Highlights

River Restoration Results in Record Fish Runs

In 2010, we replaced culverts on Bride Brook in Connecticut. With the increased flow from the new, larger culvert, fish were able to swim upstream for the first time in more than a decade. And this year, Bride Brook reaped the benefits: this year’s run was more than triple what we had seen in the past (see graph at right).

Culverts—the pipes that allow water to flow under roads and bridges—are everywhere. They might seem harmless, but they can sometimes block fish from swimming upstream. The culverts are much more narrow than the streams that channel through them, and sometimes too high for fish to jump through. When this happens, fish can’t reach their spawning habitat upstream of the culvert.

The two culverts at Bride Brook were clogged with debris and on the verge of collapsing. They restricted the flow of water into and out of a 78-acre marsh. Without free-flowing water, marsh plants died—and that marsh is critical habitat for wildlife, including herring.

The herring run on Bride Brook is the second largest in the state. In the 1970s, it was as high as 175,000 per year. But the culverts had reduced the run to less than half that number. Now, with tidal flow restored, adult fish have unimpeded access upstream to Bride Lake to spawn, and juveniles can swim downstream to feed and grow in the ocean. The herring run has rebounded: 275,000 fish swam through the new culvert this spring.

Next week, we’ll install three new tide gates nearby on the West River in New Haven. These gates, like the larger culvert at Bride Brook, will allow a more natural flow of water and improve fish passage. We anticipate similar herring run improvements at the West River next year.

Posted May 29, 2012