test4 - Aquaculture: raising fish like a domestic animal....

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Aquaculture: raising fish like a domestic animal. Raise hybrid striped bass- white bass male, striped bass female. Raised in a net in a river or stream (“net pen cultures”) o Advantages Helps keep up with increasing demand for fish Produce a lot of fish in a small volume of water Produce exactly the type of fish you want o Disadvantages Pollution problem- creates eutrophic waters because of food and feces left over Diseases spread easily Fish escape and breed with native fish – change the gene pool Watermen are opposed because they don’t want to be turned into “farmers” Oyster decline o Causes Overharvesting: millions of bushels harvested in the late 1800s; now- less than 1% of that Channel dredging: they get in the way and are pushed out by dredges. Spats have no place to settle and die Suffocation: clearing lots of land- sediment falls into water. Ever increasing nutrients- water becomes over enriched, algae forms, algae dies, bacteria eat them, water becomes anoxic Toxic pollution: problematic because oysters are filter feeders Diseases- MSX and dermo: kill oysters before they are of a harvestable size. MSX prefers salty water and thus is found more in the southern end of the bay, while dermo is throughout the bay. Predation: oyster drills, boring sponge o Consequences Economic: majoy fishery in bay for many years. Huge economic loss
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Cultural: watermen- after oysters left, they left. They couldn’t make a living and lost a way of life Gastronomic: food for humans Ecological: allowed bay to withstand stress. Filter feeders- cleaned the bay of algae, detritus, silt, and heavy metals. Reefs as habitat for all types of animals (mussels, anemones, barnacles, snails, sponges, shrimp). Good for fishing for rockfish. o Solutions Cull laws: have to be at least 3 inches wide and long. (Now 2 ½ inches because only females were being taken) Habitat restoration: taking old oyster shells and putting them back in the bay. Put chunks of concrete into the bay to have a home for the oysters Move them to a more favorable habitat Introduce exotic species that may be more resistant to diseases or pollution. Must be sterilized- made incapable of reproducing to see if they can live well. Causes of and solutions to declining fish stocks o Overfishing: taking animals out faster than they can reproduce. Reduces the genetic diversity in a population This leaves the fish with the worst genes in the bay because the biggest fish are being taken out by fishermen. o Stocking: trying to get fish to historic spawning grounds. Raise fish in hatchery and release them into rivers. o
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This note was uploaded on 12/01/2010 for the course BSCI 202 taught by Professor Opoku during the Fall '08 term at Maryland.

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test4 - Aquaculture: raising fish like a domestic animal....

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