Harvesting the Sea - Commercial fishing and its effects on Osteichthyean and

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Harvesting the Sea - Commercial fishing and its
effects on Osteichthyean and Chondrichthyean
fishes
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Between 1950 and 1994, ocean fishermen increased
their catch 400 by doubling the number of boats
and using more effective fishing gear. In 1989,
the world's catch leveled off at just over 82
million metric tons of fish per year. That's
all the ocean can produce. Sending more boats
won't help us catch more fish.
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Wait a minute, catch has increased dramatically
but fish/person has not! Why???
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• Human Population growth
• 2.5 billion
• 2000 6 billion

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Fisheries collapse - The North Atlantic Cod
Collapse
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Recent, widespread collapse of fisheries
1950s
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Multiple ecological effects of overfishing
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Bycatch Worldwide, fisheries throw away 25
of their catchFor each pound of shrimp caught in
a trawl net, an average of two to ten pounds of
other marine life is caught and discarded
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Recent research Nature 2006 Pacific coast of
US exploited fish species populations more
variable from year to year than
non-exploited Ecology Letters
2006 Overharvesting, especially of older fish,
may rapidly lead to Darwinian Debt loss of
genes coding for important characteristics like
size, age at reproduction, egg size and number
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Chilean seabass live at least 40 years, orange
roughy at least 100. A Pacific rockfish caught
in 2001 was 205 years old born when Washington
was still president! Such slow-growing fishes
are very vulnerable to overfishing Be Part of
the Solution By making better seafood choices
using the Seafood Watch card (e.g. Monterey Bay
Aquarium website www.mbayaq.org) you know which
fish are caught with little bycatch. That way you
can support responsible fishermen and help
reduce wasted catch.
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• Major evolutionary events in Vertebrate History

• Evolution of jaws and paired appendages

2) The Evolution of Tetrapods and Invasion of
Terrestrial Environments
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Devonian Age of Fishes- Ostracoderms,
placoderms, acanthodians, chondrichthyes,
actinopterygians, sarcopterygians, first
tetrapods!!
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Devonian conditions Warm shallow seas Land
with primitive plants Land with terrestrial
invertebrates Why important?
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Lots of aquatic Devonian predators and
competitors So what? Hypotheses about
evolutionary forces driving invasion of the
land
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Evolution of Tetrapods example of transitional
forms
Eusthenopteron
Acanthostega
Ichthyostega
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