Marine Fishes

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• Marine Fishes
• Chapter 8
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Figure 8.1
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Jawless Fishes Figure 8.2
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Examples of Shark Species Figure 8.4
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Rays Skates Figure 8.6b This is an image of a
manta ray.
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Ratfish, or Chimaera Figure 8.7
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Cartilaginous Fish vs. Bony FishFigure 8.8
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What does body shape tell us about how fast these
fish swim and where they live? Figure 8.9Some
typesfusiform streamlineddorsoventrally
flateel-like thin or ribbon
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Locomotion in Marine Fishes Figure 8.11a.
elongate fishes move with undulationsb. fast
fish/ shorter body flex caudal portionc. slower
fish move only finsd. slowest fish move only
caudal fin
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Myomeres Figure 8.12
Sharks have no swim bladder Bony fish have a
heavier skeleton
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Mouth Shapes indicate diet.Figure 8.13
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DigestiveOrgansFigure 8.14
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Circulatory System Figure 8.15
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Gill Functiona. CartilaginousFishb. Bony
FishFigure 8.16
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Lateral Line Sensory System Figure 8.19
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Schooling Patterns Figure 8.21a. travelingb.
feeding on planktonc. encircling a predatord.
streaming to avoid predator
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Migrations of Commerical Fish SpeciesFigure
8.22Salmon have an anadromous migration
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Figure 8.28
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Figure 8.26
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Mating Behavior of the Atlantic Cod Figure 8.25
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The Atlantic Cod, Gadus morhua
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The Atlantic Cod, Gadus morhua

• MA state House of Rep. 200 yr old sacred cod
  5ft long wooden, painted
• Atlantic fisheries have collapsed flounder,
  halibut, haddock, and cod
• 1900- 5 mill tons of fish caught
• 1980s- 86 mill tons of fish caught!
• 1895- 60,000 tons of cod caught in NE fishery
• 1954- factory trawlers introduced increase in
  fishing effort
• 1968- 810,000 tons of cod caught at Grand Banks
• Mid 1970s- cod catch drops to 200,000 tons at GB
  and 30,000 on Georges Bank

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The EEZ

• 1977 Exclusive Economic Zone established world
  wide- 200 miles offshore
• Gave Georges Bank fishing rights to only US and
  Canada, exploited fishery further with foreign
  ships gone
• NMFS (US) and DFO (Canada) badly misjudged the
  size of cod population in late 1980s
• 1992 Canada closes cod fishery at Grand Banks
  300,000 people in Newfoundland out of work out of
  a population of 570,000
• 1994 NMFS closes most of Georges Bank to cod
  fishing
• 1998 data shows the population is rebounding, but
  slowly, may take 20 years to recover fully

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The Tragedy of the Commons

• ½ of worlds fish stocks are threatened by
  overfishing
• We are fishing down the food web and altering
  ecosystems
• US fishery collapse cost govt 60 mill to
  unemployed fishermen
• Canada spent 1 billion to its unemployed
  fishermen
• open-access policy is the problem in fishery
  management- anyone can fish at no cost to
  themselves
• Even logging, mining, and ranching operations pay
  a fee to use govt land

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Sharks in Massachusetts

• Greg Skomal- Mass Shark Research Program
• Part of the Mass Division of Marine Fisheries
• research the sharks that occur in our waters
• offer expertise about the shark fisheries
• educate the public
• Attacks are rare
• Sharks are only summer residents in northeast
• 2 major groups
• 1. Coastal
• 2. Pelagic

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Coastal Species

• 1. Sand Shark
• 2 species sandbar/ brown shark and smooth
  dogfish
• 2. sand tiger shark
• Does well in captivity
• 2 strongest are born because they ate their
  siblings in the womb
• Swallows air into stomach to help with buoyancy

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Coastal Species continued

• 3. Spiney Dogfish
• Marketed a lot overseas as seafood
• About 4 ft long
• Long life span
• Bear live young

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Pelagic Species

• Tournament species
• 2 areas area S of Cape and Islands and
  Stellwegen Bank
• 1. Blue Shark
• Most abundant shark
• Mate congregate S of MV Island
• Large scale tagging and research program
• 2. Mako Shark
• Very fast species
• Commerically fished
• Can get 12 ft long, 1200 lbs!

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Pelagic Species continued

• 3. Thresher Shark
• Uses tail like a whip
• 4. Hammerhead Shark
• Very rarely found here
• 5. Tiger Shark
• Very rarely found here
• Usually feeding on a whale carcass

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Pelagic Speciescontinued

• 6. Great White Shark
• Favorite food is seals or sea lions
• Rare in this area
• Born already 3 ft long!
• Can get to be 20 ft long 3,000 lbs!
• 7. Basking Shark
• BIG! 25 ft
• Filter feeders, planktivorous
• Gill rakers collect plankton
• Beach themselves like whales
• Spend winter in Carolinas south to Florida

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Educating the Public

• Bull Sharks are responsible for most attacks in
  shallow waters
• They are never seen up here, they only go as far
  N as NJ in summertime
• Summer 2001, boy in FL attacked by one
• A few weeks later a sand bar shark caught and
  reported as a bull shark
• Media attention, etc. made people nervous about
  sharks in MA
• Greg had to do a DNA test to prove it wasnt a
  bull shark!