共查询到20条相似文献，搜索用时 78 毫秒
1.
2.
Studies at the Fairbanks Experimental Fish Hatchery (FEFH) were conducted to investigate the operational characteristics of media filtration groundwater treatment for iron and manganese reduction, water reuse and recirculation technologies for fish rearing, and conditions of fish gill tissue during rearing. Results were used to aid in the design and planned operation of the Ruth Burnett Sport Fish Hatchery (RBSFH), currently under construction in Fairbanks, Alaska. Under a two-stage filtration scenario, with hydraulic loading rates of 0.39 and 0.43 cm/s for Stages 1 and 2, respectively, manganese dioxide media filtration typically removed dissolved iron from 5 to 6.5 mg/L down to 0.1 mg/L or less, and allowed for suitable fish rearing and health (based on gill condition) in treated groundwater. Poor water quality from filter equipment malfunction or improper operation typically manifested tissue damage (epithelial lifting, hypertrophy, degeneration, and in some cases iron adhesion) observed in fish gills. Design refinements from initial use, including changes in hydraulic loading rates and transition from single-stage to two-stage filtration, were required for long-term use of media filtration and were included in the design of the future hatchery. Dissolved manganese removal from groundwater (from 0.7 to <0.05 mg/L) was also implemented by continuous low-level potassium permanganate addition. Small-scale flow-through, fully recirculating, and partial reuse rearing systems were used to mimic planned future fish production, and resulted in 97% or greater survival and adequate growth (average specific growth rate between 1 and 2%) and health of rainbow trout during most rearing trials. 相似文献
3.
Abstract Depredation can have economic, social and ecological impacts by decreasing fishery landings and threatening marine predator populations through increased risk of entanglement. This investigation quantified the loss of landings attributed to harbour seal, Phoca vitulina L., and spiny dogfish, Squalus acanthias L., depredation in the Georges Bank, Massachusetts, USA gillnet fishery. Approximately 1361 kg (2.38%) of fish was discarded from a total possible catch weight of nearly 57 300 kg because it was unsalable following depredation. Spiny dogfish accounted for 1134 kg (1.98%), and harbour seal accounted for 227 kg (0.40%) of discards. This represented an estimated US$2250 loss in profits from a total possible catch value of almost US$61 800, signifying a 3.64% market‐value loss during the assessment period. These results suggest that discarding due to harbour seal and spiny dogfish depredation results in a relatively small market loss to fishers, although additional information and research is needed before this can be confirmed. This study is the first on this subject in the fishery and provides baseline information on depredation rates that could be useful if harbour seal and spiny dogfish populations continue to increase. 相似文献
4.
Factors Influencing Early Survival and Growth of Laboratory‐reared Pacific Bluefin Tuna,Thunnus orientalis,Larvae 
下载免费PDF全文
下载免费PDF全文 Yosuke Tanaka Kazunori Kumon Kentaro Higuchi Takeshi Eba Akefumi Nishi Hideki Nikaido Satoshi Shiozawa 《Journal of the World Aquaculture Society》2018,49(3):484-492
The collection of fertilized eggs for mass culture of Pacific bluefin tuna (PBT) relies on the spontaneous spawning of broodstock in captivity, and the spawning season of the broodstock is generally from mid‐May to September. The diameter of fertilized eggs from the broodstock decreases during the spawning season. To investigate the influence of three potential factors, the egg diameter (larger or smaller), the rearing water temperature (25 or 28 C), and the aeration rate during the night (strong or weak), on early survival and on growth of PBT larvae, replicate trials were conducted to assess these three factors until 7 d after hatching (d.a.h.). At 7 d.a.h., survival rates of larvae reared with strong nighttime aeration were found by a three‐way ANOVA to be significantly higher than for larvae reared with weak aeration. Furthermore, growth rates of PBT larvae hatched from larger eggs were significantly faster than those from smaller eggs. However, a significant difference in the survival rate was not detected for the factors, egg diameter and rearing water temperature. The results indicate that rearing with strong nighttime aeration significantly improved the early survival of PBT larvae and the egg diameter (a proxy for egg quality) and influenced growth. 相似文献
5.
A major concern in larvae production is a mass mortality caused by fish diseases. In larvae production, pumped‐up natural seawater filtered through a sand filter system is used for fish rearing, and microalgae and rotifer cultures. Here, we investigated the community structures of eukaryotic microbes, as well as total bacteria and vibrios, in various processed ‘waters’ used in a larvae production site. We observed that ultraviolet irradiation of seawater was effective to reduce not only total bacteria and vibrios but also eukaryotic microbes. Moreover, the community structures of total bacteria and vibrios in rearing waters for fish larvae were different from those in rotifer cultures fed with Chlorella, but rather similar to those in natural seawater and microalgae cultures. These results suggest that the bacterial community in rearing waters may originate mainly from natural seawater and then be selected by microalgae in rearing water. Overall, this study provides useful information for avoiding the risk of fish disease outbreaks in a larvae production site. 相似文献
6.
7.
T. G. Northcote C. H. Hendy C. S. Nelson J. A. T. Boubee 《Ecology of Freshwater Fish》1992,1(1):61-72
Abstract– Stable oxygen and carbon isotopic analyses were made for water at 24 sites, mainly from the Waikato watershed (North Island, New Zealand), and for carbonate from fish sagittal otolith material at each of the sites, mainly from the common smelt ( Retropinna retropinna (Richardson)), to test their potential use in identification of resident and anadromous/migratory stocks suggested in an earlier pilot study. Results provide strong evidence that 18 O is precipitated in otoliths close to isotopic equilibrium with rearing waters. The smelt rearing and residency waters examined have characteristic oxygen and carbon isotopic 'signatures', and the 18 O composition of the smelt otoliths mirrors this within about 1%0, making it possible to use the technique for determining resident and/or migrant history of the fish. The 13 C otolith composition, though usually tracking that of probable rearing and/or residency waters, has a larger and more variable offset, possibly of metabolic origin, making its use less reliable as a habitat signature. 相似文献
8.
Assessment of the fish stock in the Theodorushaven was conducted with a dual-beam hydroacoustic system. Species composition determined by a seine and trawl fishery showed large concentrations of fish in the harbour during winter. The hydroacoustic survey showed that the distribution of fish in the harbour area was stratified with fish near the bottom. The overall density in the harbour area was 0.67 fish m–3 . The density in the associated channel area was estimated at 0.1 fish m–3 . The coefficient of variation for the estimated total fish abundance was >25%.Fish >25 cm were not caught in the Theodorushaven fishery, although analysis of the sonar data indicated their presence. Fishery data from the adjacent Volkerak-Zoommeer showed that bream was the dominant species. Therefore, the biomass estimate of the stock >25 cm in the Theodorushaven was based on the standard length–weight relationship of bream. This resulted in maximum biomass estimates of 5800 kg ha–1 for the harbour area and 1100 kg ha–1 in the channel area. The minimum biomass estimate, based on the assumption that the more slender zander was the dominant species >25 cm, gave values of 4100 kg ha–1 in the harbour area and 780 kg ha–1 in the channel area. 相似文献
9.
Interspecific competition between the round goby,Neogobius melanostomus,and the logperch,Percina caprodes,in the Duluth‐Superior Harbour 下载免费PDF全文
下载免费PDF全文 The Laurentian Great Lakes have been the site of numerous aquatic invasive species such as the sea lamprey, zebra mussel and round goby. To further understand interactions between invasive and native species in situ, competitive interactions between native logperch (Percina caprodes) and invasive round goby (Neogobius melanostomus) were examined using submerged enclosures in the Duluth‐Superior Harbour. Experiments were conducted on rocky or sandy substrate throughout the spring and summer months. Trials consisted of single fish, paired conspecifics or round goby/logperch pairs with weight change determined after 28 days. The round gobies were able to outcompete and/or negatively affect logperch on rocky substrates as a direct result of round goby/logperch interactions, as logperch fared well when round gobies were excluded from the enclosures. Although there is evidence that round gobies exclude logperch from rocky substrates, the logperch population remains close to pre‐invasion levels in the predominantly soft‐bottomed harbour. The continued coexistence of the logperch with the round goby is attributed to the vastly greater area of soft‐bottom vs. rocky substrate in the harbour, with the round gobies in the soft bottom younger and smaller than those in the rocky substrate. Recent evidence suggests that the round goby population is declining on the soft substrates indicating that the two populations will continue to coexist in the harbour. 相似文献
10.
11.
Shigeaki Shiotani Atsushi Hagiwara Yoshitaka Sakakura Hisashi Chuda 《Aquacultural Engineering》2005,32(3-4):465-481
Marine fish larvae are fragile against physical stress. However, few studies have been conducted to evaluate the flow field in a rearing tank, which is assumed to provide a high degree of physical stress to marine fish larvae. The flow field in a rearing tank (volume of 1 m3) is generated by aerators, which are commonly used to provide oxygen.
This paper is a report on the estimation of stationary flow in the rearing tank of marine fish larvae. The larvae are seven band grouper larvae of Epinephelus septemfasciatus, which have a very low survival rate immediately after the hatching of eggs. The experiments of rearing of seven band grouper larvae were carried out using rearing tanks with four aeration rates (1000, 200, 50 ml/min, and no aeration). The effects of aeration on the survival and floating death of seven band grouper larvae were examined. The experiments confirmed that the mass mortality of seven band grouper larvae depends on the flow rate in the rearing tank. Aeration at 200 ml/min resulted in the highest survival and growth rates of grouper larvae.
Larvae-rearing experiments provided evidence that the flow rates of the rearing tanks are very important design aspects of rearing tanks. The estimation of flow in a rearing tank for an aerating rate of 200 ml/min was carried out by numerical calculation. The computation was simplified by a two-dimensional flow based on experimental results. The calculated flow in the rearing tank was compared with the experimental one. The calculation of the stationary flow in the rearing tank showed good qualitative and quantitative agreement with the experimental results. The numerical estimation of the flow in a rearing tank of marine fish larvae was confirmed to be effective and satisfactory for the design of a tank that would provide optimum performance. 相似文献
12.
Fifty publications (1956–1976) concerning the use of antibiotics in rearing marine bivalve larvae are analysed. Most of the existing antibiotics have been tested alone or in combination, very frequently in an arbitrary fashion and without preliminary study to determine the most suitable antibiotic. The results obtained as regards to the survival of larvae or their growth have been variable, at times contradictory and not repeatable.The problems posed by the utilisation of antibiotics in rearing bivalve larvae are discussed and a standard routine for the use of antibiotics is proposed. 相似文献
13.
Molluscs can be cultivated as well as transferred from one rearing site to another by enclosing discrete groups of molluscs in the interior of a tube of netting material. The resulting tube is then attached to a floating raft for raft culture or buried in a suitable benthic sediment. After a sufficient period of time the molluscs are harvested, retained in the netting for depuration, or shipped directly to market. 相似文献
14.
Cephalopods are arguably the most complex and fascinating aquatic invertebrate taxa. Except for a few well known exceptions,
this group of organisms has been a challenge to study primarily due to difficulties in rearing and maintaining these animals
in a small laboratory setting. Our knowledge about cephalopod rearing comes mainly from large marine centers, with much less
known about small scale rearing facilities. This paper describes a bench top (ca. 450 litre) aquarium system that is relatively
inexpensive, easy to maintain, and suitable for long term rearing of cuttlefish in the laboratory. This closed aquarium system
uses artificial sea water and a biological filter to remove/recycle nitrogenous wastes. The simple design of this system can
be easily replicated by inland researchers interested in studying cuttlefish but who have been thwarted by the lack of suitable
housing facilities.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
15.
Abstract. To assess the merits of rearing coho salmon, Oncorhynchus kisutch (Walbaum), smolts semi-naturally, trials were made in which 17 groups of tagged smolts, from 4 brood years, were raised on a partially natural diet in a semi-natural habitat. Their subsequent survival, as determined from catch and escapement, was compared with that of four groups of smolts, from the same brood years, raised by a conventional hatchery method. The returns of the semi-natural fish proved lower than or similar to those of the hatchery fish, which attained a maximum survival to catch and escapement of 26%. The survival of the semi-natural fish showed no relation to their location in their linear rearing facility, nor to size of smolt (within a narrow range). Further trials showed that a month's delay in release of the semi-natural fish did not increase returns, contrary to a current predictive model. The distribution of the catches of both kinds of fish was broadly similar in the troll and sport fisheries. It is concludedthat semi-natural rearing of coho smolts is not superior to that of standard hatchery procedures, although it may be favoured for specific locations that lend themselves to this approach. 相似文献
16.
Andr Neveu 《Aquaculture (Amsterdam, Netherlands)》2009,295(1-2):30-37
European countries are probably the greatest consumers of frogs' legs, although this is occurring in a context of amphibian decline. Imports of frogs' legs have been increasing over the last few decades in relation to the development of deep-frozen products. This demand has stimulated farming with neotropical species for international trade. Today, in spite of some trials on European species, no production is effective. From the early 1990s, small-scale experimental rearing trials have been undertaken in Brittany (France) with a local green frog belonging to the esculenta complex (Rana ridibunda) which accepts granulated feed. This complex comprises two Mendelian species R. lessonae (LL) and R. ridibunda (RR) as well as their hybridogenetic hybrid Rana esculenta, which can be either diploid (RL) or triploid (RLL, RRL).The purpose of this study is to analyse the ability of each taxon to be reared. During the two months following metamorphosis, froglets were trained to eat pellets. The surviving individuals were reared for one year under regulated conditions to estimate the survival rate, growth and production of each frog type.The results show low survival rates (14.8 to 26.2%) for LL and RLL, higher rates (39–46.4%) for F1 and F2 from wild RR and RLL, with the highest rates (63.0 to 77.4%) for RL, RRL and all RR, using data from several years of rearing. After three years under rearing conditions, the adult survival rate is highest for rearing strain RR-Rivan 92* (53.7%). The growth rate varies greatly according to phenotype, and only frogs with an RR phenotype reach marketable size. In the wild, LL exhibits some difficulty in reaching this limit. As a result, production increases from 1.5–8.7 kg/m2 for individuals with an L hemiclone to 22.9–35.7 kg/m2 for each cohort of phenotype RR from at least two generations under rearing conditions.In relation to hybridogenesis processes, hybrids with diploid or triploid genomes do not seem to offer any advantage for production purposes. However, R. lessonae individuals from intensive rearing can produce fertile eggs and tadpoles, which could enable production for restocking to preserve wild diversity or build up new populations in suitable habitats. 相似文献
17.
18.
François‐Joël Gatesoupe Denis Covès Aurelio Ortega Nikos Papandroulakis Olav Vadstein Fernando de la Gándara 《Aquaculture Research》2013,44(10):1511-1523
During the first 2 years of larval rearing trials with Atlantic bluefin tuna, survival was a challenging issue. As bacterial colonization of the gut has been shown to play a key role for other species, we studied the profiles of the microbiota associated with individual larvae at different stages in three distant hatcheries. The Bacterial Community Profile (BCP) was quantified based on PCR‐DGGE analyses of partial amplicons from 16S rDNA. Considerable individual variability in BCP was observed before onset of feeding, and the BCP did not show regular fluctuation during ontogenesis. Microalgae were added to the rearing tanks in two of the three hatcheries, but it was not possible to distinguish the effect of location from the effect of algal addition on BCP. In one hatchery, the larvae were reared either with algal addition or in mesocosm, but due to high individual variability, no significant difference in BCP was detected between the two groups. It was hypothesized that this variability was caused by differences in health, physiological status and developmental stage of the larvae. A practical conclusion from the study is the need to analyse a considerable number of individuals to reflect statistically significant differences between the microbial communities associated with rearing groups. 相似文献
19.
N. Papandroulakis M. Suquet M.T. Spedicato A. Machias C. Fauvel P. Divanach 《Aquaculture International》2004,12(4-5):395-407
Wreckfish (Polyprion americanus) is a panoceanic, antitropical distributed species. Despite the high market price, high growth rate, good quality flesh and the potential for aquaculture, research data are scarce. In this study, the growth performance and food intake was investigated in juvenile fish, while gametogenesis was studied in adult fish. Three groups were created from 19 individuals, which were collected during neustonic sampling, using fish aggregating devices, in association with floating objects and during tuna fishing with drift nets from Greece (Crete), Italy (Ionian Sea) and the Atlantic coast of France from September 1999 to March 2001. All individuals (initial weight between 0.5 g and 4.5 kg) were reared in aquaculture facilities so as to monitor growth performance and food intake. Food (de-frozen fish – bogue, mackerel and squid – or moist pellets) was delivered ad libitum. Total length and wet weight were measured regularly. Daily food intake, the food conversion index and daily growth rate were calculated. Individuals, aging 0+, grew exceptionally fast, reaching 2.0 kg (total length 50 cm) in 12 months and 5.0 kg (total length 65 cm) in 24, while at later stages, the growth rate decreased and depended on the water temperature during rearing. Food consumption varied during the rearing period according to the developmental stage and the rearing conditions. The food conversion ratio ranged between 0.9 and 2.5 on dry weight basis during the period of the study. Gametogenesis was monitored in a separate stock of 15 individuals (11.7 ± 3.7 kg) by biopsis while blood samples were taken for steroid estimation. Increased oocyte diameter was observed in females from August to January, while plasma estradiol levels also increased from October to March. However, neither egg or sperm were collected from the stock. Young wreckfish presented a high growth rate in captivity, thus supporting the feasibility of the species for rearing. Further research, however, is required for the reproduction of the species. 相似文献
20.
Abstract. A technique which uses electrodes at the mouths of meshless water outlets of fish tanks is described. The electrical field generated by the electrodes was effective in discouraging fish from approaching the open outlet, and allowed free discharge of debris-laden water without the usual blockage of the outlets by faeces and uneaten food. The system was found to be particularly effective for the rearing of eels (from the glass eel stage on) which typically cause a rapid deterioration in water quality due to their feeding behaviour. It was also found very useful for rearing other fish larvae in tanks. 相似文献