Prey Management

• Lecture Outline

– Successful prey management

– Species accounts

• Assignments

– pp. 436 - 437 in Fisheries Techniques

Keys to successful forage introductions

1) Provide an abundant food supply

2) No wide fluctuations in abundance

3) Effectively transfer primary production to higher trophic levels

4) Be vulnerable to predation based on their size, behavior, and habitat preferences

5) Be innocuous

Establishing Invertebrate forage

1) Not generally successful

a) Opossum shrimp

i) Few success stories

ii) In many cases reduced growth and abundance of fishes

iii) Only recommended for:

(1) Deep lakes with strong thermocline

(2) Highly eutrophic lakes

(3) Shallow water systems

Emerald shiner (Notropis atherinoides)

1) Widely used

2) Not well documented

Spottail shiner (Notropis hudsonius)

1) Limnetic, spawns near shore

2) Little larger than emerald shiner

Inland silverside (Menidia beryllina) and brook sliverside (Labedesthes sicculus)

1) Labedesthes – rarely found in fish stomachs

2) Menidia – see boxrucker paper in Res. book

Rainbow smelt (Osmerus mordax)

1) Worked well in some lakes

2) Populations highly variable…limits use

Alewife (Alosa pseudoharengus)

1) Mixed results

2) May help as forage

3) Competes for zooplankton with other young fishes

4) Highly variable populations

Fathead minnow (Pimephales promelas)

1) Too vulnerable to predations

2) Best use as “starter” prey in impoundments

Golden Shiners (Notemigonus chrysoleucas)

1) Adults reach large size

2) Susceptible to predation

3) Waters with submerged macrophytes

Threadfin shad (Dorosoma petenense)

1) Stressed at 7-8 ^oC

2) Few survive at < 4 ^oC

3) Spawn at 3cm, seldom exceed 6cm

4) Stock adults in spring

a) Those adults will spawn that summer

5) Mixed results

a) Improve growth of larger bass and crappie

b) May compete with juvenile crappie and bluegill

Gizzard shad (Dorosoma cepedianum)

1) Mature at 17-18 cm, reach 3+ lbs

2) Winter mortality common

3) Compete with bluegill and juvenile largemouth bass

4) Strong effect in ecosystem

a) Nutrient transport

b) Detritus processing