{"id":102806,"date":"2017-11-15T11:34:16","date_gmt":"2017-11-15T18:34:16","guid":{"rendered":"https:\/\/dh.durangoherald.com\/tj\/walleye-delay-action-on-endangered-colorado-pikeminnow\/"},"modified":"2017-11-15T11:34:16","modified_gmt":"2017-11-15T18:34:16","slug":"walleye-delay-action-on-endangered-colorado-pikeminnow","status":"publish","type":"post","link":"https:\/\/dh.durangoherald.com\/tj\/walleye-delay-action-on-endangered-colorado-pikeminnow\/","title":{"rendered":"Walleye delay action on endangered Colorado pikeminnow"},"content":{"rendered":"
\"Unfamiliar
Unfamiliar predation on the pikeminnow in the Colorado River comes from a species of fish that\u2019s native to the flatwaters of Canada and the northern tier of the United States, the Walleye.<\/span>Associated Press file<\/span><\/figcaption><\/figure>\n

Unfamiliar predation on the pikeminnow comes from a species of fish that\u2019s native to the flatwaters of Canada and the northern tier of the United States. Walleye is a prized food fish, but its voracious appetite for pikeminnow is proving to be a setback to expectations that the pikeminnow could be removed from the endangered species list.<\/p>\n

\u201cWalleye have gone gangbusters in Lake Powell,\u201d said Tom Chart, a fisheries biologist who heads the Upper Colorado River Endangered Species Recovery Program for the U.S. Fish and Wildlife Service.<\/p>\n

It\u2019s likely that walleye found their way up the Colorado from Lake Powell, Chart said. It\u2019s also possible that the hungry newcomers could have swum down from Rifle Gap and Elkhead reservoirs in Colorado and from two reservoirs in Utah, Red Fleet and Starvation, both near Vernal, said Henry Maddux, director of Utah\u2019s species recovery programs.<\/p>\n

On a barely encouraging note, \u201cWe haven\u2019t seen walleye reproduce in the rivers,\u201d Chart said. \u201cYet.\u201d<\/p>\n

Walleye nonetheless have taken up residence in waters where they don\u2019t belong, feasting on the young pikeminnow that hatched in the critical 15-mile reach of the Colorado River through the Grand Valley and washed downriver into the slower waters where for eons they have grown to become the apex predators on the river.<\/p>\n

It\u2019s not just connecting the dots between fewer numbers of pikeminnow and the presence of walleye, Chart told The Daily Sentinel.<\/p>\n

Fish biologists checking the stomach contents of walleye caught in the Black Rocks stretch of the river have found their guts stuffed with young pikeminnow.<\/p>\n

Pikeminnow once were so numerous and large that when they moved upstream in large schools, they were dubbed \u201cwhite salmon\u201d by residents of western Colorado and eastern Utah, many of whom considered them a staple in hard times.<\/p>\n

Once they reach a length of about 18 inches, pikeminnow can fend for themselves, but they\u2019re slow to mature and can\u2019t reproduce for as many as eight years. They can live for about 40 years and grow to 6 feet in length.<\/p>\n

Walleye, however, appear to be interrupting the normal pattern, and the numbers of pikeminnow have taken a dip. After reaching a high of as many as 800 adults in the mainstem of the Colorado as recently as 2013, they\u2019re down to an estimated 400 or 450.<\/p>\n

The Fish and Wildlife Service estimated in 2013 there might be as many as 2,000 adult pikeminnow in the Green River, down from nearly 4,000 in 2008.<\/p>\n

That\u2019s enough of a stall, especially when combined with a similar drop in the Green River, that the Fish and Wildlife Service is tamping down expectations that it might downlist or delist the pikeminnow, Chart said.<\/p>\n

\u201cI think the service needs to see some stabilization and the population turning positive before they consider a change in status,\u201d Chart said.<\/p>\n

Biologists are working on an assessment of the species\u2019 long-term prospects for survival, beginning with a population estimate, Chart said.<\/p>\n

But the pikeminnow still appears to be positioned for recovery, eventually.<\/p>\n

Biologists identified more than 1,300 young-of-year pikeminnow in 2015 in Colorado River backwaters, the highest catch in 30 years, the officials said.<\/p>\n

Young-of-year are small fish, hatched from eggs spawned in the current year.<\/p>\n

\u201cWe have had one really good year,\u201d Maddux said. \u201cIt helps us buy time.\u201d<\/p>\n

\u201cI think success is on the horizon for the recovery of the endangered fish,\u201d said Eric Kuhn, outgoing chief of the Colorado River Water Conservation District, who noted that control of non-native species such as the walleye is necessary for that.<\/p>\n

\u201cJust when it looked like we were out of the woods with these fish, the invasive, predatory non-natives came into the mix and started causing trouble,\u201d said Patrick McCarthy, deputy director of the Colorado River Program for The Nature Conservancy.<\/p>\n

\u201cEverybody knew that it wasn\u2019t going to be straightforward,\u201d McCarthy said. \u201cThis is a little bit of a wrench in the works.\u201d<\/p>\n

Already efforts are underway in Colorado and Utah to put pressure on the walleye and other non-native predators. Colorado is working to make sure walleye are prevented from reaching the rivers by putting screens in flatwaters even as small as Highline Lake in Mesa County. Utah officials have introduced sterile walleye into the river to inhibit the possibility that the pointy-toothed predator establishes itself, Maddux said.<\/p>\n

Sterile walleye also have been introduced into Rifle Gap Reservoir, even though there\u2019s no evidence that the walleye in that lake have left it for the Colorado River below.<\/p>\n

The change in the prospect of delisting the pikeminnow comes as officials from three states, the U.S. Bureau of Reclamation and the Upper Colorado River Endangered Species Recovery Program changed the way they operate dams on the Colorado and Gunnison rivers to mimic the kinds of flows that allowed the pikeminnow to survive for at least 2 million years.<\/p>\n

\u201cFrom a habitat perspective, we\u2019ve really been good,\u201d Chart said.<\/p>\n

\u201cIf we could get rid of the non-natives, these fish would be doing tremendously,\u201d Maddux added.<\/p>\n","protected":false},"excerpt":{"rendered":"

Unfamiliar predation on the pikeminnow in the Colorado River comes from a species of fish that\u2019s native to the flatwaters of Canada and the northern tier of the United States, the Walleye.Associated Press file Unfamiliar predation on the pikeminnow comes from a species of fish that\u2019s native to the flatwaters of Canada and the northern […]<\/p>\n","protected":false},"author":1,"featured_media":102807,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[5736,5735],"tags":[108],"naviga_topic":[],"class_list":["post-102806","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-local-news","category-news","tag-endangered-species"],"acf":[],"author_name":"dh_admin","_links":{"self":[{"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/posts\/102806","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/comments?post=102806"}],"version-history":[{"count":0,"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/posts\/102806\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/media\/102807"}],"wp:attachment":[{"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/media?parent=102806"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/categories?post=102806"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/tags?post=102806"},{"taxonomy":"naviga_topic","embeddable":true,"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/naviga_topic?post=102806"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}