It’s a sweltering, record-hot day just north of Socorro as our group – clad in waders – walk towards the sandy banks of the Rio Grande River.
Nearby, trucks and cars noisily pass over a small bridge.
A quick glance at the treeline reveals the signs of early spring – well before the river’s signature cottonwoods have regrown their distinctive, triangular leaves.
In New Mexico, spring is a time of rebirth, signaled by wildflowers blooming across the high desert, cottonwoods beginning to bud, and snowmelt cascading from the mountains. It’s also a critical season for fish like the endangered Rio Grande silvery minnow, which rely on influxes of cold water to reproduce.
I’m here with the Albuquerque BioPark’s aquatic conservation team, taking advantage of a short window — timed perfectly with the snowmelt — when biologists can scoop up silvery minnow eggs.
They do this by lugging large, crudely made wooden boxes into the middle of the water and standing them up on metal stakes in the river bed.
The box has a rectangular hole in the front that allows water to flow in, with a removable mesh screen at the back meant to filter the naturally buoyant fish eggs for collection.
Once abundant in the Rio Grande, the small and unassuming silvery minnow has been on the endangered species list since the early 1990s due to significant habitat loss and degradation along the river.
Despite its modest size, the minnow lives up to its name, flashing a bright silver hue with hints of greenish-yellow when caught in the sunlight.
On the other hand, their eggs are quite hard to spot.
“An egg just looks like a small bubble,” said Patrick Horley, curator at the Albuquerque BioPark’s Aquatic Conservation Facility.
That’s where they take any eggs they collect each year to be hatched, mainly to ensure the survival of the fish. Typically, they release tens of thousands of minnows back into the wild annually.
“A female will release 1000s of eggs. And keep in mind, she's only two inches long, three inches long. So those eggs are very, very small.”
So, once these strange wooden contraptions are set up and ready to go, Horley and his team stand in the river and wait for the eggs to roll in.
“And then when we find the eggs, we'll scoop them with a little plastic spoon,” Horley said. “This one's from Wendy's and then we'll put it in a cup full of water, where we keep them until the end of our set.”
Four hours later? We didn’t catch a single egg – only a sunburn.
There’s plenty of reasons for our failure, according to Horley’s team. It could be bad luck. Maybe it was too early in the season and the fish haven’t spawned quite yet. Or, alternatively, climate change is at play.
“Well, they need a rush of cooler temperature water to actually get them to spawn the eggs, because they'll hold them until they feel like the conditions are right,” BioPark aquaculture technician Trinity McCoy said. She sports an impressive array of detailed wildlife tattoos on her arm, including a silvery minnow.
In reality, the fish is very fragile and at the whim of the drying Rio Grande – which poses a dilemma for a fish that gets its cue to spawn from mother nature.
Snowmelt from Colorado is a major source of water for the Rio Grande, contributing up to 75% of its flow. Though, the state’s snowpack for the 2025 season is ending at its lowest level since 2018.
That means this year will be especially difficult for the minnow’s survival, with water managers warning significant portions of the Rio Grande will dry up this summer. That, and over three-fourths of its water is used for agricultural irrigation.
“The river looks way different today than it did as these fish were evolving, and the man made changes to the river have far surpassed the speed at which a species can evolve,” Horley said.
So, while the data clearly shows an uncertain future for both the river and its endangered species, conservationists say there’s still time to shift course — if people are willing to rethink how the river is shared, and who it's meant to sustain.
