CREATURE FEATURE – Redside Dace

A Creature in Danger

in headwater streams throughout the Great Lakes and Ohio River regions. Now though, this little fish is seriously endangered. Its presence is limited to a few small, isolated populations. In Michigan, redsides are found in just three Michigan rivers (including the Rouge River), and long-term survival of the species is in question. They are listed as an endangered species in the state.

These little fish are an indicator species because they are very sensitive to changes in environmental conditions. While a strong presence of redside dace indicates pristine waters, a substantial loss of  redsides highlights declining water quality. Unfortunately, many disparate factors have come together to cause dramatic declines in the redside dace population.

• Artificial dams prevent mingling (and breeding) between isolated populations.
• Removal of natural riparian vegetation (for growth in agriculture and waterfront development) depletes natural shade canopies over streams thereby increasing water temperatures.
• Global warming increases river and stream temperatures even in the normally cooler headwaters. (Redsides require peak summer water temperatures to stay below 70⁰F.)
• Rapid storm run-off, from excessive areas of paved surface, increases chemical pollutants and water turbidity.
• And artificial stocking of “sport fish” – specifically brown trout – introduces both excess competition for food sources and unnatural predators. (Note: Brown trout, while not native to the US have been stocked in US rivers since 1883.)

The sad, but predictable, end result of such ongoing human interference is the decline of many native watershed species like the redside dace.

Researchers in both the US and Canada are working to monitor remaining populations of redside dace and to improve / restore appropriate habitat conditions where possible. In 2012, FOTR (with the help of then interns Robert Muller and Kristina Blott) conducted a special survey of redside dace in the Rouge River watershed and found only four isolated populations of a few fish each.  At that time, FOTR persuaded the Michigan DNR to discontinue the stocking of the non-native brown trout in the watershed. Unfortunately, subsequent FOTR surveys fish surveys through 2020 have found no redside dace present at any sampling sites. At this time, it is unclear if any small populations of the dace remain within the watershed.

HABITAT & LIFE CYCLE

During most of the year, the natural environment of the redside dace is a cool, clear, and moderately deep pool of clean freshwater within a gravel bottom stream. For both shade and shelter, redsides need streams with plentiful shoreline brush. Perhaps for added protection, these little guys often try to swim within mixed schools of several fish species where they flash about, jumping here and there, catching bugs, and hiding from larger fish and hungry shorebirds.

Named for the wide red band along their side, redside dace are also recognizable for a bright gold stripe above the red band. Males and females both average three inches in length and look very much alike, though males may display slightly brighter color bands during mating season.

During spring, when the waters warm to approximately 70 ⁰ F, redside dace briefly venture out of their protective pools to swim along shallow, fast flowing stream riffles. There, they seek mates and lay eggs for the next generation. However, since the dace require cool water to survive, the adults must quickly return to the cooler temperatures of the deeper pools.

Among freshwater fish, there are two primary spawning rituals. In some species, males build a protective nest and then hover nearby during spawning and incubation to aerate (by fanning) and protect the eggs. However, other fish species spawn through nest association whereby both males and females swim (and spawn) over the nest of a different species. Redside dace are nest associators. They swim over nests of other species – shiners, chubs, even sunfish – to deposit their own spawn. Then they leave, and the spawn / newly hatched fry of the redside dace are left in the care of the resident species. Though not yet fully understood by researchers, the resident nest builders permit the associators access to nesting sites; and this cooperative method of breeding appears to work well for all.

When a redside dace female spawns, she may drop as many as 2,000 eggs which will be fertilized by several males. Young fry grow quickly during their first summer and reach roughly half of their mature length by the first fall. Redsides that successfully escape predators reach maturity during their second year and enjoy a lifespan of three to four years.

TAKE ACTION

FOTR works hard every day to help protect and restore natural habitats within the Rouge River watershed. Additionally, we continue to search for the endangered redside dace as part of our annual fish surveys. Since 2012, FOTR has surveyed all major branches and tributaries as well as many of the lakes of the Rouge. Learn more about our survey results

Together, we strive to save a place for all our native creatures. And perhaps, we can still save a place in this world for a bright and shiny little fish known as the redside dace.