Food and Feeding Habits of Some Fishes in a Dredged Iowa Lake

In the last twenty years, the Iowa State Conservation Commission has dredged a number of shallow prairie lakes to enhance their recreational value. North Twin Lake, Calhoun County, was partially deepened by dredging in 1939. This lake, approximately 569 acres in area, now supports considerable boating, swimming, and fishing. In 1951 the Iowa Cooperative Fisheries Research Unit started a comparative study of the bottom fauna in the dredged and undredged portions of the lake. To determine the degree to which the various bottom organisms were being utilized as fish foods, the food habits of the more important fish species inhabiting North Twin Lake were investigated during the summers of 1953 and 1954

Utilization of Gizzard Shad By Game Fishes

Historically, the gizzard shad\u27s, Dorosoma cepedianum (Le Seuer), role in the management of warm-water sport fisheries has evolved amid considerable controversy. Initially recognized as potential forage for piscivorous species in suitable waters (e.g. see Lagler and Applegate 1943 and Eschmeyer 1944), this species is currently maligned because of its probable competitive effects on desirable species (e.g. see Jenkins 1957), suggested no doubt by its great capacity for attaining and maintaining populations of mass proportions. Prevailing management practices in most areas call for its control if not its elimination (e.g. see Bowers 1955). It is interesting to note that evidence has recently been presented to the effect that under certain conditions at least, the shad\u27s forage potential may be reflected in increased production of desirable species (Schneidermeyer and Lewis 1956)

Early peri-operative hyperglycaemia and renal allograft rejection in patients without diabetes

BACKGROUND: Patients with diabetes have an increased risk for allograft rejection, possibly related to peri-operative hyperglycaemia. Hyperglycaemia is also common following transplantation in patients without diabetes. We hypothesise that exposure of allograft tissue to hyperglycaemia could influence the risk for rejection in any patient with high sugars. To investigate the relationship of peri-operative glucose control to acute rejection in renal transplant patients without diabetes, all patients receiving their first cadaveric graft in a single center were surveyed and patients without diabetes receiving cyclosporin-based immunosuppression were reviewed (n = 230). Records of the plasma blood glucose concentration following surgery and transplant variables pertaining to allograft rejection were obtained. All variables suggestive of association were entered into multivariate logistic regression analysis, their significance analysed and modeled. RESULTS: Hyperglycaemia (>8.0 mmol/L) occurs in over 73% of non-diabetic patients following surgery. Glycaemic control immediately following renal transplantation independently predicted acute rejection (Odds ratio=1.08). 42% of patients with a glucose < 8.0 mmol/L following surgery developed rejection compared to 71% of patients who had a serum glucose above this level. Hyperglycaemia was not associated with any delay of graft function. CONCLUSION: Hyperglycaemia is associated with an increased risk for allograft rejection. This is consistent with similar findings in patients with diabetes. We hypothesise a causal link concordant with epidemiological and in vitro evidence and propose further clinical research

A statistical analysis of subsampling and an evaluation of the Folsom plankton splitter

Subsampling techniques are important for the determination of precise plankton density estimates. A binomial model of random subsampling, and its Poisson extension, were developed for the purpose of evaluating the performance of compartment-type plankton subsamplers. Two approaches were used to assess the performance of the Folsom plankton splitter on an extensive series of nearshore Lake Michigan crustacean zooplankton samples collected between 1974 and 1979. First, Folsom subsamples were observed to be significantly (p < 0.05) more variable than expected from the random model of subsampling. Second, a random effects ANOVA model was used to compare fractions of the total variance in density estimates that were attributable to subsampling and sampling phases of a specially designed study. Departures from randomness in subsampling were sufficiently small that an analysis of optimal allocation of effort between subsampling and sampling phases, based on the ANOVA model, indicated that only one to three subsamples needed to be examined per sample.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42920/1/10750_2004_Article_BF00016403.pd

Fish Bulletin No. 120. Estimating Absolute Age Composition of California Salmon Landings

Drawing valid inferences about parent populations is directly dependent upon the precision or reliability of estimated parameters. Self-evident as this statement is, however, situations frequently arise wherein unwarranted conclusions may be drawn from sample information whose reliability is imperfectly known. Thus it is clear that wherever possible, estimates of any sort should be supplemented with some measure of their precision. This implies, of course, that assumptions underlying any application of modern sampling theory have been reasonably satisfied.The present paper represents an attempt to assess estimates that permit delineating the absolute age structure of fish catches, assuming the appropriate attributes are observed in a manner that at least approximates probability sampling. Such procedure further provides a basis for modifying sampling designs so future estimates derived therefrom will possess some a priori degree of precision imposed in accordance with available manpower and monetary resources.Although specifically concerned with determining age composition of California landings of king salmon, Oncorhynchus tshawytscha (Walbaum), the techniques discussed herein could be applied to other species whose catches are handled in similar fashion. Moreover, they would be appropriate where dealing with any of several attributes commonly descriptive of fish populations. Besides the number of scale annuli, constituting the attribute of interest in the present paper, these include: (1) characteristics defining each kind of fish subject to capture; or, perhaps, for a given kind of fish, characteristics that would identify a member of a particular subpopulation, aggregations of which may comprise a commonly fished stock; (2) any artificially applied "mark"; (3) a particular class of lengths or weights; and, (4) sex.Designed to provide a basis for predicting year-to-year king salmon yield potential, the parent study from which part of my data were selected evolved during the recovery phase of a large-scale salmon marking program. In addition to sampling the California commercial salmon landings for marked fish, it was necessary to sample concurrently for other attributes. During the program's early stages, it was further decided that still others capable of yielding potentially valuable information, viz., length and age, could be sampled incidentally with little added effort and expense. To supplement those secured from the above source, I have used additional data collected during a concomitant study of the ocean sport salmon catch at various points to help develop the methods discussed