Important fish families

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Fish and Fisheries Management

• Important fish families
• Methods of collection and study
• Fish interactions
• Important limnological measurements to fisheries
  studies
• Water development and pollution Effects
• Fisheries management

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Historical neglect of fish by limnologists,
partly because

• Fisheries biology historically an applied
  science but has developed considerable basic
  theory
• Early limnologists tended to neglect fish but
  this has changed, esp. in recent years
• Commercial and recreational importance of fish
  requires management skills

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An integrated approach between fish biologist and
limnologists is necessary because

• Fish yield is a function of whole lake processes
• Fish can also alter the structure and function of
  primary and secondary lake components
• Fish can degrade or improve water quality
• Many native fish stocks are endangered

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Review of Important Families of Fish (Class
Osteichthyes)

• Acipenseridae sturgeon
• Catostomidae suckers
• Centrarchidae bass, sunfish
• Clupeidae shad, herring
• Coregonidae whitefish
• Cyprinidae minnows and carp
• Esocidae pike

• Percidae perch, walleye, saueger
• Petromyzontidae lampreys
• Ictaluridae catfish
• Salmonidae salmon, trout
• Amidae bow fin, gars

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Anadromous vs. Catadromous

• Andromous fish spawn in rivers and mature in the
  sea
• ex salmon, steelhead trout
• Catadromous fish spawn in the sea and mature in
  rivers
• ex American eel

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Methods of Collection and Study

• Fish toxicants
• ex rotenone Lake Davis problem
• Netting
• gill netting
• seining
• trammel netting
• fyke nets
• trawl nets

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• Electro-fishing
• must have sufficient salinity!
• AC or DC current
• Hook and line fishing
• Can include catch and release (non-destructive
  method
• SCUBA for fish observation

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Population Census Methods

• Creel
• Mark and recapture tagging (now electronic)
• Direct count
• Echo sounding
• Catch per unit effort
• Weirs
• Towers

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Interaction of fish with other lake components
and each other

• Direct effects of grazing
• size selective predation
• Indirect effects of grazing
• selective grazing alters zooplankton community
  which in turn alters phytoplankton community
  (Brooks and Dodson, 1965 Carpenter, Kitchel, and
  Elser)

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• Nutrient Recycling and transport by fish
• ex P transfer from the littoral to pelagic zone
  (Schlindler et. al, 1996)
• Predation on other fish
• varies with life stage
• ex Pike, Bass
• Predation on insects
• ex Gambusia (mosquitoes)
• Lepidophagy
• feeding on the scales of other fish
• ex an Amazonian fish

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Importance of Limnological Measurements to
Fisheries Studies

• Relationship of fish yield to primary
  productivity
• Goldman Mo and Castle Lake trout
• Edmondson Bear Lake fertilization
• Stockner Salmon Lake fertilization by aircraft
• Primary productivity measurements used to predict
  fish yield

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Effects of Water Development and Pollution on
Fisheries

• Dams
• converts riverine areas to impoundments
• obstruct migration to original spawning sites
  (guided by olfactory senses)
• juveniles may have trouble going downstream
• May eliminate survival of the fittest when
  hatcheries attempt to maintain fish runs
• temperature of released water
• timing of water releases

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• Irrigation
• reduces water in streams
• diverts young fish to agricultural fields
• decreases lake levels in summer and endangers
  fish stocks
• - ex Klamath Lake
• Channelization
• ex St. Lawrence waterway development allowed
  invasion of sea lamprey Petromizon marinus into
  the Great Lakes ? destroyed commercial lake trout
  fisheries
• stream channelization speeds summer runoff and
  leads to dry stream beds

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• Increased Eutrophication
• balanced fertilization can increase fish
  production, BUT
• oxygen depletion in deep water ? loss of spawning
  grounds and benthic invertebrates, an important
  fish food source
• ex near disappearance of mayfly nymphs in Lake
  Erie
• low DO concentrations in the water column
• most freshwater fish need a minimum constant DO
  concentration of 5 mg/L
• ex Stockton sewage discharge lowered DO to 5
  mg/L and formed a chemical block to migrating
  salmon

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• Thermal pollution or enhancement
• thermal enhancement
• higher temperatures can speed growth
• decline in fisheries
• stenothermal fish, like trout, will not withstand
  the higher temperatures
• more susceptible to chemical toxicity faster
  metabolic uptake of toxins
• increased parasite and fungal infections
• decreased DO concentration capacity
• ? temperature ? DO solubility

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• Chemical pollution
• pH changes
• pesticides
• some biomagnify up the food chain
• detergents
• removes protective fish slime making them less
  resistant to fungal infections
• industrial wastes
• ex methyl alcohol, silver in Silicon Valley
• heavy metal pollution
• ex Hg, Pb, Cd, Cu, and Zn
• agricultural runoff
• often high in pesticides and fertilizers

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• Logging
• erosion and sedimentation ? destruction of
  spawning grounds
• loss of riparian habitat ? less shading ? higher
  temperatures, loss of allochtonous inputs
• rotting logs ? depletion of DO conc.
• Landslides, mudslides
• ex Lake Baikals omul most imp. commercial
  fish
• spawning streams used for log flotation 10 of
  the logs sinks ? reduction in feeding and
  breeding habitats

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Fisheries Management Methods for Increasing
Sustaining Yield

• Fertilization
• ex Mo addition to Castle Lake
• Fish stocking
• ex intensive trout stocking to high Sierra Lakes
• Habitat improvements
• ex brush piles in lakes, cleaning of spawning
  gravel, pool and riffle management, dam release
  water temperature control

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• Restricted harvest
• size limitation for juvenile or adult fish
• ex sturgeon
• Hybridization centrarchids and char
• often sterile
• tend to be very aggressive
• grow bigger and faster ? better food conversion
• tend not to overpopulate