排序方式： 共有14条查询结果，搜索用时 187 毫秒
1.
The Potential for Replacement of Live Feeds in Larval Culture 总被引：6，自引：0，他引：6
David A. Jones Mohd. Salleh Kamarudin Lewis Le Vay 《Journal of the World Aquaculture Society》1993,24(2):199-210
2.
Vu Ngoc Ut Lewis Le Vay Truong Trong Nghia & Tran Thi Hong Hanh 《Aquaculture Research》2007,38(14):1563-1568
Cannibalism is one of the main causes of mortality in the culture of the mud crab Scylla paramamosain, particularly in the early post‐larval and juvenile stages when the densities of hatchery‐reared crabs may be very high before stocking into ponds or release into the wild for stock enhancement. In a series of experiments investigating cannibalism mitigation, the influence of stocking density, the effectiveness of sand substrate, brick and shell shelters and feed type were compared in culture of crabs from instar 1 for short nursery periods of 15–30 days. Inclusion of brick and shell shelters significantly increased survival over sand substrate alone. However, inclusion of shelters did not affect growth rates. In scaled‐up nursery production in lined‐ponds, with shelters, live Artemia biomass and fresh chopped shrimp or tilapia were found to be equally effective feeds for juvenile crabs stocked at a density of 70 m−2 from instar 1 and grown for 30 days [52–66% survival, 21.6–24.6 mm carapace width (CW)]. In an extended nursery period for a further 30 days, crabs of 22 mm CW, stocked at 30 m−2 in the same ponds, attained a final size of 34.5–36.2 mm CW with a survival of 64.3–67.0% using the same feeds. 相似文献
3.
Trypsin enzyme activity during larval development of Litopenaeus vannamei (Boone) fed on live feeds 总被引：1，自引：0，他引：1
Larval stages of the Pacific white shrimp, Litopenaeus vannamei (Boone) were fed standard live diets of mixed microalgae from the first to the third protozoea (PZ1 to PZ3), followed by Artemia nauplii until post‐larvae 1 (PL1). Trypsin enzyme activity for each larval stage was determined using N‐α‐p‐toluenesulphonyl‐l ‐arginine methyl ester (TAME) as a substrate. Results were expressed as enzyme content to assess ontogenetic changes during larval development. Tissue trypsin content (IU µg?1 DW for each larval stage) was significantly highest at the PZ1 stage and declined through subsequent stages to PL1. This contrasts with previously observed patterns of trypsin development in Litopenaeus setiferus (Linnaeus) and other penaeid genera, which exhibit a peak in trypsin activity at the third protozoea/first mysis (PZ3/M1) larval stage. Litopenaeus vannamei larvae transferred to a diet of Artemia at the beginning of the second protozoea (PZ2) stage were significantly heavier on reaching the first mysis stage (M1) than those fed algae, while survival was not significantly different between treatments. At both PZ2 and PZ3 stages, trypsin content in larvae feeding on Artemia was significantly lower than in those feeding on algae. The rapid decline in trypsin content from PZ1 and the flexible enzyme response from PZ2 suggest that L. vannamei is physiologically adapted to transfer to a more carnivorous diet during the mid‐protozoeal stages. 相似文献
4.
Vu Ngoc Ut Lewis Le Vay Truong Trong Nghia & Mark Walton 《Aquaculture Research》2007,38(14):1593-1599
The performance of hatchery‐reared juveniles either in aquaculture grow‐out systems or stock enhancement is likely to be dependent on a range of factors during the hatchery phase of production. With recent progress in the development of hatchery systems for the mud crabs Scylla spp., there is growing interest in evaluation of the quality of hatchery‐reared juveniles relative to wild seed crabs as currently used in aquaculture. Hatchery‐reared and wild‐collected Scylla paramamosain juveniles were stocked either together in ponds or separately. All crabs were tagged with microwire‐coded tags, so that origin could be determined in the mixed groups. Preliminary validation demonstrated that tagging did not affect survival or growth, with a tag retention of 94%. After 106 days of culture, there was no significant difference in survival at harvest between the two sources of crabs. The wild juvenile crabs had a significantly higher initial weight:carapace width (CW) ratio compared with those from the hatchery, indicating a difference in condition. However, where crabs were stocked separately, the hatchery‐reared animals exhibited significantly faster growth than those collected from the wild, both in terms of specific growth rate and CW increase per month. However, in the mixed ponds, where there was competition with wild crabs, there was no significant difference in growth rate between crabs from the two sources. Overall, the results demonstrate that the growth performance of hatchery‐reared S. paramamosain can at least equal that of wild‐collected seed crabs in ponds culture. 相似文献
5.
6.
7.
Soil solarization (SoSol) with a single layer of transparent polyethylene (PE) film, traps considerable heat and moisture in soil. Solarization of field soil with two layers of 1 mil (25 μm thick) PE film, separated by a 6-cm air layer, caused soil temperatures at 15 cm depth to rise by 12.7°C and 3.6°C over those in noncovered soil or soil covered by one layer of film, respectively; at 30 cm depth the respective differences in temperature were 11.2°C and 2.7°C. Viability of propagules (mainly chlamydospores) ofFusarium oxysporum f. sp.vasinfectum that had been buried at 30 cm depth, was reduced after 31 days of solarization by 97.5%, 58%, and 0% under a double film layer, a single layer, and in non-covered soil, respectively. The insulating effect of a double layer of PE film improved heat retention in soil and the solarization effect. 相似文献
8.
9.
Thomas H. Galley Benjamin C. Green Lloyd Watkins Lewis Le Vay 《Aquaculture International》2011,19(2):381-394
The shore crab Carcinus maenas is a commercially important species, utilised as sea angling bait as well as supporting a European-wide fishery. Hatchery
production could provide an alternative source of bait crabs, alleviating potential competition between these sectors and
environmental concerns regarding bait collection practices. A series of experiments were carried to investigate the potential
for hatchery production, focusing on effects of dietary regimes and stocking densities through the zoeal stages and the influence
of tank substrates and stocking density during the megalopa stage. Inclusion of the rotifer Brachionus plicatilis as live food for early larval stages conveyed no advantage in terms of survival or rate of development compared to a diet
of Artemia nauplii. Increasing zoea stocking densities (from 94 to 557 l−1) had a significantly negative effect upon survival to the megalopa stage (from 75% down to 47%), although this was off-set
by a significant increase in production, with 260 megalopae−1 produced from an initial density of 557 zoeae l−1. The inclusion of substrates for megalopa stages had no impact on production or development rate, compared to tanks with
no substrate. The completely benthic behaviour of megalopae indicates that tank floor area will be a limiting factor for crab
production. Increasing stocking density of megalopae was found to significantly and negatively influence survival, although
above 10,000 megalopae m−2 the rate of decline in survival stabilised and maximum production (3,114 juveniles m−2) of juvenile crabs could be achieved at the highest stocking densities tested (40,000 m−2). 相似文献
10.
Julin Gamboa-Delgado Jos Pedro Caavate Ricardo Zerolo Lewis Le Vay 《Aquaculture (Amsterdam, Netherlands)》2008,280(1-4):190-197
The relative contributions of live Artemia metanauplii and an inert diet for growth of Senegalese sole larvae and postlarvae were assessed through the analysis of carbon stable isotopes ratios (δ13C) in both diets and whole larval tissue. Larvae were reared on four dietary regimes: 100% live prey (rotifers and Artemia), 100% inert formulated diet and two co-feeding regimes of 70:30 and 30:70 ratios of Artemia and inert diet, respectively. Larvae from the live food regime and both co-feeding regimes showed a steep increase in δ13C from 10 days after hatching (DAH) as a result of the onset and continuation of Artemia consumption. From 12 DAH fish larvae from all the regimes showed significant isotopic differences as their δ13C increased to final asymptotic values of − 15.1, − 15.6 and − 16.3‰ in the live food, 70:30 and 30:70 regimes, respectively. Carbon turnover rates in larvae from both live food and co-feeding regimes were relatively high (0.071 to 0.116 d− 1) but more than 90% of the observed change in fish tissue isotopic values was accounted for by the retention of carbon in new tissue growth. A two-source, one-isotope mixing model was applied to estimate the nutritional contribution of Artemia and inert diet to postlarvae growth in the co-feeding regimes. At 23 DAH, the relative contribution of live and inert diets to tissue growth in larvae was respectively, 88 and 12% for the 70:30 co-feeding regime and 73 and 27% for the 30:70 co-feeding regime. At 17 DAH, the estimated proportion of tissue carbon derived from the inert diet was higher at 23 and 38% for the 70:30 and 30:70 regimes, respectively. The results suggest that co-feeding regimes in Solea senegalensis larvae may be adjusted to meet ontogenetic changes in the capacity for larvae to utilise inert diets. The contrasting levels of carbon isotope discrimination between diet and tissue in larvae reared on either 100% live feed or 100% inert diet indicate relatively poor utilization of nutrients from the inert diet. The use of isotopic discrimination factors as potential indicators of the digestive physiological performance of a consuming organism in regards to its diet is discussed. 相似文献