Are There Native Fish in La Milagrosa Canyon?Earth and Environmental Sciences
- Jeannette Olsson
"Native riparian fish are commonly overlooked and historically under-appreciated inhabitants of desert ecosystems. Before an historical drought in 2021, I found what I believed were longfin dace (Agosia chrysogaster) in a drying pool in La Milagrosa Canyon, a tributary of the Santa Cruz watershed. However, the pool in which I found them may have completely dried up later that summer during an historic drought. After the pool had refilled from seasonal rains I revisited the site but instead of finding dace, I found an invasive fish: green sunfish (Lepomis cyanellus). To determine whether native fish were still present, I partnered with USFWS to sample potential habitats of native species and possible source pools for invasive species to be flushed down into canyon pools. After 900 trapping hours with minnow traps, I did not find any fish but this is likely because a flood less than a month before flushed the canyon out and spread out any fish populations. Older footage of the fish from before drought indicate they may have been invasive sunfish the whole time. Revisiting these pools in the summer when water levels are lower is suggested to help answer the question of whether there are any native fish in this canyon."