Happy Fish Fry Day folks! You’ll find perch and walleye specials at our fair state’s eateries today, but here on the blog we’ve got a tiny little martyr on the menu – the blacknose shiner.
We’re working our way through the epic 13-foot long “Fishes of Wisconsin Poster” hanging in our hallway and, well, when it comes to the blacknose shiner, you don’t have to look very far for an intriguing (some would say “gruesome”) tale.
Way back in the 1930’s, Karl Von Frisch (the Nobel laureate best known for his work on the sensory abilities of bees) was conducting some laboratory experiments on fish. Von Frisch, who was also an inspiration for our own Art Hasler and his work on the homing abilities of salmon, wanted to see if fish were able to communicate via chemical cues in the water.
Specifically, Von Frisch believed that, when a minnow is under attack by a predator, its skin cells can get damaged and release chemicals into the water that, when detected by other fish in the vicinity, tells them to scram.
As Virginia Hughes reported in this fascinating article from Smithsonian, Von Frisch dubbed the chemical “Schreckstoff,” or “scary stuff” in German and, when he separated the skin mucous of zebrafish into its various components, discovered that a sugar called condroiton sulfate well….just watch the video reenactment of Von Frisch’s experiment below and wait for the red light to go on.
As you can see, when condroiton sulfate hits the water, it turns into one big fish freak out.
However, some sixty-plus years later, Magurran et. al. challenged the idea that Schreckstoff is an alarm chemical in the Proceedings of the Royal Society of London, as they conducted the experiment on wild populations of European minnows and found that the chemical produced no alarm response. Von Frisch’s fleeing fish were seen more as a context-dependent result of a lab-reared fish in an aquarium rather than a real-world example of distress.
Enter a journal called Animal Behaviour. In 2004, an article was published detailing an experiment conducted by a team of researchers from Minnesota State University, Moorhead. They picked blacknose shiners, or Notropis heterolepis, as the substitute for wild European minnows. Then the team mounted underwater cameras just off the shore of three study lakes and watched what happened when they sounded the chemical alarm. For the blacknose shiners they were monitoring, the team reported a significant decrease in fish in the vicinity. The response was similar in magnitude to when the team would drag a decoy predator through the water and, what’s more, previous exposure to the chemical alarm cues made the fish even more skittish when the wooden decoy of a rainbow trout floated into view.
So, for now, it seems Karl Von Frisch’s chemical alarm cue hypothesis is holding water. And, for the smaller fishes in our rivers and streams, one unlucky (and unwitting) fish may just have the potential to help save the rest of its school.
Special thanks to the NTL-LTER’s Ted Bier for the heads up on this phenomenon!