An investigation into the growth rates of northern pike, Esox lucius, in Wildwood Lake.

Abstract

We conducted a two week study on the age and growth rate of the northern pike, Esox lucius, population in Wildwood Lake, a very shallow and eutrophic lake in Wolverine, Michigan. Six pike were caught in an experimental gill net and their standard lengths were recorded. They were then aged using the left cleithral bone and also by scales. Five out of the six pike sampled showed a stunted growth pattern, below the average length range for their age in a normal population. We investigated into the possible reasons as to why this is occurring and discovered several possible factors. We found that the conditions in the lake during the summer months are extremely inhospitable to pike. Where the dissolved oxygen levels are tolerable (above 3.0 g/ml), the water temperature is in the zone of resistance (27.5 C), and where the water temperature is tolerable (below 25 C), the dissolved oxygen levels were near lethal. Therefore, the summer habitat available to the pike is restricted by warm water temperatures in the epilimnion and anoxic bottom waters. Furthermore, competition among the predatory fish in the lake has lowered the amount of possible prey items available, which can lead to lower energy available for growth.