A rare set of conjoined Chinook salmon twins has been discovered at the University of Windsor’s Freshwater Restoration Ecology Centre (FREC) in LaSalle, Ont. — a biological twist researchers say only shows up once in every 10,000 to 50,000 salmon hatches. The find was made on Nov. 20. Graduate students were checking thousands of newly hatched salmon fry as part of their ongoing work tracking early-life development and overall Great Lakes fish health. The twins — ventrally conjoined and sharing a yolk sac — stood out immediately. “They were just incredibly in awe of the fact that it survived, first of all,” said Trevor Pitcher, a professor at the University of Windsor’s Great Lakes Institute for Environmental Research. “And secondly, they just sort of thought it was incredibly biologically fascinating because it’s so rare.” Rare, but not unheard of Pitcher said he’s worked with salmon for 27 years and has only come across conjoined fry three times. “We’ve never seen one here in LaSalle, ever,” he said. After snapping a photograph, the team placed the twins back in with the other hatchlings. While conjoined fish usually don’t make it in the wild, Pitcher believes this pair will make it through the early developmental window. “It’ll survive at least through the juvenile stage,” he explained. “But at some point, when it runs out of yolk sac, will struggle to separate.” He said conjoined fry typically results from developmental issues early in life — not pollution, habitat problems, or broader environmental concerns. A valuable hands-on lesson For students, Pitcher said it made for a unique learning opportunity. “They learned a lot from this,” Pitcher said. “They certainly learned that the health of the fish is really incumbent upon the people taking care of them, and they were able to essentially keep this thing alive. Generally, in the wild, it wouldn’t make it.” FREC staff raise salmon, lake sturgeon, and endangered species, such as the redside dace — giving students a close-up look at how early-life differences shape survival. With thousands of fish moving through the centre each year, oddities like this help illustrate the diversity researchers see behind the scenes, according to Pitcher. “Everybody thinks they look the same, but to us they all look quite unique… from colour patterns to this developmental difference,” he said. Why it matters Pitcher said the discovery won’t rewrite fish biology, but it’s a reminder of the value of hands-on conservation work — and the sheer amount of life being raised to support Great Lakes fisheries. “It’s just part of the ongoing process that we’re doing to actually protect the Great Lakes and safeguard healthy fish for the Great Lakes at the University of Windsor,” he said. The timing also aligned with World Fisheries Day on Nov. 21, a global call to protect aquatic ecosystems and the communities that rely on them.
