1.  5 Human Impacts on the Environment: Crash Course Ecology #10 5 Human Impacts on the Environment: Crash Course Ecology #10 5 Human Impacts on the Environment: Crash Course Ecology #10

2. Collapse of the East Coast Fishery

3.  Many theories have been suggested to explain the serious decline of the groundfish  To understand, keep in mind that fish are a renewable resource, and all renewable resources must be managed properly

4. Keeping the #’s  Fish can be harvested forever if the number of fish caught each year does not exceed the number reaching maturity in that year.  This is called sustained yield management

5. The 5 Reasons 1. Overfishing 2. Improved Fishing Technology 3. Uncontrolled Foreign Fishing 4. Destructive Fishing Practices 5. Changes in Natural Conditions

6. 1. Overfishing  The catch allowed by the government appears to have been too high  Scientists may have overestimated the number of fish becoming adults each year  If this did happen (and it did), sustained yield management was not working

8. 2. Improving Fishing Technology  After WWII, larger, more powerful, engine-driven trawlers were developed  Technological developments such as sonar and satellite navigation systems helped fishermen locate fish easier  Over the years, fewer fish escaped the nets.  Ironically, the “advances” in technology made overfishing possible.

10. 3. Uncontrolled Foreign Fishing  By late 1960’s foreign fleets caught more fish than sustained yield methods would have allowed  Countries with ocean coastlines were urging the UN to allow them to extend national fishing limits  1977, the UN allowed Canada to extend its control seas to 370km  Foreign fishing fleets working inside this limit had to follow the Cdn limits

12. 4. Destructive Fishing Practices  When trawlers were trying to catch one type of fish, for example, cod, many other types of fish may have become caught in the nets.  These unwanted fish, which were already dead, were usually just thrown away.  Only the remaining fish were reported to authorities as having been caught

16. 5. Changes in Natural Environment  2 specific changes have been identified: 1. Water temperatures and ocean salinity levels have changed since the mid-1980’s. The fish may have changed their migratory routes to avoid areas where these changes have occurred. 2. Decline of the sealing industry in the late 1970’s cause an decrease in groundfish population. More seals=more competition for the same food. Fish lost.

17.  What Happened to the Grand Banks Cod? What Happened to the Grand Banks Cod? What Happened to the Grand Banks Cod?