Thesis (M.S.)--University of Wisconsin--Stevens Point, 2003. / Includes bibliographical references (leaves 39-44).

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I assessed the relationship between growth of fish in situ, food consumption, prey type and fish community descriptors in 12 perch (Perca flavescens) populations exhibiting a 1.8 to 10-fold range in growth rates. / Perch growth rates consistently decreased as fish numerical density increased (r$ sp2$ = 0.60) and increased as feeding levels increased (r$ sp2$ = 0.30). I found no significant relationship between the quantity of food consumed by perch and fish numerical density. Prey quality explained from 50 to 95% of the observed variability in growth but was related to fish numerical density in only one of the 3 perch age classes studied. / I conclude that non-exploitative interactions (operating through increased activity costs) is a more viable explanation for the among-population variability in fish growth rates than is exploitative competition (yielding decreases in the total quantities of food consumed and/or prey quality).

Little information has been published regarding the American plaice, Hippoglossoides platessoides platessoides (Fabricius), a subarctic species which is distributed from Cape Cod to Labrador. In recent years plaice has risen rapidy in commercial importance in eastern Canada. In 1940 only 3 million lb were landed compared to a total of more than 74 million lb in 1960. American plaice in 1961 made up 64 per cent by weight of the total Canadian flounder landings, excluding halibut. [...]

This study evaluates the life history responses of yellow perch to mass removal and the potential for population recovery. We removed approximately 94% of a perch population from Nepawin Lake, a 35 hectare oligotrophic lake in Algonquin Provincial Park, Ontario, as part of a study designed to enhance the recruitment success of brook trout. Several response variables were examined both before and after mass removal: (1) condition, which includes growth, diet and overall condition responses, and (2) reproduction, which includes size at maturity and fecundity. We examine the question of whether compensatory life history responses in the yellow perch will overcome brook trout predation leading to a reestablishment of a high density perch population. Results showed that prior to the manipulation, perch exhibited a narrow size distribution, high dietary overlap, and low condition, typifying a stunted population. After mass removal, the perch population remained in a narrow size distribution, exhibited decreased growth rates for older age classes, showed increased mean condition and increased consumption of zooplankton in all size classes. Perch also exhibited increased size at maturity and decreased fecundity immediately following the mass removal. A time lag is expected before compensatory recruitment is possible in the population, but it is likely that the perch will recover from the mass removal because of strong age 0+ and 1+ cohorts. However, stunting and bottlenecking may still occur in the population. Continued monitoring and management is necessary to observe further changes to the perch population dynamics in Nepawin Lake.

Yellow perch, Perca flavescens, were collected by night trawling and gill netting at 5 m in a study area near Kintzele Ditch in Indiana waters of Lake Michigan during the months of June through September, 1975. Additional collections made by the Indiana Department of Natural Resources and the U.S. Fish and Wildlife Service using gill nets were included in some aspects of the study.Population characteristics were analyzed and compared to other studies. The rate of growth was significantly greater than in past Great Lakes' populations. The calculated length-weight relationships and growth rates were comparable to those reported by recent studies for southern Lake Michigan. Growth differed between males and females of the same age, and different ages were often represented in the same length interval. Nearly all male yellow perch were mature by age I and 130 mm. About half of the age II females and most at the 200 mm length interval were mature. Sex ratios were variable.Higher catch-per-unit-effort (cpe) was related to warmer water temperatures to the thermocline level. When water temperatures were mixed resulting in low inshore temperatures, cpe values were lower.There existed a great deal of sample variability within and between gear types as a result of seasonal population availability, gear characteristics, and non-random distribution of the population.Trawling, although more efficient than gill netting at sampling total numbers and widest range of lengths, was selective for smaller fish, and gill netting was selective for larger fish. Depth (from 5 m to 18.3 m) and particular gill net methods employed had little effect upon the sizes and length-percent frequency distribution sampled.Great differences between percentage age compositions compiled from trawl and gill net catches reflected the size selectivity of the gears. These results raised questions concerning the validity of management techniques involving percentage age composition and cpe index values to determine relative year class strength.The age groups I and II were represented by the proportion 8:2 (1:11) in the trawl catch which adequately sampled the sizes including the age I and II fish. Further study would be needed to determine the validity and usefulness to management considerations of this method of relative year class strength determinations. Recommendations for additional study were made.

The potential near-shore forage fish populations were investigated by bottom trawling during the months of June through August of 1984-86 in Lake Michigan, near Michigan City, Indiana. Data were collected on the six moat common species including: yellow perch (Perca flavescens); alewife (Aloes pseudoharenqus); rainbow smelt(Osmerus mordax); bloater (Coreaonus,hovi); spottail shiner (Notroois hudsonius); and trout-perch (Perconsis omiscomavcus). Results of the 1984-86 sampling period were compared with data for 1973 in an attempt to document changes in population density, species composition, annual catch, seasonal abundance, and population structure.The total trawl catch for all species increased nearly seven-fold since 1973 even though sample methods and collection effort were unchanged. A dramatic increase in yellow perch abundance was primarily responsible for the elevated levels sampled for all species from 1984-86.The species composition of the catch shifted since 1973. In 1973, spottail shiners were the most abundant species (41%) and trout-perch and alewives were the next most abundant species comprising 20% and 17% of the catch, respectively. Yellow perch, which comprised only 12% of the catch in 1973, increased to 81% of the catch in 1986. Bloater also showed a great increase in relative importance since 1973 when they were rare in the catch. Other species, including alewife, were relatively minor components of the total catch each year from 1984-86. The trawl catch results revealed that alewife and trout-perch declined 71% and 87%, respectively, comparing 1973 with 1984-86. During the same period, yellow perch increased 72-fold and bloater over 3000-fold. By comparison, the spottail shiner population was stable with no long-term changes, but rainbow smelt populations fluctuated widely.Seasonal abundance of adult fish (age I or older) generally decreased from June to August for each fish species and year sampled with the exception of yellow perch which peaked in July of 1973, and in August of 1985-86. Young-of-the-year fish were generally captured in late July and August.Population structure changes were evaluated by examining pooled length-frequency data. Yellow perch length-frequency distributions indicated that strong year classes were produced every year from 1983 to 1986. The 1985 year class was well over twice as large as any of the other years sampled. Spottail shiner and rainbow smelt length-frequency distributions remained approximately stable since 1973, while alewife length-frequency distributions fluctuated annually. Capture of bloaters was almost entirely limited to June, and consisted primarily of age I+ fish in 1984-86.These results reveal significant changes have occurred in the potential near-shore forage fish populations in Indiana waters of Lake Michigan since the early 1970's. Although several factors may be involved in the shifts noted, the major contributing factor is likely predator-prey interactions as a result of salmonid predator density.

Thesis (M.S. - Biological Sciences)--University of Arizona. / Includes bibliographical references.

Thesis (Ph. D.)--University of Washington. / Bibliography: l. 138-143.

Thesis (Ph.D.)--University of Western Australia, 2004.