RNR 1001 : Renewable Resources Exam 3
Document Summary
Dominant commercial fisheries groups: finfishes, crustaceans, and molluscs, kelp. Many decreased during the 19th and 20th centuries. Stock fluctuations due to exploitation and environmental factors. Habitat loss and degradation have also played an important role. Fisheries are an excellent example of renewable resources. Stock increases each year from growth and reproduction. Controlling fishing effort through limits on harvest, gear, crew size, area, season, etc. Limiting the harvest per angler, controlling things, ability to harvest has surpassed the stock. Fatigue due to high density of water. Swimbladder problems because of the pressure/depth relationship. Blows out bubbles to reach water surface quickly. With rapid pressure changes the fish will die. Need to take time to rise to the surface. Stress from the temperature/dissolved oxygen relationship for poikilotherms. Turbidity problems, reduced primary production, invertebrate mortality, larval fish mortality, reduced foraging by visual predators. Bioaccumulation and biomagnification problems because of movement of chemicals across thin gill tissue.
