by Guy Middleton, Lake Manager
Despite this summer’s fish die off of a couple hundred Smelt in the Northern Basin of the Lake, recent reports from fishermen have indicated that there seems to be little to no effect to the ice fishing. Encouraged by warm summer temperatures and calm winds, the Lake saw an August smelt die-off with a few hundred smelt floating at the north end of the Lake. The two-day event was brought to many of our attentions by the increased bird congregation.
Smelt is a freshwater fish that resemble Salmon in appearance, but are much smaller, usually no longer than 7 inches. Smelt is a food source for lake trout and salmon and are a popular ice fishing catch.
Although the loons, seagulls and eagles all thrived on the summer die off, and ice fishing hasn’t seemed to be effected, there is reason for concern. This summer’s die off was attributed to oxygen depletion. Oxygen is critical to the growth, reproduction, and survival of aquatic organisms and is required for the respiration of all aerobic organisms, including plants and fish.
With more nitrates entering the water from this past spring’s run- off, bacteria increased in number and used up the dissolved oxygen in the water. When the dissolved oxygen content decreases, many fish and aquatic insects cannot survive. This is particularly impacts Trout and Salmon which require deeper and colder water temperatures. Oxygen is dissolved in the water in three ways: Through wind and wave action at the surface of the water; through aquatic plants growing in the near-shore areas (littoral zones) and phytoplankton in deep water areas, as oxygen is released through the process of photosynthesis. During stratification (formation of differing temperature layers) of the Lake in the summer months, the lower depths are isolated from the atmosphere and consumed oxygen is often not replenished until fall turnover. As a result, low levels of dissolved oxygen can cause dead areas around the Lake. The Upper Saranac Lake Foundation, in cooperation with the Aquatic Watershed Institute of Paul Smith’s College, monitors and tests the levels of dissolved oxygen in both the north and south basins of the Lake throughout the summer. The north basin in Upper Saranac Lake tends to experience lower oxygen levels sooner in the summer months. Although these low levels of oxygen are of concern, long term monitoring has shown that there is not a worsening trend, just a normal fluctuation.
So what can we do? Limiting nutrient flow into the Lake is the answer. This means
reducing runoff, improving sewage treatment and limiting fertilizers. It is also helpful to restore natural environments along the waterfront, effectively buffering the amount of phosphorus and nitrogen entering the water.