Bias Associated with Using the Eggers Model for Estimating Fish Daily Ration

1991 ◽  
Vol 48 (6) ◽  
pp. 1100-1103 ◽  
Author(s):  
Robert S. Hayward
Keyword(s):  
Yellow Perch ◽  
Perca Flavescens ◽  
Sampling Interval ◽  
Positive Bias ◽  
Daily Ration ◽  
Multiple Sources ◽  
Normalizing Transformation ◽  
Sampling Intervals

Estimates of yellow perch (Perca flavescens) daily ration derived from Eggers' model were compared with those based on the Elliott–Persson model and a 3-h within-day sampling interval. Correcting for the bias in Eggers estimates associated with food weight differences at the start and finish of estimation periods significantly reduced discrepancies between the two when Eggers estimates were also based on a 3-h sampling interval. As sampling interval was increased to 6 and 12 h for Eggers estimates, a positive bias related to variability about [Formula: see text] emerged and inflated exponentially with increasing ration levels. A third bias (typically positive) may be introduced when [Formula: see text] in Eggers' model is computed without regard to the skewness that often exits in distribution of food weights among fishes within a single collection. Use of the median or a normalizing transformation will avert this. While each bias alone can have an important effect on daily ration estimates, the possibility of accentuated bias from multiple sources also exists. Two of the potential biases are easily managed, but caution is advised when Eggers' approach is used to estimate daily rations based on expanded sampling intervals.

Daily Ration of Yellow Perch (Perca flavescens) from Lake Memphremagog, Quebec–Vermont, with a Comparison of Methods for In Situ Determinations

1978 ◽  
Vol 35 (12) ◽  
pp. 1597-1603 ◽  
Author(s):  
Brian S. Nakashima ◽  
William C. Leggett
Keyword(s):  
Body Weight ◽  
Body Size ◽  
Yellow Perch ◽  
Diet Composition ◽  
Seasonal Pattern ◽  
Feeding Activity ◽  
Perca Flavescens ◽  
Complex Method ◽  
Daily Ration

In situ estimates of daily ration for yellow perch (Perca flavescens) range from a high of 5.5–6.7% body weight in July to a low of 2.2–2.4% body weight in October. The seasonal pattern corresponds well to known patterns of growth. Comparison of three methods for in situ determination of daily ration levels indicated the method outlined here and the more complex method of Thorpe yield similar results. The method of Keast and Welsh and derivatives of this method which correct for digestion between sampling periods give unreliable values that are 50% below the other two and, in general, are below maintenance ration levels. Diet composition and feeding activity varied seasonally and with body size. Key words: body size relationships, diet composition, seasonality

An In Situ Experimental Evaluation of the Elliott and Persson and the Eggers Models for Estimating Fish Daily Ration

1988 ◽  
Vol 45 (1) ◽  
pp. 138-145 ◽  
Author(s):  
D. Boisclair ◽  
W. C. Leggett
Keyword(s):  
Confidence Intervals ◽  
Experimental Evaluation ◽  
Yellow Perch ◽  
Perca Flavescens ◽  
Sampling Frequency ◽  
Daily Ration ◽  
Fish Feeding ◽  
Feeding Periodicity ◽  
Sampling Event

We compared estimates of daily ration developed using the theoretically rigorous and logistically demanding Elliott and Persson model and the more easily applied Eggers model which is infrequently used because of its assumptions about rigid fish feeding periodicity. Comparisons were based on ten 24-h samplings of six different yellow perch (Perca flavescens) populations. Daily ration estimates from the two models did not differ significantly. This consistency occurred in spite of the fact that in some cases the observed feeding periodicity violated the assumptions of the Eggers model. A simulation model demonstrated that 95% confidence intervals were smallest for the Eggers estimates and that the Eggers model was more robust than the Elliott and Persson model to changes in both sampling frequency and number offish sacrificed at each sampling event. The latter proved particularly sensitive to changes in sampling frequency. We concluded that the two models provide estimates of daily ration comparable in magnitude and accuracy and consequently that the restriction of the Eggers model to fish with rigid feeding periodicity is not justified. Furthermore, the Eggers model, because of its robustness, reduces the sampling requirements to determine daily ration, and hence, permits its estimation on a more frequent basis.

Comparison between consumption rates of yellow perch (Perca flavescens) estimated with a digestive tract model and with a radioisotope approach

2000 ◽  
Vol 57 (12) ◽  
pp. 2547-2557 ◽  
Author(s):  
Jérôme Gingras ◽  
Daniel Boisclair
Keyword(s):  
Digestive Tract ◽  
Time Scale ◽  
Half Life ◽  
Yellow Perch ◽  
Perca Flavescens ◽  
Sampling Interval ◽  
Interval Length ◽  
Consumption Rates ◽  
Time Periods ◽  
Relative Differences

We compared consumption rates of yellow perch (Perca flavescens) obtained from surveys of complete digestive tract contents (CDTC) with two radioisotope approaches using 137Cs as a biological tracer. We sampled fish of age 1+, 2+, and 3+ from three lakes for a total of six lake - age-class combinations. The two radioisotope methods provided very similar estimates of consumption rates. The relative differences between the CDTC approach and the radioisotope approaches ranged from 67 to 128% when the sampling interval length was 28-35 days. At the time scale of 70 days, the relative differences between the approaches ranged from 15 to 20%. We propose that the ratio of the sampling interval length to the biological half-life of the contaminant determines the discrepancy between consumption estimates obtained using CDTC and radioisotopic approaches. Our analyses suggest that, under the specific conditions encountered in our study, a minimum value for this ratio to obtain adequate consumption rates may be 45%. Although our work represents a corroboration of the radioisotope approach in systems where 137Cs is present at trace levels, it also suggests that consumption rates obtained for time periods shorter than 70 days should be interpreted with caution.

Low-effort regression estimation of daily ration in young walleye, Stizostedion vitreum

1998 ◽  
Vol 55 (9) ◽  
pp. 2058-2066 ◽  
Author(s):  
Sharook P Madon
Keyword(s):  
Regression Model ◽  
Confidence Intervals ◽  
Yellow Perch ◽  
Sampling Interval ◽  
Stizostedion Vitreum ◽  
Daily Ration ◽  
Point Estimates ◽  
Wet Weight ◽  
The Mean ◽  
Predicted Values

I used a low-effort regression approach to estimate daily rations of pond-reared age 0 walleye, Stizostedion vitreum (16.0-37.2 mm total length). The regression model predicted average 24-h food mass () from two or three consecutive point estimates of food mass (Ft) in fish guts taken at a sampling interval of 3 h. Predicted values were multiplied by gastric evacuation rates and by 24 h to yield daily ration estimates. Accuracy tests of the low-effort regression model for age 0 walleye based on resampling revealed that 93-100% of predicted values fell within 2 SEs of observed values determined from nine fish collections over 24 h. The age 0 walleye regression model provided estimates of daily ration that were within the 95% confidence intervals around observed daily ration values for conspecifics in an independent test pond (this study) and in other distinct pond systems. The age 0 walleye regression model also provided estimates of daily ration that were within the 95% confidence intervals around five out of seven observed daily ration values for age 0 lake yellow perch, Perca flavescens, also a diurnal feeder like walleye. The model reliably provided estimates of daily ration for fish that were 1.5-4.5 times the mean wet weight of the largest fish included in the model's domain.

scholarly journals Cerebral CT Perfusion in Acute Stroke: The Effect of Lowering the Tube Load and Sampling Rate on the Reproducibility of Parametric Maps

Diagnostics ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1121
Author(s):  
Georgios S. Ioannidis ◽  
Søren Christensen ◽  
Katerina Nikiforaki ◽  
Eleftherios Trivizakis ◽  
Kostas Perisinakis ◽  
...  
Keyword(s):  
Cerebral Blood Volume ◽  
Ct Perfusion ◽  
Sampling Rate ◽  
Volumetric Analysis ◽  
Sampling Interval ◽  
Diagnostic Efficiency ◽  
Temporal Sampling ◽  
Sampling Intervals ◽  
The Mean ◽  
Parametric Maps

The aim of this study was to define lower dose parameters (tube load and temporal sampling) for CT perfusion that still preserve the diagnostic efficiency of the derived parametric maps. Ninety stroke CT examinations from four clinical sites with 1 s temporal sampling and a range of tube loads (mAs) (100–180) were studied. Realistic CT noise was retrospectively added to simulate a CT perfusion protocol, with a maximum reduction of 40% tube load (mAs) combined with increased sampling intervals (up to 3 s). Perfusion maps from the original and simulated protocols were compared by: (a) similarity using a voxel-wise Pearson’s correlation coefficient r with in-house software; (b) volumetric analysis of the infarcted and hypoperfused volumes using commercial software. Pearson’s r values varied for the different perfusion metrics from 0.1 to 0.85. The mean slope of increase and cerebral blood volume present the highest r values, remaining consistently above 0.7 for all protocol versions with 2 s sampling interval. Reduction of the sampling rate from 2 s to 1 s had only modest impacts on a TMAX volume of 0.4 mL (IQR −1–3) (p = 0.04) and core volume of −1.1 mL (IQR −4–0) (p < 0.001), indicating dose savings of 50%, with no practical loss of diagnostic accuracy. The lowest possible dose protocol was 2 s temporal sampling and a tube load of 100 mAs.

Survival to hatching of fishes in sulfate-saline waters, Devils Lake, North Dakota

1995 ◽  
Vol 52 (3) ◽  
pp. 464-469 ◽  
Author(s):  
Todd M. Koel ◽  
John J. Peterka
Keyword(s):  
North Dakota ◽  
Sodium Sulfate ◽  
Yellow Perch ◽  
Hatching Success ◽  
Perca Flavescens ◽  
White Sucker ◽  
Catostomus Commersoni ◽  
Devils Lake ◽  
Common Carp Cyprinus Carpio ◽  
Species Survival

Laboratory-based bioassays were conducted to determine concentrations of sodium-sulfate type salinities that limit the hatching success of several fish species. Survival to hatching (SH) was significantly lower (P < 0.05) in sodium-sulfate type waters from Devils Lake, North Dakota, of ≥ 2400 mg/L total dissolved solids (TDS) than in fresh water of 200 mg/L. In waters of 200, 1150, 2400, 4250, and 6350 mg/L TDS, walleye (Stizostedion vitreum) SH was 41, 38, 7, 1, and 0%; northern pike (Esox lucius) SH was 92, 68, 33, 2, and 0%; yellow perch (Perca flavescens) SH was 88, 70, 73, 0, and 0%; white sucker (Catostomus commersoni) SH was 87, 95, 66, 0, and 0%; common carp (Cyprinus carpio) SH was 71, 69, 49, 63, and 25%.

Metabolic Stores of Yellow Perch (Perca flavescens): Comparison of Populations from an Acidic, Dystrophic Lake and Circumneutral, Mesotrophic Lakes

1992 ◽  
Vol 49 (12) ◽  
pp. 2474-2482 ◽  
Author(s):  
Jay A. Nelson ◽  
John J. Magnuson
Keyword(s):  
Yellow Perch ◽  
Egg Production ◽  
Glycogen Content ◽  
Physiological State ◽  
Perca Flavescens ◽  
Population Level ◽  
Seasonal Effects ◽  
Life History Strategies ◽  
Dystrophic Lake ◽  
Lipid Contents

Little is known about the animals that occupy naturally acidic habitats. To better understand the physiological state of animals from temperate, naturally acidic systems, we compared metabolite stores and meristics of two yellow perch (Perca flavescens) populations in northern Wisconsin. One population originated from a naturally acidic, dystrophic lake (Acid-Lake-Perch, ALP) and had previously been shown to have enhanced tolerance to low pH. The second population came from two nearby interconnected circumneutral, mesotrophic lakes (Neutral-Lake-Perch, NLP). Perch were collected throughout the year to account for seasonal effects and to discern whether patterns of metabolite utilization differed between populations. ALP had smaller livers containing less glycogen and greater muscle glycogen content than NLP. The ALP also had significantly greater liver and visceral lipid contents, and females from this population committed a greater fraction of their body mass to egg production. We interpret these results as indicative of physiological divergence at the population level in yellow perch. These results are discussed as possible products of H+ -driven changes in metabolism and as possible products of different life history strategies between populations. Our results also show that perch living in acidic, dystrophic Wharton Lake are not acid stressed.

Walleye (Stizostedion vitreum vitreum) and Yellow Perch (Perca flavescens) Populations and Fisheries of the Red Lakes, Minnesota, 1930–75

1977 ◽  
Vol 34 (10) ◽  
pp. 1774-1783 ◽  
Author(s):  
Lloyd L. Smith Jr.
Keyword(s):  
Growth Rate ◽  
Yellow Perch ◽  
Climatic Factors ◽  
Perca Flavescens ◽  
Growing Season ◽  
Commercial Fishery ◽  
Class Strength ◽  
Parent Stock ◽  
Catch Statistics

In an investigation of the commercial fishery of Red Lakes, Minnesota, for the 46-yr period 1930–75, catch statistics were analyzed, and the dynamics of the perch and walleye populations were examined. Mean annual yields of walleye for two statistical periods, 1930–53 and 1954–75, were 309,900 and 245,100 kg, respectively for walleyes, and 96,400 and 109,500 kg for perch. Annual abundance (CPE based on average catches per day per 5-net units of gill nets) varied from 3.8 to 64.6 kg for walleye, and from 2.5 to 34.4 kg for perch. Causes of fluctuations in harvestable stock were directly related to strength of year-classes and to growth rate during the season of capture. Year-class strength was not related to the abundance of parent stock or of potential predators. The respective strengths of year-classes of perch and walleye in the same year were positively correlated (r = 0.859, P < 0.01), and are directly related to climatic factors. Growth rate of walleye in different calendar years varied from +30.7 to −42.2% of mean growth, and that of perch from +13.4 to −8.6% (1941–56). Growing season began in mid-June and was almost over by September 1. Walleye yield could be enhanced by starting harvest July 1 instead of early June. Perch yield could be improved by harvesting small perch. Key words: Percidae, Perca, population dynamics, Stizostedion, long-term yield

Zebra mussel (Dreissena polymorpha) effects on sediment, other zoobenthos, and the diet and growth of adult yellow perch (Perca flavescens) in pond enclosures

1997 ◽  
Vol 54 (8) ◽  
pp. 1903-1915 ◽  
Author(s):  
S A Thayer ◽  
R C Haas ◽  
R D Hunter ◽  
R H Kushler
Keyword(s):  
Zebra Mussel ◽  
Dreissena Polymorpha ◽  
Yellow Perch ◽  
Perca Flavescens ◽  
Structural Heterogeneity ◽  
Zebra Mussels ◽  
Zooplankton Density ◽  
Growth Differences ◽  
Percent Nitrogen ◽  
Induced Changes

Zebra mussels (Dreissena polymorpha) in enclosures located in an experimental pond adjacent to Lake St. Clair, Michigan, increased sedimentation rate but had relatively minor effects on percent organic matter and percent nitrogen content of sediment. In contrast, sediment from Lake St. Clair adjacent to zebra mussels was significantly higher in carbon than that 0.5 m away. Zebra mussels increase the nutritional value of surficial sediment and provide greater structural heterogeneity, which is probably more important in causing change among zoobenthos. Zoobenthos and yellow perch (Perca flavescens) diet were dominated by dipteran larvae and leeches. Zoobenthos was significantly different between enclosures with and without zebra mussels. Treatments with zebra mussels had significantly more oligochaetes and tended to have more crustaceans (isopods and amphipods). In June, yellow perch without zebra mussels consumed significantly more zooplankton, and those with mussels had more crustaceans in their diet. Zooplankton density was greater in treatments without zebra mussels. Yellow perch with zebra mussels grew significantly more than those without mussels. Zebra mussels in the enclosures neither reproduced nor were eaten by yellow perch; hence. the observed growth differences were due to indirect effects involving zebra mussel induced changes in benthic structure and biota.

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