Since last month 50+ juvenile salmon have been captured and released
For the first time in over 60 years, juvenile spring Chinook salmon can swim freely through newly created side channels of the Willamette River at Delta Ponds and Heron Slough.
Slow-moving, side channels such as those recently restored at Delta Ponds and Heron Slough provide areas of calm water during high-winter flows. In calm water, juvenile salmon are able rest, feed, and grow larger before migrating to the ocean. The Delta Ponds and Heron Slough projects were designed specifically to provide over-wintering habitat for juvenile Chinook salmon.
“There are many factors that impact the survival rate of listed species, such as Chinook salmon,” said Lauri Holts, natural resources coordinator for the city of Eugene. “There are many times in their life cycle when they are at risk…so while it would be really hard to determine exactly what the impact [of Heron Slough] is, we can certainly say that we are positively impacting their survival by providing much needed habitat during a critical part of their life cycle.”
With the completion of major restoration work this past year, water can now flow through the ponds for 2.2 miles, before it meanders back into the river. The addition of Heron Slough, a quarter mile of newly constructed stream-like side channel, provides another outlet for river water during high-water events like those Eugene has experienced over the past several weeks.
A grant from the National Oceanic and Atmospheric Administration (NOAA) Restoration Center has enabled the city of Eugene to hire a contractor, Cramer Fish Sciences, to monitor fish in Delta Ponds and Heron Slough through May “and perhaps longer” according to Holts.
A consultant with Cramer Fish Sciences has been running a rotary screw trap at the inlet at Delta Ponds. Since January, over 50 juvenile Chinook have been captured and released using the rotary screw trap.
A handful of Chinook were also found in the interior ponds at Delta Ponds and hiding under some submerged tree roots in Heron Slough.
“The changes that we have made to the habitat will benefit many other species aside from the salmon (including other native fish species, Western pond turtles, neo-tropical migratory birds, beaver, otter, etc.),” said Holts. “The recovery of Chinook salmon as a whole, especially the return of adults to spawn in the upper reaches of our river can certainly have a big impact on the ecology of the areas where they spawn by bringing ocean nutrients (in the form of their decaying bodies) back to the streams – and forests – of the foothills.”
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