Stocking

• Lecture Outline

– Stocking

– Reservoirs

– Ponds

– How many fish to stock?

– When to stock?

– What size to stock?

• Assignments

– pp. 419 - 420 Inland Fisheries Management

Fish culture and stocking of sport fishes

1) First hatcheries in U.S. started in mid-1800s

2) Currently 2.5 billion fishes stocked annually in the U.S. and Canada

3) Outcome of stocking programs has been quite variable

a) Successes (e.g., striped bass)

b) Catastrophic failures (e.g., common carp)

Reasons for stocking fishes

1) Enhancing condition of a fisheries resource

2) Creating fishing opportunities not supported by wild fish populations

3) Biomanipulation

a) E.g., controling aquatic vegetation

4) Providing food base for predators

5) Facilitate recovery of endangered populations

Stocking considerations

1) Can other management measures achieve the same objectives

2) Species for which the habitat is particularly well suited

3) Characteristics of the fishing demand

a) Put-and-take

b) Put-grow-and-take

4) Cost of different stocking techniques

a) Size, mortality rate

5) Characteristics of the species or strain of fish being considered

Stocking Reservoirs

1) New impoundments are highly productive

a) Stock predators immediately to reduce likelihood nongame fish will establish

2) Pelagic zone of reservoir unoccupied niche

3) Supplement populations are limited by reproduction

a) Striped bass – semi-buoyant egg

b) Pike and muskellunge – need submerged vegetation

Stocking in ponds

1) Only one to several species should be stocked in small ponds

a) Simple food web

2) Most typical species combination is largemouth bass and sunfish

a) Need balanced population

b) Restricting harvest or supplemental stocking of bass

How to many fish to stock?

1) First rigorous stocking systems were for trout (Embody 1927)

a) Classified streams based on average stream width, relative size, depth, frequency of pools and food abundance

2) Some methods account for habitat and fishing pressure

a) High mountain lakes in Colorado

3) Estimates based on total mortality rate

a) Catch curves

b) Mark recapture

4) Estimates based on total mortality and growth rate

5) Estimates based on total mortality, natural mortality and exploitation rate

When to Stock?

1) Season

a) Spring when food is abundant

b) Offset predator and prey stocking

2) Night vs. day

a) Higher crappie survival when stocked at night

What size to stock?

1) Trade-off between cost and survival

2) Fry stocked in predator free environments

a) New ponds or reservoirs

3) Fingerlings

a) Balance between cost to raise and survival

4) Adults

a) Put-and-take fisheries

5) Small pond example

a) Fingerlings

i) 40 Largemouth bass (25 – 50 mm) per hectare

ii) 200 Bluegill (50-100 mm) per hectare

iii) 40 Channel catfish (25 – 50 mm) per hectare

b) Larger fish

i) 20 Largemouth bass (200 - 300 mm) per hectare

ii) 40 Bluegill (100 - 130 mm) per hectare

iii) 20 Channel catfish (200 - 300 mm) per hectare