82: Northern Redbelly Dace

I write to you from Arapahoe, Ute, and Cheyenne land. I am interested in learning about the different animals that live in the place where I was born. Before we start with today’s animal, I want to emphasize that biological classification as understood by western society has its roots in racism, sexism, and transphobia – here’s a good explainer about why.

I’m going to confess to you that I know very little about fish and that I learned that there’s a type of fish called a “dace” from playing Animal Crossing. The Wikipedia entry for “dace” opens with the immortal line, “A dace is a small fish that can be one of many different species.” Hm. But then I did a little more research and I found an amazing story about the Northern Redbelly Dace (Phoxinus eos) in Colorado.

NRDs like to live in cold water, like small spring-fed lakes, beaver ponds, and small headwater streams. The water should be shaded and unpolluted, without large, invasive, fish-eating predator fish, because their distinctive coloration makes them vulnerable to predation. Following 160 years of colonization, irrigation and dam building, invasive sport fish stocking by the Forest Service and other agencies, and other water-polluting activities, only a single isolated population of NRDs remained in Colorado – in West Plum Creek, south of the Chatfield Reservoir in the southwestern Denver metro area. As a result, they are endangered in Colorado and within the Rocky Mountain region (though they are not endangered federally and live around the Great Lakes region and east into Maritime Canada). In Colorado, as well as in South Dakota and Nebraska, they are relict populations from the retreat of the Wisconsin Ice Sheet, something we have discussed in relation to a few other fish previously. The cold water they live in today is a reminder of the glacial rivers that their ancestors once enjoyed. They enjoy clear, unpolluted water because the females release their eggs based on seeing the bold black, yellow, and red stripes of the males.

Coloradans may remember the massive flooding of the Boulder area during 2013, when they received almost their full annual average rainfall over the course of five days. One result of this was that waterways for miles around had their courses redrawn across the landscape, including being loaded with nutrient-rich silt. Boulder County, rather than try to return some of these waterways to their colonized states, opted to leave them as wetland habitats. Webster Pond transitioned from being a fishing area to a native species nursery and Boulder County Parks & Open Space and Colorado Parks & Wildlife agreed that it should be stocked with the endangered NRD. They partnered with a Boulder-based nonprofit, Ocean First Institute, as well as the local St Vrain Valley School District, to have students raise the fish and then release them. They have successfully released NRDs in 2020 and again in 2021! You can read much more about this project here. As of right now, the fish are thriving in their new habitat, even surviving an oil spill into a nearby pond. They also made a really cute little comic about NRDs (scroll down to see).