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Fishing industry

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  • 1. Miller—Chapter 13-6
  • 2. Fisheries  3rd major food producing system  Definition: Concentrations of particular aquatic species suitable for commercial harvesting in given ocean area or inland body of water Examples: Cod, tuna, mackerel, sardine, anchovy, crab, shrimp, oyster, clam, squid, octopus Most of (99%) catch is taken from coastal waters (as a result disrupted/polluted)
  • 3. Fishing Industrialization  Fleets use: Satellite positioning equipment Sonar Huge nets Spotter planes Factory ships that can process and freeze their catches
  • 4. Types of Fish  Demersal: Mostly bottom- dwelling  Pelagic: Surface-dwelling  Crustaceans: Hard exoskeleton  Mollusks: Live in hard shell
  • 5. Harvesting Methods  To catch demersal and shellfish (shrimp)  Drag funnel-shaped net held open at the neck along the ocean bottom  Destroys bottom habitats  Nets big enough for 12 jumbo jets  Small fish escape, but other species (seals, turtles) can be trapped  Bycatch (other throwback species) get released  To catch pelagic species, such as tuna (feed near surface in schools)  Looks like a large drawstring purse to trap fish  Can also kill other species, ex: dolphins, which swim near surface with fish species
  • 6. Harvesting Methods  Put out lines of 80 mile-long hung with thousands of baited hooks to catch open-ocean fish species (swordfish, tuna, sharks)  Can hook pilot whales, dolphins, turtles and sea- feeding bird, the albatross.  Uses huge drifting nets that hang about 15 meters below surface and are up to 34 miles long  Can lead to overfishing  Traps/Kills large quantities of unwanted species, like longlining.  US has banned nets longer than 1.6 miles in international waters  Compliance is voluntary, difficult to monitor fishing fleets and now more longlines are used which are also dangerous
  • 7. Harvesting Methods
  • 8. Fishing  The remaining 1% comes from aquaculture and inland freshwater lakes/ponds, rivers  Between 1950-1982, the commercial fish catch has increased 5-fold. Since ‘82, catch amount has slowed down and will continue to decline…Why?  Want to achieve a “sustainable yield” The size of the annual catch that could be harvested indefinitely without a decline in the population of a species ○ Challenges: Hard to monitor mobile populations and populations shifts year-to-year due to climate, pollution and other factors
  • 9. Overfishing  Taking so many of the fish that too little breeding stock if left to maintain numbers (exceeds its sustainable yield) If continues, can lead to commercial extinction Too many fishing boats pursuing too few fish (tragedy of the commons) Leads to a lot of political disputes (over 100 disputes about rights between countries) There are 14 fisheries that are so depleted it would take 20 years for them to replenish the stocks if they halted everything now
  • 10. Overfishing Problem
  • 11. Other Problems  Degradation/destruction/pollution of wetlands, estuaries, coral reeds, salt marshes, mangroves  Projected global warming because there will be warmer ocean waters that would degrade or destroy coral reeds, enhance effects from habitat degradation  Thinning of ozone causes more UV radiation penetrating into the water  El Nino warming patterns
  • 12. A possible answer: Aquaculture  Fish/shellfish are raised for food, supplies. *China is leader in this practice.  Two types: Fish farming: Cultivates fish in a controlled environment (coastal/inland pond/lake/rice paddy) and harvest them when they reach desired size Fish ranching: Holding anadromous (breed in freshwater) species such as salmon, live in captivity for their first few years of their lives (fenced in areas, lagoons, estuaries) then release them and harvest when adults return to spawn  Typical fish species: Carp, catfish, tilapia, milkfish, clams and oysters
  • 13. Aquaculture  Some countries (China) combine with agriculture. They use pig manure and other waste to fertilize aquaculture ponds, promoting growth of phytoplankton to feed species  Used to stock for game fish purposes or to raise the expensive fish and shellfish  90% of all oysters  40% salmon (75% in US)  50% of internationally traded shrimp and prawns  65% freshwater fish sold in marketplace  Catfish is leading product in US (Mississippi, Louisiana, Arkansas, Alabama)  Some studies show that aquaculture has worsened the problem for fisheries by:  Raising demand for some ocean fish (anchovies) that are ground into fish meal and fed to aquaculture species  Create vast amounts of waste in the coastal areas
  • 14. Aquaculture ADVANTAGES DISADVANTAGES  Highly efficient  High yield in small volume of water  Increase yield through crossbreeding and genetic engineering  Can reduce overharvesting of conventional fisheries  Little use of fuel  Profits not tied to price of oil  High profits  Large inputs of land, feed and water needed  Produces large and concentrated outputs of waste  Destroys mangrove forests  Increased grain production needed to feed some species  Fish can be killed by pesticide runoff from nearby cropland  Dense populations are vulnerable to diseases  Tanks too contaminated to use after about 5 years