9646

• UCREFRP Catalog Number: 9646
• Author: Wiley, R. W. and R. S. Wydoski.
• Title: Management of Undesirable Fish Species.
• USFW Year: 1993.
• USFW - Doc Type: 335-354
• Copyright Material: YES

348

CHAPTER 14

Water level
manipulation

Traps

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Barn e rs

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Commercial
fishing

Electricity

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Seines

Wiers

Gill nets

Cast nets

Trawls

o

10

20

PERCENT

Figure 14.5 Mechanical methods used to manage undesirable fish species.

common carp, when to fish for them, baits that are effective, and tips on dressing
and cooking them. The American Fisheries Society published a book to stimulate
greater interest in common carp (Cooper 1987). Similar programs may be
developed for other underexploited species. For example, the Utah Division of
Wildlife Resources published brochures on fishing techniques, fishing locations,
and cooking mountain whitefish and bullhead catfish. Angling for mountain
whitefish provides stream fishing opportunities in winter when the trout fishery is
closed. In addition, many conservation agencies adopt liberal bag limits and
expand seasons to encourage increased harvest of underexploited species.

14.6 MECHANICAL METHODS FOR MANAGING
UNDESIRABLE FISH SPECIES

The most frequently used (81%) mechanical control methods include water
level manipulation, traps, barriers, commercial fishing, and electricity (Figure
14.5). Other methods include using seines, weirs, gill nets, cast nets, and trawls.
Mechanical control methods are employed on a variety of species in North
America (Table 14.4).
Water level manipulations in reservoirs can be achieved by drawdowns, by
increasing water levels, or a combination of the two (see Chapter 10). Planned
drawdowns can be used to control nuisance aquatic vegetation, to increase
predator utilization of forage fishes resulting in faster growth of the predators, to
release nutrients from bottom sediments, and to stimulate increased reproduction
and survival of young fish following reflooding. Significant increases in water
levels timed to occur just before, during, or for a short time after the spawning
season for spring spawners can be used to provide more littoral habitat and