A pikeminnow, a catfish, and a Russian olive walk into a watershed ...

Plus: Sayonara to Silverton-area sheep;

🐟Nature is Wild🦉

A native fish, a non-native fish, and an invasive shrub walk into a watershed, and the shrub says to the native fish: Is that a catfish stuck in your craw? And the native fish says: Yeah, but it’s you stuck in his belly!

Okay, it’s not a very good joke, even for one from the surreal-absurd humor genre. But the scenario does make for some interesting science, as a trio of researchers detailed in a recent study involving these very characters.

The lead native-fish role goes to the Colorado pikeminnow, with the razorback sucker in a supporting role. Both were once plentiful in the Colorado River and most of its tributaries. But dams and diversions, habitat degradation, and predation by and competition from invasive species have reduced their numbers significantly, extirpating pikeminnow from the Lower Basin altogether. The Colorado pikeminnow (née Colo. sq***fish), was among the earliest species listed under the 1973 Endangered Species Act, while the razorback sucker was listed in 1991. 

The antagonist is the channel catfish. Native to rivers east of the Continental Divide, the tenacious fish was brought West in the 1880s by wildlife officials and landowners who stocked rivers, lakes, and ponds with it for sport and food fishing. The whiskered, spiny-finned fish weren’t so keen on the chilly water of the upper tributaries, but took well to the murky, warm waters of the San Juan River, and the species has persisted. When we were kids, my brother and Frank Zeletti, our coal-miner, fisherman neighbor, used to pull huge catfish out of Navajo Reservoir — girthy, slippery, three-foot-long lake monsters that surely contributed to my enduring fear of deep water. But they did taste good, at least when beer-battered and deep fried.

The catfish compete with the native fish and eat their young. And the catfish also — get this — sometimes get stuck in pikeminnows’ throats when the native fish try to have a little invasive for dinner. I’m not kidding. There’s a full scientific paper on this topic, with this gory morsel: 

On 1 October 1999, at approximately 1145 h while electrofishing at river kilometer (RK) 138.4, 12.1 km downstream of the bridge at Montezuma Creek, Utah, we collected a sub- adult Colorado pikeminnow (346 mm TL) with a channel catfish (111 mm TL) firmly lodged in its mouth anterior to the gills. The channel catfish was alive and struggling, with spines extended. The dorsal spine had penetrated the roof of the Colorado pikeminnow’s mouth and had entered the right eye socket causing distention and hemorrhagic swelling. Both pectoral spines had penetrated the sides of the Colorado pikeminnow's mouth. The posterior end of the channel catfish, from just anterior to the adipose fin, protruded from the Colorado pikeminnow's mouth.

Quite the image, right? This doesn’t happen often, but as the author points out, the pikeminnow’s populations are so low in some areas that even losing a handful of fish in this manner can harm efforts to recover the species.

A separate study examined the stomach contents of channel catfish in the San Juan River to see how many pikeminnow fry or fingerlings they might find. This is where the plot thickens and the invasive shrub enters the scene: While the researchers found relatively few pikeminnows in the catfish’s guts, they did discover a bunch of fruit from the Russian olive, an exotic species that has colonized riparian areas across the Southwest. That inspired them to launch a Russian-olive-centric catfish-gut study, leading them to discover that San Juan River catfish rely on the shrub’s fruit for about 44% of their diet. 

On the one hand, that means catfish who have plenty of Russian olives (and other food sources, like insects and lizards and crawdads) to eat don’t need to be noshing on endangered pikeminnows or suckers. On the other hand, the Russian olives’ calories make the catfish bigger, and the bigger the catfish the more likely they are to eat other fish. 

Where does this leave us when it comes to spending millions of dollars attempting to eradicate catfish and Russian olives? Good question.

Russian olives aren’t exactly olives, but Elaeagnus angustifolia. Native to central Asia, Iran, and Turkey, they were first brought to the Western U.S. in the 1880s. They grew well in crappy soil, which we have a lot of in these parts, and worked well as hedges, windbreaks, and ornamental trees, despite their nasty thorns. In an 1887 edition of the Rocky Mountain News, a Fruita, Colorado, resident wrote that he had ten of them in his yard:

Of course, they soon strayed from yards and fields into the greater environment, clogging up ditches and infesting floodplains along with tamarisk, or salt cedar. They guzzle water, crowd out native species like cottonwood and willow, and alter stream channels.

So, land management agencies spend a lot of time, money, and energy trying to eradicate or control the species. Yet at the same time, these exotic trees and shrubs have become integrated into the native ecosystems, as the channel catfish tale reveals. Southwestern willow flycatchers, an endangered bird, nests in Russian olive and tamarisk, and several species — from bears to coyotes to turkeys — eat the fruit.

I’ve always assumed the fruit of the Russian olive, also known as oleaster, was inedible. But since this study found catfish eat it, I figured maybe I’d poke around the intertubes a bit to see if people could snack on it, too. And it turns out the answer is yes, though it did take some distinguishing between olive recipes from Russia and recipes for Russian olives.

Ripe Russian olives can be eaten fresh or dried, and used to make jellies and even liquor. Haft mewa, an Afghan dish, is made of Russian olive, or senjed — aka “paradise fruit” — and other dried fruits. Oleaster symbolizes love in the Persian New Year snack spread; whether this is Russian olive or the related autumn olive is not clear, as both go by the name “oleaster,” but apparently have different flavors. Russian olive is also “famous,” according to this paper and this one, “for its medical applications” and its antioxidant, anti-inflammatory, and analgesic properties.

Maybe when it comes to managing channel catfish and Russian olives the moral of the story is this: If you can’t beat it, eat it!

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🐑 Saying Sayonara to Silverton-area sheep

Right around the Fourth of July, as the rhubarb was ripening and nighttime temperatures stayed slightly above freezing in Silverton, Colorado, the sheep trucks would roll through town, carrying their bleating loads to high-country grazing allotments. It was a summer ritual, one that is now coming to an end.

On the one hand, the mechanized sheep drive was a charming tradition, a reminder of the days when the mountain mining towns were fed by the farms and ranches in the Animas and Uncompahgre Valleys below, and travelers on the Durango-to-Silverton road might encounter ranchers trailing hundreds of sheep to higher pastures.

But it could also be annoying: The sheep trucks would be closely followed by swarms of black flies infesting the town, (though I honestly don’t know if this was a matter of causation or mere correlation). Hikers would regularly encounter huge flocks of the wooly critters munching on mountain meadows and trampling delicate tundra. And in more recent years, hikers and bikers had problems with the big, scary sheep dogs. Later in the season, when the trucks returned to carry the sheep back down to the low country, they’d inevitably leave an animal or two behind, which might provide a nice pre-winter meal to some predator or, just as likely, might end up wandering the streets of Silverton with the Sheriff in slow-motion hot pursuit.

Far worse, however, is the threat the domestic sheep pose to endangered bighorn sheep. They carry Mycoplasma oipneumoniae, a pathogen that can cause fatal pneumonia in wild bighorns and reduce lamb survival rates. Bighorn sheep once numbered in the millions across the Western U.S., but over time they were hunted and crowded to near-extinction. Now the pathogens carried by domestic sheep are considered the greatest threat to the recovering animals.

Sheep grazing has declined significantly in the San Juan Mountains in the last several decades, but a handful of livestock operators still ship sheep to public lands grazing allotments. Until recently this included Ernie Etchart, a Montrose rancher, who leased just over 100,000 acres of Bureau of Land Management and Forest Service land around Silverton.

Etchart agreed to retire his Silverton-area allotments in exchange for an undisclosed payment, meaning domestic sheep will no longer roam that particular part of the San Juans. The National Wildlife Federation helped broker the deal. In a press release, Etchart said the allotments were good for his operation, “but with the increasing number of backcountry recreational users and proximity to bighorn sheep, the conflicts were becoming a real challenge.” He added that giving up the leases ultimately was a “business decision.”

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Public Lands Matrimony Watch

If it’s not livestock grazing, off-highway vehicle use, uranium mining, oil and gas drilling, residential development, or industrial-scale tourism and recreation wrecking the public lands around Moab, it’s tech-bro weddings. Silicon Valley investor Andrew Chen and former Miss Ireland Emma Waldron held a blowout wedding bash in September on BLM land at the base of Castleton Tower. And they left behind a huge mess, according to the Moab Times-Independent, drawing the ire of locals and national media attention. Castle Valley’s town council urged the BLM to ban or more stringently regulate such events in the future.

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👽 Parting Shot 🛸

If anyone knows what the hell this thing is — or even wants to speculate wildly — I’m all ears. It sits outside a Ticaboo, Utah, gas station. And, yes, I could have asked the person behind the counter at the gas station, but that entailed great risks: Like, what if he answered that it was just a way to hide a generator. Would I believe him? Or would I suspect that he was covering up for the space aliens that obviously built the thing? And what then?