Bluegill’s Intriguing Scar Inspires Anglers to Question its Cause

   When my grandsons catch a bluegill 7 inches or longer, it seldom swims another day.

  Catch and release? Save your breath.

   The boys haven’t yet read stories by the immortal humorist Patrick F. McManus, but their thinking aligns with his comment in “Kerplunk,” one of his 2007 stories: “I remember only one fellow who practiced catch-and-release. He was eventually nabbed, I think, and placed in an institution.”

   Therefore, I paused July 4 when my grandson Connor Switzer, 8, agreed without comment to release a 7½-inch bluegill with an ugly scar and dime-sized hole in its back. Connor caught the fish on Lake Poygan in east-central Wisconsin.

   After calling for me to come look, Connor evidently sensed my empathy as I examined the bluegill. Though the wound had mostly healed, it had amputated nearly 2 inches of the fish’s dorsal fin. I’ve seen northern pike slash perch and bluegills as I reel them in, but I had never seen such a gruesome wound on a panfish.

   I would have felt guilty eating the plucky survivor. Plus, it didn’t look appetizing. And so Connor took my advice to unhook the bluegill and toss it back to Poygan.

   A day later, I posted a photo of Connor and his battered bluegill on Facebook, and wondered if a pike had ravaged it. Of the nearly 11,000 people who viewed the photograph the next few days, none agreed with my assumption. Seven people, however, offered other explanations. One thought a blue heron speared the bluegill with its beak, and said he’d seen similar scars in trout “more often than you’d think.”

     Patrick Durkin’s grandson, Connor Switzer, age 8, caught this battle-scarred bluegill while fishing July 4 on Lake Poygan in east-central Wisconsin. He returned it to the lake moments later.     — Patrick Durkin photo

   The other six respondents thought an angler had likely used the fish for bait, only to have the hook pull free with a chunk of flesh. Again, one assured me, “It’s really more common than you think.”

   I also emailed fishing writer/editor Joe Cermele, who hosts the “Cut & Retie” podcast from his home in eastern Pennsylvania. Cermele said he’s seen nearly identical wounds on bluegills in many places he’s fished. He said the wounds were usually in the exact spot as on Connor’s bluegill, but a few were in front of the dorsal fin.

   Cermele thought it was an old hook wound from earlier in the bluegill’s life. “The hook either got pulled off or flung off, and the gash healed,” he said, adding it’s also possible a heron jabbed it. “Herons strike from the top down, so, I’d say it’s one of those two.”

   Cermele, too, discounted my assumption of a pike strike. “Predators like pike rarely attack top down,” he said. “They grab around the head most of the time or attack from below.”

   Next, I emailed the photo to five Wisconsin fisheries biologists. They said they couldn’t be certain, but agreed an angler likely used the bluegill as live bait years before. Although it’s illegal to net or trap bluegills for bait, they can be used if caught by hook-and-line (https://dnr.wisconsin.gov/topic/Fishing/questions/fishasbait.html).

   The biologists also thought the angler was probably targeting flathead catfish, Wisconsin’s largest predatory fish. Flatheads prefer live prey, and they’re common in much of the 167,000-acre Winnebago System, which includes lakes Winnebago, Poygan, Winneconne, Butte des Morts, and the Wolf and Fox rivers.

   Greg Sass, a Department of Natural Resources researcher, wouldn’t speculate on what wounded this particular bluegill, but said he’s seen many such scars on fish. “Fish are survivors, no matter the cause,” Sass said. “Nature is cruel. Maybe it was an eagle’s talon, and the fish dropped back into the lake. Or maybe it was a pike or blue heron. I could go on and on. Fish are resilient.”

   No biologist ruled out other possibilities. They noted that mink, ospreys, bald eagles, snapping turtles and great blue herons are common around Lake Poygan, and river otters are “moderately common” in the region. Those predators far outnumber anglers and “set-liners,” and when figuring in total hours of effort seven days a week, the gap between humans and winged or four-legged fish predators widens further.

   Even so, three biologists said their first thought was “fishhook.” One of them is Mark Endris, a retired DNR fisheries scientist who worked in Oshkosh, Wautoma, La Crosse and Eau Claire. “Your grandson’s bluegill could be 5 to 7 years old,” Endris said. “Its wound probably happened when it was much smaller, maybe 4 inches or so.”

   Like Cermele, Endris thinks someone hooked the bluegill beneath the dorsal fin — a common site for hooking a minnow or baitfish — and the hook tore out when cast. “The angler didn’t bury the hook beneath the bluegill’s spine, so it survived the hook ripping out, even though it took some flesh with it,” Endris said.

   “Nothing in a bluegill’s upper back would be lethal,” he continued. “The worst threat would be infection, but fish can fight off infections. You’ll sometimes see a fuzzy patch on them. Those are infections, too, Nature injures fish in many ways. It’s not just from humans, but the less we handle fish, the better off they’ll be.”

   That said, fish have proven remarkably resistant to handling, tagging and monitoring, which helps scientists manage fish species. Scientists inject tiny “PIT” transponders under their skin; clip or clamp tags to a fin or gill cover; anchor small plastic tags into skin near their dorsal fins; or slice open the abdomen, insert a disinfected transponder and sew the incision closed.

   In some cases, biologists also slide thin wires or cables through the fish’s skin to attach external transmitters. Whatever the device they carry, most fish survive and provide data for many years.

   “I’ve seen where a cable eroded the original site into a bigger hole over time, kind of like the wound on (Connor’s) bluegill,” Endris said. “I’ve seen holes that weren’t much bigger than the cable at first, but became the size of a dime. Maybe the site was infected at first, but we saw no sign of infection the next time we saw the fish. They have very good immune systems.”

   Perhaps the only thing stronger is the fish’s will to survive.