Fish

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Fish
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Characteristics of Fish

• Skeleton made of ________
• _______________ bladder for buoyancy
• Mucus to reduce friction, ________________________
  ______
• ____________ (operculum) to protect gills and
  pump water through them (oxygen)

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• Small, thin scales for rapid swimming
• ___________ fins (not stiff as in sharks)
• Lateral line and other senses, but no
  ______________
• ______________ (cold blooded)

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Major Groups of North Atlantic Fish

• Demersal Fish____________________
• ________________________________
• ________ cod, haddock, pollock, cusk, hake
• _________ flounder (sole), halibut, plaice,
  turbot

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• Pelagic Fish __________________
• ___________ herring, sardines, shad, smelt,
  menhaden, gaspereau, capelin
• _________
• Mackerel, Salmon, Eel

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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

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Grenadier 450-800 m
Gulper 500-3000 m
Hatchet 200-6000 m
Swallower 500-1500 m
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Lantern 200-1000 m
Scaly dragon 200-1500 m
Tripod 900-3500 m
Viper 500-2500 m
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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

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Fisheries and Fishing Techniques
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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

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• Fishing employs ___ million people worldwide,
  but is the most dangerous job in the US (155
  deaths100 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

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• 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

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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

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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

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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

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Trawling
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Purse Seine

• A net _________________________
• _________________________________________________
  _________________________________________

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Purse Seine
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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

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Scallop Dragger
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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 ____________

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Gill Net
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Long-lining

• Long lines of ____________ hooks 40-50 km long
• There are ____________ of baited hooks placed in
  the open ocean, or along the bottom

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Long-lining
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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

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Lobster Trap
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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

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Weirs
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Jigging

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

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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

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• 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

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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

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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

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Declining Fish Populations

• Fish stocks worldwide have been declining many
  have collapsed due to _________________
• Other reasons for declining numbers are
  __________________________________________________
  __________________________________________________
  ____________________________________

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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
  __________________________________________________
  __________________

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• 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

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• 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)

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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