Fisheries Science and the Striped Bass

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Fisheries Science and the Striped Bass
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A Classroom Lesson from theMathematics Science
Center
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Striped Bass A Success Story!
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Why? Because of .

• Fisheries Science
• and then
• proper fish management!

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Fisheries Science Involves

• Biology/Life Cycle
• Genetics
• Ecology
• Population Studies
• Taxonomy
• Fisheries Technology
• Management ( politics!)

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In the Chesapeake Bay

• Salinity 0.5 to 32 ppt
• 50 depth lt 20 ft.
• Temp range 1 30 C
• Largest U.S. Estuary
• Oxygen levels vary
• (O to saturated)

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Fish Fauna Flourish!
Not many residents most are visitors! 267
species in the bay Only 32 species are
year-round!
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Fish their Waters

• Freshwater (0 5 ppt)
• Estuarine (0.5 to 32 ppt)
• Marine (gt 30 ppt)
• Anadromous Species of fish
• Lives in Salt water, spawns in Fresh

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The Scientific Question

• How many fish do we have
• ...and how many can we catch
• without harming the fish stock?

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A Stock Assessment

• A special type of study of the carrying capacity
  of an area for a fish population that is
  harvested or managed
• Fish Biology
• Fishing Practices
• Catch Per Unit Effort (CPUE)

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Methods of Fish Science
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Otoliths How Old is a Fish?
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Otolith Rings Fish Age
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Graphs of Fish Populations
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Fish Length Graph
Fish Length (avg.)
Year
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Length Age
Female Striped Bass is able to reproduce at
4 years old!
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Tagging Where they go!
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Inserting the tag
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A Tagged Fish
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Dissections What they eat
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A Favorite treat!
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Prey of the Striped Bass
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DNA Fish Genetics
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Whose Eggs?
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DNA Patterns of Chesapeake Bay Sportfish
2,036 1,636 1,018 517/506
396 344 298 220/201 154/134
Bluefish
Southern kingfish
Summer flounder
Spanish mackerel
Spotted sea trout
Northern kingfish
Atlantic croaker
Cobia
Black sea bass
Black drum
Silver perch
Striped bass
Red drum
Weakfish
Tautog
Spot
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DNA Says ---

• Bass Mitochondrial DNA
• RFLP, Gel Electrophoresis
• Pattern for each species

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Fishing Practices

• Who is doing the fishing
• Catch Per Unit Effort (CPUE)

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By-catch A Critical Issue
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Keep or Release?
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Some Major Things Weve Learned

• Reduced populations from overfishing INCREASES
  the effects of natural stresses
• Acid rain and other chemicals (copper, aluminum)
  are toxic
• Fluctuation of water temp. in spawning grounds is
  most significant natural stress

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Maximum Sustainable Yield

• The number of fish we can catch per year and not
  hurt the stock
• Usually occurs at ½ of the carrying capacity
• Not too many fish for competition, but enough for
  a good spawning stock

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The Scientific End Result

We learn What age fish to catch How many we can
catch and when and still not hurt the fish
stock!