Transcript review fishing ch13

Food Resources
G. Tyler Miller’s
Living in the Environment
13th Edition
Chapter 13
Catching and Raising More Fish
• Fisheries – concentrations of aquatic
species suitable for commercial
harvesting in a given body of water
• 55% of annual commercial catch
comes from the ocean.
• 33% from aquaculture.
• 12 % from inland freshwater fishing.
Commercial Fishing Methods
Trawler
fishing
Fish farming
in cage
sonar
Spotter airplane
Purse-seine
fishing
trawl
trawl flap
lines
fish school
trawl
bag
Long line fishing
lines with
hooks
Fish caught
by gills
float
Drift-net
fishing
buoy
Potential to harvest more fish
• 1950-1982
+ Fish catch increased 5-fold
+ Per capita seafood catch doubled
• Since 1982
– Little increase in commercial fish
catch
– Per capita commercial fish catch
falling
Potential to harvest more fish
The primary cause of depletion of
fish stocks is too many fishing
boats pursuing too few fish or
OVERFISHING
(Tragedy of the Commons)
• Habitat destruction
• Global warming
Aquaculture
• Fish farming
– Cultivating fish in a controlled
environment.
– Harvesting them when they reach the
desired size.
– Catfish are the leading aquaculture
product in the US
Aquaculture
• Problems
– Raises demand for ocean fish as fish
meal to feed aquaculture species
– Creating vast amounts of animal waste in
coastal areas
– Farming of carnivorous fish increases
over-fishing of smaller marine species.
Future
• Increasing wild catch and aquaculture
will not increase world food supplies
significantly.
• Fish and shellfish supply only 1% of
the energy and 6% of the protein in
the human diet.