Fishy Bottoms

Have you ever, on a nice, cold wintery day, sat outside and stared at an ice-covered pond and wondered if there is anything alive under the ice sheet? No? Well, I was curious enough to recently send off an email about this to a good friend of the Gardens, City of Elkhart’s Aquatic Biologist, Daragh Deegan. This man is sharper than a pike’s tooth and passionate about the aquatic life in the region’s lakes and streams. My previous conception of fish in winter was one of swimmers in a state of hibernation doing nothing, but then I watched a great documentary on fish in alpine lakes. In it, I saw eel spawning in the middle of February…under the ice. Who knew? I did not, so I emailed Mr. Deegan asking if and what the fish in our ponds might be actively doing this time of year. Here is his response to my query. 

JOSH: What are the fish likely doing under the ice in Wellfield’s ponds? Are they just hanging out drifting around twiddling their thumbs?

DARAGH: Unfortunately, while fish may not be twiddling their thumbs during the winter, they are down there twiddling their fin rays. Fish are coldblooded animals whose metabolism and activity is controlled by water temperature. So, when the water in the ponds at the wellfield is 33 degrees, so is the body temperature of the fish. They don’t hibernate in the winter but enter a “torpid state”, where they are very inactive and feeding sparsely. While fish can be caught by ice anglers, their energy requirements are small, so very small baits will only entice them to bite. There are some fish that are a little more active in winter than others. Examples are the northern pike, walleye and yellow perch, which are all considered coldwater species that are found in colder climates. Yellow perch, for example, feed more actively during the winter to nourish their eggs, and spawn very soon after ice melt. 

An interesting phenomenon fish biologists can observe in colder climates like ours is changes in growth rings on a fish scale. As their metabolism slows down in the winter, the growth rings on their scales get closer together, making a banded pattern on the scale, and when viewed under a microscope, we can actually age the fish with these winter growth brands.  

JOSH: Are any other active life forms underwater this time of year doing stuff?

DARAGH: Most aquatic animals become far less active in the winter. But that doesn’t mean that there aren’t some kickin it. Larval insects, like some of the midges and stoneflies, are actively feeding and getting ready to transform into flying adults as soon as the ice melts. Like humans, small fur bearing mammals like beavers, muskrats, river otters, and mink are less active in the winter and like to bundle up in their homes, but they need to emerge every few days to grab a bite to eat.  

JOSH: Are there some really cool species or behaviors you think are fun to highlight about freshwater species this time of year?

DARAGH: I think the winter behavior of turtles is really interesting. Like fish, turtles are cold blooded animals that become much less active in the wintertime and will usually sit on the bottom of a pond or stream until the ice melts. The big difference with turtles, however, is they have lungs – not gills, but can survive for days on end under the water in the winter. Their metabolism shifts so they can survive in this semi-dormant state and live off body reserves. They can also pick up some oxygen in the water by swishing around and letting the dissolved oxygen bubbles hit highly vascularized tissue on their body. There’s some sources that suggest that turtles can breathe through their butts.

Okay, on that uplifting factoid, I am going to sign off. Until next time, stay warm, and as my Grandma used to say, “Always listen to the municipal aquatic biologist in your life”.
Josh Steffen, Horticulture and Facilities Manager

Missed seeing Josh’s latest posts? Click on any of these links to learn more:

  • In Defense of The Monarch Butterfly
    Seen any Monarch butterflies lately? As an endangered species, we need to care for them. But there’s more to it than just planting more milkweed.
  • A Beginner’s Look at Japanese Gardening
    Japanese gardens have a style and feel all their own. Cody takes a look at some of the different concepts he works with in our Japanese-themed Island Garden. Have you noticed any of these when you’ve visited?
  • Family-friendly Sensory Gardens
    Sensory gardens engage and excite the senses; they can be large or small, and can be created for kids and adults of all ages to enjoy.
  • Setting Fire To Burning Bush
    Invasive species are everywhere! Today, Cody helps you identify them in your environment and studies why they are deemed invasive.
  • Dances with Flowers
    Quilt Gardens are a big deal in Elkhart County – and this year is special, as it’s the 15th anniversary of Quilt Gardens on the Heritage Trail. Take a look at Wellfield’s process that led to our beautiful 2022 installation: Fresh Connections.

Want to be notified whenever we post? Enter your email here. We promise not to bug you too much, and we’ll never sell your info.

Leave a Reply