Outdoors: Cold water puts fish in energy-saving mode

Feb. 28—While, at times, the wind might be blowing 40 miles an hour and whipping snow into freestyle curvy architecture across the landscape, and the elements can throw daggers of Arctic cold fronts and unexpected warming trends with a reckless abandon that only Mom Nature understands, life is very different just a couple of feet down.

There, under the ice that will seal the surface of a lot of ponds, lakes, and reservoirs like a fresh-fitting piece of Tupperware, it is the aquatic equivalent of the library reading room. Below that frozen plateau, it is quiet, calm, and peaceful, with no temperature fluctuations and soft lighting. Things are pretty tranquil until someone gets hungry.

There are underwater cameras on the market today that ice fishermen use to get much more than a snapshot of what is going on in those chilly depths beneath their ice fishing shanty. With its camera mounted on a 125-foot cable that is linked to a 10-inch monitor, one Aqua-Vu model gives fishermen a high-definition, panoramic, 360-degree view of the environment below, enhanced by infrared lights and a zoom lens.

Anglers can watch in real time as fish casually and cautiously approach a bait, size it up, and then decide whether to partake. It is akin to starring in your own unedited episode of "Wicked Walleye". These remarkably sophisticated camera systems, which are compact, portable, and suitably rugged for the work surroundings, can take the fisherman under the ice, but we need biologists to tell us what they know about the under-ice world beyond the reach of that camera lens.

Travis Hartman, the Lake Erie Fisheries Program Administrator for the Ohio Division of Wildlife, said there is not much hard research on the topic, but general knowledge of fish behavior should tell us a few things about life under the ice.

"In some regards, 'winter' conditions aren't as variable for fish as they are for us," Hartman said. "Ice can have a substantial impact on water clarity by eliminating wave action, but water temperature doesn't vary a lot regardless of the presence or absence of ice."

Ice conditions have been undergoing a rapid change on Lake Erie this past week, with more sunshine, warmer daytime temperatures, and brisk winds opening up some sections while the ice remains in other places. Hartman said when areas are ice-covered, the sediment usually settles to the bottom and the water column clears.

"I suppose the baitfish might move around trying to optimize the amount of food available to them and any level of 'stain' [in the water] that would help protect them from predators but, other than that, the presence of ice doesn't change much for walleye," he said about Lake Erie's most-prized residents.

Hartman said he believes stable water temperatures at depth in the winter months of January and February, combined with nature's clock marching toward the spawning ritual in March and April, likely produce a fairly consistent pattern of movement for the lake's walleye.

"The only real change is what access [anglers] have to them and if we are fishing from a boat or a shanty," he said. "At this point, fish should be piling up from Huron to Toledo in various staging areas and opportunistically feeding when they find the right bait during the right activity window."

He added that walleye likely spent the month of February traveling to a staging area that will be their last stop before spawning, but the location of baitfish will have an impact on where those fish move, under the ice or without ice.

"If ice persists into March, then we would expect the large females to really congregate right off spawning habitat, waiting for the ice to break up and start spawning," he said. "In years like that, the late ice fishing and earliest boat fishing can be incredible around the reefs."

Hartman lamented the fact that Erie's ice coverage has not been consistent and extensive in recent years, since that potentially would have provided the opportunity to collect valuable data on just what those walleye are doing under that ice cap.

"With the number of tagged fish and receivers that we have out there, we would learn a lot about under-ice migration if we got another really hard winter soon," he said.

Mike Wilkerson, the Division of Wildlife's Fisheries Management Supervisor for the northwest part of the state, monitors the fish populations and angling activity on the inland waters, and he said that in reservoirs, ponds, and lakes, as long as the fish are getting enough oxygen, they are likely content to take winter and ice cover in stride.

"I don't think ice cover affects them that much, outside of any biological problems if there's a low oxygen level. It is mostly the water temperature they are reacting to," he said. "In that very cold water, they feed less and move less. It generally just slows them down."

Speaking primarily about the largemouth bass, crappie, and bluegill populations in those inland waters, Wilkerson said those species spawn in warmer water temperatures than walleye, so those fish likely don't function with the same sense of urgency as walleye, which are often in a pre-spawn feeding pattern during the late winter/early spring time frame.

Walleye reach their spawning peak in water that is 42 to 50 degrees, while largemouth bass require water more in the 55-65 degree range, crappie spawn at 68 to 72-degree water temperatures, and bluegill spawn in water about 70 degrees or warmer. Wilkerson said the bass and panfish won't pass up an easy meal under the ice, but they also won't expend a lot of energy to chase one down.

"It doesn't mean they completely shut down, they just don't need as much and they won't eat as much when they're under the ice or in very cold water," Wilkerson said. "They won't make those fast lunges for things, but if you put something in front of their face, they'll take it."

Fish are much better adapted to deal with that cold winter water, whether under the ice or in the wintertime absence of ice. They are cold-blooded animals, so their body temperature will match their environment and, as their temperature drops, there is also a reduction in their metabolism. In general, there is a subsequent lessening in their respiration, digestion, and activity level in that cold water.

Contact Blade outdoors editor Matt Markey at: mmarkey@theblade.com or 419-724-6068.