Fish, wildlife and drought

Fish, wildlife and drought

MassWildlife has received questions about how fish and wildlife may react to current drought conditions. It is important to remember that the fish and wildlife of New England have adapted to fluctuating weather conditions, including harsh winters and droughts. That said, prolonged drought conditions can have the most direct and severe impacts on fish communities and fish habitats. Below are some examples of the impacts drought can have on certain fish and wildlife.

river fish suffer from a reduction in the quantity and quality of habitat, as the reduction in the flow of surface and ground water compresses them into isolated and increasingly reduced pools of water. The decrease in the amount of cold groundwater can change the quality of these remaining water pools, which can have dramatic effects on trout and other fish. Stagnant water heats up quickly in the summer, causing a loss of dissolved oxygen needed to keep fish alive. As fish become trapped in smaller tanks, they also become easy targets for a host of predators ranging from herons and raccoons to larger fish in the same tank. There is also an increased likelihood of disease outbreaks and lower reproductive success for fish during drought. Some very small streams may dry up completely. In these extreme cases, it may take months or years for fish to recolonize the affected reaches. As a drought increases in severity and duration, the impacts felt in headwater streams are transferred to larger systems and affect fish communities on an ever-wider scale.

MassWildlife monitors fish communities to better understand the effects of drought in a human-dominated landscape. Currently, MassWildlife is collaborating with the USGS to study changing stream flow patterns and warming temperatures in streams across the state. The goal of this project is to identify areas, called climate change refuges, that are least likely to change over the coming decades.

Lake and pond fish are generally less affected by drought than those living in waterways, but prolonged drought can have repercussions. Very shallow ponds that are heavily vegetated experience wide variations in dissolved oxygen levels. The ability of water to hold oxygen decreases as water temperature increases. This is aggravated when, at night, aquatic plants begin to consume oxygen. As drought causes water levels to drop in already shallow ponds, these oxygen level fluctuations worsen and can lead to fish kills.

Whether in lakes, ponds, streams, or rivers, anyone who witnesses a fish kill caused by any reason should report it to the Massachusetts Environmental Police 24-hour radio room. at 1-800 632-8075.

Trout stocking this autumn could be impacted by drought, although it is too early to know. Drought in the northeast is difficult to predict because, unlike the western states, we don’t have snowpack to watch out for in the high mountains. Long-term precipitation forecasts are difficult to make, so variables such as stream flow and groundwater levels are among our best ways to monitor drought. Trout stocking usually begins in mid-September, depending on the temperature. Reduced stocking of some trout in rivers and streams this fall may occur due to low flows, but little impact on stocking of lakes and ponds is expected. MassWildlife’s fisheries biologists will assess the condition (temperature, flow, etc.) of each body of water before making a final stocking decision.

Bear rely on summer berries, which can be diminished with prolonged drought. As a result, bears search for other types of food, causing them to visit residential areas more often than in a normal year. During dry summers, nuisance bear complaints tend to be higher because bears use residential areas more frequently, taking advantage of bird feeders and garbage. Dry summer conditions can also affect the timing and quality of fall acorn harvests, an important fall food source for bears. This can cause bears to forage in agricultural areas and damage crops.

Stag will likely experience little direct impact from the drought, as deer feed on a variety of food sources. Extremely dry conditions can cause deer to congregate in areas where food and water are more readily available. The provision of watering sites for deer is strongly discouraged because the artificial concentration of deer on small bodies of water increases the risk of disease transmission between deer.

Momentum also graze on a variety of food sources, but are more likely to experience stress in hot, dry weather. Moose seek shelter from hot temperatures in forested wetlands and use mud and shallow water to cool off. When these wetlands begin to dry out during drought, moose may struggle to find relief from the heat.

waterfowl like ducks, geese and swans can fly to bodies of water with adequate water levels when needed.

Turkeys are likely to experience few negative impacts. In general, turkey populations are more sensitive to spring weather and nest predators.

Beaver have the ability to regulate water levels, so if the water gets too shallow, they can increase dam-building activity. If they cannot raise the water level with additional dams, beavers may leave the wetland in search of deeper water.

Learn about drought conditions and steps you can take to conserve water.

Image courtesy of Theodore Beauvais.

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