What lies beneath the waves

The striped bass

The striped bass

The month of May started with a characteristic “striper wind” — a warm southerly breeze coinciding with striped bass spawning migration up the Hudson River. When striper season gets underway, the mouth of the creek experiences an obvious uptick in boat traffic. Powerboats motor their way from marinas and launch ramps to the Hudson River, throttling up as they pass the Lighthouse and exit the “no wake” zone of the creek, eager to get within casting distance of a striped bass.

Every fisherman has their own ideal fishing spot in mind. Conventional fishing wisdom says stripers like to hang around drop-offs where there is some water movement, so anglers usually focus there, anchoring along the edge of the flats where the shallows meet the deepwater channel of the Hudson. When stripers are running, boats dot the shoals from the Green Flats of Malden to the Saddlebags of Glasco.

Recently, an unusual watercraft entered the creek— a flat-bottom aluminum boat with a pair of metallic spider-like electrodes dangling in the water from the bow. This was the electrofishing boat used by the DEC fisheries unit. With one person at the controls and two stationed in the bow with dip nets, the electrofishing boat trolled alongside the jetties. Powered by a generator onboard, the electrodes create an electric field in front of the boat that stuns fish for a few seconds, just long enough to be scooped up in a dip net and tossed into a holding tank on the boat, where they quickly revive. Then, the fisheries biologists measure, weigh, and tag the fish before releasing them back into the water unscathed.


Another DEC fisheries boat also piqued the curiosity of onlookers. This one was equipped with a large directional antennae like an old-fashioned television aerial. That’s basically what it is — a VHF antenna. Mounted on a pivoting pole, this is part of a receiver system used for radio telemetry to track fish. The receiver is tuned to the frequency transmitted from a fish tag. By rotating the antenna to where the signal is strongest, a technician can listen for and zero-in on the radio-tagged fish. This effort is part of a study to track the seasonal movements and habitat preference of largemouth bass and walleye in the tidal Hudson River. Using the electrofishing boat to capture the fish, radio tags are surgically implanted in dozens of largemouth bass and walleye. The radio telemetry boat is then used to pinpoint their location at different times of the year.

Knowing the whereabouts of the walleye and largemouth bass will help identify and protect important habitat areas of these popular sport fish. For instance, the largemouth bass population in the Hudson River estuary concentrates into only five known wintering areas, including the mouth of the Esopus Creek. The largemouth bass gather and hang out in the tidal Esopus from October to April. By early May, they disperse back into the main stem of the Hudson. The reasons for this seasonal bass movement are not fully understood, but the telemetry study may eventually provide insight into this quirk of fish behavior. With nearly the entire Hudson River population of largemouth bass wintering in just a handful of locations, it underscores the need to protect these areas as irreplaceable habitat.

A large powerboat called attention to itself while cruising past the Lighthouse one evening. It was hard to overlook since it was emblazoned with the word survey in large capital letters on the hull. Of course, this immediately prompted the question, “What is being surveyed?” Closer inspection revealed that it was outfitted with specialized equipment. Smaller writing indicated that the boat belonged to Prudent Engineering, a firm handling environmental compliance monitoring for the Tappan Zee Bridge Project. The boat was here for servicing at the marina before getting underway for the season. It carries specialized acoustic equipment for locating fish underwater. The permit for the bridge replacement requires that sturgeon monitoring be conducted throughout the project to see whether bridge construction impacts the fish. Additionally, the monitoring program is an effort to learn more about their habits such as where they swim, what areas of the river they prefer, and how long they stay.

The river is a dense wilderness to us air-breathing, terrestrial mammals. Beneath the mirrored surface of the water, our eyesight only extends a couple of feet. The sunlit shallows quickly drop off into the green darkness of the deepwater channel. How do we know what’s down there? Anglers probe with hooks and nets, but the river’s secret depths remain opaque. We extend our vision with technology, using radio signals to reach below the surface. Where radio signals fade, acoustic equipment allows us to peer even deeper. To maintain a thriving fish population, it is not enough to know where to catch them during fishing season. It is also important to know where they are the rest of the year in order to protect significant habitat and endangered species from disturbance or destruction.

Patrick Landewe is the Saugerties Lighthouse keeper. His column appears monthly.