Waveform Selection for an Electrically Enhanced Seine for Use in Harvesting Channel Catfish Ictalurus punctatus from Ponds

Abstract.— A series of rapid screening trials was used to identify a waveform with the potential to repel channel catfish Ictalurus punctarus away from a seine. Waveforms were not considered effective unless they repelled catfish away from an advancing electrical array without causing electrotaxis, narcosis, or observable injuries. Over 600 varying combinations of waveform types, voltages, pulse frequencies, pulse widths, and pulse sweeps were evaluated in order to select the best waveform for use in constructing an electrically enhanced seine. A number of electrode designs were evaluated to determine the most efficient and effective electrode combination, size, and configuration to use in the screening trials. In studies conducted in concrete vats, harvest efficiencies (the percentage offish present that were captured) greater than 92% were achieved using a low to high frequency waveform with a 6.0–60 Hz sweep and a 2 msec pulse width over a 4 sec sweep time. This waveform was selected for use in the construction of an electrically enhanced seine that will be used in future pond harvest studies.     

Chlorination of Channel Catfish Ponds

Abstract— Laboratory studies with pond water samples revealed that 5 mg/L active chlorine was needed to provide enough chlorine residual to reduce biological activity. Treatment of channel catfish ponds with repeated, 0.1-mg/L doses of active chlorine from calcium hypochlorite at 6- to 8-d intervals, as sometimes done by catfish farmers, had little influence on water quality. Dissolved oxygen, total ammonia-nitrogen, and chlorophyll a concentrations and pH were similar between treated and control ponds. Concentrations of chemical oxygen demand and particulate organic matter were seldom different between treated and control ponds. Channel catfish survival and net production were not improved by chlorine treatment. Thus, chlorination of production ponds during the grow-out period is not a useful technique. Treatment of sediment samples from ponds with up to 1,200-mg active chlorinelkg soil did not reduce bacterial abundance, so chlorination of bottoms of empty ponds may not he an effective disinfection procedure. Chlorination of pond waters with 30-mg/L active chlorine caused complete kill of bacteria 24 h after treatment, although heterotrophic bacteria quickly re-populated the water. Thus, chlorination can be an effective way to disinfect ponds before stocking.     

Refrigerated Storage of Channel Catfish Sperm

Abstract.— Refrigerated storage of sperm is useful for genetic study and artificial breeding of fishes. Due to the potential loss of donor males, storage is important in species such as channel catfish Icralurus punctatus from which sperm cannot be stripped. This study addresses short-term storage (at 4 C) of channel catfish sperm by evaluation of storage methods employed for other species and for cryopreservation of channel catfish sperm. The objectives were to evaluate: 1) storage of intact testes and storage of sperm suspended in an extender solution; 2) use of various storage containers with and without supplemental oxygen; 3) use of extender solution with and without the addition of an antibiotic/antimycotic cocktail; 4) use of extender solution with and without the addition of methanol; and 5) use of extender solution with and without the addition of glucose and methanol. Sperm suspended in extender solution retained motility significantly longer (9 d) than did sperm in intact testis (2 d). Sperm stored in Zip-loc® plastic bags inflated with pure oxygen retained motility significantly longer (12 d) than did sperm stored in Zip-loc® plastic bags without supplemental oxygen (7 d), or sperm stored in plastic beakers (8 d) or test tubes (8 d) without supplemental oxygen. Sperm stored with the addition of antibiotic/antimycotic cocktail or methanol retained motility significantly longer (10–12 d) than did sperm stored without additives (6–8 d). Sperm stored in extender solution without glucose retained motility significantly longer (19–21 d) than did sperm stored in extender with glucose (13–16 d). Motility was retained for as long as 21 d in sperm stored in extender solution with 5% methanol and without glucose. In each experiment, loss of motility was associated with bacterial growth.     

斑点叉尾鮰亲鱼的运输

2000年3月30日,将美国密西西比品系原种斑点叉尾鮰(Ictalurus punctalus)亲鱼,自湖北荆州张家山渔场运往辽宁铁岭三家子渔场.起运亲鱼698尾共1 087kg,经20 h到达目的地,成活率97.9%.     

斑点叉尾(魚回)产业化深加工技术

斑点叉尾(魚回)是从美国引种培育的一种淡水温水性(魚回)科鱼类,在我国已有十多年的养殖历史,具有肉味鲜美、出肉率高、无肌间刺等特点,适宜加工利用.     

Vaccination of Full‐sib Channel Catfish Families Against Enteric Septicemia of Catfish with an Oral Live Attenuated Edwardsiella ictaluri Vaccine

This study evaluated the efficacy of an oral live attenuated Edwardsiella ictaluri vaccine against enteric septicemia of catfish in 20 full‐sib fingerling channel catfish families. The vaccine was delivered orally by feeding fish a diet coated with an attenuated E. ictaluri isolate. Sixty‐nine days postvaccination, control and vaccinated fish were challenged with virulent E. ictaluri and mortality was examined for 21 d postchallenge. Vaccinated fish had significantly lower mortality than nonvaccinated fish following challenge (P < 0.001). Mortality of vaccinated fish was 1.7 ± 1.4% as opposed to 47.8 ± 28.7% in nonvaccinated fish. Relative percent survival ranged from 87.7 to 100% with an average of 95.2 ± 4.0% (±SE) among the 20 families of fish. There were significant differences in mortality among families in nonvaccinated fish (P < 0.01) while there were no differences among vaccinated families of fish. Results indicate that the live attenuated E. ictaluri vaccine is effective at reducing mortality in channel catfish exposed to virulent E. ictaluri. These data demonstrate that genetic differences among healthy families of channel catfish are not major considerations in developing an effective vaccination program utilizing the oral vaccination platform described in this study.     

Folate-Degrading Bacteria in Channel Catfish Feeds

Two "Pseudomonas" spp., designated as PF1 and PF2, were isolated from 147 of 148 channel catfish feed samples and 10 different orgns from anemic and healthy channel catfish, "Ictalurus punctatus." Both PF1 and PF2 are capable of using folic acid as the sole source of carbon and nitrogen, and they hydrolized folic acid to pteroic acid. They did not utilize common carbohydrates. In vitro, the bacteria destroyed over 93% of folic acid in media containing only folic acid and inorganic salts. The morphological and biochemical properties of the bacteria indicate that they are "Pseudomonas" spp. and similar to some other "Pseudomonas" spp. and similar to some other "Pseudomonas" species that utilize folic acid. It is suspected that these folate degrading bacteria are involved in a nutritionally related anemia of cultured channel catfish.     

斑点叉尾鮰主要疾病及其防治概述

分别对斑点叉尾(Ictalurus punctatus)病毒病(CCVD)、肠道败血症(ESC)、柱形病(Columnaris)、“肠套叠”症(Intestinal intussusception symptom)的流行情况、病原体、临床症状、诊断及防治方法进行了综述。     

Enhanced Disease Resistance to Enteric Speticemia in Channel Catfish,Ictalurus punctatus,Administered Lytic Peptide

Lytic peptides have been shown in vitro to be toxic to a wide range of fish bacterial pathogens, including Edwardsiella ictaluri, the causative agent for enteric septicemia. Fingerling channel catfish, Ictalurus punctatus, were challenged with an injection of Edwardsiella ictaluri, and lytic peptide was administered with a single intraperitoneal injection 24 hours later. In a second group, lyptic peptide was also administered by osmotic pump 7 days before the bacterial challenge. A range of peptide concentrations (20-400µg/g fish) was used. Mortalities were recorded for 7 days after injection of bacteria, and E. icraluri was isolated and quantified by standard plate counts from livers. Various tissues were examined for abnormalities due to bacteria and peptide treatment. Fish injected with lytic peptide at 400 µg/g had up to a 95% reduction in bacteria and a 65% reduction in mortality compared to complete mortality in bacteria-injected controls. Fish implanted with osmotic pumps had 99.3% reduction in bacterial counts and had 6% mortality. Tissue samples from infected fish showed changes typical of reaction to immunologic stimuli and infection, while control fish injected with saline or peptide had normal gills, spleens, and kidneys. This study shows the potential for enhancing channel catfish disease resistance to E. ictaluri and other diseases by transferring the gene coding for the lytic peptide into channel catfish.     

斑点叉尾鮰腐皮病的治疗

斑点叉尾鱼回是我国重点推广的名特优水产养殖品种之一,它原产于北美洲。在美国的淡水养殖中占主要地位,我国于1984年从美国引种获得成功。其具有广温性、杂食性、产量高、抗病力较强等优点,受到养殖户的欢迎。但在早春对斑点叉尾鱼回鱼种进行分规格饲养时,如预防措施不当或操作不仔细,极易造成其发生腐皮病并大量死亡。现将2003年3月的一例斑点叉尾鱼回腐皮病诊治情况介绍如下。1　发病情况某养殖场2001年7月至9月从四川省成都购进斑点叉尾鱼回鱼种,2002年3月初越冬结束,苗种生长正常,最大个体达300g/尾,一般在100g/尾左右,成活率在90%…     

Acclimation of Channel Catfish to Environmental Nitrite

Empirical indications that channel catfish ( Ictalurus punctatus ) may acclimate to environmental nitrite were studied in the laboratory. Channel catfish were exposed to 1.31, 2.49, 4.42 or 6.30 mg/L nitrite-N for 15 days. Methemoglobin concentrations in test fish indicated acclimation occurred in the fish exposed to 2.49 and 4.42 mg/L nitrite-N. Acclimation was not observed in fish exposed to the highest or the lowest concentration of nitrite. Fish exposed to 6.30 mg/L nitrite-N also developed anemia. The results indicate that channel catfish do have the ability to acclimate to nitrite and that this acclimation is concentration and time dependent.     

Water Quality and Plankton Communities in Hybrid Catfish (♀ Channel Catfish,Ictalurus punctatus × ♂ Blue Catfish,Ictalurus furcatus) Ponds After Partial Fish Harvest

Twelve 0.4‐ha ponds were stocked with 10,000 hybrid catfish fingerlings in March 2015. Six ponds were partially harvested in August to remove fish larger than ～0.57 kg. All remaining fish were removed in October and November. Partial harvest of faster‐growing fish removed ～26% of the fish initially stocked; feeding rate (and therefore external nutrient loading) was reduced by about the same amount. However, reduced nutrient loading after partial fish harvest had no meaningful effects on water quality, phytoplankton biomass, phytoplankton and zooplankton community structure, or supplemental aeration. Lack of ecosystem change was caused by persistent internal recycling of nutrients added to the system before partial harvest and continued high (albeit reduced) external nutrient loading after partial harvest. Decisions to employ partial fish harvest to manage single‐cropped hybrid catfish ponds should be based on economic considerations and risk reduction rather than the expectation that fish biomass reduction will improve water quality.     

Standardization of Ultraviolet Irradiation of Channel Catfish Sperm

Gynogenesis is a naturally occurring phenomenon in lower vertebrates in which offspring receive two sets of chromosomes from the female (Dawley 1989). This occurs when development is activated by sperm, but genetic material from the male is not incorporated into the embryo. Normally, haploid offspring result that do not survive to hatching, although in certain instances suppression of meiosis II or first mitosis can result in diploid gynogenetic offspring (Purdom 1993). Artificially induced gynogenesis has been used in the breeding and genetic study of several fishes, including salmonids (Chourrout 1982; Allendorf et al. 1986), tilapia (Don and Avtalion 1988), and channel catfish (Liu et al. 1992). Gynogenesis has been applied to production of monosex populations, isogenic populations, and inbred lines of fish (Ihssen et al. 1990; Tave 1993). Gynogenesis can be induced artificially by irradiating sperm with ultraviolet (UV) radiation to inactivate genetic material. Eggs are fertilized with the irradiated sperm and shocked by temperature or pressure change to restore diploidy.     

Use of Cottonseed Meal in Channel Catfish Feeds

Solvent extracted cottonseed meal was substituted for soybean meal in catfish feeds on a nitrogen basis. The feeds, which contained either 0, 10, or 20% cottonseed meal, were formulated to contain about 32% protein and 2.9 kcal digestible energy/g. The fish were reared in 6 m³ net pens suspended in a 1.6 ha earthen pond. Twelve pens (four per treatment) were stocked with 400 fish with an initial average weight of 95 g/fish. All fish were fed to satiation once daily. A sample of 60 fish from each pen was weighed at 76 days to evaluate feed consumption, feed conversion, and weight gain. At the end of the experiment (132 days), fish from each net pen were weighed collectively and samples were taken to determine tissue free gossypol concentrations, proximate composition of fillets, and dressout percentages. There were no significant differences in weight gain, feed conversion, or survival of fish sampled at 76 days or of fish at the end of the experiment regardless of dietary treatment. At 76 days, feed consumption of fish fed the 20% cottonseed meal feed was significantly higher than that of other fish, but there were no significant differences in feed consumption at the end of the experiment. Free gossypol levels were below detectable limits in fish tissue. There were no significant differences in percentage dressout or in body composition, except for a slightly higher ash content in fish fed the feed containing 10% cottonseed meal. It appears that cottonseed meal can be used to partially substitute for soybean meal in catfish feeds. At the present, it is recommended that cottonseed meal be limited to 15% of the catfish diet.     

Coliform Organisms in Waters of Channel Catfish Ponds

Water from 48 channel catfish Ictalurus punctatus ponds at Auburn and Greensboro, Alabama, USA, usually contained less than 1,000 total coliform and 200 fecal coliform bacteria per 100 mL. There were no sources of human fecal matter to ponds. Also, the fecal coliform: fecal streptococci ratio was less than 1.0 and typical of fecal contamination by warm-blooded animals other than humans. The abundance of coliforms was greater in spring and summer than in fall and winter in catfish ponds and sportfish ponds at Auburn, Alabama. In spite of high organic matter inputs in feed, catfish ponds had no greater abundance of coliforms than sportfish ponds.     

Multi-Locus DNA Fingerprinting of Channel Catfish Ictalurus punctatus

Abstract.— Similarities among multi-locus DNA fingerprints of five channel catfish Ictalurus punctatus strains and the ability to identify the strain of a fish based on its fingerprint pattern were investigated. Five restriction enzymes and 13 multi-locus DNA probes were screened to identify enzyme-probe combination useful for DNA fingerprinting channel catfish. Restriction enzymes Hinf I and Dpn II, in combination with probes (CAC)n, (CGC)n, (CTC)n, (ATCC)n, and (GATA)n, produced useful fingerprints (20–30 resolvable bands for each enzyme-probe combination). Thirty individuals (3 pools of 10 individuals each) from each of five channel catfish strains (albino, Mississippi normal, USDA-102, USDA-102 select, and USDA-103) were fingerprinted with all useful enzyme-probe combinations. Band sharing among samples was higher within strains than among strains and band sharing among strains was higher for strains whose breeding history indicated a high degree of relatedness. Individual fingerprints of 18 fish from each of the USDA-102 select and USDA-103 strains revealed no strain-specific bands, but several diagnostic bands (present at high frequencies in either USDA-102 select or USDA-103 strains and at a low frequencies in other strains) were identified. Band sharing at diagnostic bands was used to correctly identify fish as USDA-102 select or USDA-103 strains with 82% accuracy from fingerprints of 17 USDA-102 select strain fish, 18 USDA-103 strain fish, and 38 fish collected from three commercial farms.     

Palatability of Sarafloxacin HCl-Medicated Feed to Channel Catfish

Two experiments were conducted to evaluate the palatability of sarafloxacin HCl to channel catfish, Ictalurus punctatus. Fingerling channel catfish were raised in 110-1 glass aquaria supplied with flowing well water at a rate of 1 l/min. Fish were fed to satiation once daily either a purified or a practical diet formulated to contain 0, 500, 1,000, 2,000, or 4,000 mg active sarafloxin HCl/kg of diet. Feed consumption was quantified daily for 5 days. All fish were weighed at the beginning and at the end of each experiment. There was a significant decrease in feed consumption of fish fed purified diets with increasing levels of sarafloxacin HCl. However, feed consumption was adequate to provide the proposed dosage regardless of drug concentration. Fingerling channel catfish readily consumed practical diets containing sarafloxacin HCl; feed consumption and weight gain of fish fed medicated and non-medicated practical diets did not differ. There were no apparent palatability problems that would negate use of sarafloxacin HCl in commercial channel catfish feeds.