Transcript Fishing Methods

Fishing Methods
•
•
•
•
•
•
•
•
•
Traditional analogues for modern methods
Spears, arrows
Active traps
Passive traps, fish ponds
Hooks
Active nets
Passive nets
Inland & nearshore subsistence fishing
spears exploding harpoons
Old & New Methods
• Spear
• Hook-n-line
• Traps
•
•
•
•
•
•
•
•
Exploding harpoon
Trolling
Trolling-n-chumming
Demersal Trawl line
Pelagic Trawl line
2000 hooks; 3-4%
Traps
FADs
Nets
• Gill Nets
• Floats & weights
• Drift nets
–
–
–
–
–
Efficiency
Fiber advances
Bycatch
33000km—80%
Banned in 1992
•
•
•
•
•
•
•
•
Trawl Nets
demersal & pelagic
Power needed
Beam
beam  Otter
10-100m opening
Echo-sounder
sonar
A comparison between typical trawl catch and a typical gillnet catch associated with
the pre-industrial fishing. Note that the cod end of the net on the factory trawler is
bigger than the entire boat housing the traditional fisher.
Table 2.2 Major species of fish caught with otter trawls
Species
Major fishing countries
Areas fished
Alaska pollock
Russia, Japan, South Korea
Northwestern
Pacific
USA
Northeastern
Pacific
Atlantic cod
Iceland, Norway, Russia
Northeastern
Atlantic
Blue whiting
Norway, Iceland, Russia,
Faeroe Islands
Northeastern
Atlantic
Largehead hairtail
China, South Korea
Northwestern
Pacific
Largehead hairtail (Trichiurus lepturus). Weight to 5 kg, length to 2.3 meters
Purse Seines
•
•
•
•
•
•
Globally, most fish catch…by far
Catch fish schooling near surface
100km x 100m
Fish must aggregate in large schools
Powerful means to deploy & retrieve
Dories (50’s) to power block
Icelandic freezer
trawler Svalbakur,
capable of catching 60
tonnes per haul
Purse seine boats beginning a set on a 64-tonne school of Atlantic menhaden
in coastal waters of North Carolina.
Table 2.1 Major species of fish caught with purse seines
Species
Major fishing countries
Areas fished
Atlantic herring
Canada, USA,
Northwestern Atlantic
Denmark, Iceland, Norway
Northeastern Atlantic
capelin
Iceland, Norway
Northeastern Atlantic
Chilean jack mackerel
Chile, Peru
Southeastern Pacific
Chub mackerel
China, South Korea, Russia
Northwestern Pacific
Chile
Southeastern Pacific
European pilchard
Morocco
East Central Atlantic
Japanese anchovy
China, Japan, South Korea
Northwestern Pacific
Peruvian anchovy
Peru
Southwestern Pacific
Skipjack tuna
Indonesia, Taiwan, Japan, South Korea,
Philippines, USA, Palau
West central Pacific
Ecuador
Southeastern Pacific
Japan
Northwestern Pacific
Spain, Maldives
Indian Ocean
Philippines, Taiwan, Japan, USA
West Central Pacific
Mexico, Venezeula
East central Pacific
Ecuador
Southeastern Pacific
France
Western Indian
Yellowfin tuna
Catch Amount by type
• Purse Seine
~50%
– Herring,sardine,anchovies,tuna,mackerel
• Otter Trawl
~17%
– Pollock, cod,whiting
• Lines
~ 9%
– Tunas,swordfish,cod,halibut,haddock,etc
• Pound/trap nets
– Lobsters,crabs
• Gill Nets
~6%
– Squid,salmon,billfish
~8%
Technology
•
•
•
•
•
Echo sounders
Synthetic fibers
Power
Boat range
Preservation of catch
– Drying/salting icing,canning,freezing
Artisanal Fishing
A fisherman in
Cochin, India
The beachfront market of St.-Louis, Senegal
Fishing technology
in Senegal. Wives
parcel out the dregs
of catches. The
best fish are sold to
European traders
or seafood
processors.
Schematic of modern, high-tech fishing vessel. From left to right: purse
seine, squid jigger, long liner, trawl net equipped with sonar to
automatically track schools of fish. The factory trawler depicted above is
the Alaska Ocean. It is capable of processing more than 600 tonnes of
pollock per day into surimi, the protein paste used in imitation seafood
products.