Category Archives: Alewife

Progress on Fish Passage at Beaver Lake Spillway

Check out any river on Long Island and chances are you will find a series of dams running its length. Thus virtually every river on Long Island has compromised to completely blocked fish passage resulting in the virtual elimination of anadromous fish from our waters. The Shu Swamp/Beaver Lake watershed  is impacted by four dams. About the only LI stream I can think of that doesn’t have at least one dam is Alewife Creek in Southamptom, famous for its huge alewife run in March and April, and considered an “ecosystem rarity” by New York Department of Environmental Conservation.


Nature Conservancy and its partners meeting with engineers for Fuss and O’Neill at the Beaver Lake Spillway May 19.

This past fall the Nature Conservancy was awarded Long Island Sound Future Fund money towards fish passage plan development and implementation for three sites in Connecticut and New York. The site in New York is the spillway on Beaver Lake that impedes passage to and from the brackish Mill Creek. The grant provides money to develop plans for a fish ladder and apply for the necessary construction permits. I am a matching partner on the grant, providing data on water levels below the spillway as well as observations on river herring approaching the spillway. This Monday we had a “project kickoff” meeting at the spillway in which the various partners and supporters of the project met with Josh Wilson the engineer from Fuss and O’Neill, the environmental engineering firm contracted by Nature Conservancy. As you can see, there was a pretty good crowd in attendance including Sally Harold of the Nature Conservancy, director of the project,  other members of the Nature Conservancy, and representatives from the Town of Mill Neck, New York DEC, North Shore Wildlife Sanctuary, North Shore Land Alliance, USGS, Trout Unlimited, and Friends of the Bay.

It seems like the engineer is leaning towards installing a steeppass ladder, which I think is  similar to this one:

Alaska steeppass ladder

The engineer hopes to have a completed “permit-ready” design by August. And assuming funds can be found and the permits are approved in a timely manner, installation may occur as early as next Spring!

So that will solve one big problem for anadromous river herring and brook trout by allowing easier passage through the Oyster Bay estuary up into Shu Swamp. I hope to document an improvement in passage through PIT-tagging studies. But we have one other really big problem. Namely, if you don’t have fish it doesn’t matter how easy it is to pass! For the past three years I have been monitoring the herring spawning runs at the spillway. The previous two years I witnessed at best a handful of alewives attempting to enter the lake (see my post from last May). This year I have yet to see a single alewife. Lifelong residents of the area report seeing hundreds perhaps thousands of alewives  entering the lake, and as one person told me “backing up” in Beaver Lake like it was a traffic jam. This occurred in spite of a dam with minimal passage! What happened and how are we going to bring them back? One thought we tossed around was bringing in some spawning alewives from one of the successful runs elsewhere on Long Island. These would be used to “seed” the swamp and lake with babies imprinted to the watershed and likely to return as spawning adults in three years. This strategy may have shown some success when applied at other places such as the Bronx River.

According to Lehman College Professor Joseph Rachelin featured in the video, adult progeny of the spawning alewives released into the Bronx River in 2006 returned in 2009 indicating success. However, Queens College Professor John Waldman, reports in his excellent book, Running Silver, that the returning alewives were too old to have been progeny of the 2006 spawning alewives and were more likely native alewives, which is quite a suprise since everyone thought they had been eradicated long ago.

I think a big step forward was taken this week at Beaver Lake. Improving fish passage has been kicked around for a long time but finally people are acting. Given the amount of collaborative interest I am optimistic.

Finally, we have an alewife run at Beaver Lake Dam

Alewife at Beaver Lake Dam

Alewife at Beaver Lake Dam

We have been monitoring the dam since March for spawning alewives. The season is almost over with probably just one full moon to go. Yesterday afternoon we saw our first alewife swimming up the ramp of the dam. It would reach the top where it was then blocked by an impassable 1 foot vertical lip. Finally it would slip back down to the pool at the base of the ramp to try again. When I went back this morning near high tide I saw two, one of which I managed to net (photo). Unfortunately the photo is poor quality so you can’t see the abrasions on it’s belly and sides, most likely from its struggles up the rough wall of the dam.

Oddly enough I just started seeing a bunch of carp pooling downstream of the dam about a week ago. You don’t normally think of carp as being saltwater fish.. Even more bizarre the carp were also trying to negotiate the dam! I saw the same thing at this time last year at the dam; both carp and alewives attempting to get up the dam. The rest of the year the “saltwater” carp disappear.

Based on my extremely small sample size of N=2, it looks to me like 1) alewives can’t enter the lake unless the tide practically floods over the top, a rare event,  2) the current ladder is worthless (the fish have to positioned perfectly to enter the ladder and even if they do I doubt they could make it up the “rungs”), and 3) they can almost make it to the top by swimming up the ramp; it’s just that last vertical drop that keeps them from success. I would think that it shouldn’t take a great deal of engineering to allow successful entry. For example the ramp could be built up so it starts at the very top and slopes down from there.

Tide Gauges and Run-ins with the Law

My graduate student, Maryanne, and I visited the Beaver Lake Dam antenna today. Fortunately most of the snowfall had melted away so we were able to access the box with the data logger without too much shoveling.

We also installed a simple tide gauge. We would like to know when high tide reaches the dam and also try to calibrate tidal heights with a nearby tidal gauge (King’s Point). Whenever a tagged alewife is detected Maryanne will know based on the time what the tide height is relative to the top of the dam.

We had a little drama though. First one of Brookville’s finest decided that we can’t park where we have been parking for almost year now. He was nice about it but we will have to make other arrangements I guess. Second while we were picking up the car to leave some guy stopped his truck next to the discharged batteries and looked like he was about to pick them up! Fortunately, Maryann scared him away.

Alewives and Beaver Brook

Some members of the Diadromous Fish Working Group visited Shu Swamp to check out the area. Here we are shivering at the Cleft Road Bridge:

Alewife group 1

And here’s the spillway with antenna on this icy day:

Beaver Lake Dam Antenna with Ice

This spring mature alewives were observed trying to make it over the dam. This fall we observed young-of-year alewives shoaling in the pond just south of LIRR. There is a lot of interest in opening up more spawning areas to alewives so this looks promising. Of course the dam may be acting as a significant barrier (although apparently some are getting through). We want to see just how many are so we are going to PIT-tag arriving alewives this spring and see whether they make it into the lake.

North of Mill Creek you can see a bunch of Canada Geese resting on the ice. Four of these geese have orange collar tags around their necks. They are from Canada! Imagine that, real Canadian Canada Geese!

Geese in Mill Creek