Sample Life Histories

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Teleost Fish

• Sample Life Histories

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• Class Osteichthyes
• Subclass Sarcopterygii (lobe-finned)
• Relict bony fishes
• Coelacanths, lungfish
• Subclass Actinopterygii (ray-finned)
• Infraclass Chondrostei
• Sturgeons, paddlefish
• Infraclass Neopterygii
• Gars, bowfin
• Teleostei
• Remaining 22,000 or so species

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TeleosteiThe Teleosts

• All bony fish not covered in previous lecture
• Modern ray-finned fishfins composed of bony rays
  with skin between rays

lionfish
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Teleost Characteristics

• Skeleton almost completely bony
• Thin ctenoid or cycloid scales (or no scales at
  all)
• Air bladder used for buoyancy, not breathing
• Homocercal tail
• Fully moveable upper jaw

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Reproductive strategy
r

• Most teleosts are r-selected
• Reproduce at an early age
• Produce a huge number of offspring that mature
  quickly
• Offspring have a very low survival rate
• Adults (of most species) have short lifespan
• BUT

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they do not live uncomplicated lives!
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• SpawnTo lay and fertilize eggs in the act of
  reproduction
• CatadromyMoving from fresh to salt water to
  spawn
• AnadromyMoving from salt to fresh water to spawn

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• Anadromous
• Some salmon, trout, sturgeon, shad, smelt,
  striped bass, lampreys.

• Catadromous
• Eels, gobies, galaxiids

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Life History of a Catadramous Speciesthe
American Eel(Anguilla rostrata)

• Family Anguillidae 15 species
• Only one species in North America
• Present in West Virginia

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Range

• Atlantic coast of North America, throughout the
  Gulf of Mexico and the Caribbean, to Venezuela,
  and inland in the St. Lawrence Seaway and the
  Great Lakes.
• In WV Potomac, New, and Ohio Rivers and
  tributaries of Ohio River

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Birth

• Baby eels are born in the Sargasso Sea (north of
  the Bahamas)
• Larvae are known as leptocephalus
• 7mm long at hatching
• Drift around for 9-12 months

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Sargasso Sea
Also known as
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THE BERMUDA TRIANGLE
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Glass Eels

• 1 ½ years old
• 2.4 inches long
• Metamorphoses into a glass eel
• Body is flat
• Transparent

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Glass Eel

• Body rounds out
• Drift with the current

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Elvers

• 3 years old
• In autumn, the glass eel enters a coastal estuary
  (like the Chesapeake Bay)
• Becomes pigmented
• Is now known as an elver

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Adulthoodthe Yellow Eel Phase

• Turns greenish-brown to yellowish-brown on back,
  whitish-gray below

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Migration

• Migrates upstream up to hundreds of miles
• As far as Minnesota
• Passes through dams, spillways, falls and rapids
• Uses eel ladders
• Can move over land

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Life in the River

• Lives in a freshwater river for 5-20 years
• Noctural
• Hides in the mud by day
• Eats insects, worms, crustaceans, molluscs, small
  fish, crayfish and recently dead animals
• To eat large items, must grab it and spin around
  to break a chunk off

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Gender Differences

• Males
• Southern latitudes
• Mouths of estuaries
• Begin migration when up to 2 feet long
• Change into females if population density low and
  food competition minimal

• Females
• Northern latitudes
• Inland rivers and streams
• Begin migration when up to 5 feet long
• Change into males if population density is high
  and food competition strong

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The Sea is Calling

• Quits eating
• Metamorphoses into a silver eel
• Changes color back is gray, underside is pure
  white, sides have a silvery-bronze sheen
• Eyes get bigger and visual pigments change (his
  faraway look in enhanced?)
• Pectoral fins get bigger

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Final Migration

• In autumn, migrates up streams and rivers,
  through ditches and shallow waters, back to the
  coast
• Swims up to 5600 km (3500 miles) to reach the
  the Sargasso Sea
• How does he find his way?

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Spawning

• January-February
• Somewhere in the Sargasso Sea (no one knows
  where!)
• Female lays 400,000-2,500,000 eggs
• Adults die afterwards

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Population Status

• Declining!
• European eels also declining

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Trials and Tribulations

• In coastal areas of US, glass eels are caught in
  eel pots and fyke nets
• Most are exported to Europe and Asia for sushi
• 325/lb

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How do you like your eel?

• Japanbarbecued
• Hollandsmoked
• Germany, Scandinavia,
• Belgium and Portugalstewed
• Francewith spinach and white wine
• Englanddiced with jelly and vinegar
• Spainas appetizers
• Italyat Christmas

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or raw
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Problems at home?

• Decline may be related to changing ocean currents
  due to global warming

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Parasites?

• Anguillicola crassus, an exotic nematode from
  Asia
• Discovered in American eels in 1995
• Causes reduced swimming speed, reduced ability to
  change buoyancy, rupture of the swim bladder and
  occasionally death

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Life History of an Anadromous Speciesthe Brook
Trout(Salvelinus fontinalis)

• Brook trout are found in 3 types of habitats
• Freshwater lakes
• Freshwater streams
• Marine areas

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Anadromous Populations

• Only populations near the coast and Great Lakes
  are anadromous (none in WV)
• Called coasters, sea-run trout, silver
  trout or salters

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J.F. Scarola
(An anadromous individual would be darker green
above, have silvery sides, a white belly and
very pale pink spots. )
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Range

• Northeastern North America, as far south as
  Georgia in the Appalachian Mountains, as far
  north as arctic Canada, and as far west as the
  upper Midwest.

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Birth

• Born in March/April
• A brook trout hatches from an egg laid in a
  gravel redd (nest) in a freshwater stream
• Remain in gravel until yolk sac is absorbed

J Kirshner
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Alevin

• Egg hatches in spring
• Baby trout is known as an alevin
• Resembles a tadpole because of yolk sac
• Remains in gravel nest, receives nutrition from
  yolk

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Fry

• Swims up out of gravel
• Now known as a fry
• Moves to shallow water for protection
• Eats immature forms of insects and microscopic
  crustaceans that drift below the surface of the
  water
• Less than 1 will survive to 1 year old

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Parr

• When several weeks old, dark bands (parr marks)
  appear on sides
• Now known as parr
• Eats mid-sized insect larvae such as mayfly or
  caddis fly larvae

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Juvenile

• Parr marks eventually fade
• Now known as a juvenile
• Eats larger insects and small fish
• Use vision to find food so hunt during the day
  (mostly morning) and on moonlit nights

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• Establishes a territory by being aggressive
  toward other fish
• Chases and charge other brook trout
• Establish dominance hierarchies
• Anadromous individuals spend 3 months at sea

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Size at 4 years old

• In a small stream 15 cm
• Lake 38-51 cm
• Largest ever caught was in Nipigon River in
  Rabbit Rapids, Ontario 6.57 kg
• Largest in WV 23 ½ inches
• Heaviest in WV 6 ½ pounds
• In WV, must weigh 1 ½ pounds to receive a trophy
  fish citation
• Uncommon to live to 5 years, very rarely to 8
• Record is 15 years

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Diet

• They eat anything!
• Aquatic insects, worms, leeches, crustaceans,
  terrestrial insects, spiders, mollusks, other
  fish, baby brook trout, frogs, salamanders,
  snakes, and small mammals
• Eat more fish as they get older
• Anadromous trout eat marine fish and invertebrates

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Migration

• First time when 2 years old, then every year
  afterwards
• Late summer or fall
• Anadromous individuals leave saltwater and enter
  fresh water
• Freshwater residents travel shorter distance
• Will travel upstream for miles to reach an
  appropriate area

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Spawning Habitat

• An area of loose clean gravel in a shallow riffle
  or shallow shoreline with upwelling of oxygenated
  water
• Shallow water, but not so shallow that the nest
  will be damaged by ice over the winter

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Spawningfemales

• Begin in October or so
• Female makes a nest called a redd by lying on her
  side and rapidly fanning caudal fin to clear away
  debris and silt
• Digs a 4-12 inch deep pit
• Will lay 15-60m pea-sized eggs per redd
• A 4 lb female will lay a total of 400-600 eggs in
  all (more or less depending on females size)

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Spawningmales

• Belly and fins turn red
• Jaw gets bigger
• More males than females at spawning site
• Male competes for a female by nipping and
  displaying to other males

T OStergaard
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male
female
JM McDowall
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Spawning

• One male and one female
• Male holds female to the bottom of the redd
• They both vibrate
• Eggs and milt (a cloud of sperm) are deposited
  simultaneously
• (almost) nobody dies!

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• Eggs are sticky at first and adhere to gravel
• Female covers redd with gravel using her tail
• Swims upstream, constructs another redd
• Eggs hatch in 44-144 days, depending on water
  temperature

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Where do the anadromous populations live?

• In US, only significant population is near Isle
  Royale National Park in Michigan
• In Canada, in rivers that flow into Nigipon Bay
  in Ontario
• Other small, struggling populations near east
  coast

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Reasons for decline in 1800s

• Logging
• Eliminated shade from streams
• Siltation
• Blocked spawning areas with dams
• Over-fishing
• Water pollution
• Lack of intelligence (brookies are not too
  bright!)

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• "The brook trout is an object of wanton
  destruction in northeastern Minnesota . . . One
  stream after another is visited. A camp is
  pitched beside each where it empties into the
  lake. Then for several days, perhaps a week, the
  river banks are lined with the creeping, stealthy
  forms of the fishermen throwing every temptation
  the ingenuity of man can devise before the eyes
  of the wary trout. By diligently and patiently
  continuing at their posts through every hour from
  daylight until evening, it is surprising if any
  fish are spared in the stream." 
• A.N. Winchell, in Natural History
• Survey of Minnesota,
  1879

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Acid mine drainage

• A big problem in WV
• Many brook trout are stocked in streams where
  they cant maintain a population

Kenneth Rastall
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Competition doesnt help

• Non-native species with similar habitat
  requirements have been stocked
• Coho salmon
• Chinook salmon
• Rainbow trout
• Brown trout

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Restoration efforts

• Bag limits
• Rehabilitation of entire watersheds
• Restocking with captive-raised fish

JM McDowall
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Why such complicated life histories?

• Anadromy and catadromy place adults in a
  favorable place for eating well and growing big,
  then in a favorable place for reproducing
• Place larval and juvenile fish in a favorable
  place for survival

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Advantages of Anadromy

• Dispersal mechanism to colonize new habitats (ie
  after glacial retreat)
• Adult fish grow more quickly in ocean and can
  thus produce more eggs
• Young fish are safer in small freshwater streams

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Advantages of Catadromy

• In tropics, where catadromous fishes are most
  common, freshwater streams are more productive
  than the ocean
• For eels, there is not as much food in the
  Sargasso Sea as there is in freshwater streams