Fisheries Science and the Striped Bass
Jan 23, 2016
Fisheries Science and the Striped Bass
A Classroom Lesson from theMathematics & Science Center
Striped Bass: A Success Story!
Why? Because of ….
Fisheries Science …
and then…
proper fish management!
Fisheries Science Involves: Biology/Life Cycle Genetics Ecology Population Studies Taxonomy Fisheries Technology Management ( & politics!)
In the Chesapeake Bay…• Salinity = 0.5 to 32 ppt
• 50% depth < 20 ft.
• Temp range = 1 – 30° C
• Largest U.S. Estuary
• Oxygen levels vary
(O to saturated)
…Fish Fauna Flourish!
Not many “residents” – most are visitors!
267 species in the bay
Only 32 species are year-round!
Fish & their Waters… Freshwater (0 – 5 ppt) Estuarine (0.5 to 32 ppt) Marine (> 30 ppt)
Anadromous Species of fish– Lives in Salt water, spawns in
Fresh
The Scientific Question:
How many fish do we have…
...and how many can we catch… …without harming the fish stock?
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)
Methods of Fish Science
Otoliths – How Old is a Fish?
Otolith Rings = Fish Age
Graphs of Fish Populations
Fish Length Graph
Fish
Length
(avg.)
Year
Length = Age
Female Striped Bass…
…is able to reproduce…
… at 4 years old!
Tagging – Where they go!
Inserting the tag
A Tagged Fish
Dissections – What they eat
A Favorite treat!
Prey of the Striped Bass
DNA – Fish Genetics
Whose Eggs?
2,036 1,636 1,018
517/506
396 344 298
220/201
154/134
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DNA Patterns of Chesapeake Bay Sportfish
DNA Says ---
• Bass Mitochondrial DNA
• RFLP, Gel Electrophoresis
• Pattern for each species
Fishing Practices Who is doing the
fishing… Catch Per Unit
Effort (CPUE)
By-catch – A Critical Issue
Keep or Release?
Some Major Things We’ve 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
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
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!