1 / 16

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

Harvesting the Sea - Commercial fishing and its effects on Osteichthyean and Chondrichthyean fishes. 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

kaoru
Download Presentation

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

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Harvesting the Sea - Commercial fishing and its effects on Osteichthyean and Chondrichthyean fishes

  2. 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”.

  3. Wait a minute, catch has increased dramatically but fish/person has not! Why???

  4. Human Population growth • 2.5 billion • 2000 6 billion

  5. Fisheries collapse - The North Atlantic Cod Collapse

  6. Recent, widespread collapse of fisheries 1950’s

  7. Multiple ecological effects of overfishing

  8. “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

  9. 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

  10. 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.

  11. Major evolutionary events in Vertebrate History • Evolution of jaws and paired appendages 2) The Evolution of Tetrapods and Invasion of Terrestrial Environments

  12. Devonian Age of Fishes- Ostracoderms, placoderms, acanthodians, chondrichthyes, actinopterygians, sarcopterygians, first tetrapods!!

  13. Devonian conditions Warm shallow seas Land with primitive plants Land with terrestrial invertebrates Why important?

  14. Lots of aquatic Devonian predators and competitors So what? Hypotheses about evolutionary forces driving invasion of the land

  15. Evolution of Tetrapods – example of transitional forms Eusthenopteron Acanthostega Ichthyostega

More Related