Thesis--University of Wisconsin--Madison. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographies.

The focus of this study was to design and evaluate a trapping system that would reduce populations of common carp within water bodies in conjunction with establishment of native aquatic macrophytes founder colonies. A pond study and field study were conducted. A pond study was performed at the Lewisville Aquatic Ecosystem Research Facility, located in Lewisville, Texas, followed by a field study within a constructed wetland located in southern Dallas, Texas. For the pond study, twelve funnel traps were constructed (four reps of each type: control, dual-walled and ring cage). Two anti-escape devices were tested with funnels including steel fingers and hinged flaps. Ring cage and dual-walled treatments were planted using native pondweeds, while controls were left unplanted (additional bait and a drift fence scenarios were also tested). Common carp were introduced into the study pond. Chi-square statistical analyses were utilized and showed ring cage treatments using fingers as well as the use of a drift fence to be most effective. Following completion of the pond study, the two most effective treatments (controls and ring cages) were tested within the Dallas, Texas wetland; no carp were caught during the field test.

The hybrid grass carp, a cross between the male bighead carp (Hypothalmichthys nobilis) and the female grass carp (Ctenopharyngodonidella), was first produced in the United States in 1979 for biocontrol purposes. Unlike the fish produced in 1979 and 1980, the hybrid grass carp spawned in 1981 were assumed to be uniform, triploid, and to have growth and feeding rates comparable to those of grass carp. A comparison study to determine differences in the morphology of the 1979, 1980, and 1981 hybrid grass carp revealed that the hybrid grass carp spawned in 1981 have a longer relative gut length, fewer deformities of the gill rakers, and fewer diploid fish than the previous spawns. In feeding trials, the growth rate of the 1981 hybrid grass carp (2.5 to 3.9 g fish-1 day-1) were similar to that of the 1979 and 1980 fish (2.8 and 3.9 g fish-1 day-1, respectively). In field tests, their mortality rate ranged from 20.8 to 97.4% and was similar to that of other hybrid grass carp. Due to the increased gut length, low feeding rate, and high mortality, the 1981 hybrid grass carp were unable to control (eliminate) the growth of aquatic vegetation in field trials in Blue Lake and in a detention pond which had been treated with herbicide prior to stocking. The 1981 hybrid grass carp has proven to be less effective than previous hybrid grass carp spawns as a biocontrol agent.

In November, 1983, 93 sexually immature and 33 mature grass carp (Ctenopharyngodon idella Val.) were surgically sterilized by clipping the gonaduct or removing a section of the ovaries of testes through a ventral incision between the pelvic girdle and the vent. No mortality occurred from this procedure. After six months (May, 1984), 95.7% of the immature and 100% of the mature grass carp had at least some gonadal tissue regeneration. Fifty-nine percent of the immature fish regenerated a pathway for the eggs or milt to enter the environment. Artificial spawning of the mature female grass carp was 66.7% successful. Over 20,000 fry resulted from the four females that ovulated. Due to the rapid regeneration of functional reproductive tissues, and the extrusion of the viable eggs by surgically altered fish, surgical sterilization was determined to be impractical for producing sterile grass carp for weed control.

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D.Litt et Phil. / Please refer to full text to view abstract

Thesis (M. Sc.)--University of Hong Kong, 1963. / Type-written copy. Includes bibliographical references.

The amylolytic activities of alpha-amylase extracted from Mirror carp (Cyprinus carpio) and Nile tilapia (Oreochromis niloticus) were significantly reduced by purified amylase inhibitor albumin of wheat when tested under in vitro conditions. The action of this inhibitor was rapid and maximum levels of inhibition were attained within 20 minutes. For both carp and tilapia, the enzyme residual activities after inhibition were found to be related inversely to inhibitor concentration and positively to the initial enzyme activity levels. The curvilinear relationships between these parameters were explained by deriving equations of the type: A2 = a+b A1 - c I + d I2 where a, b, c and d are constants, Ai = Initial amylase activity (mU/min), A2 = Residual amylase activity (MU/min), I= Inhibitor concentration as ug protein. Inhibitions were greatest for amylases from gut tissue and ýowest for amylases from gut fluids. 1ug of purified inhibitor was found to contain a potency, to reduce 298 Units of carp gut tissue alpha-amylase and 532 Units of tilapia intestinal tissue alpha-amylase, by 50%. When amylase inhibitor extracted from wheat was incorporated in the feed of carp in its active form for three weeks, it caused a significant reduction in the specific growth rate to only 0.16%/day, while in carp fed autoclaved inhibitort such reduction in growth was not seen and the SGR was maintained at over 1.00%/day. However, despite the presence of active inhibitor in the intestine, the fish were able to maintain alpha-amylase activities in the gut contents at a level similar to that in fish fed denatured inhibitor. This was achieved by hyperactivation of enzyme secretions in the tissues of hepatopancreas and intestine. Hepatopancreas from fish fed active inhibitor exhibited more than two-fold increase in amylase, activity compared to those fed denatured inhibitor. By the third week of the experiment this difference in enzyme activity levels was not apparent but there were also no indications of adaptation or improvement in growth rate. Degenerations in hepatopancreas were also not apparent. Feeding carp with diet containing wheat with its inherent content of inhibitor also caused pancreas hyperactivity and some reduction in growth rate for a short period in comparison to those fish fed autoclaved wheat. In carp, the alpha-amylase activity did not vary depending on the raw or gelatinized nature of starch, both forms elicited equal increases in enzyme activity. However, autoclaving wheat, though effective in inactivating the inhibitor, was found to lower the biological value and digestibility of wheat proteins. Contrary to the result of the carp trials in Nile tilapia, the growth was not significantly reduced by feeding on diet containing active inhibitor and a SGR of 1.57%/day was recorded in comparison to 1.81i/day in tilapia fed denatured inhibitor. Samples of stomach and intestinal contents collected 4 hours after feeding did not reveal the presence of active inhibitor. Apparently the acidic protease, pepsin, in the stomach of tilapia caused the total destruction of the inhibitor in the diet before the contents were passed into the intestinal region. The presence of active amylase inhibitor in tilapia feed did not affect the digestibilities of starch and protein in the diet. Both the groups were able to digest carbohydrates and protein to levels of over 90%. The implications of these results are discussed in relation to feed formulation and fish nutrition.

published_or_final_version / Zoology / Master / Master of Philosophy

Common Carp, (Cyprinus carpio), have long been associated with the degradation of wetlands worldwide. Through their feeding activities they resuspend sediments leading to reductions in the abundance and diversity of submerged macrophytes, and the alteration of water chemistry which can lead to the phytoplankton-dominated state. This study took in Delta Marsh, a freshwater coastal wetland of Lake Manitoba, in Manitoba, Canada. It was the second part of a four-year study in which baseline data were collected in 2001 from ten ponds (1-13 ha) with varying degrees of connectivity to the main marsh and carp-accessibility. I continued to monitor a subset of the control and altered ponds two and three years following their alteration (2003 and 2004); I included new ponds, including one large open bay (20.3 ha). The overall four-year study has shown that the presence of carp is at least partially responsible for the turbid, phytoplankton-dominated state that exists in Delta Marsh, and that carp abundance is an important factor. Ponds previously isolated then exposed to carp activity, particularly in the spring when they were gathered at high densities, shifted to the turbid, phytoplankton-dominated state with few macrophytes, and the removal of carp from ponds led to the clear-water state, though not necessarily an abundance of macrophytes. Due to the complexity of natural ecosystems, the effects of carp were not as predictable as smaller-scale studies would suggest. In my study, water quality, submerged vegetation biomass and algal growth varied both temporally and spatially in carp-accessible and carp-free ponds. Nutrient deficiency among periphyton assemblages was hypothesized to be alleviated by the presence of carp. Using nutrient diffusing substrata, I found that nutrient deficiencies varied from year to year among carp-free and carp-accessible ponds. In 2003 the hypothesis was supported, however, in 2004 two of the carp-free ponds exhibited no-nutrient limitations to periphyton assemblages while N and P co-limitation became prevalent in one carp-accessible pond. Parameters over which there was no control, such as the spatial and temporal distribution of carp, their density within a pond, water depth and unquantified top-down effects, including zooplankton grazing, may have contributed to the variability of the results.