First there was the Nautilus. Then there was the Seaview. And who can forget the Yellow Submarine? Well, now there’s the S. S. Haldeman, and today we celebrated her shakedown cruise and maiden voyage. The Haldeman is powered by spent fuel that first saw light of day near Conewago Falls at a dismantled site that presently amounts to nothing more than an electrical substation. Though antique in appearance, the vessel discharges few emissions, provided there aren’t any burps or hiccups while underway. So, climb aboard as we take a cruise up the Susquehanna at periscope depth to have a quick look around!
Brunner Island as seen from the east channel.Close-in approach to emergent Water Willow growing on an alluvial Island.The approach to York Haven Dam and Conewago Falls from the west channel.A pair of Powdered Dancers on a midriver log.
Watertight and working fine. Let’s flood the tanks and have a peek at the benthos. Dive, all dive!
American Eelgrass, also known as Tapegrass, looks to be growing well in the channels. Historically, vast mats of this plant were the primary food source for the thousands of Canvasback ducks that once visited the lower Susquehanna each autumn.As is Water Stargrass (Heteranthera dubia). When mature, both of these native plants provide excellent cover for young fish. Note the abundance of shells from deceased Asiatic Clams (Corbicula fluminea) covering the substrate.A three-tailed mayfly (Ephemeroptera) nymph and a several exoskeletons cling to the downstream side of a rock.This hollowed-out stick may be a portable protective shelter belonging to a Comb-lipped Casemaker Caddisfly larva (Calamoceratidae). The larva itself appears to be extending from the end of the “case” in the upper right of the image. Heteroplectron americanum, a species known for such behavior, is a possibility. In the Susquehanna and its tributaries, the Rusty Crayfish (Faxonius rusticus) is an introduced invasive species. It has little difficulty displacing native species due to its size and aggressiveness.A Rusty Crayfish.Summers with conditions that promote eelgrass and stargrass growth tend to be big years for Virginian River Horn Snails (Elimia virginica). 2022 appears to be one of those years. They’re abundant and they’re everywhere on the rocks and gravel substrate in midriver. Feeding almost incessantly on algae and detritus, these snails are an essential component of the riverine ecosystem, breaking down organic matter for final decomposition by bacteria and fungi.Bits of debris suspended in the flowing water streak by this Virginian River Horn Snail. The spire-shaped shell is a streamlining adaptation for maneuvering and holding fast in the strong current.A young Virginian River Horn Snail following a mature adult. Note the green algae growing among the decaying plant and animal remains that blanket the river bottom.Two of a population that may presently include millions of Virginian River Horn Snails living downstream of Conewago Falls.Virginian River Horn Snails with Lesser Mystery Snails (Campeloma decisum), another native species commonly encountered at Conewago Falls and in surrounding waters.A River Snail (Leptoxis carinata), also known as a Crested Mudalia, hitching a ride on a Virginian River Horn Snail. The two species are frequently found together.A River Snail cleaning the shell of a native freshwater Unionidae mussel, Lampsilis cariosa, commonly called the Yellow Lampmussel or Carried Lampmussel. Because of their general decline in abundance and range, all Unionidae mussels are protected in Pennsylvania.The Banded Darter (Etheostoma zonale) is a member of the perch family (Percidae).A Smallmouth Bass in strong current.Along the edge of an alluvial island at midriver, Cyprinella (Spotfin or Satinfin) Shiners gather in the cover of an emergent stand of Water Willow. The closely related Spotfin Shiner (Cyprinella spiloptera) and Satinfin Shiner (Cyprinella analostanus) are nearly impossible to differentiate in the field.A breeding condition male Cyprinella (Spotfin or Satinfin) Shiner.A juvenile Channel Catfish.
We’re finding that a sonar “pinger” isn’t very useful while running in shallow water. Instead, we should consider bringing along a set of Pings—for the more than a dozen golf balls seen on the river bottom. It appears they’ve been here for a while, having rolled in from the links upstream during the floods. Interestingly, several aquatic species were making use of them.
River Snail cleaning a golf ball.A golf ball used as an anchor point for silk cases woven by Net-spinning Caddisfly (Hydropsychidae) larvae to snare food from the water column.A Creeping Ancylid (Ferrissia species), a tiny gastropod also known as a Coolie Hat Snail, River Limpet, or Brook Freshwater Limpet, inhabits the dimple on a “Top Flight”.A closeup view of the Creeping Ancylid. The shell sits atop the snail’s body like a helmet.We now know why your golf balls always end up in the drink, it’s where they go to have their young.
Well, it looks like the skipper’s tired and grumpy, so that’s all for now. Until next time, bon voyage!
Meet the Double-crested Cormorant, a strangely handsome bird with a special talent for catching fish. You see, cormorants are superb swimmers when under water—using their webbed feet to propel and maneuver themselves with exceptional speed in pursuit of prey.
Like many species of birds that dive for their food, Double-crested Cormorants run across the surface of the water to gain speed for a takeoff. Smaller wings may make it more difficult to get airborne, but when folded, they provide improved streamlining for submerged swimming.
Double-crested Cormorants, hundreds of them, are presently gathered along with several other species of piscivorous (fish-eating) birds on the lower Susquehanna River below Conowingo Dam near Rising Sun, Maryland. Fish are coming up the river and these birds are taking advantage of their concentrations on the downstream side of the impoundment to provide food to fuel their migration or, in some cases, to feed their young.
Double-crested Cormorants, mostly adult birds migrating toward breeding grounds to the north, are gathered on the rocks on the east side of the river channel below Conowingo Dam. A Great Blue Heron from a nearby rookery can be seen at the center of the image.Bald Eagles normally gather in large numbers at Conowingo Dam in the late fall and early winter. Presently there are more than 50 there, and the majority of them are breeding age adults. Presumably they are still on their way north to nest. Meanwhile, local pairs are already feeding young, so it seems these transient birds are running a bit late. Many of them can be seen on the rocks along the east side of the river channel,……on the powerline trestles on the island below the dam……in the trees along the east shore,……and in the trees surrounding Fisherman’s Park on the west shore.
In addition to the birds, the movements of fish attract larger fish, and even larger fishermen.
Anglers gather to fish the placid waters below the dam’s hydroelectric powerhouse . Only a few of the generating turbines are operating, so the flow through the dam is minimal.Some water is being released along the west shoreline to attract migratory river herring to the west fish lift for sorting and retention as breeding stock for a propagation program. The east lift, the passage that hoists American Shad (Alosa sapidissima) to a trough that allows them to swim over the top of the dam to waters upriver, will begin operating as soon as these larger migratory fish begin arriving.
The excitement starts when the sirens start to wail and the red lights begin flashing. Yes friends, it’s showtime.
Red lights and sirens are a warning that additional flow is about to be released from the dam. Boaters should anticipate rough water and persons in and along the river need to seek higher ground immediately.Gates are opened at mid-river to release a surge of water through the dam.The wake from the release quickly reaches the shoreline, raising the water level in moments.Experienced anglers know that the flow through the dam gets fish moving and can improve the catch significantly, especially in spring when many species are ascending the river.
Within minutes of the renewed flow, birds are catching fish.
A Double-crested Cormorant with a young Channel Catfish (Ictalurus punctatus).A Double-crested Cormorant fleeing others trying to steal its Channel Catfish.Another Double-crested Cormorant eating a Channel Catfish. Did you realize that Channel Catfish were an introduced species in the Susquehanna River system?An Osprey with a stick, it’s too busy building a nest right now to fish.Great Blue Herons swallow their prey at the spot of capture, then fly back to the nest to regurgitate a sort of “minced congealed fish product” to their young.
Then the anglers along the wave-washed shoreline began catching fish too.
This young man led off a flurry of catches that would last for the remainder of the afternoon.Though Gizzard Shad are filter feeders that don’t readily take baits and lures, they are regularly foul-hooked and reeled in from the large schools that ascend the river in spring.Gizzard Shad are very abundant in the lower Susquehanna, providing year-round forage for many species of predatory animals including Bald Eagles.A Double-crested Cormorant swallowing a Gizzard Shad.This angler soon helped another fisherman by landing his large catch, a Northern Snakehead (Channa argus).The teeth of a Northern Snakehead are razor sharp. It is an aggressive non-native invasive species currently overtaking much of the Lower Susquehanna River Watershed. Anglers are encouraged to fish for them, catch them, keep them, and kill them at the site of capture. Never transport a live Northern Snakehead anywhere at any time. It is illegal in both Maryland and Pennsylvania to possess a live snakehead. Northern Snakehead advisory sign posted at Exelon Energy’s Conowingo Fishermen’s Park.A stringer of Northern Snakeheads. This species was imported from Asia as a food fish, so it has excellent culinary possibilities. It’s better suited for a broiler or frying pan than a river or stream.Another stringer of Northern Snakeheads. It’s pretty safe to say that they have quickly become one of the most abundant predatory fish in the river. Their impact on native species won’t be good, so catch and eat as many as you can. Remember, snakeheads swim better in butter and garlic than in waters with native fish.This foul-hooked Shorthead Redhorse (Moxostoma macrolepidotum), a native species of sucker, was promptly released.Striped Bass are anadromous fish that leave the sea in spring to spawn in fresh water. They ascend the Susquehanna in small numbers, relying upon the operation of the fish passages at the Conowingo, Holtwood, Safe Harbor, and York Haven Dams to continue their journey upstream. During spring spawning, Striped Bass in the Susquehanna River and on the Susquehanna Flats portion of the upper Chesapeake Bay are not in season and may not be targeted, even for catch-and-release. This accidental catch was immediately turned loose.After removal from the hook, this hefty Smallmouth Bass was returned to the river. Many anglers are surprised to learn that Smallmouth Bass are not native to the Susquehanna basin.This angler’s creel contains a Northern Snakehead (left) and a Walleye (right). Did you know that the Walleye (Sander vitreus) is an introduced species in the Susquehanna watershed?By late afternoon, anglers using shad darts began hooking into migrating Hickory Shad (Alosa mediocris), a catch-and-release species in Maryland.Hickory Shad are recognized by their lengthy lower jaw. They are anadromous herring that leave the sea to spawn in freshwater streams. Hickory Shad ascend the Susquehanna as far as Conowingo Dam each year, but shy away from the fish lifts. Downriver from the dam, they do ascend Deer Creek along the river’s west shore and Octoraro Creek on the east side. In Pennsylvania, the Hickory Shad is an endangered species.A Hickory Shad angled on a dual shad dart rig. During the spring spawning run, they feed mostly on small fish, and are the most likely of the Susquehanna’s herring to take the hook.Simultaneous hook-ups became common after fours hours worth of release water from the dam worked its way toward the mouth of the river and got the schools moving. Water temperatures in the mid-to-upper-fifties trigger the ascent of Hickory Shad. On the Susquehanna, those temperatures were slow to materialize in the spring of 2021, so the Hickory Shad migration is a bit late.Catch-and-release fishing for Hickory Shad appears to be in full swing not only at the dam, but along the downstream shoreline to at least the mouth of Deer Creek at Susquehanna State Park too.Many Hickory Shad could be seen feeding on some of the millions of caddisflies (Trichoptera) swarming on the river. These insects, along with earlier hatches of Winter Stoneflies (Taeniopterygidae), not only provide forage for many species of fish, but are a vital source of natural food for birds that migrate up the river in March and April each year. Swallows, Ring-billed Gulls, and Bonaparte’s Gulls are particularly fond of snatching them from the surface of the water.A Winter Stonefly (Taeniopterygidae) from an early-season hatch on the Susquehanna River at the Veteran’s Memorial Bridge at Columbia/Wrightsville, Pennsylvania. (March 3, 2021)Just below Conowingo Dam, a lone fly fisherman was doing a good job mimicking the late-April caddisfly hatch, successfully reeling in numerous surface-feeding Hickory Shad.You may have noticed the extraordinary number of introduced fish species listed in this account of a visit to Conowingo Dam. Sorry to say that there are two more: the Flathead Catfish (Pylodictis olivaris) and the Blue Catfish (Ictalurus furcatus). Like the Northern Snakehead, each has become a plentiful invasive species during recent years. Unlike the Northern Snakehead, these catfish are “native transplants”, species introduced from populations in the Mississippi River and Gulf Slope drainages of the United States. So if you visit the area, consider getting a fishing license and catching a few. Like the snakeheads, they too are quite palatable.
The arrival of migrating Hickory Shad heralds the start of a movement that will soon include White Perch, anadromous American Shad, and dozens of other fish species that swim upstream during the springtime. Do visit Fisherman’s Park at Conowingo Dam to see this spectacle before it’s gone. The fish and birds have no time to waste, they’ll soon be moving on.
To reach Exelon’s Conowingo Fisherman’s Park from Rising Sun, Maryland, follow U.S. Route 1 south across the Conowingo Dam, then turn left onto Shuresville Road, then make a sharp left onto Shureslanding Road. Drive down the hill to the parking area along the river. The park’s address is 2569 Shureslanding Road, Darlington, Maryland.
A water release schedule for the Conowingo Dam can be obtained by calling Exelon Energy’s Conowingo Generation Hotline at 888-457-4076. The recording is updated daily at 5 P.M. to provide information for the following day.
And remember, the park can get crowded during the weekends, so consider a weekday visit.
