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Transcript
Fisheries Conservation
• Important vertebrate animal – commercial
& sport fisheries
• Indicators of environmental health
• Poor track record – pollution & sustainable
mgt
• Mgt relies on understanding responses to
changes in environmental conditions
Freshwater Fishery
• Primarily recreation – small commercial
• Sport fishery – resident & anadromous fish
Freshwater Fishery
Habitat – influence on fish life cycle
1) Temperature – influence on reproduction
2) Water Depth & Velocity – reproduction
& growth
3) Turbidity – sedimentation
4) Dissolved Oxygen – streams & lakes
(oxygen depletion) – relation to organics
Freshwater Fishery
Habitat – influence on fish life cycle
5) Substrate – material on bottom of water
body
redd: substrate nest for eggs
6) Cover – “in-water” & terrestrial shelter
Environmental Limits to
Reproduction
1) Natural Limitations
2) Human-Caused Limitations
Environmental Limits to
Reproduction
1) Natural Limitations
* Storms
* Soil Mass Movements
* Activities of other Animals
* Natural Barriers
* Natural Disturbance to Vegetation
* Predation
* Winterkill
Thermal Stratification
(temperate lakes)
dimictic vs. monomictic
Winter
cool water less dense
Spring/Fall
turnover (“mixing”)
Summer
epilimnion
metalimnion
thermocline
hypolimnion
Some Fisheries Legislation
• 1950 Sportfish Restoration Act
(Dingle-Johnson Act)
- tax on sportfish equipment
• ESA, etc…
• 1984 Wallop-Breaux Amendment
- new taxes (e.g., boat fuel)
- new trust fund
- aquatic education, marine fisheries
Pacific Salmonid Fishery
• State of Washington has 4 federally listed
species -Snake & Columbia River drainages
• sockeye (red) salmon, steelhead, chinook
salmon, bull trout
• Estimated 435 separate stocks in WA
• 1 extinct
• 113 unknown status
• 134 depressed
• 187 healthy
• Harvest of chinook
salmon
500,000 to 0 to 2,000+
(1970s to 1994 to 1996)
• Harvest of coho
salmon
2.5 M to 1,000+
Pacific Salmonid Fishery
• 75% of steelhead stocks = unhealthy
• 68% of chum salmon = healthy
• 60% of sockeye salmon = unhealthy
• Average size (age) of chinook & chum
salmon declined 50% since 1920’s due to:
- modified habitat
- selective harvest
- genetic change (hatchery vs. wild fish)
Pacific Salmonid Fishery
• Goal of fish hatcheries = replenish fish
stocks to meet harvest demands (~125
federal/state/tribal)
• Dramatic increase in hatchery fish can
(~200 M salmon/steelhead):
- lead to overfishing of remaining wild fish
- spread disease to wild fish (e.g., whirling
disease)
- reduce genetic diversity (homogenize
unique salmon stocks)
Marine Fisheries: Conservation
Topics
MSY
vs.
optimum yield
Marine Fisheries: Conservation
Topics
• Trawling & Turtle Exclusion Devices
(TEDs)
• Trawling & Marine Benthos
150,000 turtles annually in
shrimp nets
Marine Fisheries: Conservation
Topics
• Tropical Fish Industry
• Low Frequency Active Sonar (US Navy)
• High resolution detection (monitoring)
• National Security
• Invasive
• Sonar waves cause disorientation
• Sonar waves shatter tympanic bullae
(“ear drums”)
Passive Sonar
Active Sonar
Low Frequency Active Sonar (LFA)
Low Frequency Active Sonar (LFA)
Low Frequency Active Sonar (LFA)