Mixing Up Some Mystery Fish | South Carolina Aquarium

Mixing Up Some Mystery Fish

Jun 07

Mixing Up Some Mystery Fish

Robust redhorse have an interesting history, as they were a mystery for 122 years. They were lost to science until fishery biologists found five “mystery fish” in the Oconee River that they couldn’t identify. Sure, it looked like other sucker species but these guys had a fleshy lower lip, were bronze, black and rose in color and were much larger. Lo and behold, they were the long forgotten robust redhorse!

That being said, robust redhorse haven’t had an easy comeback. Their numbers are still pretty low, which is why the Robust Redhorse Conservation Committee was formed. Members working in the Pee Dee River include the Aquarium, Duke Energy, South Carolina Department of Natural Resources, North Carolina Wildlife Resource Commission, among others. Each spring, curator David Wilkins or aquarist Stephen Beaman make the trek up to the Pee Dee River to assist our partners in spawning the robust redhorse to raise the young in hatcheries for a few months.

The days begin early when everyone boards the boat, starting at the upper end of a shoal close to Rockingham, NC and working downriver for hours at a time. The boat is rigged for robust redhorse fieldwork, including probes connected by a generator that drop in the water. These probes release a signal that quickly stuns the fish, making the collection non-invasive and without hooks.

Once they are safely on the boat, we do a typical workup – measure their length and weight, check for tags, take a quick fin clip for genetic testing and add a pit tag if need be for future identification.

Next comes the reproductive collection and “mixing.” Since it’s their spawning season, we look for both males and females ready to release their sperm and eggs, respectively. By tilting them at an angle, males release their sperm in test tubes and females drop their eggs in a bucket. Since the ultimate goal is to grow the population and maintain genetic diversity, we need to work fast onsite to mix the sperm and eggs for fertilization so they are still viable.

Using a turkey feather for gentle stirring, we mix the sperm and eggs. This mixture will be taken to one of two hatcheries, where robust redhorse are reared and later returned to the wild once they reach a certain size.

In 2019 alone, we were able to collect and release 56 total robust redhorse, 32 of which had never been captured before and assumed to have been hatched from past efforts!

Want to check out robust redhorse for yourself? Take a walk through our Piedmont Gallery at the Aquarium and see if you can spot them!

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