a) The greatest decline took place between 1965 and 1970.
700,000 metric tons - 200,000 metric tons = 500,000 metric tons
500,000 metric tons/5 years = 100,000 metric tons per year
the gorundfish harvest depleted by aproximately 100 thousand metric tons per year between 1965 and 1970. b) Bottom trawling is the act of scraping the bottom of a fishing area with a large net in order to catch fish. The net, however, catches more than the intended product. The nets destroy the bottom vegetation, catch unwanted animals, and stir up silt and debris. The bottom is important because benthos dwelling organisms make their homes there and scraping it kills them and removes their habitats. The unwanted catch (bycatch) is thrown back into the water but it does not replace what was harmed. Finally, the silt that the net stirs up gets suspended in the water column and blocks out the sun. Primary production and photosynthesis cannot occur without that sunlight so the ecosystem cannot recover. Long line fishing is another method of fishing that involves setting up lines with thousands of hooks and having it span over many miles of ocean. The lines and hooks, like the net, catch more than needed. Many marine organisms such as dolphins, otters, and sea turtles get caught on the hooks and die because they cannot reach oxygen. c) The endangered species act applies to the ocean and harvestng food sources. This law states that endangered species cannot be disturbed. Ocean animals whose numbers are depleting may not be hunted (for exaple some species of whale and tuna). This act and others like it ensure that fishermen do not harm the habitat and potential for population growth in species when they are catching food. d) Another commons is the rangeland in the western United States. This federally owned land is open for grazing to the public for privately owned cattle and other livestock. Overgrazing in those areas is a huge problem. Everyone wants to use them but when...
Please join StudyMode to read the full document