By Eric Fowler
If you’ve spent much time fishing, chances are you’ve seen a male bluegill guarding its spawning bed, a bowl-shaped depression that it fans out in the lakebed using its tail. Or numerous bluegills in a nesting colony, each guarding its own bed.
If, instead of casting to those beds hoping to catch dinner, you put down your rod and reel and watched for a time, you may have seen another male bluegill approach a bed, only to be run off by the male. Or females making their rounds, trying to decide which male they deemed worthy of the right to fertilize their eggs.
In 2021, I had the opportunity to witness, up close, the next step in the spawning process, and something I would be willing to bet few have seen: the interaction between male and female prior to spawning.
I was snorkeling in an Elkhorn River backwater at Red Wing Wildlife Management Area near Neligh, gathering underwater photos for a story on the area and the aftereffects of the 2019 flood that changed the river’s course (see “A River Used to Run Through It,” November 2023). In one section of the backwater, not far from the river, I found a handful of bluegills, most gathered in or around tangles of beaver-chewed sticks and rushes in a pool that was no deeper than 3 or 4 feet.
In one tangle, I watched for 6 minutes as a 7- or 8-inch long male and a female two-thirds its size, circled the nest, rubbing against each other, with the female occasionally tipping on her side. At the time, I had no idea what I was watching. And I’m a nose breather and, as such, not a very good diver, so I stood to clear my mask and my nose and moved on in search of more photos.
I’m also blind without my glasses, and don’t swim with a corrected mask, so it wasn’t until I pulled the photos up on my computer that I could see the eggs beneath that fish, and two others I’d photographed. These fish were on spawning beds that looked nothing like others I’d seen.
So what were the fish doing? A little Googling found the answer, described by Vernon Lee Avila in A Field Study of Nesting Behavior of Male Bluegill Sunfish, published in The American Midland Naturalist by the University of Notre Dame in 1978.
“Spawning was accomplished in a manner typical of all centrarchids. Once the female is settled in the nest the male swims close beside her. They face in the same direction and circle together in the nest, with the male on the outside and the female inside. During the spawning act the male’s anterior ventral surface darkens. As they circle in the nest the male remains upright, but the female tilts her dorsum away from the male and, leaning to one side, rubs the ventral surface near her genital pore in a quick ‘vibrating’ movement against the side of the male near his anal fin. As they circle together, the female tilts into this spawning posture every 60-100 sec. As contact is made, eggs and presumably milt are deposited (Miller, 1963). Spawning sessions varied in length from 15-90 min.”
Yep. That’s exactly what I saw.
I’d always assumed females simply came to the nest and deposited their eggs, and the male fertilized them. I had no idea there was some lovey-dovey stuff going on down there.
Game and Parks fisheries biologist Daryl Bauer summed up that aspect of my observation in simple terms. “You’ve got to coax her into laying the eggs,” he said. “Like anybody else, I get zoned in on fishing for them and catching them. But sometimes it’s just really interesting to stop for a second and watch them. It’s similar to going to the prairie grouse leks and watching all of that mating behavior.”
Bauer said males will make a clicking sound, and if you watch closely enough, you might see them flare their gills and pop their head to do so. Some won’t have anything to do with your lure because they are too preoccupied with guarding their nest. And you might see the “sneakers” in action. These small male fish take on the dull coloration of a female. When a female does approach a nest, he follows. Thinking he has two females on his nest, the parental male won’t chase the other male away, allowing the sneaker a chance to deposit its sperm when the female releases her eggs. This behavior, Bauer said, extends the inferior genetics and can lead to stunted populations, a good reason to release the big males.
“If you only knew some of the things that are going on below the surface,” Bauer said.
As for the solitary nests built in tangles sticks and rushes? Studies have found that while colony nesting is the norm — one found as many as 272 nests in a single colony — about 5 percent of bluegills are solitary nesters. And research in Wisconsin found that while bluegills will nest in muck, sand or gravel, they preferred gravel mixed with sticks.
One nest I saw was entirely on sticks. The nest in which I observed the spawning behavior was on sand, full of sticks and one chunk of log, and surrounded by vertical and overhead rushes and sticks. Another nearby was in cover that was identical.
The first question Tony Barada, another fisheries biologist, asked when I showed him the photos and questioned the location of the nest was if there were predators nearby. Indeed, there were. On my previous visit to Red Wing two weeks earlier, I found a school of small bluegills in shallows of the same backwater. Lurking nearby in deeper water were three largemouth bass that would periodically dart into the school, hoping for lunch.
“Maybe that was a mechanism of getting out of the way, or being sheltered from the bass,” Barada said of the nests. “But it is such an odd observation you saw in general. In a setting like that, where it’s not a big backwater area, that could’ve been the only way to potentially have success in that deal.
“It’s amazing, in our natural world, how many anomalies there are. There’s stuff that organisms do that are very unorthodox. They’re all individuals.”
Had I been smart enough to know what I was watching, I would’ve lingered longer. Had I done so, I may have been able to watch the female actually deposit her eggs.
One thing I know for sure, however, is the next time I find a bluegill nesting colony, I’m going to put down my fishing rod and watch. And come back later with the underwater gear.