five ablated females spawned, producing an average of 296,160±26,589 eggs, only eight non–ablated females spawned, producing an average of 195,462±20,565 eggs during the investigation period of 120 days. A significant positive correlation between fecundity and female body weight (P<0.05; P<0.001) was observed. Throughout the experiment, the average number of spawning per female was 1.8±0.14 for ablated and one for non–ablated females. Multiple spawning (up to three times) occurred within the same moulting cycle in ablated females. Among the ablated P. monodon females, 36% spawn once, 48% second time, and 16% third time. The average fertility rate of the eggs was high, ranging between 80 and 90% in non-ablated females, while in ablated females; the range was between 72 and 88% and differ significantly (p<0.05) ablated and non ablated females. Average hatching rate ranges between 70 and 80% for ablated and 75 and 82% for non-ablated females (p<0.05). From eggs to nauplii production per female was 167,838 for ablated and 127,500for non–ablated females. This study indicates that eyestalk ablation and environmental condition were important inducing tools for re-maturation of spent P. monodon that continued supply of seed stock for effective commercial shrimp farming.
J. Bangladesh Agril. Univ. 13(2): 315-322, December 2015</p
... Eye stalk ablation is still the most effective and common method used for the induction of ovarian maturation in penaeid shrimps. As with other species [3,[20][21][22] the eyestalk ablation was found to be the best technique in the maturation and spawning of the pacific white shrimp L. vannamei. In agreement with [21,22] the eyestalk ablation generated more spawning and egg-production, but higher fertilization or hatching rates were increase in our present study (Table 1 and Figure 4). ...
... As with other species [3,[20][21][22] the eyestalk ablation was found to be the best technique in the maturation and spawning of the pacific white shrimp L. vannamei. In agreement with [21,22] the eyestalk ablation generated more spawning and egg-production, but higher fertilization or hatching rates were increase in our present study (Table 1 and Figure 4). ...
The reproductive performance of the broodstock was assessed at each stage of the maturation and spawning process. Measures of maturation rate, spawning rate, fecundity, hatch rate and nauplii production rate were obtained. The reproductive performance was found for the imported Specific Pathogen Free (SPF) broodstock from Shrimp Improvement system (SIS), Florida, USA. The no.of spawning, eggs quantity, fertility, hatching rate and nauplii production were lowest in 1st to 3rd spawning when females were 7 months old and increased from 4th spawning rate onwards. As the size of females increased from 30 g to 52 g the mean number of eggs per spawning increased from 150,000 to 442,000. Although female body weight was increasingly larger through the study period and the larger females would be expected to produce more eggs per spawning and hatching. The hatching rate was increased from 3rd spawning onwards. The nauplii production rate (NPR), which is a function of egg production and hatching rate, showed a significant increasing from 48% to 96%. In 10th spawning all the activities were increased. This information can be used to select broodstock for hatchery production.
... This shows that the protein consumed is not necessarily used for growth. In general, nutrition must be available first for metabolism, and second for growth and third for reproduction biology (Bray & Lawrence 1992). This means that, once the nutrients or energy needed for metabolism and growth are met, excess nutrients or energy will be stored or used for reproduction. ...
This study was conducted to evaluate the effect of feeding with different protein levels on growth performance and body composition of kelabau fish (Osteochilus melanopleurus). Four experimental feeds with different protein levels but same fat content were formulated. The experimental variants were A, B, C and D containing protein levels of 25.14, 28.26, 31.88 and 34.73% respectively. O. melanopleurus was obtained from breeding unit of the Freshwater Aquaculture Center (BBAT) Mandiangin within an average weight of 2.09±0.16 g with a density of 20 fish maintained in plastic box sized 54.3 x 38 x 31.5 cm and filled with 40 L of water. O. melanopleurus were given experimental feed 2 times a day at satiation for 60 days. O. melanopleurus feed C (31% protein) showed higher growth rate, relative growth rate, total feed consumed, feed utilization efficiency were higher compared to other treatments (P<0.05). The highest mean growth rate was in the C feed treatment (31%) with an average of 4.14±0.54%, while the lowest relative growth in the feed treatment A (25%) with an average of 2.92±0.54%. Protein efficiency ratio (PER) of fish group which consumed feed formulation C = 1.50±0.06%, feed A = 1.45±0.13%, feed B = 1.40±0.04% and significantly different from fish group fish that consumed feed D = 1.16±0.07%.
... CHO), non-protein feed energy sources are better processed and more efficient in growth, compared treatments C (34.82% CHO) and A (30.50% CHO). Bray & Lawrence (1992), states that the availability of energy mainly from carbohydrates as an energy source other than lipids and proteins is mainly used for metabolism, both for growth and subsequently for reproduction in nature. Therefore, if the energy needed for metabolism and growth is sufficient, the exceeding nutrients or energy will be stored or used for reproduction. ...
This study was conducted to evaluate the effect of feeding with different carbohydrate (CHO) content on growth performance and body composition in kelabau (Osteochilus melanopleurus). Treatments consisted in 3 experimental iso-nitrogenous and iso-lipid diets, at different CHO levels: 30.50% (A), 32.76% (B), and 34.83% (C). Treatments were applied to O. melanopleurus culture specimens, with an average weight of 3.18±0.26 g and a stocking density of 20 individuals, maintained in plastic tubs measuring 54.3 x 38 x 31.5 cm and filled with 40 L of water. O. melanopleurus was fed 2 times a day at satiation basis, for 60 days. The result showed that fish fed with diet B (32.76%) had higher growth performance and feed utilization compared to the other groups (A and C) (P<0.05). The increase in carbohydrate administration in O. melanopleurus from 30.50% to 34.82% CHO does not affect the liver and muscle glycogen levels, but does affect the lipid liver content.
... Poor sperm count was previously reported in L. vannamei (Perez-Velasquez et al. 2003) and Farfantepenaeus paulensis (Braga et al. 2013), which were both fed with fresh diet similar to what was provided in the control group. Previous studies suggested fresh maturation diets should be fortified with vitamins and minerals to increase sperm count (Bray and Lawrence 1992). In this regard, the provision of vitamins and minerals in the BD and all formulated dietary treatments gave better sperm counts than the group fed with a fresh diet alone. ...
... On the other hand, somatic growth and reproduction have been known to be antagonistic (Charmantier et al. 1997). It is commonly accepted that nutrients must be available rst for metabolism, and then for growth, and third for reproduction in nature (Bray and Lawrence 1992). In other words, once the nutrient or energy needed for metabolism and growth was met, the surplus nutrient or energy will be stored or used for reproduction. ...
The effects of intermittent starvation on the growth, precocity, digestive enzyme activity, feeding and body chemical composition of juvenile Chinese mitten crab Eriocheir sinensis were investigated in two independent experiments. Crabs were reared individually during Experiment I and cultured in aggregate during Experiment Ⅱ. Five treatments were involved in both experiments: crabs in the control group (Group C) were fed continuously; crabs in Group S3, S6, S10 and S15 were starved for 3, 6, 10 and 15 days and then re-fed for 3, 6, 10 and 15 days, respectively. Procedures were then repeated. The precocity rate of Group C was significantly higher than that of the other groups. In Experiment I, the final mean body weight and the mean specific growth rate in dry matter (SGRdm) of groups C and S3 was significantly higher than that of the other groups. In Experiment Ⅱ, the mean specific growth rate in body weight (SGRw) in Group C was similar to that of groups S3, S6 and S10, but significantly higher than S15. Crabs in groups S3, S6 and S10 compensated for starving-induced growth depression after being re-fed, and compensatory growth was realized by both higher feeding rate and improved feed efficiency. There was no significant difference in trypsin and alkaline phosphatase activity among treatment groups and the control. However, steapsin and amylase activity were significantly affected by starvation period. There was no significant difference in dry matter, ash and protein content among groups C, S3, S6 and S10 in Experiment I. Collectively, results demonstrated that proper intermittent starvation was sufficient for reducing the precocity rate of cultured juvenile E. sinensis , and we recommend subjecting juvenile crabs to intermittent fasting for 6 to 10 days to maintain precocity rates at acceptable levels without inhibiting growth and yield.
... While Artemia and Tubifex have been proved to be the best diets for the early stages of numerous teleosts ( Jayalekshmi et al., 2017), use of these live feeds in catfish hatcheries is not economically feasible. In addition to high cost, the nutritional values of live feeds can also vary depending on the season of collection, environment, and life stages (Bray and Lawrence, 1992). Thus the main objective of our study was to develop a cost-effective artificial diet using locally available ingredients that is comparable to live feed. ...
Abstract | Substitute of live feed in mass production of fish larvae has recently drawn a great attention due to
inadequate supply and inconsistent price. The present study evaluated the effects of early introduction of formulated
feed as a substitute for live feed on growth performances of Asian stinging catfish, Heteropneustes fossilis larvae reared in
laboratory conditions. Three-day-old larvae hatched through induced breeding (2.0±0.00016 mg; 0.57±0.09cm) were
subjected to four feeding treatments in triplicates (100 larvae/aquarium). The catfish larvae were fed with live Tubifex
(LT), dry Tubifex (DT), formulated feed (FF), and commercial feed (CF) two times a day for 60 days. Results showed
that larvae fed with formulated feed (FF) grew significantly faster than the other treatments (p<0.05). The weight
gains were observed as 2.6 g in FF; 2.0 g in CF and 1.9g in LT and 1.54g in DT, respectively. Similarly, FF showed the
highest specific growth rate (SGR) of 11.85±0.71%, but significantly differed only from that of DT (SGR=11.1; P<
0.5). Length-weight analysis revealed that the growth of larvae in all treatments showed negative allometric growth
(regression slope b ˂3). The highest b value (2.64) was observed in larvae fed with FF. Proximate analysis showed
that larvae fed with FF had significantly higher protein content than the other treatments (p<0.05). Water quality
parameters remained optimum throughout the experimental period. The feeds used in treatments did not show any
deleterious effect on survival. Physiologically, FF led to significantly higher amylase activity in comparison to other
feeds, while protease activity was comparable among the feeds except for DT. The results suggest that formulated feed
can be used as a potential substitute for live Tubifex for the early stage of larvae of stinging catfish.
Keywords | Enzyme activity, Formulated feed, Growth performance, Stinging catfish, Tubifex
... This shows that the protein consumed is not necessarily used for growth. In general, nutrition must be available first for metabolism, and second for growth and third for reproduction biology (Bray & Lawrence 1992). This means that, once the nutrients or energy needed for metabolism and growth are met, excess nutrients or energy will be stored or used for reproduction. ...
This study was conducted to evaluate the effect of feeding with different protein levels on growth performance and body composition of kelabau fish (Osteochilus melanopleurus). Four experimental feeds with different protein levels but same fat content were formulated. The experimental variants were A, B, C and D containing protein levels of 25.14, 28.26, 31.88 and 34.73% respectively. O. melanopleurus was obtained from breeding unit of the Freshwater Aquaculture Center (BBAT) Mandiangin within an average weight of 2.09±0.16 g with a density of 20 fish maintained in plastic box sized 54.3 x 38 x 31.5 cm and filled with 40 L of water. O. melanopleurus were given experimental feed 2 times a day at satiation for 60 days. O. melanopleurus feed C (31% protein) showed higher growth rate, relative growth rate, total feed consumed, feed utilization efficiency were higher compared to other treatments (P<0.05). The highest mean growth rate was in the C feed treatment (31%) with an average of 4.14±0.54%, while the lowest relative growth in the feed treatment A (25%) with an average of 2.92±0.54%. Protein efficiency ratio (PER) of fish group which consumed feed formulation C = 1.50±0.06%, feed A = 1.45±0.13%, feed B = 1.40±0.04% and significantly different from fish group fish that consumed feed D = 1.16±0.07%.
... CHO), non-protein feed energy sources are better processed and more efficient in growth, compared treatments C (34.82% CHO) and A (30.50% CHO). Bray & Lawrence (1992), states that the availability of energy mainly from carbohydrates as an energy source other than lipids and proteins is mainly used for metabolism, both for growth and subsequently for reproduction in nature. Therefore, if the energy needed for metabolism and growth is sufficient, the exceeding nutrients or energy will be stored or used for reproduction. ...
This study was conducted to evaluate the effect of feeding with different carbohydrate (CHO) content on growth performance and body composition in kelabau (Osteochilus melanopleurus). Treatments consisted in 3 experimental iso-nitrogenous and iso-lipid diets, at different CHO levels: 30.50% (A), 32.76% (B), and 34.83% (C). Treatments were applied to O. melanopleurus culture specimens, with an average weight of 3.18±0.26 g and a stocking density of 20 individuals, maintained in plastic tubs measuring 54.3 x 38 x 31.5 cm and filled with 40 L of water. O. melanopleurus was fed 2 times a day at satiation basis, for 60 days. The result showed that fish fed with diet B (32.76%) had higher growth performance and feed utilization compared to the other groups (A and C) (P<0.05). The increase in carbohydrate administration in O. melanopleurus from 30.50% to 34.82% CHO does not affect the liver and muscle glycogen levels, but does affect the lipid liver content.
... Nevertheless, there is ample scientific evidence of the potential of marine worms as feed for aquatic animals. Bray & Lawrence (1992), and Oddsen (2014) found that the use of marine worms (Nereis virens) in the feeding of whiteleg shrimp broodstock resulted in higher nauplii production per female and that the larval growth and survival obtained from these females increased due to LC-PUFA, prostaglandins and bromophenols present in the contents of marine worms (Lytle et al., 1990). Wouters et al. (1999) recommended an n-3 / n-6 PUFA ratio of 2-3, while Palacios et al. (1999) showed that triacylglycerols meet the basic energy needs of shrimp embryos and nauplii and are effective on reproduction, egg and postlarval quality. ...
This study assessed the potential of omega-3 long chain polyunsaturated fatty acids (n-3 LC-PUFA) enrichment in red earthworm (Eisenia fetida, REW), via the addition of fish oil (FO, anchovy oil) to the culture-compost. FO addition to compost was tested at graded inclusion doses (0, 2.5, 5 and 10 g/100 g compost) and for different timeperiods, up to 96 h. Dose, time, as well as dose and time interactions of FO compost enrichment had significant effects on all fatty acids of earthworm bodies. The enrichment with 10 g FO/100 g compost sharply increased DHA levels of the worms (14.01 mol%) within just 24 h, compared to the control group (0.92 mol%). Similar increases (ranging between 10.99 and 15.55 mol%) occurred only after 48 and 96 h in lower FO enrichment levels (2.5 and 5.0 g/100 g compost, respectively). Therefore, it was concluded that, to obtain maximum n-3 LC-PUFA enrichment efficiency in REW, an enrichment period of 24 h is ideal and recommended for the 10 g FO/ 100 g compost, whereas longer enrichment periods (48-96 h) are more suitable for lower levels of FO inclusions (2.5 or 5 g/100 g compost).
... Among these neuropeptides, GIH is considered to play a key role in regulating female crustacean reproduction by repressing ovarian maturation and spawning (3). In decapod aquaculture practice, removal of GIH by eyestalk ablation (ESA) has been the most common method to induce ovarian maturation (4). However, in addition to GIH, secretion of other neuropeptides from the eyestalk is also impaired by this method, which results in significant hormonal imbalance and undesired impacts on not only the survival of broodstock, but also the quantity and quality of larvae produced (5). ...
Eyestalk ablation is the most common method to induce ovarian maturation in decapod crustacean aquaculture, but it jeopardizes broodstock survival and larvae production. It is important to understand the molecular basis underlying the maturation triggered by ablation and thereby develop an alternative measure for maturation manipulation. In this study, we investigate alterations of ovarian proteome and miRNA profile after ablation in a commercially important marine crab Portunus trituberculatus. Quantitative proteomic analysis using iTRAQ reveals that 163 proteins are differentially expressed following ablation, and modulation of methyl farnesoate metabolism and activation of calcium signaling may play important roles in the ovarian maturation induced by ablation. miRNA expression profiling identifies 31 miRNAs that show statistically significant changes. Integration of miRNA and proteome expression data with miRNA target prediction algorithms generates a potential regulatory network consisting of 26 miRNAs and 30 proteins linked by 71 possible functional associations. The miRNA-protein network analysis suggests that miRNAs are involved in promoting ovarian maturation by controlling expression of proteins related to methyl farnesoate synthesis, calcium signals, and energy metabolism. Experimental validation and temporal expression analysis indicate multiple miRNAs can act synergistically to regulate expression of Farnesoic acid O-methyltransferase and Calmodulin. Our findings provide new insights for elucidating the mechanisms underlying eyestalk ablation-induced ovarian maturation and could be useful for devising an alternative technique for manipulating reproduction in P. trituberculatus and other decapods.
... Hence, the passage of the viral pathogen to shrimp brood-stock in the hatchery through feeding of infected prey items is a realistic possibility. Polychaetes form an indispensable component of the maturation diet of penaeid shrimp brood stock in hatcheries all over the world due to their high nutritive value [26]. In India, almost all penaeid hatcheries use polychaete worms to promote maturation and spawning of wild caught brood-stock/ spawners of Fenneropenaeus indicus. ...
The present study was White spot syndrome virus (WSSV) collected from Polychaete-Perinereis cultrifera which was orally transmitted with white spot syndrome virus (WSSV) and conformed with PCR identification is transferred to Fenneropenaeus indicus by intramuscularly injection and through oral rout.100% mortality of Fenneropenaeus indicus was resulted on 13 th day in oral rooted and on 15 th day for intramuscularly injected shrimp. Mortality rate of 90.0 and 93.30 % were observed during 12 and 14 days of post infection of WSSV in Fenneropenaeus indicus treated by oral route and intramuscularly. Whilst the appearance of a prominent band of PCR amplified product of WSSV-DNA at 650 bp and 296 bp continued from day 3 to 9. On days 8, 9, 10 and 14 the product band observed as 650 bp. The product band of 296 bp, 650 bp and 910 bp were noticed during 11, 12, 13 and 15 days of post-inoculum respectively. No evidence of DNA band observed in the control group. Hence it is conclude that the immunity of F.indicus is more against pathogens while comparing with other Phenaied shrimps. This result that F.indicus can survive more days than other shrimps. The histopathological analysis in hematopoietic tissue on the fifth day of post inoculated shrimp shows ranges on low level infection. The results from the study strongly suggest developing specific pathogen resistant brooders would immensely useful in rearing of shrimp for commercial purposes. Even though, shrimp hatcheries in India and other Asian countries depend almost entirely all natural polychaete stocks, continuation of while polychaete population with lethal pathogen such as WSSV demonstrate the need to produces pathogen free polychaete worm especially P.cultrifera through aquaculture. However, by implementing quarantine prior bring P.cultrifera commercial shrimp breeding purposes will immensely boot the industry.
... Since the sinus glands are the sites that release gonad inhibiting hormone (GIH), and moult inhibiting hormone (MIH), the removal of eyestalks leads to an increased rate of gonadal development (Laufer et al., 1993). The increased use of eyestalk ablation technique in the captive breeding of crabs has brought forth both positive and negative effects on the quality of spawning and seed production (Bray and Lawrence, 1992). ...
The suitability of bilateral eye stalk ablation as a means of induced breeding technique in S. hydrodroma was tested under laboratory conditions by considering growth and survival indices, reproductive indices, biochemical and histological indices. The daily growth rate (g) was higher for ablated males(0.3±0.2) against 0.16±0.09 in control males. A positive correlation with feed intake of 0.71±0.04 (g) in ablated males against 0.62±0.84 in control males and a negative correlation with Hepatosomatic Index (%) of 7.02±2.4 against 13.77±3.2 are recorded. Female crabs shows less survival rate (%)compared to males (64±12.7/88±10.33). Ovarian and testicular index in comparison to control were found to be higher (0.2±0.08/0.15±0.02 and 2.6±0.33/1.08±0.06 respectively). Nutrient mobilization was evident from decreased muscular protein and carbohydrates as of hepatopancreatic lipid after extirpation and increased gonadal proteins, carbohydrates and lipids. The double extirpation procedure increased the number of oocytes, follicle diameter and number in females and an increase spermatozoa and spermatocytes in males as reveled by histological indices
... However, it is not clear if these variations result from differences in osmoregulatory mechanisms or to other interactive traits associated with the physiological condition of PL. The focus of the present review is to update studies that use the SST as a PL quality criterion (Bray and Lawrence, 1992;Racotta et al., 2003), while attempting to critically analyze its validity as a predictive criterion and its physiological bases, which implies a discussion on osmoregulation mechanisms in crustaceans. ...
A high survival rate to a salinity stress test applied to 15-day-old shrimp postlarva (P15) is supposed to be associated with improved performance during growout, or at least during pond stocking. However, there is no direct evidence (e.g. correlation) for this association. The present study analyzed survival to a salinity stress for correlation to subsequent performance in 40 larval batches (individual spawns) that were cultured simultaneously under the same conditions, as a predictive criterion of survival during stocking and growout to juvenile stages. We also determined some osmoregulatory capacities (gill area, Na+/K+-ATPase) associated with survival to the salinity stress test. The activity of Na+/K+-ATPase was higher in P15 subjected to lower salinities, but it did not reach significance in batches with higher survival to the salinity stress test. Survival to a stress test was positively correlated to P15 length (r=0.62; P0.05), and thus it was not reliable as predictive indicator of performance (survival and growth) during growout under our experimental conditions. To our knowledge, these are the first published results of a relationship between survival to a salinity stress test applied to P15, and subsequent survival during stocking and growout assessed in controlled experiments.
... Food is an important factor for sexual maturation (Browday, 1992) and male reproductive performance (Meunpol et al., 2005) Many advances were made in the development of technology for maturation and reproduction of penaeid shrimp Lawrence, 1992 andBrowday, 1992). The present study was undertaken to demonstrate the larval survival of ablated pond -reared P. monodon by using five different practical diets. ...
The impact of various combinations of live feeds and frozen feeds such as polychaete, squid meat, crab meat and beef liver was tested on the maturity and spawning of the shrimp Penaeus monodon. Females with weight ranges 86g to 96g were selected for the present experimentation. The shrimps were fed with five different combinations at the rate of 15% of their body weight. Feed combinations selected for current study was crab and polychaete, oyster and polychaete, squid and clam, beef liver and squid, and oyster and beef liver. We applied different ablated methods to evaluate the reproductive ability of wild and pond reared Penaeus monodon The great reproductive performance was achieved when shrimps fed with Feed-I, the reproductive performance based on fecundity was identified by the number of eggs in gravid females. Future research efforts focused on the artificial diets which contain both live and frozen feed combinations will be essential for the improved egg quality in tank-reared Penaeus monodon. Thereby increasing the consistency and reliability of maturation diets for better quality nauplii production.
... Since 1970, eyestalk ablation (EA) has been used to improve the production of Penaeus spp. larvae in aquaculture [1,2]. In the white shrimp Litopenaeus vannamei, Macrobrachiumrosenbergii, Farfantepenaeus aztecus [3] and Farfantepenaeus duorarum [4], eyestalk ablation promotes several metabolic changes that improve reproductive performance. ...
Volume 3 • Issue 8 • 1000156 J Aquacult Res Dev ISSN: 2155-9546 JARD, an open access journal Research Article Open Access Asusena et al., J Aquacult Res Dev 2012, 3:8 http://dx.http://dx.doi.org/10.4172/2155-9546.1000156
... These modifications have been reported only after the storage of the spermatophore within (closed thelycum) or while adhered to (open thelycum) the female thelycum (Alfaro et al., 2003;Braga et al., 2014). The disability of spermatozoa directly extruded from the terminal ampoule to fertilize the egg has been demonstrated by lower fertilization rates compared to those obtained when spermatozoa are previously stored in the thelycum (Bray and Lawrence, 1992;Alfaro et al., 1993). Also, low or zero rates of in vitro induction of the acrosomal reaction by egg water are obtained when spermatozoa collected from the terminal ampoule are used (Alfaro et al., 2003Wikramanayake et al., 1992). ...
Shrimp farming worldwide is based on a similar technological package, characterized by three phases: Controlled Reproduction, Larvae Culture, and Grow-out Culture. This basic aquaculture package uses broodstock animals, with different levels of fundamental genetic selection, induced to mature and reproduce based on unilateral eyestalk ablation. This review identified ten reproduction-related research subjects that can improve the shrimp industry based on basic scientific knowledge and four levels of application: eyestalk ablation alternatives, larvae production, product protection, and grow-out yield improvement. Species-specificity must be considered in developing biotechnology solutions. Alternatives to eyestalk ablation for controlling ovarian maturation are based on neurotransmitter regulation in Litopenaeus; however, the environmental impact of this
approach has to be evaluated. Maturation by RNAi requires further evaluation, and maturation pheromones have not been explored. Sex reversal, hybridization, in vitro fertilization, and seedstock cryopreservation of penaeids require fundamental research. Triploid culture and genetic selection can be applied to some species for product protection; however, for L. vannamei, triploidization is not practical yet.
... In the wild, adult shrimp eat a wide variety of microinvertebrates (gastropods, bivalves, crustaceans, and polychaetes) and plant material (Rothlisberg 1998). Moreover, shrimp maturation and reproduction are greatly affected by the environmental factors (Bray and Lawrence 1992;Ogle 1992). Therefore, we also suggest that other factors may negatively affect the ornamental shrimp reproduction in captivity, such as the social structure in which these shrimp live in the wild population; and stress conditions in which breeding shrimp are kept in culture. ...
Reproductive output parameters (fecundity and egg volume) of Lysmata vittata were examined in a population in northeastern Brazil. Effect of maturation diets on the reproductive output of these shrimp under laboratory conditions was evaluated. Reproductive output was estimated for 25 shrimp collected in the wild. Another 45 pairs of shrimp were used for diet experiments, 15 pairs per treatment (T1: industrialized food, T2: fresh food, T3: mixed diets). For wild population, mean fecundity and egg volume were differed between developmental stages of the eggs. Fecundity was significantly lower in the specimens subjected to T1 diet (267 ± 141 eggs) compared with shrimp from the wild population (393 ± 183 eggs). Egg volume was significantly lower in shrimp subjected to three diets tested compared with those from wild population. Egg loss during embryonic development in L. vittata may be caused by several factors (e.g. aborted development and maternal cannibalism). Fresh food proved to be important for improving reproductive output in L. vittata reared in culture. We emphasize the significance of improving nutritional value and palatability of diets to improve cultivation efficiency. Lysmata vittata can be used as a model organism for future studies aiming to improve the cultivation techniques for shrimp of the genus.
Abbreviations PSH: protandric simultaneous hermaphroditism; ARS: artificial refuge structures; CL: carapace length; EV: egg volume; L: largest diameter of the egg; S: smallest diameter of the egg; T1: industrialized pellets; T2: fresh ingredients; T3: mixed diets; ANCOVA: analysis of covariancr; SD: standard deviation.
... Hence, the quality parameters of water need to be checked regularly during shrimp rearing. The physico-chemical quality parameters of the water in the present experimental tanks are shown in table 1. Temperature is a very important environmental factor, which strongly influences the growth of shrimps (Bray and Lawrence, 1992). Temperature ranging from 24 to 32 o C is optimum for penaeid larval culture. ...
The present study evaluated the effect of stocking density on growth and survival of post larvae (PL) of Fenneropenaeus merguiensis (de Man, 1888), commonly known as banana shrimp. PL was stocked at four different densities i.e., 10, 20, 30 and 40/m2(T10, T20, T30 and T40, respectively) and reared for a period of 60 days. Water quality and growth performance parameters of different treatments were compared during the experiment. A significant (p<0.05) decrease in dissolved oxygen (DO) concentration relative with the higher stocking density was observed. Though some parameters showed significant (p<0.05) difference among the treatments, the water quality remained within safe level, throughout the experiment. Increase in stocking density led to significant reduction (p<0.05) in BWG and SGR of PL. The highest value of FCR was in T40 and lowest in T10. Stocking density also showed an inverse relationship with survival percentage of shrimp. Results of the present study revealed that high stocking density (≥30/m
2) can seriously impair the growth of F. merguiensis PL.
... Of the spawns obtained at 21°C, the majority were produced in 0L:24D conditions. This concurs with earlier findings where decapod crustaceans such as mud crabs, crayfish, spiny lobster and shrimp, in captivity tended to spawn primarily during dark periods (Andrews, 1906;Bray & Lawrence, 1992;Dall, Hill, Rothlisberg & Sharples, 1990;Nakamura, 2000;Zeng, 2007). ...
Like all poikilotherms, the growth and reproduction of blue crab, Callinectes sapidus depends on temperature and season. Warmer water temperatures in the Chesapeake Bay allow for ovarian development and spawning, while colder water temperatures slow their metabolism and reproduction. The current study aimed to identify optimal environmental conditions for inducing reproduction in animals held in long-term captivity for year round production in aquaculture through environmental manipulations. Temperature and photoperiod were the main environmental factors tested for 25 weeks: 11°C and 21°C, with the following photoperiods: 0L:24D, 8L:16D, 16L:8D and 24L:0D. At 21°C, the females increased spawning frequency, which was arrested at 11°C. Shorter light exposure at 21°C increased spawning frequency, while constant light inhibited and did not produce spawning. Constant dark (0L:24D) at 21°C produced the most (86%) spawns, but yielded poor larval quality. At 21°C with all photoperiod conditions except constant light, the first spawning took 94.8 ± 32.4 days to occur (n = 17). With females producing multiple spawns, the intervals between the first and second spawns and the second and third spawns were 37.7 ± 8.7 days (n = 6) and 31.0 ± 7.1 days (n = 2) respectively. Analysis of our data using response surface methodology (RSM) predicts the following conditions: at 15–19°C and 0–10 hr darkness for maximal survival and at 19–22°C and 0–8 hr darkness for spawning. The number of larvae produced was positively correlated with size (weight) of the female C. sapidus, suggesting the importance of female size in reproduction.
... It is generally accepted by hatchery managers and researchers that captive broodstock should be of an appropriate age and size for successful maturation (Browdy, 1998). Nevertheless, it is difficult to separate whether reproductive performance is age-or size-dependent as shrimps of similar size may not be of the same age and vice versa (Bray and Lawrence, 1992). Although it has been generally accepted that larger, presumably older, penaeid females present a superior spawning performance, the influence of age has been poorly explored (Minagawa et al., 2000). ...
Aquaculture is considered the main source for the supply of seafood in Egypt in the last 10 years due to overexploitation of fisheries. For aquaculture to continue growing to meets the needs of seafood for human consumption, it must reduce or completely avoid the dependency on fisheries for the supply of the seeds and broodstock. Recognition of the necessity to close the life cycle in captivity will provide sustainable seeds source for aquaculture and help in planning the production due to the availability of the seeds year around. Comparison of the reproductive performance of wild females (F0), and pond-reared females from two generations (F1) and (F2) of Penaeus semisulcatus were carried out under commercial maturation facilities in Egypt. Significant differences were found between the wild (F0) females and the two generations (F1) and (F2) of domestication in the average number of eggs, the (F0) had higher number of eggs compared to (F1) and (F2) (87503 ± 27012, 76355 ± 30471 and 81888 ± 31283, respectively). On the other hand, there were no significant difference in the fertility, hatchability and average number of nauplii per spawn between the wild (F0) females and the two generations (F1) and (F2) of domestication and the average number of nauplii were (48000.80 ± 28.25 , 43503.57 ± 33.25 , 46508.44 ± 33.23, respectively). This proof the potential of domestication as sustainable source for seed supply required for the expansion of shrimp aquaculture, in the same time farmer will benefit from the possibility of design breeding program for high performance in growout ponds. Finally, protection of natural fisheries is an advantage of domestication by reducing pressure on natural fisheries and giving chance to wild broodstock to spawn and grow to increase capture fisheries production. 2
... Thus, the use of the frequently adopted procedure of eyestalk ablation to promote faster gonadal maturation especially in male crustaceans for aquaculture production need to be reviewed because although eyestalk ablation removes testis inhibiting factors and resulted in the increase in the size of testis and the number of number of mature spermatocytes [101,102], it also removes beta crystallin like proteins, which promotes testicular maturation and the absence of it may influence fertility. The negative effect of eyestalk ablation on the quantity and quality of spawning, and subsequent larvae viability have been reported in female crustaceans [103,104]. Further study on this specific beta crystallin like gene that was found upregulated in immature male S. olivacea might provide more insight on its involvement in crustacean fertility and reproductive development. ...
Adequate genetic information is essential for sustainable crustacean fisheries and aquaculture management. The commercially important orange mud crab, Scylla olivacea, is prevalent in Southeast Asia region and is highly sought after. Although it is a suitable aquaculture candidate, full domestication of this species is hampered by the lack of knowledge about the sexual maturation process and the molecular mechanisms behind it, especially in males. To date, data on its whole genome is yet to be reported for S. olivacea. The available transcriptome data published previously on this species focus primarily on females and the role of central nervous system in reproductive development. De novo transcriptome sequencing for the testes of S. olivacea from immature, maturing and mature stages were performed. A total of approximately 144 million high-quality reads were generated and de novo assembled into 160,569 transcripts with a total length of 142.2 Mb. Approximately 15–23% of the total assembled transcripts were annotated when compared to public protein sequence databases (i.e. UniProt database, Interpro database, Pfam database and Drosophila melanogaster protein database), and GO-categorised with GO Ontology terms. A total of 156,181 high-quality Single-Nucleotide Polymorphisms (SNPs) were mined from the transcriptome data of present study. Transcriptome comparison among the testes of different maturation stages revealed one gene (beta crystallin like gene) with the most significant differential expression—up-regulated in immature stage and down-regulated in maturing and mature stages. This was further validated by qRT-PCR. In conclusion, a comprehensive transcriptome of the testis of orange mud crabs from different maturation stages were obtained. This report provides an invaluable resource for enhancing our understanding of this species’ genome structure and biology, as expressed and controlled by their gonads.
... The mechanisms of spermatozoal capacitation are poorly understood, preventing in vitro reproduction of shrimp in laboratories. Some authors have demonstrated low in vitro fertilization rates using spermatophores collected from the terminal ampoules (Bray & Lawrence 1992;Alfaro et al. 1993). The main reason for separately for each collected region of the male reproductive system and sperm mass. ...
The present study demonstrates ultrastructurally the model of Litopenaeus vannamei male sexual maturation and spermatozoal capacitation. The results show that phase 1 of the model occurred in the seminiferous tubules and includes spermatogenesis. In this phase, throughout differentiation of spermatogonia into late spermatids the following processes were observed: (1) decondensation of chromatin; (2) rupture of the nuclear envelope; (3) reduction of the cytoplasm and degeneration of organelles; (4) formation of the acrosome via fusion of cytoplasmic vesicles. Phase 2 comprised of spermatozoal maturation, a process that started with the transfer of late spermatids into the seminiferous ducts and ended with the formation of the acrosomal spike in the terminal ampoules. During this phase, development of the subacrosomal region and lateral electron-dense particles occurred in the seminiferous ducts, which is a novel finding of this species. Phase 3 was observed after spermatophore placement on the female thelycum and was mainly characterized by ultrastructural changes in the nucleus and the subacrosomal region. These results are in agreement with the model of male sexual maturation and spermatozoal capacitation proposed for L. vannamei.
... In this process, the male places the spermatophore into the open thelycum of the female, which retains it for a few hours before spawning. Multiple spawns may occur within one molt cycle (Bray & Lawrence 1992). ...
Development and use of standardized white spot syndrome virus (WSSV) inoculation procedures for studies on pathogenesis and control
... The nutritional status of crustacean broodstock is of utmost importance for reproduction and offspring quality and unbalanced or incomplete diet cause poor reproductive performance or may even stop animals from reproducing (Harrison et al., 1990;Bray and Lawrence, 1992;Wouters et al., 2001a). Hence, a better understanding of the nutritional requirements of Eriocheir sinensis broodstock could lead to improved hatchery output both quantitatively and qualitatively. ...
... Variability of fecundity estimates based on weight can be related to the fact that shrimp are partial and multiple spawners. Precise data of the number of spawns produced by a female in nature is unavailable (Bray and Lawrence 1992); however, evidence of repeated spawning has been presented for a number of penaeid species. Multiple spawning in wild penaeid shrimp has been reported in the Gulf of Mexico (Lindner and Anderson 1956, Cummings 1961, Eldred et al. 1961, Martosubroto 1974. ...
Fecundity of white shrimp, Litopenaeus setiferus, brown shrimp, Farfantepenaeus aztecus, and pink shrimp F. duorarum and relationships to gonad weights and total and carapace length were estimated. Ovigerous females were collected in the southern Gulf of Mexico in February, May, August and November 1993. Fecundity was estimated by means of a gravimetric method. The equations relating fecundity to total weight and fecundity to gonad weight were linear in the 3 species. However, an exponential relationship was found between fecundity and carapace length in L. setiferus and F. aztecus. Of the relationships examined, gonad weight was considered a more precise indicator of fecundity. Fecundity estimates ranged from 70,647 to 558,270 eggs for 0.203 and 5.639 g gonad weight of L. setiferus, from 23,298 to 494,292 eggs for 0.061 to 2.561 g gonad weight in F. aztecus and from 138,618 to 225,543 eggs for 0.120 to 0.998 g gonad weight in F. duorarum.
... Nevertheless, Vijayan et al. (2005) (Bray and Lawrence 1992). In India, the annual consumption of polychaetes by shrimp hatcheries is estimated to be about 16 to 20 tonnes (Vijayan et al. 2005). ...
In this study the breeding of the shrimp Litopenaeus vannamei was achieved by two methods; the first was stock breeding to estimate total number of eggs, and the second was individual breeding to recognize the relationship between weight and eggs number. The environmental factors in the hatchery were measured, the averages of water temperature and salinity were recorded to be 31 º C and 32 ppt., respectively, while the dissolved oxygen and pH were 7.5 mg/ l and 8.2 respectively. The results of stock breeding showed that total number of eggs (fecundity) and nauplii produced from 20 ablated females with weight of 35.5 + 3.1 g were 3000000 eggs per spawning and about 2 400000 nauplii respectively. Fertilization rate and hatching rates were 86.5 %, and 78.7 % respectively. The results of individual breeding showed that maximum number of eggs (164000 eggs / female) was achieved in these females that weight 42.0 g, while the minimum were 95000 eggs / female for female weighted 32.5 g. Maximum fertilization rate was 95.2 % in those females with lower weight, while the minimum fertility rate was 77.5 % in those with higher weight.
This datasheet on Litopenaeus vannamei covers Identity, Overview, Associated Diseases, Pests or Pathogens, Distribution, Dispersal, Biology & Ecology, Environmental Requirements, Natural Enemies, Impacts, Uses, Management, Genetics and Breeding, Economics, Further Information.
Long non-coding RNAs (lncRNAs) have been linked to immunological modulation. Unfortunately, little is known about the processes of immune control in shrimp. In crustaceans such as Litopenaeus vannamei, a prominent aquaculture species, the X-organ-sinus gland complex (XO-SG) in the eyestalk is an essential neuroendocrine regulatory organ. Eyestalk ablation is commonly employed in aquaculture to accelerate ovarian maturation in shrimp. It does, however, have a negative impact on the shrimps' immunocompetence and causes death. As a result, we used RNA-seq to profile the transcriptomes of L. vannamei hemocytes infected with Vibrio parahaemolyticus after the eyestalk ablation. Following strict transcript screening procedures, 2307 lncRNAs were identified from L. vannamei hemocytes in this study. Pearson correlation analysis was finally used to uncover 535 DElncRNAs and 1566 DEmRNA targets. According to the Venn diagram analysis, 326 non-eyestalk regulatory lncRNAs (NElncRNAs) with a target of 1014 non-eyestalk regulatory genes (NEmRNAs), 47 eyestalk negative regulatory lncRNAs (ENRlncRNAs) with a target of 95 eyestalk negative regulatory genes (ENRmRNAs), and 162 eyestalk positive regulatory lncRNAs (EPRlncRNAs) with a target of 457 eyestalk positive regulatory genes (EPRmRNAs) were screened. The bioinformatics analysis revealed that lncRNAs were associated with Axon regeneration, Rap1 signaling pathway, Thyroid hormone signaling pathway, TGF-beta signaling pathway, and PI3K-Akt signaling pathway, implying that lncRNAs may play a role in the regulation of the neuroendocrine-immune (NEI) system. Furthermore, several lncRNAs targeting HSP70, YWHAZ, FER2, HIF1α, and Notch were discovered and verified by qRT-PCR. These findings showed that regulation of lncRNAs in hemocytes which were controlled by the eyestalk might be one of the impact variables in controlling the differential expression of mRNAs associated with immune response in L. vannamei infected with V. parahaemolyticus.
The X-organ-sinus gland complex (XO-SG) in the eyestalk is an important neuroendocrine regulatory organ of crustaceans such as Litopenaeus vannamei, a prominent aquaculture species. The current study found significant changes in the enzyme activities of ALP, ACP, and T-SOD of hepatopancreatic in response to Vibrio parahaemolyticus exposure following eyestalk ablation, indicating that they were all involved in the immunological regulation of shrimps against V. parahaemolyticus infection. A total of 52,656 unigenes were obtained after RNA-Seq, with an average length of 1036 bp and an N50 of 1847 bp. Subsequently, 1899 eyestalk positive regulation genes (EPRGs), 745 eyestalk negative regulation genes (ENRGs), and 2077 non-eyestalk regulatory genes (NEGs) were identified. KEGG analysis of EPRGs revealed that eyestalk ablation might activate the neuroendocrine-immune (NEI) system. The RNA-Seq data were validated using quantitative real-time PCR (qRT-PCR). The findings suggested that eyestalk ablation might affect the expression of genes involved in the prophenoloxidase-activating system, the TLR signaling pathway, and numerous other immune-related genes in L. vannamei. All of these findings revealed that the eyestalk might have a role in the immune response of L. vannamei. The genes and pathways discovered in this study will help to elucidate the molecular mechanisms of hemocytes’ immune response to V. parahaemolyticus following eyestalk ablation in shrimp, as well as provide the framework for building crustacean immunity theory.
We investigated the effects of eyestalk ablation and cheliped autotomy in inducing molting in Callinectes ornatus. The specimens in intermolt stage were divided into two size classes: 1 (30-50 mm) and 2 (51-70 mm) and were further divided into four experimental groups. In the CA group (Cheliped Autotomy, n=76), crabs were submitted to cheliped autotomy; in the UA group (Unilateral Ablation, n=66) and BA group (Bilateral Ablation, n=66) to unilateral and bilateral eyestalk ablation, respectively. The C group (Control, n=70) was used as control. The animals were individually kept in tanks interconnected to a recirculation system for 30 days. The highest frequency of premolt was recorded in the BA group (32%), followed by the CA group (16%). The premolt frequency of class 1 (28%) was significantly higher (p<0.05) than of class 2 (8%). The mean time until molt in the BA group was significantly lower (p <0.05) than other groups tested. The highest mortality rates were 55% and 25% in crabs from the BA and CA groups, respectively. The results indicate bilateral eyestalk ablation and cheliped autotomy are potentially capable of inducing molt in C. ornatus, but these techniques have limited efficiency for the commercial application of large-scale soft-shell crab.
The effects of water temperature on the spawning of the kuruma prawn, Penaeus (Marsupenaeus) japonicus, after unilateral eyestalk ablation were studied. Females (average BL, 159 mm) with early vitellogenic ovary ablated on day 3 after molting were reared individually in a 100 l tank at 22°C, 25°C, or 28°C. The average period until the first spawning was 8.4±4.2, 4.6±3.0, and 3.0±1.0 days in the 22°C, 25°C, and 28°C groups, respectively. The period was shorter when the water temperature was higher (P<0.05) . In contrast, the number of eggs spawned did not vary among the groups.
In decapod crustaceans, eyestalk ablation is widely used to expedite ovarian maturation and spawning because of the removal of a gonad inhibiting hormone produced by the X-organ sinus gland. However, eyestalk ablation also results in negative impacts on the immunocompetence of the eyestalk-ablated females. In the current study, we investigated the impact of eyestalk ablation on the transcriptomic responses of three major nervous organs of shrimp, including the eyestalk ganglion, brain and thoracic ganglion, using the Illumina Hiseq™ 4000 platform. A total of 48,249 unigenes with an average length of 1253 bp and a N50 value of 2482 bp were obtained. Following eyestalk ablation treatment, a total of 2,983, 6325 and 6575 unigenes were detected as differentially expressed (log2Ratio >1 and FDR <0.05) from the eyestalk, brain and thoracic ganglia, respectively. Functional GO and KEGG analysis of these differential expression genes (DEGs) showed that these DEGs were associated with a wide variety of biological processes and pathways. The distribution of DEGs among three comparison groups was similar, and many DEGs were mapped to the phagosome pathway, indicating that eyestalk ablation triggers activation of the neuroendocrine-immune (NEI) system. Interestingly, several important pathways were uniquely enriched in the brain tissue, suggesting that the brain may play a crucial role in the NEI system in response to eyestalk ablation. This is the first report on the transcriptomic regulation of the nervous system in response to eyestalk ablation in L. vannamei. The genes and pathways identified in this study will help to elucidate the molecular mechanisms of neuroendocrine-immune responses to eyestalk ablation in penaeid shrimp.
To reveal molecular mechanism of how polychaetes enhanced reproductive maturation in the male black tiger shrimp (Penaeus monodon), transcriptomic profiles of male reproductive organs (testes and vas deferens) between polychaete-fed and commercial pellet-fed male brooders were compared using cDNA microarray. The overall profiles were distinguishingly different between the two feed groups as well as between testes and vas deferens. Additionally, six of 11 differentially expressed gene identified by the microarray (HNRPUL1 and GCP4 in testes, MAT2B, CDC16, and CSN5 in vas deferens, and SLD5 in both organs) were validated by quantitative real-time PCR (qPCR) and found to exhibit significantly higher expression levels in polychaete-fed shrimp than those in commercial pellet-fed shrimp. From microarray and qPCR results, the differentially expressed transcripts in both testes and vas deferens between different feeds belonged to DNA replication and microtubule nucleation pathways. Interestingly, while the transcripts involved in nutrient uptake and nucleotide biosynthesis were increased only in testes, those involved in protein refolding and apoptosis were increased only in vas deferens. These findings suggest that polychaetes may enhance spermatogenesis by increasing spermatogonia proliferation in testes and by regulating mature spermatozoa in vas deferens.
Very low naturally mating rate of pond-reared tiger shrimp broodstock is probably due to the slow maturation of the male stock. The aim of this study was to evaluate the salmon gonadotrophin releasing hormone analoque (sGnRHa) in stimulating the gonadal maturation of male stock of pond-reared tiger shrimp. The treatments were three dosages of sGnRHa at 0.1 (OV-1), 0.2 (OV-2), and 0.3 (OV-3) mL/kg of shrimp weight and control was eye stalk ablation (AB). The sGnRHa was administered via injection three times with one week interval. Male stocks with average initial body weight of 82.1 g were randomly distributed into four of 10 m3 concrete tanks, 26 males for each tank. Variables observed were performances of spermatophores and profiles of amino acid and fatty acid of muscle of the male stocks. After induction, number of male maturing indicated by spermatophores releasing from terminal ampullas was higher in shrimp induced with OV-1 (80.8%) compared to control which was only 46.1%. Furthermore, shrimp treated OV-2 had the highest spermatophore weight of 0.16 g compared to control (0.11 g) and other two groups. Amino acid profiles improved as the dose of sGnRHa increased up to 0.2 mL/kg from 61.23% for ablated male becoming 71.27% for OV-2. Total fatty acid also tended to improve by increasing the dose of hormone injection, however, the ablated male had higher total fatty acid content than that of OV-1. The present finding demonstrated that the dose of sGnRHa to stimulate the gonadal maturation of pond-reared male tiger shrimp could be applied at range between 0.1-0.2 mL/kg of shrimp weight.
As no indigenous species of commercial penaeid shrimp live in the waters of French Polynesia, the preliminary step in developing shrimp aquaculture was to obtain maturation and spawning in captivity.
Five species have been investigated. Wild‐caught juveniles from the New Caledonia lagoon (P. merguiensis, P. semisulcatus, M. ensis) and postlarvae from the Galveston NMFS laboratory (P. aztecus) and Fujinaga Institute (P. japonicus) have been used to obtain adult stock.
Experiments on larval rearing and growth of these species are in progress.
Shrimps are reared in circular tanks of 12 m ³ with a continuous water circulation through a coral sand bed. Rate of exchange is from 1 to 3 times a day. Throughout the year water temperature is between 25 and 29 C, salinity around 34.5 ppt, and pH 8.2. Solar energy is reduced by shade covers. Artificial pellets of different composition are given as food. In these conditions we have obtained: 1) about 1,000 spawnings and two generations in captivity from September 1973 to September 1974 with P. merguiensis; 2) spawnings of M. ensis in 1973; 3) four spawnings of P. japonicus in September 1974; 4) about 20 spawnings of P. aztecus, but only after removing one eyestalk; 5) maturation signs in P. semisulcatus but no spawning.
Double tracer experiment using radioactive fatty acids was conducted in order to verify the transfer of lipid reserves to the ovaries during the ovarian maturation of the prawn Penaeus japonicus. The prawns were fed with a diet containing both palmitic acid (16:0)-3H and linolenic acid (18:3ω3)-14C, held for 1 day, and then maintained for 5 days with and without destalking. One day after feeding of the diet, both lipids-3H and lipids-14C were mainly distributed in the hepatopancreas as phosphatidylcholines (PC) and free fatty acids (FA) and in the muscle as PC. Bilateral destalk-ing resulted in the induction of ovarian maturation and also the increase in ovarian radioactive triglycerides (TG) and PC with a concomitant decrease in hepatopancreatic radioactive TG and PC. Thus, the destalking enhanced a transfer of body lipid reserves, particularly hepatopancreatic lipids, to the ovaries which accumulated TG and PC as the major lipid classes. From the 3H/14C ratios of ovarian PC and TG, it is likely that the major ovarian PC accumulated during the induced ovarian maturation are rich in ω3-fatty acids, possibly 18:30, 20:5ω3, 22:6ω3, etc., rather than 16:0 and its metabolites, whereas the major ovarian TG consist of 16:0 and its metabolites rather than ω3-fatty acids as acyl groups.
The present investigation was undertaken to see the postprandial variation in lipid com-positions of the hepatopancreas, hemolymph, and muscle after feeding of the test diets with 3% soybean lecithin (diet A) and without supplemental phospholipids (PL) (diet D) to understand the nutritional role of dietary PL in the prawn Penaeus japonicus. Total lipid (TL) concentrations of the hepatopancreas and hemolymph were higher in the prawns receiving diet A than in those receiving diet D during the holding period from 1h to 6h after feeding. The increase of TL concentrations of the hepatopancreas was mostly attributable to that of neutral lipids (NL) such as triglycerides (TG) and cholesterol (CH), whereas that of the hemolymph was mainly due to PL such as phosphatidylcholine besides NL such as TG and CH. On the other hand, no re-mazkable difference was seen about the variation of lipid class concentrations of the muscle between the two diet groups as observed in the hepatopancreas and hemolymph. On the basis of these data, dietary PL was suggested to take some part in the transport of dietary lipids such as chole-sterol and triglycerides in the body through the hemolymph.
Utilization of the dietary sterols by prawn, Penaeus japonicus, was studied. After 30 day-feeding on the diets containing only cholesterol, ergosterol, stigmasterol, and β-sitosterol, the content and composition of sterols in the tissues of the prawn were analyzed. in the prawn fed on the sterol-supplemented diets, the sterol content of the body tissues was similar to that of the prawn before feeding though in the prawn fed on the sterolfree diet, the sterol content decreased. in the prawn fed on several sterol-supplemented diets, 96-99% of the sterol content was composed of cholesterol. From these results, it may be assumed that the dietary ergosterol, stigmasterol, and β-sitosterol were digested by the prawn, and converted to cholesterol. © 1971, The Japanese Society of Fisheries Science. All rights reserved.
Small samples of gavid shrimp with spermatophore of the white shrimp, P. vannamei BooNE, were fished by small trawl net on the Pacific coast of Mexico, and induced spawning in the labora-tory. Hatched nauplii were separated into glass beakers, and the larval devolopment was studied and compared with other Penaeus shrimps such as the brown shrimp and the blue shrimp, which are distributed. in the same Pacific coastal waters. The result reveals very close similarities in morphological characters among thcse Penaeus shrimps. Meanwhile the growth of larvac was measured continuously, and the moulting times of naupliar stages were examined from a statistical viewpoint.
The present paper describes spermatophare transplantation and artificial fertilization in wild or pond-reared female grass shrimp whose golladal development was induced by the method of eyestalk ablation. The hatching rates from the uncopulated soft-thelycum females implanted with two spermatophores were 82.35% and 39.11% for the first and the subsequent spawnings, respectively, while from those implanted with only one spermatophare, the hatching rates of 71.87% and 13.17% were similarly obtained. In addition to spawning success with an improved hatching, the spermatophore transplantation will allow repeated use of the ablated females, bene-fitting the hatchery operation. To the uncopulated hard-thelycum females, artificial fertilization was found applicable by release of spermatozoa into the spawning tank right before the spawning took place. The timely release of spermatozoa for 3 individuals resulted in the hatching rates of 63.11, 52.29 and 49.44%.
The requirements of linoleic and linolenic acids for the growth of the prawn, Penaeus japonicus, were studied by using a purified diet.
In this feeding experiment conducted for 50 days, the growth of prawn on the diet containing oleic acid was extremely slow. Addition of linoleic and linolenic acids to the diet remarkably improved weight gain. The recovery tests initiated after 30-days of feeding linolenic acids were concluded to be essential for the growth of prawn. Also, the nutritive value of linolenic acid for prawn was found to be higher than that of linoleic acid.
The effect of light quality on the maturation, condition and growth of the penaeid prawn Penaeus indicus was tested by comparing dim green and blue illumination against that of diffuse natural light as a control. Initially growth and condition were depressed in all three tanks and this could be regarded as a ‘settling down’ period, while spawning activity decreased in the blue and green tanks, but increased in the control tank. After three to five months the growth slopes became positive under green and blue light and condition improved, though the spawning levels still remained low (consolidation phase). Spawning and condition then continued to improve with time. It appeared that once growth and condition had normalized under blue and green light, spawning activity resumed. In the control, however, both prawn condition and subsequent spawning activity declined steadily after the end of the second month and this could be explained as a final reproductive effort with decreasing condition until the conditio...