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At least 541 records · Page 30Linked to original sources
USGS1992

Effects of sodium and calcium on acute toxicity of un-ionized ammonia to Atlantic salmon and lake trout

Acute, static 6-hour toxicity tests were conducted on two sizes each of lake trout and Atlantic salmon in the presence of three levels each of NaCl and CaCl 2 . Calcium did not protect smolts from NH 3 toxicity but had no effect on the tolerance of Atlantic salmon fry to NH 3 . Both cations increased the tolerance of 8-g lake trout fingerlings to NH 3 , but neither significantly affected the toxicity of NH 3 to 0.9-g lake trout fry. These results suggest that the mitigating effects of solution cations of NH 3 toxicity may be related to species, size, and life stage.

Journal of Applied Aquaculture↗
USGS1993

Survival in pond water of four reoviruses isolated from aquatic animals

The viabilities of golden shiner virus (GSV), chum salmon virus (CSV), oyster reovirus 13P2 (13P2). and catfish reovirus (CRV) were compared following viruses incubation in pond water samples held at 4°. 20°, 25°, and 30°C for one month. At the three higher temperatures tested, viral infectivity was lost by day 15 for GSV, day 20 for CSV, and day 10 for CRV and 13P2. At 4°C. no infectious GSV was detected at day 15, while the other viruses showed little or no loss of infectivity during the 30-day incubation period. The survival of these viruses in natural waters appears to be sufficient to sustain fish-to-fish transmission.

Journal of Applied Aquaculture↗
USGS2010

Influence of fish oils in production catfish feeds on selected disease resistance factors

Healthy channel calfish, Ictalurus punctatus (mean weight: 62.5g), were fed two production feeds that were identical except for the lipid portion, which was either catfish oil or menhaden oil. Fish were held at 18 or 28°C and fed the experimental feeds for four monlhs. A subsample of fish from each of the four treatments was then used to measure scrum antibody titers to Edwardsiella ictaluri , macrophage phagocytic index, phagocytic capacity, and production of intracellular and extracellular superoxide anion. The remaining fish were vaccinated with an E. icraluri bacterin, held for 18-24 days, and the assays were repeated. Fatty acid profiles of the diets indicated catfish oil had a higher percentage of monounsaturated fatty acids and slightly higher n-6 fatty acids. The menhaden oil diet had a higher percentage of the n-3 fatty acids. At 28°C, weight gain and feed conversion were slightly higher in calfish fed the feed containing menhaden oil. Weight gains and feed conversion were similar in fish maintained on the two feeds at 18°C. At the lower temperature, fish fed the diet containing menhaden oil appeared to have enhanced disease resistance factors, particularly phagocytic capacity. However, at 28°C, fish fed the diet containing catfish oil had enhanced phagocytic ability and intracellular superoxide production. Antibody titers were not sigmficantly (P > 0.05) affected by dietary lipid in this study. Vaccination amplified phagocytic ability in both diets at both temperatures and intensified the production of superoxide anion at 28°C.

Journal of Applied Aquaculture↗
USGS1999

Immunostimulants in fish diets

Various immunostimulants and their methods of application in fish culture are examined in this review. Important variables such as life stage and innate disease resistance of the fish; immunostimulant used, its structure and mode of action; and the fish's environment are discussed. Conflicting results have been published about the efficacy of immunostimulants in fish diets. Some researchers have had positive responses demonstrated as increased fish survival, others have not. Generally, immunostimulants enhance individual components of the non-specific immune response but that does not always translate into increased fish survival. In addition, immunostimulants fed at too high a dose or for too long can be immunosuppressive. [Article copies available for a fee from The Haworth Document Delivery Service: 1-800-342-9678. E-mail address: getinfo@haworthpressinc.com ].

Journal of Applied Aquaculture↗
USGS2003

Phosphorous digestibility and activity of intestinal phytase in hybrid tilapia, Oreochromis niloticus X O. aureus

Experiments were conducted to determine the degree to which phytate-bound phosphorus from plant protein sources could be used by hybrid tilapia (Oreochromis niloticus X O. aureus). Utilizing an inert marker technique with chromic oxide, hybrid tilapia in our study were effective at utilizing both inorganic and phytate phosphorus as evidenced by average apparent digestibility values of 93.2% and 90.0% for total and phytate phosphorus, respectively. Analysis of the intestinal brush border membrane of the tilapia revealed enzyme activity that was capable of hydrolyzing phytic acid. The presence of phytic acid hydrolyzing enzyme activity in the intestinal brush border provides a probable mechanism by which these hybrid tilapia are able to utilize phytate phosphorus effectively. ?? 2003 by The Haworth Press, Inc. All rights reserved.

Journal of Applied Aquaculture↗
USGS2003

Comparative hydraulics of two fishery research circular tanks and recommendations for control of experimental bias

Hydraulic characteristics inside two research circular tanks (1.5-m and 1.2-m diameter) with the same volume of water were studied to understand how they might affect experimental bias by influencing the behavior and development of juvenile fish. Water velocities inside each tank were documented extensively and flow behavior studied. Surface inflow to the 1.5-m tank created a highly turbulent and aerated surface, and produced unevenly distributed velocities within the tank. A low-flow velocity, or "dead" zone, persisted just upstream of the surface inflow. A single submerged nozzle in the 1.2-m tank created uniform flow and did not cause undue turbulence or introduce air. Flow behavior in the 1.5-m tank is believed to have negatively affected the feeding behavior and physiological development of a group of juvenile fall chinook salmon, Oncorhynchus tshawytscha. A new inflow nozzle design provided comparable flow behavior regardless of tank size and water depth. Maintaining similar hydraulic conditions inside tanks used for various biological purposes, including fish research, would minimize experimental bias caused by differences in flow behavior. Other sources of experimental bias are discussed and recommendations given for reporting and control of experimental conditions in fishery research tank experiments.

Journal of Applied Aquaculture↗
USGS1999

Bioenergetics estimate of the effects of stocking density on hatchery production of smallmouth bass fingerlings

Production of and consumption by hatchery-reared fingerling (age-0) smallmouth bass Micropterus dolomieu at various simulated stocking densities were estimated with a bioenergetics model. Fish growth rates and pond water temperatures during the 1996 growing season at two hatcheries in Oklahoma were used in the model. Fish growth and simulated consumption and production differed greatly between the two hatcheries, probably because of differences in pond fertilization and mortality rates. Our results suggest that appropriate stocking density depends largely on prey availability as affected by pond fertilization and on fingerling mortality rates. The bioenergetics model provided a useful tool for estimating production at various stocking density rates. However, verification of physiological parameters for age-0 fish of hatchery-reared species is needed.

Oklahoma↗
USGS2000

Effect of dietary ingredient substition on dorsal fin erosion of steelhead

A feeding trial was conducted to determine the effect of supplementing a diet based on hydrolyzed fish meal with either 6% chitin (as ground krill shell), 6% squid meal, or 200 mg carotenoid pigment (canthaxanthin) per kilogram on dorsal fin erosion in juvenile steelhead Oncorhynchus mykiss. Three hundred fry in triplicate tanks were fed one of the four test diets, and 300 fry in a single tank were fed a commercial trout starter diet. The feeding trial was conducted for 15 weeks at a water temperature of 15°C. Growth was significantly higher ( P < 0.05) for fish fed the diet containing chitin than for those fed other feeds. Dorsal fin index (100 × mean dorsal fin height/total fish length) was similar among fish consuming the hydrolyzed fish meal diets but lower for fish consuming the commercial formulation. Results suggest that removal of bones from fish meal may influence dorsal fin condition in steelhead, perhaps through altered dietary mineral composition or form.

North American Journal of Aquaculture↗
USGS2003

Control of predacious flatworms Macrostomum sp. in culturing juvenile freshwater mussels

Flatworms of the genus Macrostomum are voracious predators on newly metamorphosed juvenile freshwater mussels (Unionidae), which require a fish host to transform mussel larvae into free-living juveniles. Toxicity tests were performed with formalin (paracide-F, 37% formaldehyde) to determine the appropriate levels of treatment for eradicating these flatworms from host fish tanks without adversely affecting the culture of juvenile mussels. Results indicate that a 1-h shock treatment of 250 mg/L formalin or a 3-d continuous exposure to 20 mg/L of formalin kills adult Macrostomum but not fish. Observations indicate that a single treatment is insufficient to kill Macrostomum eggs, so a second treatment after 3 d is necessary to kill newly hatched flatworms. Newly metamorphosed freshwater mussels exposed to similar shock and continuous treatments of formalin were also killed. Thus, all host fish introduced for the purpose of mussel production should be quarantined and treated prophylactically to avoid the infestation of mussel culture systems with predacious flatworms.

North American Journal of Aquaculture↗
USGS1993

Probabalistic projections for recovery of the endangered Cui-ui

The cui-ui Chamistes cujus , a lake sucker found in only Pyramid Lake, Nevada, is listed as endangered under the U.S. Endangered Species Act, and a recovery plan has been formulated in an effort to save it. We used a population simulation model that incorporated environmental stochasticity in water availability to project the persistence of cui-ui over 200 years, Based on this approach, recovery of the species in terms of persistence was evaluated for the existing hydrological situation and for situations involving water supplementation in various amounts. Our calculations indicate that immediate (as of spring 1991) acquisition of 70,000 acre-feet per year of supplemental water to raise levels in Pyramid Lake would have assured recovery and persistence over 200 years with a probability of 0.95. Postponement of acquisition for 3 years followed by incremental increases of 3,000 or 10,000 acre-feet per year would require, respectively, 83,000 and 120,000 acre-feet of annual supplemental water to assure persistence. The approach is applicable to a wide range of species and conditions.

North American Journal of Aquaculture↗
USGS2004

Use of hydrogen peroxide during incubation of landlocked fall Chinook salmon eggs in vertical-flow incubators

Six different hydrogen peroxide treatment regimes were evaluated in a series of three trials with landlocked fall Chinook salmon Oncorhynchus tshawytscha eggs incubated in vertical-flow incubators. Six daily 15-min hydrogen peroxide treatment regimes (1,000 mg/L; 1,000 mg/L with a decrease to 500 mg/L during estimated blastopore formation; 2,000 mg/L; 2,000 mg/L with a decrease to 500 mg/L during estimated blastopore formation; 2,500 mg/L; and 2,500 mg/L with a decrease to 500 mg/L during estimated blastopore formation) were compared with daily 15-min treatments of 1,667 mg/L of formalin. Mortality at egg eye-up and fry hatch and from eye-up to hatch was significantly greater in eggs receiving the 2,500-mg/L hydrogen peroxide treatments throughout incubation and in those receiving 2,500 mg/L hydrogen peroxide with a decrease to 500 mg/L during blastopore formation than in either of the 1,000-mg/L hydrogen peroxide treatment regimes or the formalin-treated eggs in the first trial. No significant differences in mortality were observed among any of the treatments in the subsequent two trials with maximum hydrogen peroxide concentrations of 2,000 mg/L. Fungal infestations were observed primarily in the incubation trays treated at either of the 1,000-mg/L hydrogen peroxide regimens, as well as in those trays whose treatment concentrations were dropped to 500 mg/L during blastopore formation. Infestations were not observed in any of the formalin-treated trays. If minor fungal infestation is acceptable, then daily hydrogen peroxide treatments of 1,000 mg/L for 15 min would probably provide adequate fungal control compared with formalin usage.

South Dakota↗
USGS2004

Dietary uptake of polychlorinated biphenyls (PCBs) by rainbow trout

The presence of detectable levels of polychlorinated biphenyls (PCBs) in commercially produced fish feed has raised a concern about the degree of biomagnification of these contaminants in hatchery-reared trout. Our objectives were to (1) define the relationship between concentrations of PCBs in fish feed and in fish tissue and (2) estimate the relative contributions of feed and hatchery supply water to PCB concentrations in fish. We conducted a 6-month feeding trial with fingerling rainbow trout Oncorhynchus mykiss fed commercial diets with four concentrations of PCBs: a low-PCB diet (69 ng/g); a typical commercial diet (126 ng/g); and the typical diet spiked with PCBs at two levels (220 and 280 ng/g). The concentrations of PCBs in fillets after 1 month were commensurate with those in the feeds and remained relatively stable for the next 5 months; mean PCB concentrations in fillets ranged from 54 to 94 ng/g. Low levels of PCBs were detected in the hatchery supply water. We used the concentrations of PCBs in the feeds, absorption rates of PCBs, and two different rates of PCB depuration to estimate the potential uptake of PCBs from supply water. When we used a low depuration rate (half-life = 219 d), the computed body burdens of PCBs could be entirely attributed to the feeds. When a high depuration rate (half-life = 66 d) was used, some uptake of PCBs from the supply water was likely, but most of the total body burden originated from the feeds. We concluded that rainbow trout fed a diet with 126 ng/g PCBs would have a PCB concentration of about 60 ng/g in their fillets, which is high enough to warrant issuance of a consumption advisory (no more than one meal of fish per week) under a protocol adopted by some Great Lakes states.

North American Journal of Aquaculture↗
USGS2005

Use of prepositioned grid electrofishers for the collection of robust redhorse broodstock

We investigated the potential of prepositioned grid electrofishers as a means of collecting broodstock for the rare robust redhorse Moxostoma robustum. We found that combined with visual observation, this technique allowed for the efficient capture of fish in breeding condition. We were able to harvest eggs in the field and bring only fertilized eggs into the hatchery. There was no need to induce spawning hormonally. Although their use is limited by water depth and clarity, prepositioned grid electrofishers used in conjunction with visual observation warrants further consideration as an effective tool for the collection of reproductively active broodstock for conservation purposes. ?? Copyright by the American Fisheries Society 2005.

North American Journal of Aquaculture↗
USGS2009

Survival and passage of ingested New Zealand mudsnails through the intestinal tract of rainbow trout

We conducted laboratory trials to determine the transit time and survival of New Zealand mudsnails Potamopyrgus antipodarum in the gastrointestinal tract of rainbow trout Oncorhynchus mykiss. To assess the rate of snail passage, we force-fed groups of fish a known quantity of snails and then held them in tanks. At selected intervals we removed individual fish from the test tanks and recorded the number of snails, their condition (live or dead), and their location in the gastrointestinal tract (stomach, anterior intestine, and posterior intestine). Feces were removed from tanks and examined for live snails. We repeated evaluations of passage rate and snail survival to determine the effects of varying the number of snails ingested, fish size, snail size, and feeding a commercial diet to fish after snail ingestion. We plotted and modeled gut evacuation using a stochastic model for ordinal data to consider each test variable. Snail passage rates were faster in fish that were fed smaller snails. Surprisingly, fish fed snails and then administered rations of commercial fish feed retained the snails longer in their stomach than did fish that were not administered fish feeds after being fed snails. Increased retention time of snails in the stomach decreased the probability of snail survival when voided in fecal material. Snails that passed through the gastrointestinal tract within 12–24 h of ingestion were often recovered live in fecal samples. However, no live snails were recovered from the posterior intestine or fecal material collected 24 h after ingestion. Using our results we propose potential management options that could reduce the risks of introducing live snails into new locations when stocking fish from infested hatcheries.

Idaho↗
USGS2010

A minimally invasive method for extraction of sturgeon oocytes

Fishery biologists, hatchery personnel, and caviar fishers routinely extract oocytes from sturgeon (Acipenseridae) to determine the stage of maturation by checking egg quality. Typically, oocytes are removed either by inserting a catheter into the oviduct or by making an incision in the body cavity. Both methods can be time-consuming and stressful to the fish. We describe a device to collect mature oocytes from sturgeons quickly and effectively with minimal stress on the fish. The device is made by creating a needle from stainless steel tubing and connecting it to a syringe with polyvinyl chloride tubing. The device is filled with saline solution or water, the needle is inserted into the abdominal wall, and eggs are extracted from the fish. Using this device, an oocyte sample can be collected in less than 30 s. Such sampling leaves a minute wound that heals quickly and does not require suturing. The extractor device can easily be used in the field or hatchery, reduces fish handling time, and minimizes stress.

North American Journal of Aquaculture↗
USGS2003

An evaluation of selective feeding by three age-groups of the rainbow mussel Villosa iris

A tri-algal diet was fed to three age-groups of the rainbow mussel Villosa iris: ages 2-3 d, 50-53 d, and 3-6 years. Changes in the relative abundance of each algal species were determined in 5-h feeding trials from feeding chambers and by gut content analyses. All age-groups rejected Scenedesmus quadricauda and preferentially selected Nannochloropsis oculata and Selenastrum capricornutum, principally on the basis of size. Changes in the relative abundance of algae in feeding chambers did not differ significantly among age-groups. Observed differences in the ingested quantities of the similar-sized N. oculata and S. capricornutum were attributed to other particle-related characteristics. Results indicate that the rainbow mussel can be fed similar-sized algae at ali ages in captive propagation facilities. When developing a suitable algal diet for rearing juvenile mussels, one probably need not investigate different species at each stage of development if the algae used are in the 2.8-8.5-??m size range.

North American Journal of Aquaculture↗
USGS2004

Cryopreservation of Sperm from the Endangered Colorado Pikeminnow

We developed methods for the cryopreservation of sperm of the endangered Colorado pikeminnow Ptychocheilus lucius. Sperm were collected from a captive broodstock population of Colorado pikeminnow reared and maintained at the Dexter National Fish Hatchery and Technology Center. Our objectives were to (1) evaluate the effects on sperm motility of 24-h storage in Hanks' balanced salt solution (HBSS); (2) characterize sperm motility and duration; (3) examine the relationship between sperm motility and osmotic pressure; (4) examine the effect of four cryoprotectants (dimethyl sulfoxide [DMSO], dimethyl acetamide [DMA], glycerol, and methanol [MeOH] at two concentrations [5% and 10%]) on postthaw motility; and (5) compare the effect of two cooling rates (40??C/ min and 4??C/min) on postthaw motility. The sperm samples diluted with HBSS retained higher motility (mean ??SD, 77 ?? 22%; n = 9) than did undiluted samples (12 ?? 30%; n = 9) after 24 h of storage. When exposed to HBSS at 274 mosmols/kg or more, few sperm became motile (???1%). Exposure to HBSS at 265 mosmols/kg elicited threshold activation (defined as 10% motility), and maximum motility (>95%) was observed at 93 mosmols/ kg. The maximum motility of sperm was observed within 10 s after activation with deionized water, and sperm remained motile for 57 s. The sperm that were cooled at a rate of 40??C/min and cryopreserved with 5% MeOH retained higher postthaw motility (56 ?? 13%) than did sperm cryopreserved with DMSO, DMA, or glycerol (at 5% and 10%). When the sperm samples were cooled at a rate of 4??C/min, sperm cryopreserved with MeOH (5% or 10%) or DMSO (5% or 10%) retained the highest postthaw motilities (???14%). The use of cryopreserved sperm can assist hatchery managers in the production of fish, provide for the long-term conservation of genetic resources, and assist in the recovery of endangered species such as the Colorado pikeminnow.

North American Journal of Aquaculture↗
USGS2003

Efficacy of hydrogen peroxide in controlling mortality associated with saprolegniasis on walleye, white sucker, and paddlefish eggs

The efficacy of hydrogen peroxide in controlling saprolegniasis on eggs of walleye Stizostedion vitreum, white sucker Catostomus commersoni, and paddlefish Polyodon spathula was evaluated at four private, state, and federal production hatcheries participating in an Investigational New Animal Drug efficacy study (experiment 1; walleyes) and in a laboratory-based miniature egg jar incubation system (experiment 2; walleyes, white suckers, and paddlefish). Naturally occurring fungal infestations (saprolegniasis) were observed on eggs in both experiments. Confirmatory diagnosis of infested eggs from one hatchery in experiment 1 identified the pathogen as Saprolegnia parasitica. During experiment 1, eggs were treated daily for 15 min with either 0, 500, or 750 mg/L of hydrogen peroxide, and one trial compared a 500-mg/L hydrogen peroxide treatment with a formalin treatment at 1,667 mg/L. Saprolegniasis infestation was observed in control egg jars, whereas treatment with either formalin or hydrogen peroxide virtually eliminated the infestation. Hydrogen peroxide treatments of 500 mg/L either increased egg hatch or were as effective as physical removal of infested eggs in controlling mortality. Although treatment with formalin at 1,667 mg/L significantly increased the percent eye-up of walleye eggs compared with that of those treated with hydrogen peroxide at 500 mg/L, the difference was only 1.9-2.6%. In experiment 2, noneyed eggs were treated for 15 min every other day with 0, 283, 565, or 1,130 mg/L of hydrogen peroxide until the viable eggs hatched. Saprolegniasis infestation engulfed most control eggs, whereas infestation of treated eggs was either reduced or not visible. Hydrogen peroxide significantly increased egg hatch for all three species tested in experiment 2. Although hydrogen peroxide treatments as low as 283 mg/L significantly increased walleye and white sucker hatch, treatments between 500 and 1,000 mg/L are more likely to be effective in production egg incubation systems.

North American Journal of Aquaculture↗