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NOAA Trust Species Life History

Alewife and Blueback Herring (River herring)

Alewife

Blueback herring

Alewife and blueback herring, commonly referred to as river herring, are migratory fish that live most of their life in the ocean and only migrate into freshwater streams to spawn.  Alewife spawn in streams and rivers with sluggish to slow currents in fairly shallow areas, while blueback herring require swifter and stronger currents (Fay, Neves, and Pardue 1983).  Both species can tolerate a variety of substrates including silt, mud, sand, gravel, and boulders.  Eggs and sperm are released in the water column where fertilization takes place.  Eggs stay suspended in the water column until eggs hatch (Fay, Neves, and Pardue 1983).  Spawning occurs far enough upstream for eggs to develop and hatch before reaching saltwater.  In Little Elk Creek alewife and blueback herring generally spawn from April through May with a peak in mid-April (Schaefer 2005).

Both river herring species spend their first spring and summer in the freshwater and tidal reaches of their natal stream where they forage on aquatic insects and small crustaceans.  During the spring, the river herring migrate throughout the tidal and freshwater segments of the tributaries of Chesapeake Bay including Little Elk Creek (Schaefer 2005; USFWS 2005a).  In the summer the salinity increases in the lower sections of Chesapeake Bay tributaries causing river herring to migrate upstream toward freshwater.  In the fall they migrate downstream through Chesapeake Bay and into the ocean.  Juveniles stay in the ocean until they are mature, which generally takes three to six years (USFWS 2005a).

For more information on alewife:

• FishBase: Alewife
• Marine Biology Laboratory: Alewife
• NatureServe Explorer: Alewife
• Virginia Institute of Marine Science: Alewife

For more information on blueback herring:

• FishBase: Blueback Herring
• NatureServe Explorer: Blueback Herring
• Virginia Institute of Marine Science: Blueback Herring

And a very good watercolor comparing the two, on the U.S. Fish and Wildlife site:

• New Jersey Field Office Partnership and Habitat Restoration

White Perch

White perch migrate into tributaries of the Chesapeake Bay including Little Elk Creek in the spring (Schaefer 2005).  Spawning is triggered when water temperatures warm to approximately 10°C (50°F).  Water temperatures ranging from 10°C to 16°C (50°F to 61°F) are ideal for white perch spawning (EA Engineering 2001).  Spawning in Chesapeake Bay tributaries including Little Elk Creek generally takes place February through March (Schaefer 2005).  High concentrations of suspended solids and low concentrations of dissolved oxygen can be lethal to developing eggs and larvae (EA Engineering 2001).

White perch are also migratory but in this area they generally only migrate as far as Chesapeake Bay and do not migrate into the ocean (Chesapeake Bay Program 2004).  Once white perch release their eggs and sperm into the water column and the eggs are fertilized they immediately attach to the substrate.  White perch also have the ability to spawn in free flowing areas, in these instances eggs may be so abundant they adhere to one another and are carried downstream on the current (Stanley and Danie 1983).  Once hatched, larvae remain near the spawning area foraging on aquatic insects and small crustaceans.  Juveniles use the shoreline or edge habitat of estuaries and streams near their spawning grounds as nurseries.  Juveniles remain in these freshwater tidal habitats for up to one year before migrating downstream into Chesapeake Bay (Chesapeake Bay Program 2004).

For more information on white perch:

• FishBase: White Perch
• NatureServe Explorer: White Perch

American Eel

American eel spend the majority of their lives in estuaries and freshwater streams including Chesapeake Bay and its associated tributaries.  American eel are able to migrate upstream of many barriers including spillways, low dams, falls, and rapids that are impassable to other migratory fish (Chesapeake Bay Program 2004).  American eel spend between 5 to 20 years in the estuary and freshwater streams before returning to their birthplace in the Sargasso Sea to spawn.  The eel begin migrating back to the Sargasso Sea in the fall and then spawn in January (Chesapeake Bay Program 2004).

American eel are able to live in a variety of habitats and have a very large geographic range.  American eel migrate and forage at night.  Adult American eel forage on insects, mollusks, crustaceans, worms, and other fish (Chesapeake Bay Program 2004).

For more information on American eel:

• NOAA Chesapeake Bay Office - Species Information: American Eel
• FishBase: American Eel
• Marine Biology Laboratory: American Eel
• NatureServe Explorer: American Eel

American Shad

American shad spend most of their life at sea, returning to freshwater streams to breed.  Non-spawning adults are found in schools near the surface of continental shelf waters in the spring, summer and fall, and are also found in brackish waters.  Newly hatched larvae are found in rivers during the summer; by autumn they enter the sea and remain there until maturity.  Juveniles form schools and gradually move downstream.  American shad feed on plankton and occasionally on small fishes.  Feeding ceases during upstream spawning migration and resumes during the downstream post-spawning migration.  American shad are commercially caught in rivers and estuaries during spawning migration.

For more information on American shad:

• NOAA Chesapeake Bay Office - Species Information: American Shad
• Status of Fisheries Resources off Northeastern United States - American Shad
• FishBase: American Shad
• Marine Biology Laboratory: American Shad
• NatureServe Explorer: American Shad

Gizzard Shad

The gizzard shad inhabits fresh and brackish waters in the United States, including in Chesapeake Bay and its tributaries.  Gizzard shad spawn in spring and early summer; they have no obvious spawning migration pattern, except that fish in brackish or salt water return to fresh water.  Spawning occurs mainly in low gradient tributaries or ditches, where large spawning aggregations move upstream as far as water depth will allow, to spawn in shallow water usually less than 1.5 m (5 ft) deep.  The spawning period varies from two weeks up to two months (Williamson and Nelson 1985).

Habitat conditions are optimal for gizzard shad in warm, fertile, shallow bodies of water with soft mud bottoms, high turbidity, and relatively few predators.  Gizzard shad feed on plankton and detritus (Williamson and Nelson 1985).

For more information on gizzard shad:

• FishBase: Gizzard Shad
• NatureServe Explorer: Gizzard Shad
• Virginia Institute of Marine Science: Gizzard Shad

Pictures of alewife, white perch, American shad and gizzard shad obtained from NOAA, Great Lakes Environmental Research Laboratory gallery.  Picture of American eel obtained from NOAA Cheasapeake Bay Office.  Picture of blueback herring obtained from MDNR: Commonly seen species of herring and shad in the Chesapeake Bay and its tributaries