Shakedown Cruise of the S. S. Haldeman

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.
Mayfly nymph
A three-tailed mayfly (Ephemeroptera) nymph and a several exoskeletons cling to the downstream side of a rock.
Comb-lipped Casemaker Caddisfly larva and case.
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. 
Rusty Crayfish
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.
Rusty Crayfish
A Rusty Crayfish.
Freshwater Snails Susquehanna: Virginian River Horn Snail
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.
Freshwater Snails Susquehanna: Virginian River Horn Snail
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.
Freshwater Snails Susquehanna: Virginian River Horn Snail
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.
Freshwater Snails Susquehanna: Virginian River Horn Snail
Two of a population that may presently include millions of Virginian River Horn Snails living downstream of Conewago Falls.
Susquehanna Snails: Virginian River Horn Snails and Lesser Mystery Snails
Virginian River Horn Snails with Lesser Mystery Snails (Campeloma decisum), another native species commonly encountered at Conewago Falls and in surrounding waters.
Freshwater Snails Susquehanna: River Snail and Virginian River Horn Snail
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.
Mollusks of the Susquehanna: Yellow Lampmussel and River Snail
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.
Fishes of the Susquehanna: Banded Darter
The Banded Darter (Etheostoma zonale) is a member of the perch family (Percidae).
Fishes of the Susquehanna: Smallmouth Bass
A Smallmouth Bass in strong current.
Fishes of the Susquehanna: Spotfin or Satinfin Shiners
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.
Fishes of the Susquehanna: Spotfin or Satinfin Shiner
A breeding condition male Cyprinella (Spotfin or Satinfin) Shiner.
Fishes of the Susquehanna; Juvenile Channel Catfish
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.
River Snail cleaning a golf ball.
Net-spinning Caddisfly (Hydropsychidae)
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.
Freshwater Snails (Gastropods) of the Lower Susquehanna River Watershed: Creeping Ancylid (Ferrissia species)
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”.
Freshwater Snails (Gastropods) of the Lower Susquehanna River Watershed: Creeping Ancylid (Ferrissia species)
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!

Conowingo Dam: Cormorants, Eagles, Snakeheads and a Run of Hickory Shad

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.

Bald Eagles Arriving at Conowingo Dam

You need to see this to believe it—dozens, sometimes hundreds, of Bald Eagles doing their thing and you can stand or sit in just one place to take it all in.

Conowingo Dam on the Susquehanna River near Darlington, Maryland, attracts piscivores galore.  Young Gizzard Shad (Dorosoma cepedianum) and other small fishes are temporarily stunned as they pass through the turbines and gated discharges at the hydroelectric facility’s power house.  Waiting for them in the rapids below are predatory fishes including Striped Bass (Morone saxatilis), White Perch (Morone americana), several species of catfishes, and more.  From above, fish-eating birds are on the alert for a disoriented turbine-traveler they can easily seize for a quick meal.

U.S. Route 1 crosses the Susquehanna River atop the Conowingo Dam.  Conowingo Fisherman’s Park, the observation site for the dam’s Bald Eagles and other birds, is located downstream of the turbine building along the river’s west (south) shore.  As the name implies, the park is a superb location for angling.
Heed this warning.  Close your windows and sunroof or the vultures will subject your vehicle’s contents to a thorough search for food.  Then they’ll deposit a little consolation prize on your paint.
Scavenging Black Vultures congregate by the hundreds at Conowingo Dam to clean up the scraps left behind by people and predators.  They’ll greet you right in the parking lot.
Photographers line up downstream of the turbine building for an opportunity to get the perfect shot of a Bald Eagle.
The operator of the Conowingo Hydroelectric Generating Station, Exelon Energy, provides clean comfortable facilities for fishing, sightseeing, and wildlife observation.
There’s almost always a Peregrine Falcon zooming around the dam to keep the pigeons on their toes.
Double-crested Cormorants on the boulders that line the channel below the dam.  Hundreds are there right now.
Double-crested Cormorants dive for fish near the power house discharge, which, while just one small generator is operating, seems nearly placid.  The feeding frenzy really gets going when Conowingo begins generating with multiple large turbines and these gently flowing waters become torrential rapids filled with disoriented fishes.
Ring-billed Gulls seek to snag a small fish from the water’s surface.
After successfully nabbing shad or perch, these Double-crested Cormorants need to swallow their catch fast or risk losing it.  Stealing food is a common means of survival for the gulls, eagles, and other birds found here.
Where do migrating eagles go?  There are, right now, at least 50 Bald Eagles at Conowingo Dam, with more arriving daily.  Numbers are likely to peak during the coming weeks.
Eagles can be seen perched in the woods along both river shorelines, even in the trees adjacent to the Conowingo Fisherman’s Park car lot.  Others take stand-by positions on the boulders below the dam.
To remind visiting eagles that they are merely guests at Conowingo, a resident Bald Eagle maintains a presence at its nest on the wooded slope above Fisherman’s Park.  Along the lower Susquehanna, female Bald Eagles lay eggs and begin incubation in January.
When an eagle decides to venture out and attempt a dive at a fish, that’s when the photographers rush to their cameras for a chance at a perfect shot.
The extraordinary concentrations of Bald Eagles at Conowingo make it an excellent place to study the plumage differences between birds of various ages.
Here’s a first-year Bald Eagle, also known as a hatch-year or juvenile bird.
A second-year or Basic I immature Bald Eagle.  Note the long juvenile secondaries giving the wings a ragged-looking trailing edge.
A third-year or Basic II immature Bald Eagle.
A second-year/Basic I immature Bald Eagle (top) and a third-year/Basic II immature Bald Eagle (bottom).
A second-year/Basic I immature Bald Eagle (bottom) and a third-year/Basic II immature Bald Eagle (top).  Note the white feathers on the backs of eagles in these age classes.
A third-year/Basic II immature Bald Eagle perched in a tree alongside the parking area.  Note the Osprey-like head plumage.
A sixth-year or older adult Bald Eagle in definitive plumage (left) and a fourth-year or Basic III immature Bald Eagle (right).
If you want to see the Bald Eagles at Conowingo Dam, don’t wait.  While many birds are usually present throughout the winter, the large concentrations may start dispersing as early as December when eagles begin wandering in search of other food sources, particularly if the river freezes.
A pair of Bald Eagles is already working on a nest atop this powerline trestle downstream of Conowingo Dam.  By late December, most adult eagles will depart Conowingo to begin spending their days establishing and defending breeding territories elsewhere.  Any non-adult eagles still loitering around the dam will certainly begin receiving encouragement from the local nesting pair(s) to move along as well.

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.

As Bald Eagle numbers continue to increase, expect the parking lot to become full during weekends and over the Thanksgiving holiday.  To avoid the crowds, plan to visit during a weekday.

You can get the generating schedule for the Conowingo Dam by calling the Conowingo Generation Hotline at 888-457-4076.  The recording is updated daily at 5 P.M. to provide information for the following day.

Shocking Fish Photos!

There are two Conewago Creek systems in the Lower Susquehanna River Watershed.  One drains the Gettysburg Basin west of the river, mostly in Adams and York Counties, then flows into the Susquehanna at the base of Conewago Falls.  The other drains the Gettysburg Basin east of the river, flowing through Triassic redbeds of the Gettysburg Formation and York Haven Diabase before entering Conewago Falls near the south tip of Three Mile Island.  Both Conewago Creeks flow through suburbia, farm, and forest.  Both have their capacity to support aquatic life impaired and diminished by nutrient and sediment pollution.

This week, some of the many partners engaged in a long-term collaboration to restore the east shore’s Conewago Creek met to have a look at one of the prime indicators of overall stream habitat health—the fishes.  Kristen Kyler of the Lower Susquehanna Initiative organized the effort.  Portable backpack-mounted electrofishing units and nets were used by crews to capture, identify, and count the native and non-native fishes at sampling locations which have remained constant since prior to the numerous stream improvement projects which began more than ten years ago.  Some of the present-day sample sites were first used following Hurricane Agnes in 1972 by Stambaugh and Denoncourt and pre-date any implementation of sediment and nutrient mitigation practices like cover crops, no-till farming, field terracing, stormwater control, nutrient management, wetland restoration, streambank fencing, renewed forested stream buffers, or modernized wastewater treatment plants.  By comparing more recent surveys with this baseline data, it may be possible to discern trends in fish populations resulting not only from conservation practices, but from many other variables which may impact the Conewago Creek Warmwater Stream ecosystem in Dauphin, Lancaster, and Lebanon Counties.

So here they are.  Enjoy these shocking fish photos.

Matt Kofroth, Watershed Specialist with the Lancaster County Conservation District, operates the electrofishing wand in Conewago Creek while his team members prepare to net and collect momentarily-stunned fish.  Three other electrofishing units operated by staff from the Susquehanna River Basin Commission and aided by teams of netters were in action at other sample locations along the Conewago on this day.
Really big fish, such as this Common Carp (Cyprinus carpio), were identified, counted, and immediately returned to the water downstream of the advancing electrofishing team.  Koi of the garden pond are a familiar variety of Common Carp, a native of Asia.
Other fish, such as the Swallowtail Shiner, Redbreast Sunfish (Lepomis auritus), Fallfish, and suckers seen here,  were placed in a sorting tank.
Fallfish (Semotilus corporalis) are very active and require plenty of dissolved oxygen in the water to survive.  Fallfish, Rainbow Trout (Oncorhynchus mykiss), and Smallmouth Bass (Micropterus dolomieu) were quickly identified and removed from the sorting tank for release back into the stream.  Other larger, but less active fish, including suckers, quickly followed.
Small fish like minnows were removed from the sorting tank for a closer look in a hand-held viewing tank.  This Fathead Minnow (Pimephales promelas) was identified, added to the tally sheet, and released back into the Conewago.  The Fathead Minnow is not native to the Susquehanna drainage.  It is the minnow most frequently sold as bait by vendors.
A breeding condition male Bluntnose Minnow (Pimephales notatus).
The Cutlips Minnow (Exoglossum maxillingua) is a resident of clear rocky streams.  Of the more than 30 species collected during the day, two native species which are classified as intolerant of persisting stream impairment were found: Cutlips Minnow and Swallowtail Shiner.
This young River Chub (Nocomis micropogon) is losing its side stripe.  It will be at least twice as large at adulthood.
The Eastern Blacknose Dace (Rhinichthys atratulus) is found in clear water over pebble and stone substrate..
The Longnose Dace (Rhinichthys cataractae) is another species of pebbly rocky streams.
A juvenile Golden Shiner (Notemigonus crysoleucas).  Adults lack the side stripe and grow to the size of a sunfish.
A Swallowtail Shiner (Notropis procne) and a very young White Sucker (Catostomus commersonii) in the upper left of the tank.
A Spotfin Shiner (Cyprinella spiloptera).
A breeding male Spotfin Shiner.  Show-off!
The Margined Madtom (Noturus insignis) is a small native catfish of pebbly streams.
The Banded Killifish (Fundulus diaphanus) is adept at feeding upon insects, including mosquitos.
A young Rock Bass (Ambloplites rupestris).  This species was introduced to the Susquehanna and its tributaries.
The Greenside Darter (Etheostoma blennioides) is not native to the Susquehanna basin.  The species colonized the Conewago Creek (east) from introduced local populations within the last five years.
The Tessellated Darter (Etheostoma olmstedi) is a native inhabitant of the Susquehanna and its tributaries.
The stars of the day were the American Eels (Anguilla rostrata).
After collection, each eel was measured and weighed using a scale and dry bucket.  This specimen checked in at 20 inches and one pound before being released.
Prior to the construction of large dams, American Eels were plentiful in the Susquehanna and its tributaries, including the Conewago.  They’ve since been rarities for more than half a century.  Now they’re getting a lift.
American Eels serve as an intermediate host for the microscopic parasitic glochidia (larvae) of the Eastern Elliptio (Elliptio complanata), a declining native freshwater mussel of the Lower Susquehanna River Watershed.  While feeding on their host (usually in its gills), the glochidia cause little injury and soon drop off to continue growth, often having assured distribution of their species by accepting the free ride.  Freshwater mussels are filter feeders and improve water quality.  They grow slowly and can live for decades.
American Eels are a catadromous species, starting life as tiny glass eels in the saltwater of the Atlantic Ocean, then migrating to tidal brackish marshes and streams (males) or freshwater streams (females) to mature.  This 20-incher probably attempted to ascend the Susquehanna as an elver in 2016 or 2017.  After hitching a ride with some friendly folks, she bypassed the three largest dams on the lower Susquehanna (Conowingo, Holtwood, and Safe Harbor) and arrived in the Conewago where she may remain and grow for ten years or more.  To spawn, a perilous and terminally fatal journey to the Sargasso Sea awaits her.  (You may better know the area of the Sargasso Sea as The Bermuda Triangle…a perilous place to travel indeed!)

SOURCES

Normandeau Associates,  Inc. and Gomez and Sullivan.  2018.  Muddy Run Pumped Storage Project Conowingo Eel Collection Facility FERC Project 2355.  Prepared for Exelon.

Stambaugh, Jr., John W., and Robert P. Denoncourt.  1974.  A Preliminary Report on the Conewago Creek Faunal Survey, Lancaster County, Pennsylvania.  Proceedings of the Pennsylvania Academy of Sciences.  48: 55-60.