摘要:

Fundulus grandis, the gulf killifish, was provided a prey choice of grass shrimp, Palaemonetes pugio, and juvenile sheepshead minnows, Cyprinodon variegatus. Fundulus grandis consumed a greater proportion of grass shrimp when both prey species were exposed to the pesticide methyl parathion than when prey were not exposed. The relative number of shrimp eaten increased with the concentration of methyl parathion. Such an effect in an estuary could result in altered species composition and species diversity.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1978)107<87:TEOMPO>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Fish production, biofiltration, and hydroponics were linked in a closed system of recirculating water. Fish tanks were stocked with channel catfish (Ictalurus punctatus) and the fish were fed daily. A revolving plate-type biofilter was used. Three field varieties of tomatoes (Lycopericon esculentum) were planted in outdoor hydroponic tanks. Three production units were operated during the 1976 growing season. All significant water quality variables were monitored. Performance was evaluated in terms of water quality, vegetative and fruit production of the tomatoes, and growth of the fish. Fish survival was high, but growth was below maximum because the temperature in the system was below optimum. The average loading rate of fish for the three units at harvest was 31.5 kg/unit, 489 g/tomato plant, 1.9 kg/m2of hydroponic area, and 691 g/m2of biofilter surface. Excellent water quality was maintained. The biofilter satisfactorily converted the waste to nitrate-N and phosphate-P and the hydroponic system removed these end products from the water. Nutrients were periodically added to supplement the nutrients from fish waste. Tomato yield was approximately twice that either demonstrated or expected in field production of the same varieties, and the hydroponically produced tomatoes were of better quality than the same varieties grown under field conditions.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1978)107<92:UOHTMQ>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

A spaghetti tag for marking juvenile spiny lobsters, Panulirus argus, was evaluated for retention by the lobsters in Biscayne Bay, Florida. Floy FD-68B tags were inserted into the dorsolateral extensor muscle between the cephalothorax and the abdomen. Mean monthly tag loss was 3.8% for 9 months, or about 10% per molt for the first three molts after tagging. These tags effectively marked P. argus as small as 35-mm carapace length for up to 27 months, but for studies of population dynamics they were only useful for about 12 months.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1978)107<100:FEOATF>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

ISSN:0002-8487    

DOI:10.1577/1548-8659(1978)107<104:SS>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Since 1963, the grass carp, Ctenopharyngodon idella Val., has spread to at least 35 states through stockings and subsequent dispersal. Grass carp have been found in several major river systems and in areas near research sites. Further spread of the species will probably occur with increased research and stocking of grass carp for weed control.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1978)107<105:ZOTGCI>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Grass carp (Ctenopharyngodon idella) were present in Missouri waters as early as 1971, and by 1976 were widely distributed in the Missouri, Mississippi, and St. Francis rivers. The few reports of grass carp in other Missouri streams were of specimens taken within a few kilometers of the Missouri River. The commercial harvest of grass carp has increased each year since 1971, and during the first 6 months of 1976 this species comprised 0.8% of the 308,200 kg of commercial fish reported.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1978)107<113:DASOTG>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Information on reproductive requirements of grass carp (Ctenopharyngodon idella Val.) was obtained from published accounts, from a visit to rivers in the USSR where introduced grass carp have reproduced, and from discussions with Soviet fishery workers. Turbulent areas at the confluence of rivers or below dams are the focal points for reproduction. Successful spawning occurs only in large rivers or canals where water velocity exceeds 0.8 m/s and volume is roughly 400 m3/s. The eggs are carried 50 to 180 km, depending on water temperature and current speed. The larvae hatch 1 day after spawning and make their way to vegetated lagoons, impoundments, or lakes closely connected to the river. They begin feeding on rotifers at 2 to 4 days and change to larger zooplankton in about a week. Temperatures required for stimulation of sexual maturation, egg incubation, and survival of young range from 19 to 30 C, with an optimum of about 23 C. Because requirements for each factor must be found in juxtaposition, successful reproduction occurs in only a few locations. Vulnerability to predators further checks population growth, once egg laying occurs. Although successful spawning of escaped grass carp in the United States is predicted, we believe that the resulting populations are likely to be small and to have little environmental impact except in local situations.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1978)107<119:RRALFN>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

An electrophoretic survey was conducted to estimate the amount of genetic variation that was detectable in proteins of grass carp stocks being artifically propagated in the United States. Staining procedures for nonspecific protein and 18 specific enzymes revealed an estimated 49 loci among the five tissues that were examined. The three polymorphic loci identified included the enzymes phosphoglucose isomerase (PGI) and esterase (Est), and the serum protein haptoglobin (Hp). The somewhat low average heterozygosity per locus (0.021) was partially attributed to the fact that four of the five stocks examined were derived from progeny of a single mating. This small common gene pool indicates that these stocks are inbred relative to wild populations and are therefore probably less capable of adapting to suboptimal spawning conditions. The intentional breeding of different homozygous combinations of variant alleles in hatchery stocks is recommended as an effective means of monitoring the spread and the relative contributions of these stocks.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1978)107<129:PSOGC>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Grass carp introductions at Red Haw Lake, Iowa resulted in a decrease of aquatic macrophytes from 2,438 g/m2in 1973 to 211 g/m2in 1976, with species of Potamogeton, Elodea, Ceratophyllum, and Najas all controlled effectively by grass carp. During 1974-1976 mean nitrites, nitrates, biological oxygen demand, and turbidity showed significant decreases, while alkalinity increased significantly from a mean of 115 mg/liter in 1974 to 132 mg/liter in 1976. Mean concentrations of organic and inorganic phosphates gradually increased during the investigation, but were not statistically different. Average primary production was nearly identical in 1974-1975 at about 2 g carbon/m2/day, but decreased significantly to 1.35 g carbon/m2/day in 1976. Growth of stocked grass carp was rapidly increasing from a mean weight of 380 g in July, 1973 to 6,847 g by October, 1976. Body condition ranged from 1.05-2.02 with average condition over 1.37 in October and 1.25-1.30 in January-February. Greatest population biomass was estimated in 1975 at 61 kg/hectare. Grass carp consumed all major plant groups at the lake with greatest selection for Najas and Potamogeton. Movement, behavior, and activity as determined by ultrasonic telemetry showed grass carp inbabited all areas of the lake, but overall there was a preference for sballow areas of the main lake with lesser selection for embayments. Most of the time grass carp were sedentary near weed beds with more rapid and extended movement in midwater. Normal swimming speed in midwater was 0.12-0.35 m/s with maximum speed of 1.46 m/s. Homing tendency was shown in two of nine tagged fish. There was similarity in nocturnal and diurnal activity. Reduction in vegetation biomass by 91% in four years increased the opportunity for anglers to fish from shore. During the investigation popularity of shoreline fishing increased by 241% with catch success remaining greater than 0.70 fish per hour.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1978)107<135:EOBCON>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Ultrasonic transmitters were placed in the peritoneal cavity of twelve adult grass crap in a Florida reservoir. Tagged grass crap ranged in size from 3.68 kg to 12.72 kg. No mortality of tagged grass carp was observed, but some difficulty was encountered with sound reception due to heavy vegetation and thermoclines. Fish took long rest periods between moves during both day and night. They were more active during the day than at night, with water temperatures limiting activity more than any other parameter tested. Displacement ranged from 182.9 m to 18,292.6 m.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1978)107<146:MOGCCI>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor