{"id":24803,"date":"2024-02-29T11:20:31","date_gmt":"2024-02-29T05:35:31","guid":{"rendered":"https:\/\/www.revoscience.com\/en\/?p=24803"},"modified":"2024-02-29T11:25:39","modified_gmt":"2024-02-29T05:40:39","slug":"walleye-struggle-with-changes-to-timing-of-spring-thaw","status":"publish","type":"post","link":"https:\/\/www.revoscience.com\/en\/walleye-struggle-with-changes-to-timing-of-spring-thaw\/","title":{"rendered":"Walleye struggle with changes to timing of spring thaw"},"content":{"rendered":"\n
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Within a few days of ice-off, when a lake\u2019s frozen lid has melted away, walleye begin laying eggs and fertilizing them. When lakes thaw earlier than usual, the young walleye that hatch in Midwestern waters may have a more difficult time surviving. iStock \/ Willard<\/sup><\/figcaption><\/figure>\n\n\n

Adam Hinterthuer<\/p><\/div><\/div>\n\n\n

MADISON \u2014 Walleye are one of the most sought-after species in freshwater sportfishing, a delicacy on Midwestern menus, and a critically important part of the culture of many Indigenous communities. They are also struggling to survive in the warming waters of the Midwestern United States and Canada.<\/p>\n\n\n\n

According to a new study published Feb. 26 in the journal Limnology and Oceanography Letters, part of the problem is that walleye are creatures of habit, and the seasons \u2014 especially winter \u2014 are changing so fast that this iconic species of freshwater fish can\u2019t keep up.<\/p>\n\n\n\n

The timing of walleye spawning \u2014 when the fish mate and lay their eggs \u2014 has historically been tied to the thawing of frozen lakes each spring, says the study\u2019s lead author, Martha Barta, a research technician at the University of Wisconsin\u2013Madison. Now, due to our changing climate, walleye have been \u201cunable to keep up with increasingly early and more variable ice-off dates,\u201d Barta says.<\/p>\n\n\n\n

Within a few days of ice-off, when a lake\u2019s frozen lid has melted away, walleye begin laying eggs and fertilizing them. In a normal year, that timing sets baby fish up for success once they hatch. But, Barta says, \u201cclimate change is interrupting the historical pairing of ice-off and walleye spawning, and that threatens the persistence of walleye populations across the Upper Midwest.\u201d<\/p>\n\n\n\n

Barta \u2014 who began working on the study as an undergraduate student at UW\u2013Madison\u2019s Center for Limnology \u2014 and her colleagues used data from walleye surveys from various state natural resource departments and the Great Lakes Indian Fish & Wildlife Commission, as well as the spring harvest counts from Ojibwe tribal nations to track the fate of walleye populations on 194 lakes across Minnesota, Wisconsin, and Michigan. The data revealed \u201cmismatches\u201d in ice-off and spawning on almost every single lake. While there has been a slight shift to earlier spring spawning dates for walleye, the ice-off dates on those lakes were shifting at a rate of three times faster.<\/p>\n\n\n\n

Suddenly, the timing is all wrong for walleye, explains Zach Feiner, a fisheries scientist with both the UW\u2013Madison Center for Limnology and the Wisconsin Department of Natural Resources.<\/p>\n\n\n\n

\u201cIn an average ice-off year, you have this nice progression of events,\u201d Feiner says. \u201cThe ice goes off, you get light and warmer water that creates a bloom of small plant life called phytoplankton. And then tiny animals called zooplankton emerge and eat the phytoplankton, and usually, the walleye spawning is timed for them to hatch when zooplankton are around in high abundance and can serve as fish food for the baby walleye.\u201d<\/p>\n\n\n\n

But lately, the timing of yearly thaws has gotten \u201cweird,\u201d says Feiner. Lakes are, on average, thawing earlier, but the number of winters where lakes thaw late is also increasing. The shifts throw off the timing of phytoplankton blooms, zooplankton emergence, and walleye hatch, breaking their linked progression as winter transitions to spring.<\/p>\n\n\n\n

\u201cWhen the fish hatch, there aren\u2019t enough zooplankton around, and walleye don\u2019t have enough food to survive,\u201d Feiner says.<\/p>\n\n\n\n

On a year-to-year basis, that isn\u2019t necessarily a problem, as adult walleye can always spawn again the next year, when conditions may be more favorable and more of their offspring can survive and increase the population. But, Feiner says, the heightened variability of spring thaws is \u201cincreasing the frequency of bust years, and we\u2019re not seeing many or any boom years for a lot of walleye populations.\u201d<\/p>\n\n\n\n

While this is obviously bad news for walleye and the people who depend on them, the study underscores the need to identify and protect lakes that can offer refuge in bad years.<\/p>\n\n\n\n

\u201cThere is a need now to find places where, through management of things we can control \u2014 like land use, fish harvest, and invasive species \u2014 we can buffer or boost their resiliency to be able to handle stuff we can\u2019t control, like climate change,\u201d Feiner says<\/p>\n\n\n\n

If fisheries managers can identify lakes where walleye populations are doing relatively well, they can try to keep conditions optimal so that the fish can take advantage during the increasingly rare years when ice-off and their spring spawn do line up.<\/p>\n\n\n\n

Then there is also the question of what our \u201cweird\u201d winters mean for other fish species.<\/p>\n\n\n\n

\u201cMost of our big-time sportfish species in the Midwest, like walleye, perch, pike, bass, bluegill, and muskies, spawn in springtime,\u201d Feiner says. Other species like lake trout and whitefish spawn in the fall, and their eggs overwinter under the ice.<\/p>\n\n\n\n

Feiner hopes to expand the research to see if a pattern extends to other fish prized by people \u2014 or if some of them are resilient to less-predictable ice-off timing.<\/p>\n","protected":false},"excerpt":{"rendered":"

MADISON \u2014 Walleye are one of the most sought-after species in freshwater sportfishing, a delicacy on Midwestern menus, and a critically important part of the culture of many Indigenous communities. They are also struggling to survive in the warming waters of the Midwestern United States and Canada. According to a new study published Feb. 26 […]<\/p>\n","protected":false},"author":2,"featured_media":24804,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[15,17],"tags":[],"class_list":["post-24803","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-environment","category-research"],"featured_image_urls":{"full":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2024\/02\/lakes-frozen-lid-uw-madison-press.jpg",775,517,false],"thumbnail":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2024\/02\/lakes-frozen-lid-uw-madison-press-200x200.jpg",200,200,true],"medium":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2024\/02\/lakes-frozen-lid-uw-madison-press-600x400.jpg",600,400,true],"medium_large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2024\/02\/lakes-frozen-lid-uw-madison-press-768x512.jpg",750,500,true],"large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2024\/02\/lakes-frozen-lid-uw-madison-press-675x450.jpg",675,450,true],"1536x1536":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2024\/02\/lakes-frozen-lid-uw-madison-press.jpg",775,517,false],"2048x2048":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2024\/02\/lakes-frozen-lid-uw-madison-press.jpg",775,517,false],"ultp_layout_landscape_large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2024\/02\/lakes-frozen-lid-uw-madison-press.jpg",775,517,false],"ultp_layout_landscape":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2024\/02\/lakes-frozen-lid-uw-madison-press.jpg",775,517,false],"ultp_layout_portrait":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2024\/02\/lakes-frozen-lid-uw-madison-press-600x517.jpg",600,517,true],"ultp_layout_square":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2024\/02\/lakes-frozen-lid-uw-madison-press-600x517.jpg",600,517,true],"newspaper-x-single-post":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2024\/02\/lakes-frozen-lid-uw-madison-press-760x490.jpg",760,490,true],"newspaper-x-recent-post-big":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2024\/02\/lakes-frozen-lid-uw-madison-press-550x360.jpg",550,360,true],"newspaper-x-recent-post-list-image":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2024\/02\/lakes-frozen-lid-uw-madison-press-95x65.jpg",95,65,true],"web-stories-poster-portrait":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2024\/02\/lakes-frozen-lid-uw-madison-press.jpg",640,427,false],"web-stories-publisher-logo":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2024\/02\/lakes-frozen-lid-uw-madison-press.jpg",96,64,false],"web-stories-thumbnail":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2024\/02\/lakes-frozen-lid-uw-madison-press.jpg",150,100,false]},"author_info":{"info":["Adam Hinterthuer"]},"category_info":"Environment<\/a> Research<\/a>","tag_info":"Research","comment_count":"0","_links":{"self":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/24803","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/comments?post=24803"}],"version-history":[{"count":2,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/24803\/revisions"}],"predecessor-version":[{"id":24806,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/24803\/revisions\/24806"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/media\/24804"}],"wp:attachment":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/media?parent=24803"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/categories?post=24803"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/tags?post=24803"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}