摘要:

ABSTRACTIn temperate areas the stocking of small juveniles may be required for pond culture of prawns,Macrobrachium rosenbergii, to be economically attractive. Twelve nursery trials were conducted focused primarily on a two‐phase nursery system. In phase I trials, prawns grew from 0.01 g to 0.2‐0.4 g at densities of 1,194‐6,276 prawns/m2tank bottom during 67–105 days. Estimated survival rates at densities of 1,194‐1,663/m2were comparable after 4, 8, and 12 weeks of culture and averaged 96, 93, and 90%, respectively. At high densities survival rates were substantially lower. in the phase II trials, prawn stocking size varied from 0.09‐0.70 g and density from 538–904/m2. Prawns attained a weight of 0.9‐2.1 g during 42–64 days of culture. Estimated survival averaged 91% after 4 weeks and 84% after 8 weeks. One monophasic or continuous phase trial was conducted at a density of 323/m2. During this 8‐week trial, prawns grew from 0.05 to 1.64 g and exhibited a survival rate of 92%.The biological and economic effect of stocking larger juveniles (1 and 2 g size) was estimated for seasonal pond production of prawns. when 1 and 2 g prawns were stocked in ponds at a density of 43,100/ha, final prawn size increased 13 and 25%, respectively, and total production increased 111 and 208 kg/ha. At stocking density 64,600/ha, harvest size of prawns increased 17 and 27%, respectively, and production increased 183 and 299 kg/ha. Estimated revenues were increased when the additional cost of producing or purchasing these large juveniles was ≤ $15/1,000 for 1 g animals or ≤ $3

ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1983.tb00064.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1983.tb00065.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACTA study was conducted to determine the feasibility of growing the giant prawn (Macrobrachium rosenbergii) in polyculture with channel catfish (Ictalurus punctatus) fingerlings and adults. Nursed juvenile prawns, 0.5‐1 g, were stocked in 18 0.04 ha ponds at 2,500/ha. Eight ponds were stocked with 0.05 g catfish fry at 100,000/ha or 200,000/ha; eight ponds received 13 g catfish fingerlings at 3,700 or 7,400/ha. Two ponds received prawns only as a control. Prawn survival from all ponds averaged 96%, and in no case was survival less than 84%. Prawn survival was not affected by the size or stocking density of catfish. Prawn yields averaged 170 kg/ha after a 107‐day grow‐out period. Overall, males averaged 87±25.3 g and females 55±13.9 g at harvest. Prawn yields and male weight at harvest were independent of catfish stocking size and stocking density. Harvest weight of individual female prawns was affected by catfish treatment. Prawn morphotypic profile was independent of catfish stocking treatment. Average adult catfish survival and yield were 52% and 1,305 kg/ha at the high stocking density, and 51% and 735 kg/ha at the low stocking density. Fingerling catfish survival and yield in fry‐stocked ponds averaged 41% and 963 kg/ha at the high density and 50% and 603 kg/ha at the low stocking densities. Poor catfish performance was not believed to be related to the presence

ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1983.tb00066.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1983.tb00067.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACTSpawning, larval rearing, and settlement ofMytilus californianuswere performed over a one‐year period at the University of California, Bodega Marine Laboratory in northern California. A combination of shell scraping followed by a 30 to 60 min immersion in 30 or 60 mM hydrogen peroxide was the most successful spawning stimulus tested. Larvae fed a diet ofIsochrysis galbanagrew significantly faster than did larvae fedDunaliellasp. Larval growth rate was significantly more rapid at 20°C than at either 14 or 17°C and no significant differences in mortality rates between these three temperatures were detected. At 17 and 20°C, larvae fed a diet of 80Isochrysiscells/μ1 daily grew significantly faster than those fed 20Isochrysiscells/μ1 daily. Mortality of pedi‐veligers was high, but survivors settled and metamorphosed on byssal threads cut from adultM. californianus.Plantigrades had a mean growth rate of 7.8 μm/day between days 15 and 33 following settlement. In this study, a temperature of 20°C, a diet ofIsochrysis galbanaof at least 80 cells/μ1 daily, and a settlement substrate of byssal threads were the most successful conditions for artificial spat production of this potentially valuable biva

ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1983.tb00068.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACTApproximately 100 species of abalone are known to exist in the world and commercial abalone fisheries have been established in at least 6 countries. In Japan, 5 species of abalone provide an annual catch of 5,000 metric tons (whole weight with shell) which sells for 6,000/kg (US$27/kg). To increase productivity of coastal waters, juvenile abalone “seed” (10–30 mm) are produced at government operated Fish Farming Centers. Production has increased from 200,000 seed in 1970 to more than 10.7 million in 1978. Survival of artificially reared abalone from larvae to 20 mm averages 1%. Problems still exist in providing the quality and quantity of food required by postlarvae and older juvenile abalone. Twenty millimeter seed is sold by the farming centers to fishermen at a price of $0.10‐0.12 each, which represents only 1/2 to 1/4 of the production costs. Seed is placed in coastal waters for grow‐out to 11–12 cm in 3–5 years. Recapture rates may exceed 10%. Production costs at the only private abalone hatchery in Japan are estimated to be $0.018/mm of shell length. Based on Japanese methods for seed production, an assessment of production costs for an abalone hatchery in the USA is presented. With an annual production of one million abalone (20 mm each) the production cost is estimated to be $0.022/mm of shell length or $0.44/20 mm abalone. The success of abalone production in the USA will be determined by cost effective hatcheries and a strong market for the aba

ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1983.tb00069.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1983.tb00070.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACTMolluscan mariculture species of interest include four oysters,Crassostrea virginica, C. gigas, Ostrea edulisandO. lurida; four clam species,Mercenaria mercenaria, Tapes japonica, Spisula solidissima, andMya arenaria; blue musselsMytilus edulis, several abaloneHaliotisspp., bay scallopsArgopecten irradiansand queen conchStrombus gigas.The American oysterC. virginicaleads all molluscan species in landings and about 60% or 12.1 million kilograms of total national production in 1981 was a result of some form of culture. This includes state and private planters' efforts to increase harvest. West coast production of the Pacific oyster was 2.9 million kilograms resulting entirely from mariculture in 1981. The most intense oyster cultivation occurs in New England with production of European oysters,O. edulis, from hatchery produced seed and off bottom culture.Mariculture in some form accounted for about 4% of total national landings of 1.8 million kilograms for all species of clams in 1980. The hard clam,Mercenaria mercenaria, presently accounts for just about all clam commercial mariculture production.Blue mussel farming on both the east and west coasts are viable commercial ventures.Several molluscan mariculture programs have as their goal augmentation of natural stocks which have been reduced by loss of habitat and overfishing.

ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1983.tb00071.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACTA pilot study was conducted to evaluate air dried rice hay as a detrital feeding substrate for culture ofMacrobrachium rosenbergii.Six 0.13 ha earthen ponds were stocked with post‐larval prawns at a rate of 30,000/ha on 25 May 1982. Two ponds received rice hay biweekly at 9.8 g/m2/week; two ponds received a pelleted ration 5 days/week at 6.2 g/m2/week, and two ponds received both rice hay at 9.8 g/m2/week and the pelleted ration at 3.1 g/m2/week. “Boom and bust” phytoplankton cycles prevailed in ponds receiving rice hay, and sub‐lethal dissolved oxygen levels resulted in reduced prawn survival in ponds. One hay‐only pond had complete prawn mortality due to a sudden die‐off of an algal bloom. Prawns were harvested 12 October after a 133‐day grow‐out period. Prawn yield from a single hay‐only pond was 439 kg/ha; survival was 97.5% and individuals averaged 15 g. Prawn yield in the pellet‐only treatment averaged 600 kg/ha; survival was 90% and individuals averaged 22 g. Prawn yield in ponds receiving both hay and pellets averaged 427 kg/ha; survival was 48%, and individual prawns averaged 29 g. Rice hay or similar agricultural by‐products may have promise as detrital forage to supplement pelletized rations in prawn culture ponds, but further research is required to quantify optimum loading rates, nutritional contribution, and eff

ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1983.tb00072.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACTA number of commercially available prawn and shrimp diets were tested in situ in response to a Hawaiian prawn industry mandate to conduct such an investigation under experimental conditions. In trial 1, feeds were delivered to juvenileMacrobrachium rosenbergii(initial weight 1.9 g) in cages within a commercial prawn pond. Animals were stocked at a density of 10/m2and fed at a rate of 5% of body weight daily for 10 weeks. There were 5 replicates in each treatment; group weights were taken. Diets varied in ingredients, leading to varying nutrient composition and degree of water stability. There was no statistical difference among 4 diets in promoting the highest average prawn gain of approximately 9 g. However, one of the 4 diets gave the highest increase in biomass (approximately 80 g). Best growth was seen on 27% protein/low water stability ration, followed in order by more water stable feeds of 41%, 28% and 44% protein. To evaluate the effect of water stability of different quality feeds on prawn production, trial 2 tested 3 commercial aquatic feeds in two forms each: 1) bound and water stable, and 2) unbound and less water stable. Fifty‐fifty combinations of the feeds in the two forms were also used. The trial was conducted as described in trial 1. There was no difference in growth of prawns fed bound or unbound forms of a given diet, nor among those fed the 3 types of feed. Results are applicable to animals of this size, reared in cages at this standing crop and fed at this rat

ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1983.tb00073.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY