摘要:

AbstractThe induction of tetraploidy was attempted in three intraspecies crosses (autotetraploid) of sal‐monid: chinook salmon (Oncorhynchus tshawytscha), coho salmon (O. kisutch) and rainbow trout (Salmo gairdneri), and in the interspecies hybrid (allotetraploid) coho × Atlantic salmon (Salmo salar).Pressure treatments of 6.2 × 104kPa (9,000 psi) were applied for six minutes at intervals from 50% of the time to cleavage to beyond first cleavage. Analysis of eyed stage embryos via flow cytometry indicated two periods of tetraploid induction existed corresponding to 55–75% and 100–110% of the first cleavage interval (FCI).The effects of different pressures and the times of application were analyzed in a study with rainbow trout. Treatments of 4.8 × 104kPa (7,000 psi) for eight minutes, and 5.5 and 6.2 × 104kPa (8,000 and 9,000 psi) for four minutes, were applied at 65, 78, and 100% FCI. Tetraploids were found in the 5.5 and 6.2 × 104kPa group treatments only when applied at 65% FCI.The results indicate that, while tetraploidy is inducible in salmonids, further experimentation is necessary to discern the appropriate time and treatment for optimal tetraploid induction in ea

ISSN:0893-8849    

DOI:10.1111/j.1749-7345.1986.tb00546.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractTreflan (trifluralin, Elanco) is among the compounds used in the treatment of larval mycosis in penaeid shrimp caused by the phycomycetous fungihagenidiumsp. andSirolpidiumsp. Some culturists have reported treatments for these fungi with trifluralin to be ineffective while others have found it to be quite efficacious.To study losses of trifluralin in seawater systems, experiments were conducted under varying conditions of aeration, lighting, and algal biomass using nominal concentrations of 19.3 to 65.5 ppb trifluralin. There was no detectable loss of trifluralin over a six hour period in seawater mechanically stirred and covered to prevent photodegradation. Under varying conditions of aeration and light, the estimated half‐life of trifluralin ranged from 30 to 138 min. When diatoms were added to the seawater, trifluralin levels dropped to 4% of theoretical within two to three min. These observations confirm the need for a continuous administration for trifluralin to be effective in treating larval mycoses in penaeid shrimp hatching facilitie

ISSN:0893-8849    

DOI:10.1111/j.1749-7345.1986.tb00547.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractThe toxicities of erythromycin, minocycline, malachite green, and formalin to nauplii of the shrimpPenaeus stylirostriswere determined in a static bioassay. Toxicity was assessed on the basis of survival of nauplii after 12 and 24 hours of exposure to the compounds and metamorphosis of the nauplii to protozwa. The results suggested that metamorphosis to protozoea is more susceptible to toxic effects than is naupliar survival. Metamorphosis was either reduced or completely inhibited by lower concentrations of erythromycin, minocycline, and malachite green than was naupliar survival at 12 or 24 hours. Metamorphosis was either reduced or completely inhibited by erythromycin, minocycline, malachite green, and formalin concentrations of 80, 100, 0.08, and 27 mg/ L, respectively. Toxic effects were not observed at erythromycin, minocycline, malachite green, and formalin concentrations of 16, 62.5, 0.016, and 2.7 mg/L, respectively. The results suggest that formalin may be toxic at therapeutic levels frequently recommended for post larvae and older penaeids, but that erythromycin, minocycline and malachite green are not.

ISSN:0893-8849    

DOI:10.1111/j.1749-7345.1986.tb00548.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractAdult red swamp crayfish (Procambarus clarkii) were held in fecal collection chambers and fed common feedstuffs isosubstituted in experimental diets. Apparent dry matter digestibility (ADMD) and apparent crude protein digestibility (ACPD) coefficients were determined by the total collection and indicator (chromic oxide) methods. Feedstuffs tested were menhaden fish meal, soybean meal, alpha‐soy protein, casein, gelatin, wheat bran, rice bran, wheat gluten, shrimp meal, crab chitin, cellulose, squid meal, corn starch and diatomaceous sand. Rate of consumption of plant feedstuffs was generally higher than feedstuffs of animal origin. Consumption of fish meal and shrimp meal was low (0.59 and 0.44% body weightlday, respectively). Fecal chromium concentrations were lower than chromium concentrations of experimental diets and precluded calculation of realistic coefficients by the indicator method. Analysis of refused feed samples indicated that crayfish did not consume the indicator in the same proportion as the remainder of the diet; therefore, the total collection method was judged the better approach to determining digestion coefficients. ADMD and ACPD coefficients of plant feedstuffs were generally higher than coefficients determined for animal feedstuffs. ADMD coefficients indicated substantial carbohydrate digestion by crayfis

ISSN:0893-8849    

DOI:10.1111/j.1749-7345.1986.tb00549.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractStocking of juveniles is widely practiced in marine shrimp production. A simple mechanical device is needed to sort juvenile shrimp by their physical dimensions. By analyzing a sample of 551 commercially producedPenacus stylirostrisjuveniles, ranging from 0.07 to 10.33 g, it was determined that a regression equation of the form Y = (A*X**B)*ccan be used to adequately describe the relationships between weight, width and length. In particular:Weight (g) = 0.01223427*(length. cm)**2.943696 R = 0.989978Width (cm) = 0.6172958*(weight, g)**0.3317764 R = 0.989318Width (cm) = 0.1422887*(length, cm)**0.9808952 R = 0.983662

ISSN:0893-8849    

DOI:10.1111/j.1749-7345.1986.tb00550.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractA 34‐day study was conducted to estimate the effect of stocking density on growth, biomass, and yield of harvestable animals in red swamp crawfish,Procambarus clarkii(Girard). Juvenile crawfish were stocked at l, 2, 4, 8, and 16 crawfish per m2into plastic‐lined metal pools planted with rice (Oryza sativa) with three replicate pools at each density. Crawfish averaged 35 ± 1.5 mm (SE) total length at the time of stocking.Growth in total length and weight was significantly affected by density (P75 mm total length) ranged from 100% at 1 per m2to 0.7% at 16 per m2. Gross revenues per ha were projected for crawfish yields at each stocking density with and without a graded pro

ISSN:0893-8849    

DOI:10.1111/j.1749-7345.1986.tb00551.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractSix isonitrogenous and isoenergetic diets containing graded levels of lipid (menhaden fish oil) were fed to juvenile white crayfish (Procambarus acutus acutus) over a 10 week period. A significant depression in weight gain was observed in crayfish fed diets containing 9% or more lipid. There were no significant differences in growth of crayfish fed diets containing 0 to 6% lipid. Whole‐body percentages of lipid and dry matter decreased, and protein increased in crayfish fed high‐lipid diets. Dietary lipid did not appear to influence survival or molting frequency. Whole‐body lipids generally reflected dietary fatty acid compos

ISSN:0893-8849    

DOI:10.1111/j.1749-7345.1986.tb00552.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractEffective purified and unrefined diets have been developed and evaluated for use in studying the nutrition of lobsters (Homarussp.). A 4‐month growth experiment showed that the purified diets yielded weight increases nearly 80% of that achieved on a live food diet, with concomitant high survival rates. Lower‐cost unrefined diets supported growth over half of that observed on live food diets. Supplementation of a purified diet with an astaxanthin concentrate derived from crayfish waste enhanced growth significantly, and all the diets tested promoted growth and survival with only 0.2% dietary cholesterol.Growth and survival are the most useful criteria for evaluating crustacean diets, but other factors such as proximate analyses of feeds, physical characteristics such as pellet leaching rates, and measurable physiological effects can provide important supplemental information. Our analysis of some of these factors suggests that pellet integrity and resistance to leaching may not be directly related either to growth, or to levels of binder in the di

ISSN:0893-8849    

DOI:10.1111/j.1749-7345.1986.tb00553.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractReported maximum carrying capacities ofTilapia niloticareared in cages are Iow ranging from 10 to 70 kg/m3. This may be related to total numbers of caged fish reared in a body of water and not simply density per cage volume. An experiment was conducted to demonstrate such effects.Sixteen cages in a 0.77 ha pond were stocked withT. niloticaat either 250, 500, 750, or 1,000 fish/cage for a total of 12,987 fish/ha. One cage in each of four 0.13 ha ponds was stocked with either 250 or 1,000 fish/cage for a total of 1,923 or 7,692 fish/hectare, respectively. Fish were fed a 32% protein diet at equal rates for 169 days. In the 0.77 ha pond, yield per cage was positively correlated with stocking density, while individual mean weights were negatively correlated with stocking density. However, among equal densities per cage between ponds, fish in the 0.13 ha ponds gained about 26% more than in the 0.77 ha pond. An interaction of the effects of density per cage volume and per pond area may have occurred.

ISSN:0893-8849    

DOI:10.1111/j.1749-7345.1986.tb00554.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

AbstractAnax junius(Odonata: Aeschnidae) predation on young crawfish,Procambarus clarkii, was measured in the laboratory. Predation rates (0.066–1.16 crawfish/day) were estimated at 25, 15, and 5 C and for two sizes of crawfish (11–20 and 21–30 mm total length). Naiad predation increased with increasing temperature and decreasing crawfish size. At 5 C, naiads had no significant effect on survival of large crawfish but did significantly reduce survival of small crawfish. At 15 and 25 C, predation rates were significantly affected by temperature and prey size. Relative naiad abundance in a 0.8 ha crawfish pond was estimated from September through May. Larger naiads (head width,>6.5 mm; total length,>30 mm) capable of preying on young crawfish were not present until after most crawfish had reached invulnerable sizes. Large naiads, as a result, may not affect crawfish production under normal management condi

ISSN:0893-8849    

DOI:10.1111/j.1749-7345.1986.tb00555.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY