142 research outputs found
Proceedings: Aquaculture Effluents: Overview of EPA Guidelines and Standards and BMPs for Ponds, Raceways, and Recycle Culture Systems
Aquaculture is the production of aquatic organisms, both plant and animal under controlled or semi-controlled conditions. The “controlled or semi-controlled conditions” distinguishes aquaculture from traditional “hunt-and-capture” fishing of wild stocks of marine and freshwater fish, shrimp, and shellfish. The combination of world aquaculture and commercial catches (wild stocks) have grown from 98.6 million metric tons (mmt) in 1990 to 126.2 mmt in 1999, but in 1990 aquaculture was only 13.2% of the total compared with 26.4% in 1999
Pond Culture of Walleye Fingerlings
Walleye, Stitzostedion vitreum, has potential to be an aquaculture species in the North Central Region because: it is native to the region; it maintains optimum growth at temperatures lower than many other current aquaculture species (such as channel catfish); it is a highly-prized sport fish; its flesh is considered a delicacy; and the fillets are high in protein and . low in fat, making walleye an attractive food selection for today’s health conscious consumer
Effect of Relative Volume on Radio Transmitter Expulsion in Subadult Common Carp
Expulsion of surgically implanted radio transmitters is a problem in some fish telemetry studies. We conducted a 109-d experiment to test the hypothesis that variation in relative volume of transmitters surgically implanted in subadult common carp Cyprinus carpio would affect transmitter expulsion. We also necropsied fish at the end of the experiment to evaluate histological evidence for the mechanism of expulsion. Survival rate was high during our experiment; all control fish and 88% of the fish subjected to the implantation surgery survived. Expulsion rate was low; of the 23 fish that received transmitters and survived the experiment, only two (9%) expelled the transmitters. One of these expulsions occurred through a rupture of the incision and the other occurred via the intestine. Retained transmitters were all encapsulated by tissue, and most exhibited multiple adhesions to the intestine, gonads, and body wall. Adhesions were more numerous in fish that received larger transmitters
Seasonal Distribution, Aggregation, and Habitat Selection of Common Carp in Clear Lake, Iowa
The common carp Cyprinus carpio is widely distributed and frequently considered a nuisance species outside its native range. Common carp are abundant in Clear Lake, Iowa, where their presence is both a symptom of degradation and an impediment to improving water quality and the sport fishery. We used radiotelemetry to quantify seasonal distribution, aggregation, and habitat selection of adult and subadult common carp in Clear Lake during 2005–2006 in an effort to guide future control strategies. Over a 22-month period, we recorded 1,951 locations of 54 adults and 60 subadults implanted with radio transmitters. Adults demonstrated a clear tendency to aggregate in an offshore area during the late fall and winter and in shallow, vegetated areas before and during spring spawning. Late-fall and winter aggregations were estimated to include a larger percentage of the tracked adults than spring aggregations. Subadults aggregated in shallow, vegetated areas during the spring and early summer. Our study, when considered in combination with previous research, suggests repeatable patterns of distribution, aggregation, and habitat selection that should facilitate common carp reduction programs in Clear Lake and similar systems
Growth Rate Responses of Missouri and Lower Yellowstone River Fishes to a Latitudinal Gradient
Notropis atherinoides, freshwater drums Aplodinotus grunniens, river carpsuckers Carpiodes carpio and saugers Stizostedion canadense collected in 1996-1998 from nine river sections of the Missouri and lower Yellowstone rivers at two life-stages (young-of-the-year and age 1+ years) were significantly different among sections. However, they showed no river-wide latitudinal trend except for age 1+ years emerald shiners that did show a weak negative relation between growth and both latitude and length of growing season. The results suggest growth rates of fishes along the Missouri River system are complex and could be of significance in the management and conservation of fish communities in this altered system
Movement and Habitat Selection by Invasive Asian Carps in a Large River
We evaluated the habitat use and movements of 50 adult bighead carp Hypophthalmichthys nobilis and 50 silver carp H. molitrix by means of ultrasonic telemetry during spring–summer 2004 and 2005 to gain insight into the conditions that facilitate their establishment, persistence, and dispersal in the lower Illinois River (river kilometer 0–130). Movement and habitat use were monitored with stationary receivers and boat-mounted tracking. The relative availability of four macrohabitat categories (main channel, island side channel, channel border, and connected backwater) was quantified to determine selection; discriminant function analysis was used to evaluate changes in physical characteristics within each category. A flood pulse occurred in spring through early summer of 2004 but not 2005. Movement rates (km/week) of both species were positively correlated with flow but not with temperature. Including data from stationary receivers greatly increased estimates of daily movement. During low summer flow, both species typically selected channel borders and avoided the main channel and backwaters. Both species rarely occupied depths over 4 m, regardless of abiotic conditions. Flood pulses appear to trigger dispersal, while habitat use is only specific during low summer flow. Thus, movement prevention efforts (e.g., dispersal barriers) will require particular vigilance during late-winter or spring flooding, and controlled removal (e.g., harvest) should be directed toward selected habitats during summer
Appraisal of health care: from patient value to societal benefit
Aim: This paper summarizes the deficiencies and weaknesses of the most frequently used methods for the allocation of health-care resources. New, more transparent and practical methods for optimizing the allocation of these resources are proposed. Method: The examples of quality-adjusted life years (QALYs) and efficiency frontier (EF) are analyzed to describe weaknesses and problems in decisions regulating health-care provision. After conducting a literature search and discussions with an international group of professionals, three groups of professionals were formed to discuss the assessment and appraisal of health-care services and allocation of available resources. Results: At least seven essential variables were identified that should be heeded when applying the concept of QALYs for decisions concerning health-care provision. The efficiency frontier (EF) concept can be used to set a ceiling price and perform a cost-benefit analysis of provision, but different stakeholders—a biostatistician (efficacy), an economist (costs), a clinician (effectiveness), and the patient (value)—could provide a fairer appraisal of health-care services. Efficacy and costs are often based on falsifiable data. Effectiveness and value depend on the success with which a particular clinical problem has been solved. These data cannot be falsified. The societal perspective is generated by an informal cost-benefit analysis including appraisals by the above-mentioned stakeholders and carried out by an authorized institution. Conclusion: Our analysis suggests that study results expressed in QALYs or as EF cannot be compared unless the variables included in the calculation are specified. It would be far more objective and comprehensive if an authorized institution made an informal decision based on formal assessments of the effectiveness of health-care services evaluated by health-care providers, of the value assessed by consumers, of efficacy described by biostatisticians, and of costs calculated by economists
The essential oil from Lippia alba induces biochemical stress in the silver catfish (Rhamdia quelen) after transportation
Growth rate responses of Missouri and Lower Yellowstone River fishes to a latitudinal gradient
- …