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CHESAPEAKE BAY & VIRGINIA BARRIER ISALNDS: The Chesapeake Bay and its great tidal riversjoin to form the largest and most productive estuarine
complex in North America. They supply vast amount of nutrients into coastal waters
and provide a huge spawning and nursery area for many species of fish. The warm waters of the Gulf Stream flow north along the East Coast until they collide with
the cool, plankton-rich waters of the Labrador Current flowing south. The
intermixing of these currents occurs near Cape Hatteras, North Carolina, and in
adjacent waters. This puts the southern coast of Virginia in the dynamic area where
the Mid-Atlantic Bight and South Atlantic Bight are joined, and brings a huge mix of finfish species into local waters. In fact, Virginia is the southernmost range of real abundance for
many temperate species of fish and the northern range of abundance for many subtropical
species. The large peninsula which forms the Eastern Shore of Virginia is flanked
by a chain of uninhabited and unspoiled barrier islands. These islands protect
a rich complex of marshes, bays and sounds which provide a haven for a variety
of marine life. The main portion of the Chesapeake Bay follows the ancient bed
of the Susquehanna River. Dramatic forces during the Ice Age, which helped shape
the Susquehanna Valley, and the rising ocean waters caused by the melting ice cap as the Ice Age ended, transformed the southern portion of this river valley into the vast estuarine
complex that today is the Chesapeake Bay. The Chesapeake Bay continues as the
placewhere several of the great rivers in the eastern United States meet the ocean.
The Susquehanna River has the greatest impact on the Bay contributing, on average,
almost 50% of the freshwater flowing into the Bay. The Potomac and the James Rivers
provide more than 15% each, leaving under 20% for the combined inflows from more than a dozen other rivers including the Rappahannock, York, Chester, Choptank and Nanticoke. Water also flows into the Chesapeake Bay from the ocean. A relatively constant inward flow
of ocean water occurs along the bottom at the mouth of the Chesapeake Bay. These
ocean waters, laden with salts and minerals, are heavier and more dense than the
freshwaters flowing from the rivers into the Bay and out its mouth in the upper
portions of the water column. This pattern of water circulation, with heavier saltwaters flowing into the Bay along the bottom while lighter freshwaters flow out near the surface,
was documented in a scientific study by the Virginia Institute of Marine Science.
The mixing of ocean and rivers waters in the Chesapeake Bay produces waters which
are variably salty and fresh, often changing based upon short term weather phenomena,
long term weather or climatic patterns, tides,depth and location. However, certain
patterns remain constant. Bay waters along the eastern side of the Bay are saltier
than waters along the western shore. This is due in large measure to the large
inflows of freshwater from the western rivers and a phenomenon called the coriolis effect
– a result of the rotation of the earth. Tides, which are caused by the rise and fall of ocean waters due primarily to the gravitational forces of the moon and the sun, cause variations
in salinity. During high or rising tides salinities increase in the Bay and move
further up the Bay, while the opposite occurs on low or falling tides. Since tidal
movement originates at the mouth of the Bay (tides are the rise and fall of ocean waters),
the times of the peak high and low tides vary by location. The "wave" of tidal flow starts
at the mouth of the Bay and must physically move to its upper reaches and up its
tributary rivers. This takes time and the difference between the time of the high
tide at places near the mouth of the Bay and others farther up the Bay or in the tidal
portion of its tributary rivers can vary by as much as 4 – 6 hours. Forces
with seemingly little connection to the Chesapeake Bay can have major impacts on salinity
levels. For example, heavy rains in western Virginia, Maryland and Pennsylvania mountains may create flash floods which can send pulses of freshwater down major rivers. These pulses are called "freshets" as they reach the brackish waters of the rivers near
the Chesapeake Bay, and these sudden changes in salinity can have pronounced impacts
upon marine life. In fact, the torrential rains in Pennsylvania during Hurricane
Agnes in 1972, creating epic floods from the Susquehanna River, had catastrophic
effects on the Chesapeake Bay. In fact, Agnes may have been the "trigger" mechanism for the disappearance of vast areas of underwater sea grasses in the Bay. Unfortunately, the sea grasses have not been able to recover, probably due to the combination of pollution,
excess nutrients and turbidity associated with water quality problems. Changing salinty levels are not the only dynamic forces impacting the Bay environment. Water
temperatures vary dramatically on an annual basis. The water temperatures found
in the Chesapeake Bay probably have the highest average annual variance of any
location on the East Coast. Winter often produces skim ice and even harder freezes
on the lower Bay tributary rivers, and several times in this century portions of the main
stem of the Chesapeake Bay have been covered with ice. Summertime surface water temperatures
in shallow bays may approach, or exceed, 90 degrees. Sudden changes in temperature,
which may occur during extended cold snaps in the fall or early winter, can cause
water temperatures to drop dramatically resulting in severe stress to fish and other
marine life. Even events outside of the Bay can impact its water temperature regimen.
Heavy snowfall early in the fall in the Blue Ridge mountains can result in a drastic
lowering of the water temperatures in the tributary rivers running to the Bay. As these rivers feed into the Bay, the water temperature can be lowered rapidly with often severe impacts
on marine life. For these reasons, the marine life found in the Chesapeake Bay is among the hardiest and most adaptable found anywhere in the world. While life in these dynamic surroundings is not easy, estuarine environments are extraordinary
in their richness and diversity of life. Most of the commercially and recreationally
important finfish species of Virgnia spend a portion of their lives in an estuarine
environment. Estuarine communities begin with intertidal salt marshes. These
low areas, characterized by muddy tidal flats, spartina grasses, and small creeks,
are nature's "buffer" zones. They provide filtering areas that trap nutrients and, in recent years, pollutants, preventing them from overburdening the tidal rivers and bays. The tidal
marshes are teeming with life from the everpresent snails, fiddler crabs and worms
to shrimps, "fundulus" minnows, blue crabs and juvenile fish. Unfortunately, intertidal salt marshes and wetlands have been disappearing in modern times due to the increasing pressure todevelop waterfront properties caused by the desire of more people to live near the coast. While this trend continues, the rate at
which marshes and wetlands have been declining is slowing, as regulations have
focused efforts on environmentally "friendly" development which provides
protection for these critical and sensitive areas. Increased protection of tidal marshes and wetlands is a key component in maintaining the water quality of the Chesapeake Bay and
preserving much of its marine life. Sea grasses, mainly eelgrass, thrives in shallow
waters, often growing best in waters that are somewhat protected from excessive
wave and current movements. They provide protection for many small fish and molting
blue crabs, making this habitat attractive for numerous game fish. In addition,
sea grass beds serve a filtering role, helping sediments to trickle to the bottom which
produces better water clarity. Sea grass beds dissipate wave energy, which helps to reduce
shoreline erosion and improves water clarity. Ironically, many scientists believe excessive runoffs, a form of non-point source pollution which causes increased water turbidity, was responsible for killing many sea grass beds in the Chesapeake Bay during the 1970’s, probably triggered by the torrential rains and massive floods associated with
Hurricane Agnes in 1972. Thus, while sea grasses are important in preserving and
improving water quality, it may have been poor water quality which killed massive
sea grass beds 30 years ago. During the last fifteen years, however, the Chesapeake Bay clean-up initiatives have focused on controlling agricultural and urban runoff,
and sea grass beds are starting to make comebacks. In many ways the health
of sea grass beds may be a good measure of the health of the Bay, since sea grasses
require good water quality, low in suspended sedimentary runoff, nutrients, pollutants and phytoplankton, to thrive. Oyster rocks and bars are the major types of natural
"reef communities" in the Chesapeake Bay. A host of small invertebrates are attracted to the oyster rocks and contribute to the food chain. In turn, these "live bottom" areas
attract a host of small finfish, which are sought out by even larger game fish.
Oysters are filter feeders, straining small plankton and nutrients from the water
column, which is an important component of maintaining the Chesapeake Bay's water
quality. At the start of the 20th century oyster rocks rising ten feet off the bottom
were not uncommon. Oysters were so numerous they were thought to be able to filter an amount
of water equivalent in volume to the entire Chesapeake Bay in less than a week. Disease,
pollution and overharvesting have reduced oyster populations to a fraction of that level,
and today’s population of oysters would take nearly a year to filter the water volume of the Chesapeake Bay. Rebuilding the oyster population is a major priority of fishery managers in
Virginia. Another concern in recent years has been a declining
trend in some of the prime forage fish, especially menhaden and bay anchovies, in the Chesapeake
Bay. Menhaden are the other major filter feeder associated with the Bay, thus serving a
dual role as forage for many important recreation fish and a component in the Bay water quality equation. Observers are unsure whether this decline is a short term phenomenon or a
longer term problem, but efforts are being mobilized to investigate this issue.
The Chesapeake Bay offers a tremendous variety of recreational fishing opportunities,
but no fish is more symbolic of the Bay than the striped bass. The Chesapeake
Bay is the largest spawning and nursery area for striped bass on the East Coast.
As much as 80% of the coastwide migratory population is thought to be native to the Bay.
Striped bass, like shad and herring, are anadromous; this means they spend the
majority of their lives in saltwater but return to freshwater rivers to spawn.
They can be caught in virtually every portion of the Chesapeake Bay and its tributary
rivers. In addition, stripers can be found at some place in the Bay every day
of the year. The resurgence of striped bass populations in recent years from the population
collapse in the 1970’s, which nearly culminated in their listing as a threatened species, is one of the spectacular success stories of modern fisheries management. Striped bass provide just one of several opportunities for small boat fishermen to do battle
with adversaries which may weigh 50 pounds or more. In addition, the Bay offers
seasonal runs of cobia, red drum and black drum. Red drum and black drum appear
in Bay waters in mid-April, while cobia usually appear on the Memorial Day weekend. The
reappearance of seagrass beds in several locations in the Bay may be the reason speckled trout populations have grown in recent years.Since the late 1980’s, speckled trout populations
have been increasing, and the favorite haunts of this popular game fish are shallow
water flats with abundant seagrass beds. The Chesapeake Bay is a summertime
home for many species of "panfish". Summer flounder, croaker, spot,
and small gray trout are the favorite targets for many anglers bouncing baits along
the bottom. Spanish mackerel and small bluefish can be taken by a variety of methods using
artificial lures and bait, and in recent years anglers have started to learn the methods
which are productive for catching the visiting populations of spadefish and sheepshead.
The reappearance of some larger gray trout is welcome news for recreational fishermen approaching
the new millenium and is another example of the positive contributions of serious
fisheries management. Tautog can be found over wrecks and obstructions in the
lower Chesapeake Bay all year but are most active when the water is cool. They remain active
throughout the winter, as long as water temperatures remain in the low 40’s, or higher.
Black sea bass can be found in the same areas from late spring through the fall.
REF: Virginia Saltwater Angler’s Guide, Prepaired for the VMRC
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