130 research outputs found

    A Partial Bibliography of Cyprinodon variegatus (Osteichthyes: Cyprinodontidae)

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    A partial bibliography of the sheepshead minnow Cyprinodon variegatus Lacépède, 1803, is presented. Scientific works related to systematics and general biology are listed along with references to recent work involving toxicological bioassays. An extensive search of the literature on parasites of C. variegatus was not conducted

    A Partial Bibliography of Cyprinodon variegatus (Osteichthyes: Cyprinodontidae)

    Get PDF
    A partial bibliography of the sheepshead minnow Cyprinodon variegatus Lacépède, 1803, is presented. Scientific works related to systematics and general biology are listed along with references to recent work involving toxicological bioassays. An extensive search of the literature on parasites of C. variegatus was not conducted

    Green-Water Rearing and Delayed Weaning Improve Growth and Survival of Summer Flounder

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    The advent of an aquaculture industry for summer flounder Paralichthys dentatus requires that optimal methods be identified for hatchery production. Two experiments were conducted to test strategies for larval rearing and for weaning newly metamorphosed juveniles from live to artificial diets. Rearing of larvae in ‘‘green water’’ (with algae added) resulted in better survival (76.1 6 6.5%) from days 5–42 after hatching than did rearing in ‘‘clear water’’ (no algae added; 27.8 6 13.6%), although no differences in growth were apparent. When fish were weaned from live feed beginning at day 45 versus day 57 by either a ‘‘gradual’’ method (7-d weaning period) or an ‘‘immediate’’ method (no weaning period), better survival and growth were obtained with fish weaned at the later age. For both agegroups, fish weaned by the gradual method exhibited better growth, but not better survival, than those weaned by the immediate method. With these data as examples, commercial hatcheries can conduct cost : benefit analyses of the different rearing methods

    Spatial and temporal variation in otolith chemistry for tautog (Tautoga onitis) in Narragansett Bay and Rhode Island coastal ponds

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    The elemental composition of otoliths may provide valuable information for establishing connectivity between fish nursery grounds and adult fish populations. Concentrations of Rb, Mg, Ca, Mn, Sr, Na, K, Sr, Pb, and Ba were determined by using solution-based inductively coupled plasma mass spectrometry in otoliths of young-of-the year tautog (Tautoga onitis) captured in nursery areas along the Rhode Island coast during two consecutive years. Stable oxygen (δ18O) and carbon (δ13C) isotopic ratios in young-of-the year otoliths were also analyzed with isotope ratio mass spectrometry. Chemical signatures differed significantly among the distinct nurseries within Narragansett Bay and the coastal ponds across years. Significant differences were also observed within nurseries from year to year. Classification accuracy to each of the five tautog nursery areas ranged from 85% to 92% across years. Because accurate classification of juvenile tautog nursery sites was achieved, otolith chemistry can potentially be used as a natural habitat tag

    Consumption Rates of Summer Flounder Larvae on Rotifer and Brine Shrimp Prey During Larval Rearing

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    Larval summer flounder Paralichthys dentatus were hatched and reared through metamorphosis in the laboratory. At several points in the rearing cycle, larvae were removed from their rearing chambers and placed in small bowls, where they were fed known quantities of the rotifer Brachionus plicatilis (flounder larvae age 6, 10, or 13 d posthatch) or nauplii of brine shrimp Artemia sp. (flounder larvae age 23, 28, 34, or 47 d posthatch). Counts of prey organisms remaining in the bowls after 24 h allowed us to calculate numbers of prey consumed. Consumption rates increased from 62 rotifers/24 h (6-d larvae) to 301 rotifers/24 h (13-d larvae) and from 59 brine shrimp/24 h (23-d larvae) to 394 brine shrimp/24 h (47-d larvae). These rates can be used to calculate the approximate rotifer and brine shrimp production necessary for rearing summer flounder through metamorphosis in aquaculture hatcheries

    Spatial and temporal variation in otolith chemistry for tautog (\u3cem\u3eTautoga onitis\u3c/em\u3e) in Narragansett Bay and Rhode Island coastal ponds

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    The elemental composition of otoliths may provide valuable information for establishing connectivity between fish nursery grounds and adult fish populations. Concentrations of Rb, Mg, Ca, Mn, Sr, Na, K, Sr, Pb, and Ba were determined by using solution-based inductively coupled plasma mass spectrometry in otoliths of young-of-the year tautog (Tautoga onitis) captured in nursery areas along the Rhode Island coast during two consecutive years. Stable oxygen (δ18O) and carbon (δ13C) isotopic ratios in young-of-the year otoliths were also analyzed with isotope ratio mass spectrometry. Chemical signatures differed significantly among the distinct nurseries within Narragansett Bay and the coastal ponds across years. Significant differences were also observed within nurseries from year to year. Classification accuracy to each of the five tautog nursery areas ranged from 85% to 92% across years. Because accurate classification of juvenile tautog nursery sites was achieved, otolith chemistry can potentially be used as a natural habitat tag

    Replacement of freshwater small-size fish by formulated feed in snakehead (Channa striata) aquaculture: Experimental and commercial-scale pond trials, with economic analysis

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    Traditional snakehead culture in Southeast Asia relies on use of small-size (trash) fish as food, an unsustainable practice. Following development of weaning methods and testing of formulated feed (FF) in laboratory experiments, we conducted feeding trials of FF vs. trash fish (TF) in experimental ponds at Can Tho University (CTU), followed by similar trials on commercial farms in two provinces in Vietnam. CTU pond trials consisted of five treatments (in triplicate), in which TF was replaced by FF in increasing percentages: 0 (control), 25, 50, 75, and 100% replacement of TF by FF (i.e., three treatments had mixed TF/FF diets). Although survival was significantly reduced in the 100% replacement treatment, and growth was significantly reduced in the 75% and 100% replacement treatments, the cost per kg of fish produced was 28–35% less in those high-replacement treatments compared to the 0% replacement treatment. On-farm trials were then conducted at two farms in An Giang and Dong Thap provinces for 6 months with snakehead fed TF only or FF only. At both farms, survival (73–80%) was not significantly different, but growth was significantly better on FF diet at both; however, FF-fed fish at the An Giang farm showed significantly higher levels of abnormal development. Overall production was about twice as high at the An Giang farm as at Dong Thap, but significantly greater production by FF-fed fish vs. TF-fed fish was only seen at Dong Thap. Sensory evaluation by a tasting panel found no difference in product quality between FF-fed fish, TF-fed fish, and a commercial sample bought in the market. Economic analysis indicated that profits were higher for FF-fed fish from both farms, although production costs and sales varied greatly, reflecting market differences in the two provinces

    Managing aquaculture in multi-use freshwater bodies: the case of Jatiluhur reservoir

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    The pressure on scarce freshwater resources from intensifying human activity is rising across the globe. This study presents the case of Jatiluhur - Indonesia's largest reservoir, where unregulated aquaculture expansion has contributed to environmental degradation and associated conflicts with other water-users. Aiming to identify a strategy to improve the sustainability of cage aquaculture within Jatilihur reservoir and other freshwater bodies facing similar challenges, this study consisted of an initial analysis of time bound satellite images of the reservoir and a systematic survey of 112 aquaculture farms. The results revealed that, with more than 45,000 production units in 2020, more than half of which are placed outside government-approved aquaculture zones, the carrying capacity of the reservoir is exceeded. An analysis of the farm-level production practices, pertinent to environmental regulation, indicated the existence of three main production strategies, with significant differences in eutrophication potential among them that would lead to better articulated policy actions. A feed manufacturer-focused policy to reduce total phosphorus levels in formulated diets by more than half, but still within the optimal level for fish performance, would have the most impact. Enforcement of registration and removal of illegal production units supported by satellite-based monitoring of compliance are key recommendations to support intensive cage culture remaining an important economic activity

    Bridging Alone: Religious Conservatism, Marital Homogamy, and Voluntary Association Membership

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    This study characterizes social insularity of religiously conservative American married couples by examining patterns of voluntary associationmembership. Constructing a dataset of 3938 marital dyads from the second wave of the National Survey of Families and Households, the author investigates whether conservative religious homogamy encourages membership in religious voluntary groups and discourages membership in secular voluntary groups. Results indicate that couples’ shared affiliation with conservative denominations, paired with beliefs in biblical authority and inerrancy, increases the likelihood of religious group membership for husbands and wives and reduces the likelihood of secular group membership for wives, but not for husbands. The social insularity of conservative religious groups appears to be reinforced by homogamy—particularly by wives who share faith with husbands
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