fisheries importance - major source of protein for humans, important for economy of some countries
and many coastal communities
human consumption of fish - fishes account for 20% of animal protein consumption by people,
additional 5% consumed indirectly by livestock
economic impact of fisheries - recreational or sport fishery in 2001 spent $36 billion; 85% in freshwater
systems. Commercial fishing in U.S. is worth $3.5 billion, in coastal and island regions fishing is very
important. fishery related jobs are now threatened by over-fishing, pollution, and poor management.
world's fishers currently possess about twice the capacity needed to fish the oceans.
freshwater fisheries - primarily recreational, but some commercial species. harvested species: catfish,
bass, sunfish, perch, walleye, salmon, sturgeon, and trout.
littoral zone - by edge of lake, primary productivity is here.
what is the most significant factor affecting freshwater fisheries? - water quality or invasive species
water quality - Physical: temp., depth, velocity, turbidity, substrate, and cover. Chemical: oxygen, pH,
salinity, organic material, pollutants
fishing pressure - Predation by non-humans- other fish, birds, mammals. sport, subsistence, and
commercial- recreational users, Native Americans, commercial harvest of select species.
Introduced Species - non-native fishes: compete for resources, prey on native fishes, alter habitat. Non-
fishes: compete for resources, alter habitat, alter trophic structure. impacts- competition, predation,
hybridization.
ex: zebra mussels-accidentally introduced from boats.
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