GE CLST M1A Lecture Notes - Lecture 10: Demersal Fish, Pelagic Fish, Sustainable Yield
11 Nov 2016
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Pelagic fish: higher in water - herring, tuna, mackerel. If we remove too many reproducing adults, too few births occur to sustain the population. A population that hasn"t (cid:297)et filled its en(cid:290)ironment (cid:291)ill gro(cid:291) If harvest ust the growth each year, the population will maintain a constant size. Half of carrying capacity is when growth rate is highest (k/2) Bycatch: non-target species that get caught in nets used for target species. 3:1 - 15:1 (kg bycatch: kg shrimp) Wrong species, size, sex, fish are damaged. Late 1960s ~300,000-700,000 dolphins/yr killed as bycatch. Shrimp bottom trawling: gathers shrimp and their habitat. Blast fishing: dynamite causes fish to float to top. Demand is high for jobs and food. You can"t fish on the protected side but (cid:297)ou can right ne(cid:296)t to it. Getting food to our tables uses 10% of us energy budget. As much as 40% of food in us goes uneaten. 25% of all freshwater plus chemicals, energy, and land.
