Pond-Specific Dynamics of Fish at the Outdoor Discovery Center and the Influence of Predatory Fish on Species Interactions
Dr. Kathy Winnett-Murray, Hope College
Micropterus salmoides (largemouth bass) are the most common piscivorous fish in North American fresh water bodies and have been shown to have profound effects on the growth patterns of their prey species. Species composition, size and age distribution of bass and Lepomis species (green sunfish, pumpkinseed sunfish, bluegill and hybrid sunfish) were determined in 5 stocked ponds at the Outdoor Discovery Center /Macatawa Greenway of Holland, Michigan. Human-created ponds are becoming more common in this region, and we hoped to understand bass-prey interactions in ponds of varying characteristics. The average lengths of all Lepomis species were about 3.5cm (130%) longer in ponds with bass than in ponds without bass, suggesting a decrease in competition and selection favoring faster growth rates. However, in ponds with few or no bass, there was greater species richness of the Lepomis sunfishes. Pumpkinseeds appear to be the most successful in co-existing with bass; only a small decrease in population size of pumpkinseeds was measured in ponds with bass, and this may be related to behaviors and/or habitat use that most effectively limits detection by bass. The average age of Lepomis in ponds with bass was higher than in ponds with no bass, 4.098 years and 3.333 years, respectively. Hybrid sunfish, known for their hardiness for cold, unfavorable water conditions, had the oldest mean age of all prey species: 4.875 years in ponds with bass, 3.214 years in ponds without bass. Overall, there was a greater mean age, weight and length of Lepomis prey species when co-occurring with bass. In conclusion, bass appear to have a significant impact on the growth dynamics and species composition of these human-created ponds. Future research will explore in more detail how that impact may be mediated by physical attributes of the ponds (e.g. size, depth, etc.).
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