GE CLST M1A Lecture Notes - Lecture 10: Drift Netting, Bottom Trawling, Fish Aggregating Device

• School: UCLA
• Department: General Education Clusters
• Course: GE CLST M1A
• Professor: Jay, J.A.

Document Summary

Ocean fish: harvest is about 90 million tons/year. Ocean fish food sources: demersal dish: bottom dwelling, pelagic fish: in all water column, crustaceans: along bottom mainly, mollusks and cephalopods: significant food source, m(cid:28660)(cid:28677)(cid:28668)(cid:28673)(cid:28664) (cid:28672)(cid:28660)(cid:28672)(cid:28672)(cid:28660)(cid:28671)(cid:28678): (cid:28672)(cid:28664)(cid:28660)(cid:28679), (cid:28674)(cid:28668)(cid:28671). (cid:28632)(cid:28666). If remove too many reproducing adults, too few births can sustain the population. This is a sustainable harvesting policy, if only harvest the growth, population remains: theory---population biology. K/2: the fastest rate of growth, the maximum sustainable growth=yield. Modern fishing: very effective, the scale is huge. A drift net, which could be as long as 40 miles. long lines and baited hooks, up to 80 miles long. If the nets are ripped or lost, then they are pollution and harm to ocean. Able to increase and peak the fishing, but they over harvested and resulted in a huge drop in the fish populations. (cid:28633)(cid:28668)(cid:28678)(cid:28667) (cid:28675)(cid:28674)(cid:28675)(cid:28680)(cid:28671)(cid:28660)(cid:28679)(cid:28668)(cid:28674)(cid:28673) (cid:28662)(cid:28660)(cid:28673)"(cid:28679) (cid:28677)(cid:28664)(cid:28662)(cid:28674)(cid:28681)(cid:28664)(cid:28677), (cid:28660)(cid:28661)(cid:28674)(cid:28680)(cid:28679) 20,000 (cid:28669)(cid:28674)(cid:28661)(cid:28678) (cid:28682)(cid:28664)(cid:28677)(cid:28664) (cid:28671)(cid:28674)(cid:28678)(cid:28679) (cid:28660)(cid:28678) (cid:28682)(cid:28664)(cid:28671)(cid:28671). Kg bycatch: kg shrimp=3:1 to 15:1--------many bycatch, damage.