How does drought impact fish?

The National Wildlife Federation, in an article published July 10, says that the “hotter, dryer weather is creating a ‘new normal’ in the Southwestern U.S., affecting wildlife, communities and outdoor activities across the region.”

Continued lack of snowfall and precipitation in the White Mountains has resulted in the Arizona Game & Fish Department as well as the Arizona Elk Society and Rocky Mountain Elk Foundation to haul more water to forest catchments than they have ever done before. Ranchers are also hauling water for their herds. And, multiple agencies have been collaborating to haul water to free-roaming horses in Heber.

But hauling water to fish is another matter.

So, when the conversation turns to fish, information and strategies seem somewhat less obvious than elk, deer, cattle and horses. The Independent contacted the experts at the Arizona Game & Fish Department’s (AZGFD) Pinetop Region office to find out how the drought impacts fish.

AZGFD lake biologist, Veronica Corbett, has been with the AZGFD holds a bachelors of science degree in wildlife, fisheries and conservation biology from the University of California, Davis.

“I’ve worked in fisheries for the last six years throughout the western U.S. I started with AZGFD in January 2018 as the Lakes Biologist for Region 1 Aquatics in Pinetop,” she explained.

First and foremost, the AZGFD confirmed that fish and aquatic species are going to be negatively affected in drought conditions. “A well below average snow pack means less water running through the watershed during spring runoff,” says Corbett. “This can easily be seen through most of our lakes and reservoirs not filling completely this year. In streams, this is evident with lower flows and some smaller streams even going dry,” she added.

Water quality

When it comes to fish, water is not enough; water quality must also be part of the equation.

Corbett explained that, without that water, fish simply have less or even no habitat. “When our lakes don’t fill, there is less overall space for fish to occupy. This can lead to higher competition for resources like food, cover, and spawning habitat. In streams, less water can concentrate fish into deeper pools or push them downstream to better conditions,” she explains.

In short, drought cycles mean less water and warmer conditions which can lead to poor water quality earlier in the year said Corbett.

“Most lakes in the White Mountains develop high pH levels and low oxygen conditions as the summer progresses. This year, with less water, we’ve seen conditions degrade sooner than they have in the past. However, heavy monsoons and, especially, a good winter would help fish immensely,” says Corbett.

Which species are affected most?

Native fish like roundtail chub and speckled dace are adapted to the dry conditions of Arizona. Corbett reiterates that drought years are hard on all species, however, the native aquatic species are better able to tolerate low, warmer water conditions.

“In contrast, stocked rainbow trout prefer cold, oxygenated water, and are less adapted to warm conditions,” says Corbett. “In the White Mountains, most of our stocked lakes and streams are managed as ‘put-and-take’ fisheries, meaning we only stock fish that we expect anglers to catch. Therefore, stocked trout are not particularly affected by drought conditions because they are not persisting in our waters long enough to be impacted.”

How are fish counted/measured?

The AZGFD routinely stocks lakes and streams statewide and partners with other entities to provide Community Fishing areas. Last fall, the agency partnered with the city of Show Low to stock Show Low Creek with rainbow trout in the fall and sunfish and catfish in the summer months. But how does AZGFD determine how many fish are in a lake or stream once they stock?

Corbett explained that stocking rates are determined based on data from annual population surveys and angler interview census. “In lakes like Woodland and Rainbow, we stock trout in the spring months when water quality is best and expect those fish will be caught before the following year,” says Corbett.

“In years like this where our lakes are low, trout can be stocked because they are still being caught by our anglers. When poor conditions arise, we can divert fish to different waters. For example, Scott Reservoir was not stocked this year due to the scheduled maintenance,” Corbett said.

The AZGFD uses annual surveys to track the survival rates of fish.

“Adult survival impacts may be apparent in our annual spring population surveys next year,” says Corbett. “However, if drought conditions decrease spawning success or juvenile fish survival, those impacts will not be seen for several years in population surveys,” she adds.

Keeping fish healthy, viable

There is certainly a science and an expertise required in stocking fish because the goal is survival and longevity.

“Survival is highest when fish are stocked during the best water conditions possible,” says Corbett. “However, they can acclimate to poor water conditions as the summer progresses. By policy, fish are never stocked at waters with a pH higher than 9.”

She also says that water quality does degrade throughout the summer and the pH can increase to lethal levels so AZGFD monitors water quality throughout the year, measuring temperature, pH, and dissolved oxygen levels.

Which lakes are impacted?

Corbett described how the White Mountains are at the top of the watershed which means that, most lakes are impacted similarly by drought conditions. She went on to say that White Mountain lakes like Big Lake and Crescent Lake are lower than normal due to drought, just like the lakes in town such as Show Low Lake or Fool Hollow Lake.

Some lakes maintain good water quality throughout the year and can be stocked later in the summer. Some are not stocked past April. Every lake is unique,” explains Diane Tilton, AZGFD public information officer said.

For example, “Scott Reservoir is low due to drought conditions, but it is nearly empty due to scheduled maintenance,” says Tilton. The Show Low Pinetop Woodland Irrigation Company owns and manages the reservoir for their shareholders. They reported in early May that they were working on funding to make the repair. “… The irrigation company took advantage of a multi-year drought cycle and chose a time when the reservoir was at the lowest to draw it down and complete this maintenance,” explained Tilton.

“With regard to Woodland Lake, AZGFD doesn’t have any control over the water levels … Woodland Lake was not originally intended for recreation; most of these lakes and reservoirs were all created for some type of water management,” adds Tilton.

“All we can do is manage the fish based on the water quality and amount of water,” says Tilton. “We didn’t change anything in this year’s stocking schedule.”

Long-term impacts?

The long-term impacts of the drought on fish and aquatic life are critical. Corbett says that long-term drought cycles can drain groundwater and lead to less flow in spring fed systems.

“Most watersheds are simultaneously fed by seasonal snow melt and year-round springs,” explains Corbett. “Without water on the landscape, more catastrophic fires are likely, which destroy streams, fill in river pools and lake bottoms, and ultimately kill fish.”

Consistently low water levels in lakes will eventually decrease population sizes and diminish fishing opportunities.

“In areas where the stream or lake dries up entirely, it could take decades for fish to repopulate a water,” says Diane Tilton. “Some lakes have been hit harder by the lack of water...Other lakes are maintaining adequate water quality, despite the low water levels and we expect them to recover fine.”

“Water quality metrics such as temperature, dissolved oxygen, water levels, and pH are measured monthly,” says Tilton. “This is to ensure that trout are not being stocked into inhospitable conditions and that if conditions do degrade, we have data to show when those conditions start declining.”