An examination of the ecology of the cisco (Coregonus artedii) in Ontario lakes
By: By Kris Vascotto.
Published: 2006
Language: eng
Number of pages: 270
ISBN-13: 9780494159682
Description: This research explores two aspects of cisco ecology: life history variation and behavioral variation. The life history investigation encompasses a spatial comparison of the life histories exhibited by populations from across Ontario; an assessment of changes made in life history exhibited by several populations over several decades; and an examination of the association between variation in life history and variation in the character of the higher trophic levels that are supported by cisco. Results indicate that there is a broad range in maximum attainable size, growth, condition and size at maturity, and these characteristics show strong positive correlations with one another. These traits had weak relationships with environmental measures of primary productivity (total dissolved solids), however the structure of the predator community (specifically the presence of walleye) was linked with larger body sizes and associated traits. Results from a detailed examination of the establishment of 3 new, independent and self-sustaining populations from the introduction of a single stock into three separate water-bodies in 1948, suggest that the life history strategy of a population of cisco can shift over short time scales (25 years or less). These life history shifts appear to be the result of plastic changes in phenotype, and are precipitated by significant changes in the predator community. Shifts in life history strategies can actually prevent the predator population from regaining the position once held in the community. The impact of predation on cisco behaviour was also examined. Results suggest that the presence of a visual predator increases the size of schools that cisco form during the day and forces those schools deeper into the water column, into less favorable environments. However, the presence of a visual predator does not impact the timing of school dissociation at the end of the day or the nighttime behavior itself. These findings are put into a larger context that emphasizes the importance of environmental characteristics and community characteristics in shaping the observed life history and behaviour of cisco populations.
Notes: Source: Dissertation Abstracts International, Volume: 67-07, Section: B, page: 3559.

Thesis (Ph.D.)--University of Toronto, 2006.

Includes bibliographic references.

Electronic version licensed for access by U. of T. users.