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!