Fish

Characteristics of Fish

• Skeleton made of ________

• _______________ bladder for buoyancy

• Mucus to reduce friction, ______________________________

• ____________ (operculum) to protect gills and pump water through them (oxygen)

• Small, thin scales for rapid swimming

• ___________ fins (not stiff as in sharks)

• Lateral line and other senses, but no ______________

• ______________ (cold blooded)

Major Groups of North Atlantic Fish

• Demersal Fish:____________________

________________________________–________: cod, haddock, pollock,

cusk, hake

–_________: flounder (sole), halibut, plaice, turbot

• Pelagic Fish: __________________

– ___________: herring, sardines, shad, smelt, menhaden, gaspereau, capelin

– _________

– Mackerel, Salmon, Eel

Deep Sea Fish

• Deep sea fish tend to live below ____ m

• They have anatomical adaptations to live at these depths such as: ________

________________________________________________________________

• Many are smaller than ___ inches

Grenadier: 450-800 m Gulper: 500-3000 m

Hatchet: 200-6000 m Swallower: 500-1500 m

Lantern: 200-1000 m Scaly dragon: 200-1500 m

Viper: 500-2500 m Tripod: 900-3500 m

Angler Fish

• There are several different species

• They usually live between _________m

• Some have a ____________

• They use a ______ to attract prey

• There is one species where the female is ___x the size of the male; he lives as a ___________ on her body

Fisheries and Fishing Techniques

Fisheries Facts

• Unlike other natural resources such as oil and gas, fish are a ______________

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

• In 1997, the global fishery took ________ million tons of fish, crustaceans and molluscs

• Fishing employs ~___ million people worldwide, but is the most dangerous job in the US (155 deaths:100 000 fishers)

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

• The largest commercial harvest is _________ and relatives (sardines, anchovies) which comprise 20% of the worldwide catch each year

• The top five fish harvesters in order from greatest to least are:

Commercial Fisheries

• Major types of commercial fisheries include:– ______________: cod, haddock, hake– ______________: sardine, anchovy, herring,

mackerel, tuna– ______________: crab, lobster, shrimp, krill– ______________: oyster, mussel, clam,

squid, scallop

Technology Improves Catches

• ____% of fishers are cast commercial fleets who find fish using:

→

→

→

→

→• Huge factory ships follow along to can and

freeze the fish as soon as they are caught

Fishing Techniques: Trawling (dragging)

• The most common method of fishing

• A _______________ net is towed behind the fishing vessel

• Can be towed on the _______________ to catch groundfish or at _____________ to catch pelagic fish

• Bottom dragging is very ____________ to the benthic ecosystems

Trawling

Purse Seine

• A net _________________________

__________________________________________________________________________________________

Purse Seine

Scallop Dragger

• Scallops are caught by __________ – a metal frame with a net attached rakes the sandy bottom

• This method is also destructive to the benthic environment

Scallop Dragger

Gillnetting/Driftnetting

• A passive fishing method (_______ km long)

• A gillnet is a wall of netting set in a straight line equipped with ________ at the bottom and _________ at the top

• Fish swim through the net and are caught when their gills become entangled in the net

• If the nets are allowed to drift freely, the method is called ____________

• Must be checked ____________

Gill Net

Long-lining

• Long lines of ____________ hooks 40-50 km long

• There are ____________ of baited hooks placed in the open ocean, or along the bottom

Long-lining

Lobster Pots

• Lobsters are caught in baited traps with funned shaped openings allowing only ______ direction of travel – in

• They can be single traps, or in groups on a line

Lobster Trap

Weirs

• A passive fishing method

• A weir is an enclosure made of nets and poles _____________ attached to the bottom

• Leader fences direct fish into the circular weir where they will ______________ until they are removed by the fisher

• ___________ and ____________ are often caught in weirs

Weirs

Jigging

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

Fishery Problems: By-catch

• Animals that are _______________ killed when desirable organisms are fished

• In many cases, _____________________

___________________________

• Thousands of _____________ were caught in tuna nets until regulations changed the net design and ship maneuvers

• Every method of fishing has this problem

• About ______________________ of unwanted fish may be discarded annually either because regulations prevent capture of these fish or because it is not ___________________ to process them

Ghost Fishing

• Nets will keep fishing after they have been lost due to _________________________

• Fish and other organisms will rot in the nets because there is no-one to collect them

• _________________________________ cause the most problems

Habitat Destruction

• Destroying the ocean floor in the process of dragging nets

• The bottom becomes ‘_________’ and it takes a long time to recover – if it does

• ______________ and _________________ cause the most damage

Declining Fish Populations

• Fish stocks worldwide have been declining; many have collapsed due to _________________

• Other reasons for declining numbers are: ________________________________________________________________________________________________________________________________________

Fisheries Management

• Scientists study fish stocks to determine estimates of the _________________ and the reproductive biology of the species

• This information allows scientists to estimate the _______________________ and determine the ____________________________________________________________________

• Scientists can determine the minimum size of fish to be caught to ensure _____________ are not being harvested

• They can also determine times of the year when no fishing should be allowed to __________________________________

• Scientists make ____________________ to the fisheries managers

• Fisheries managers set the ___________

___________________________ (total tonnage of fish that a fleet can catch)

• They also set ________ (total tonnage of fish that a fisher can catch)

Fisheries Mismanagement

• Poor science leads to poor estimates

• Managers disregard scientists recommendations

• Fishers do not obey quotas

• Other factors (not taken into consideration) may deplete the population: foreign fishers, weather, pollution etc…