摘要:

AbstractShrimp maturation and reproduction has long been one of the hurdles that must be surmounted to make shrimp farming commercially feasible. Nauplii are now successfully being produced and the commercial feasibility of their production is investigated in this study. The generalized budget simulation model for aquacultural facilities recently developed at Texas A&M University was used for the analysis.An annual budget was estimated to determine costs, returns and profit. Annual cash flow was generated for a 10‐year planning horizon. Opportunity cost, initial investment, costs and break‐even quantities and prices were also determi

ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1981.tb00247.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractWhite sturgeon juveniles were raised for 10 months posthatch under various regimens of feeding, water temperature, and stocking density. Transition to external feeding in larvae occurred 9 to 11 days posthatch and was accompanied by major changes in allometric growth and larval behavior. Condition factor, hepatosomatic index, and survival rate varied significantly throughout the rearing period in the 4 progenies investigated. Growth in body weight for all progenies was largely dependent on water temperature and feeding. On the average, fingerlings raised on natural diets (brine shrimp and tubifex, followed by ground fish) grew 6% of their body weight per day, whereas fingerlings fed artificial pelleted diets (Oregon Moist Pellets) or a mixture of pelleted and natural feeds grew 1–4% per day. Certain individuals (20% of population investigated), however, established a strong feeding performance on artificial diets and exhibited twice the growth rate of fish raised on natural diets; these fish reached a mean body weight of 282 g at 10 months post‐hatch. Assuming more efficient procedures are developed for weaning this fish onto artificial diets, the white sturgeon has demonstrated a potential for use in intensive grow‐out sy

ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1981.tb00248.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractHeretofore few quantitative studies on the tolerance of red drum (Sciaenops ocellataLinnaeus) to freshwater (FW) or dilute sea water have been conducted. In the laboratory we subjected larval and juvenile stages of red drum to dechlorinated FW for 96 hours and found 5% survival in larvae (23‐day‐old, 6.2 mm SL), 70% for postlarvae (34 and 47‐day‐old, 16.2 mm to 19.7 mm SL) and 95% for juveniles (57‐day‐old, 56.9 mm SL). Survival in control salinities of 10 ppt was 90% or greater. The results indicate that tolerance to dilute media is size dependent.In a separate experiment growth of juvenile red drum (52 mm SL) over a 30‐day period was compared in two raceways with flow‐through supplies of dechlorinated FW, and SW of ambient (35±2 ppt) salinity. SW fish grew significantly larger (P20 mm SL) red drum promote the feasibility of this valuable sport and commercial species in both FW and SW aquaculture. Its potential as a control fish in FW fishery management deserves furth

ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1981.tb00249.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractFirst and second generation (F1and F2), laboratory reared juvenile Coryphaena hippurus were used in preliminary growth studies. Fish were stocked in circular tanks and fed a diet of chopped herring and squid. Initial size and age of fish used in these studies were as follows: 61 mm TL, 1.6 g, and 45 days old for F1and 87 mm TL, 5.95 g, and 65 days old for F2. Mean size at 130 days of age was 560 mm TL and 1,305 g for F1and 540 mm TL and 1,150 g for F2. Food conversion ratios were 3.05 and 2.9 4 for F1and F2fish, respectively.

ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1981.tb00250.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractStandard accounting procedures in ecological energetics would approach the carrying capacity problem by attempting to quantify gross energy needs of a cultivated population and comparing these with “available” energy (seston) flow through the culture area. Inability to distinguish between “available” and “utilizable” particles is only one of several difficulties encountered in formulating energy budgets for large‐scale cultivation in natural waters, however. A model based on maintaining critical levels of particle flow through culture areas is offered as an alternative. This approach reduces the problem to terms which are easier to obtain than those involved in equations of energy flow. Application of the model depends on a priori knowledge that seasonal patterns in seston composition and other environmental conditions are conducive to growth of the culti

ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1981.tb00251.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractThe purple‐hinge rock scallop is receiving increasing interest as a candidate for commercial mariculture. Hatchery culture of juveniles is prerequisite since natural recruitment of juveniles is variable and not dependable as a source of stock. Success in carrying larvae through metamorphosis has been limited. Critical to larval culture is a sound understanding of optimal food and feeding strategies.Growth and survival were examined in early larvae fed six algal diets at four separate concentrations. The data clearly illustrate the superiority of bothIsochrysis galbanaand a Tahitian (T) strain ofIsochrysis.Feed concentrations of 1 × 105cells/ml were found to be optimal for these species ofIsochrysis.AnI. galbanadiet supported 80% survival through metamorphosis. The other algae examined includedMono‐chrysis lutheri, Rhodomonassp.,Carteria pallida, and a 1:1:1 mixture ofRhodomonas, Monochrysis, andIsochrysis.All these diets supported 5–6% survival, and the growth was only slightly better than starvation controls.A similar study was done with early juveniles (1 mm dia). The diets included:I. galbana, M. lutheri, Thalassiosira pseudonana(3H), T‐Isochrysissp., andPhaedactylum tricornutum.As with the larvae, superior growth and survival occurred with diets of both species ofIsochrysis.Cell concentrations between 1 × 105and 2 × 105cells/ml were optimal. The other diets supported minimal growth. In the feeding runs of both larvae and early juveniles, cell densities in excess of 5 × 105cells/ml were

ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1981.tb00252.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractLarvae and juveniles of the green abalone grow and survive well at temperatures in the range 20–28°C. A program of hatchery research with this species utilizing thermal effluent has been in progress since 1979 at the Redondo Beach Electric Power Facility, Southern California Edison Company. All life stages may be cultured in the effluent seawater with temperature regulation by admixture of ambient seawater when required. Using thermal effluent, growth rates of juveniles are increased by a factor of 1.5–2.0 over those reared at ambient temperatures (14–20°C) characteristic of southern California. The time to harvest for seed 1–2 cm is reduced from about one year to six months.While optimal temperatures for larvae and postlarvae fall in the range 20–24°C, juveniles are more broadly tolerant of heat and exhibit a growth optimum in the range 24–28°C. The upper lethal limit for juveniles is 31.5°C (LD50, 48 hours). Postlarvae, juveniles and adults have exhibited no indications of unfavorable conditions in power plant effluent.Young adults at 1.5 years (4–5 cm) became reproductively mature and yielded viable larvae. Both hatchery‐reared and wild‐caught adult green abalone were conditioned to spawning readiness during winter months (natural period, spring‐fall) when held in a mixture of effluent and ambient seawater at 20–24°C.Progeny from this research were provided to the California Department of Fish and Game for release in experimental plants. Approximately 30,000 juvenil

ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1981.tb00253.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractResults from both previous and ongoing investigations on hard clam culture in South Carolina indicate a reasonable commercial potential for intensive clam culture on an industrial scale. To assess this potential and provide an appropriate economic feasibility analysis, the State of South Carolina, in cooperation with private industry and the U.S. Office of Sea Grant, has established a demonstration scale hard clam culture project near Charleston, S.C. The project operates on a two‐stage grow‐out protocol: raceways are used to provide initial grow‐out (to 10 mm) and allow acclimation and disease monitoring for imported seed; final grow‐out is accomplished in field units which provide protection from predators and substrate for support and orientation. Seed clams ranging in size from 300 μ to 10 mm are imported from commercial hatcheries, held in the raceway system for growth and observation and transferred to field units as they acclimate or attain minimum field planting size. Using this protocol, over 2.7 million seed are being planted in South Carolina estuaries over a 13‐month period (October 1980‐October 1981). Field units are stocked at three densities, 2,150, 4,300, and 6,450 m‐2, using both intertidal and floating (raft) formats and a variety of substrates (crushed granite, chromium oxide slag, coarse sand, etc.). Units are sampled monthly to determine growth and survival, and these data are correlated with coincidental monitoring of various environmental parameters (temperature, salinity, particulate, dissolved, and total organic carbon, chlorophylla, and turbidity). This paper reviews results to date and provides descriptive data concerning the raceway system, field units, and sup

ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1981.tb00254.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractLarvae and early postlarvae of the ocean quahog,Arctica islandica, were reared under experimental hatchery conditions. Mature eggs were stripped from ripe adults and exposed to a dilute solution of ammonium hydroxide for various lengths of time prior to addition of stripped sperm. The larval clams were reared through settlement and metamorphosis using the Wells‐Glancy (centrifuged, incubated seawater) method of algal culture and/or modifications of standard hatchery techniques developed by Loosanoff and Davis. Experimental cultures were maintained at various temperatures ranging from 8.5° to 14.5°C. At temperatures of approximately 13°C, the minimum time to settlement was 32 days, while settlement was not observed in a culture maintained between 8.5° and 10.0°C until approximately 55 days after fertilization. Larval growth rates were significantly lower in the culture maintained at 8.5–10.0°C than in cultures maintained at 11.0–14.5°C. An optical micrograph sequence of larval stages from the straight‐hinge stage through metamorphosis is presented to facilitate identification ofArctica islandicaspecimens isolated from plankton samples. While various workers have reported exceedingly low growth rates of juvenile and adultArctica, growth rates of larvalArcticaappear to be fairly “typical” of rates encountered within

ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1981.tb00255.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractA variety of natural foods have been reported to induce ovarian maturation of penaeid shrimp. In this study, conducted from 19 June to 11 September 1980, four single‐food diets (clams, shrimp, squid, and worms) and one composite diet consisting of all four foods were fed toPenaeus vannameiin 3.7‐m diameter indoor circular tanks. The shrimp, averaging 28 g, were stocked at a rate of 6.9 m‐2with a 1:1 male to female ratio. Unilateral eyestalk ablation was performed on half of the females in each tank. Tanks received one turnover of water volume daily and the water temperature and salinity averaged 27.0°C and 28.6 ppt, respectively. Daily photoperiod was maintained at 13 hours of light. Ovarian maturation, spawning, molting rate, and survival were monitored daily and growth and gonad size were measured at termination. The composite diet was the best overall diet, while squid was the best single‐food diet, followed by shrimp, worms, and clams. No maturation of unablated females was observed with the exception of one female that developed to stage 3. Although the size of the shrimp was considered marginal for spawning, 5 mated females were observed, but only one (squid treatment) produced viable nauplii. After termination of this study, all shrimp were fed the composite diet for 41 days. During this period, ovarian maturation and spawning occurred in the previously unproductive treatment receiving only clams, and growth rate of shrimp in all previously single‐food treatments increased 4 to 7 fold. The composite diet was also fed to two tanks ofP. stylirostris(mean initial weight = 45.4 g) for a period of 118 days. During that time, 50 spawns were obtained with up to 3 spawns per female. A total of 4.3 × 105P. stylirostrisnauplii we

ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1981.tb00256.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY