Fisheries

• Unlike other natural resources such as oil and gas, fish are a renewable resource.

• People in coastal regions have been using fish as a major food source for thousands of years.

Fisheries, cont’d

• In 1997, the global fishery took 100.8 million tons of fish, crustaceans and mollusks.

• Fishing also employs 15 million people worldwide, but is the most dangerous job in the US (155 deaths per 100,000 fishers).

Fisheries, cont’d

• Of the thousands of species of marine organisms in the ocean, only ~500 species are regularly caught as part of a commercial fishery.

• The largest commercial harvest is of the herring and its relatives (sardines, anchovies) which comprise a fifth of the worldwide catch of marine resources caught each year.

Major Types of Commercial Fisheries

Groundfish Cod, haddock, hake

Pelagic fish Sardine, Anchovy,Herring, Mackerel, Tuna

Crustaceans Crab, Lobster, Shrimp,Krill

Molluscs Oyster, Mussel, Clam,Squid, Scallop

Top 5 Fish Harvesters (1998)

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Fishing Methods

Trawling (Dragging)– the most common method of fishing– a funnel-shaped net is towed behind the

fishing vessel– can be towed on the bottom to catch

groundfish or at mid water to catch pelagic fish

– bottom dragging is very destructive to the benthic ecosystems

Trawling

Fishing Methods Gillnetting (Driftnetting)

– a passive fishing method– a gillnet is a wall of netting set in a straight line,

equipped with weights at the bottom and floats at the top

– fish swim through the net and are caught when their gills become entangled in the net, hence the name

– if the nets are allowed to drift freely, the method is called driftnetting

Drift Net

Video on Driftnetting: https://www.youtube.com/watch?v=gOouXhkeXtw&list=PLO3IBTSyEdMpFocH6sNbsZcDEb3LixUwd&index=4

Fishing Methods Weirs

– a passive fishing method

– a weir is an enclosure made of nets and poles permanently attached to the bottom

– leader fences direct fish into the circular weir where they will swim in circles until they are purse seined out

– herring and sardines are often caught in weirs– Video on Weir Fishing: https://www.youtube.com/watch?v=eMlKTV_BFo0

Weir Off Grand Manan

Fishing Methods Other

– Lobster are caught with lobster pots - baited traps with funnel shaped openings allowing only one direction of travel - in!

– Scallops are caught by dredging - a metal frame with a net attached rakes the sandy bottom

– Squid and cod are often caught by jigging - a line of hooks are continually jerked to lure the fish to bite

Lobster Pots

Lobster Traps

• A lobster first enters the trap. • After successfully entering through one of these

doors the lobster enters the kitchen where the bait is tied.

• When a lobster tries to escape from the kitchen it is led through another door into the parlor.

• Small vents in the parlor allow undersize lobsters to escape, but larger lobsters are stuck there to await their fate.

• GoPro Camera in Lobster Trap: https://www.youtube.com/watch?v=bEolF1dS3Pw

Jigging

• Jigging is a common tactic for many species that spend some or all of their lives in relatively shallow salt water.

• Once the jig is cast, anglers normally allow the jig to flutter naturally to the bottom.

• it should be kept in motion during the retrieve, whether in an up-and-down jigging motion or slow, steady swimming motion.

• Rick Mercer goes cod jigging: https://www.youtube.com/watch?v=BJlHTTQ-3fA

Oyster Tonging

• Hand tonging is hard, slow work.

• Sometimes each "lick" of the tongs brings up only a few oysters.

• Most of the oyster harvest from the Chesapeake is taken with hand tongs.

Gill Nets

• The nets are used mainly by fishing fleets from Japan, Taiwan and South Korea, to catch squid, salmon and tuna in the North and South Pacific, Indian and Atlantic Oceans.

• The nets are often put into the sea at night, where they drift with the current, catching and killing anything that gets in their way.

• In December 1989 the United Nations recommended that all drift/gill net fishing be phased out by 1992.

Gill Nets

Long Lining

• Deep-sea long-liners  are big, able boats ranging from 50 ft to more than 100 ft in length.

• The long-liner operates by setting lines many hundreds of meters in length, anchored and buoyed at each end, with shorter lines and baited hooks tied to the main lines.

• Bottom fish (cod, haddock, halibut) and pelagic fish (swordfish, tuna, shark) are caught on long lines.

• Long line fishing https://www.youtube.com/watch?v=3HsKj7wO17g

Bottom Trawling

• The net is held open by a solid metal beam, attached to two "shoes", which are solid metal plates, welded to the ends of the beam, which slide over and disturb the seabed.

• This method is mainly used on smaller vessels, fishing for flatfish or prawns, relatively close inshore.

• https://www.youtube.com/watch?v=BnmGbDN278Y

Bottom Trawling

By-Catch animals that are unintentionally killed

when desirable organisms are fished in many cases, by-kill exceeds the

target catch thousands of dolphins were by-caught

in tuna nets until regulations changed the net design and ship maneuvers

Trawling Bykill

Drift Net By-Kill

Technology Improves Catches• 75% of fishers are vast commercial

fleets who find fish by using:– satellite sensors– aerial photography– scouting vessels– sonar– global positioning systems

• Huge factory ships follow along to can and freeze the fish as they are caught

Declining Fish Populations

• Fish stocks worldwide have been declining; many have collapsed, due to overfishing - too many fishers, too little fish

• Other reasons for declining numbers are mismanagement, habitat destruction, interference with breeding, increased ocean pollution