Brown Trout vs. Brook Trout

A recently published U.S. Geological Survey study examined how native brook trout interact with non-native brown trout under rising stream temperatures.

During the study, which is one of the first experimental studies linking climate change and invasive species biology, researchers found that non-native brown trout limited the ability of native brook trout to utilize warmer stream temperatures.

In contrast, removal of brown trout resulted in the expansion of brook trout into warmer waters.

The brook trout is a freshwater fish species native to eastern North America and threatened by climate change because of its requirement for cold stream temperatures.

Brown trout are native to Europe and have been introduced throughout much of the territory of native Brook Trout.

The research indicates that native brook trout were less resilient to climate change compared to the invasive brown trout because the native fish has less tolerance to higher water temperatures.

The study was published in the Canadian Journal of Fisheries and Aquatic Sciences.

source: U.S. Geological Survey

Wisconsin Brook Trout Distribution Predictions

The distribution of brook trout, which requires cold water for survival, could shrink by 60 percent in some Wisconsin streams by mid-century, according to recent climate change models for the Great Lakes region.

Loss of suitable freshwater habitat for brook trout and other popular sport fish species due to climate change are likely to have economic implications for the Great Lakes system.

Recreational fishing opportunities in the region contribute to a multi-billion dollar tourism and recreation industry.

Climate change models for the Great Lakes system are being made by researchers with U.S. Geological Survey, alongside Wisconsin Department of Natural Resources (DNR), Michigan Institute of Fisheries Research, and Michigan State University.

Researchers hope to predict the potential impacts of increasing air temperatures and changes in precipitation on water temperature and flow in freshwater streams that are part of the Great Lakes system.

The models project future distributions for 14 fish species based on known fish locations, their habitat preferences, their adaptability to different water temperatures, existing and future stream conditions, and projected climatic changes.

source: greatlakeslcc.org

Freshwater Fishing After Floods

floodwaters pour over a dam

Floods can disrupt fishing for days or weeks. Eventually, high water levels subside enough for anglers to fish again. During these periods, anglers often gain valuable knowledge about lake structure and fish behavior.

In creeks and streams, anglers can look for areas where logs, rocks, and other debris are piled up by floodwaters. These structures can create large eddies where fish are likely to congregate.

In man-made lakes and reservoirs that are fed by streams or creeks, floodwaters can cause major structural changes. After major floods, anglers may find logs, brush, or other debris along the shoreline, partially submerged or sunken on the bottom. Where creeks enter these bodies of water, deltas are often formed by gravel, sand, mud, or other materials.

Immediately after flooding, fishing may be impossible, but as each day passes, fishing opportunities tend to improve. Forage is often abundant, especially along shorelines. During floods, insects, minnows, and other small prey take refuge in shoreline vegetation.

As floodwaters recede, forage species are forced back into the lake where hungry fish are waiting. Some lakes experience insect hatches following high water levels, which also helps trigger fish to feed heavily.

Scouting a lake for the signs of fish is usually a good first step following periods of high water. Territory to be investigated include areas near dam spillways (if regulations allow), shoreline vegetation, protruding stumps, mats of floating debris, and other obstructions. Lure designs are critical when snags are abundant.

When scouting deeper parts of lakes, fishfinders may help locate logs, debris, or other structure that was deposited during a flood. Fishfinders are also useful for detecting suspended fish that may be taking refuge in clearer portions of the lake.

Depending on local variations, fishing after a flood may improve or be unproductive for days or weeks afterward. In either case, a trip following a flood can provide important information for future fishing.