Chapter 12: Food from the Oceans (pg. 197 213) Introduction: It s estimated 100 million people in developing countries depend on fishing for livelihood. Issue of sustainable development of marine resources gaining prominence. This is due to recent environmental problems. Ex: commercial whaling industry in NL, cod stocks in Iceland, groundfish in NL. We are beginning to better appreciate the fragility and complexities of the marine food web. Nature strives for a natural balance. When humans harvest fish, there's risk of over-exploitation. The natural balance is disrupted ex. NL's seal fishery. Fish is valued because of its rich protein. Despite this, fish comprise only ~16% of total animal protein consumed worldwide. In 1995, each person ate 14.4 kg of fish worldwide. Note: these are averages which hide the extreme measures on these variables. The importance & consumption of fish varies greatly from place to place. ** see Fig.12-2 p.198 1
TYPES OF FISHING: Fishing: primary activity by which fishers harvest marine zoological life of varying sizes. 1. Subsistence Fishing: meet own needs basic technology labour-intensive small yields 2. Commercial Fishing: fish for surplus to earn profit complex, expensive technologies less labour intensive higher yields possible occurs in oceans as well as fresh water may involve: 1. Capture Fishing: catching fish in the wild 2. Aquaculture: raising fish in a controlled environment LOCATION OF FISH STOCKS AND FISHING GROUNDS: A. Freshwater Stocks: rivers, lakes (ex. Great lakes) aquaculture is expanding in these waters eastern and southern Asia source of greatest supply of these fish B. Marine Stock: ~75% of globe covered by water most of which is oceans fish stocks are unevenly distributed Why? the answer is related to how fish get their nourishment and the location of these sources of nourishment 2
PLANKTON is the foundation of marine food chain. 2 types: zooplankton (animal) & phytoplankton (plant). These are small marine organisms that float passively in the oceans. Small fish feed on plankton. These fish are food for progressively bigger fish. ** See Fig.12-4 p.200** Phytoplankton requires sunlight, adequate water temp & specific nutrients. These requirements are best met in shallow areas of the ocean. In particular on the continental shelves. shallow water offers two benefits to phytoplankton: 1. Sun can penetrate 80-90 m into ocean allowing photosynthesis to occur. 2. allows circulation systems which result in a churning of the oceans Results in uplifting of nutrients of decayed plants and animals from seafloor to sunlight zone. Mixing of warm and cold water also contributes to ocean circulation. 3
Question: Given these factors, where would you expect to find the world's capture fisheries taking place? fish feed on phytoplankton which thrive: over continental shelves, & where warm and cold currents meet Shallow water also tends to result in lower fish harvesting costs. Therefore, you'd expect fishing activities to be concentrated in these areas. Issues in a sustainable fishery During the last half of the 20 th century, the traditional view that Earth's resources are inexhaustible has been increasingly called into question. A sustainable future requires controlling the quantity and quality of our resource use. The patterns of fish consumption already established throughout the world by the late 20 th century have brought the worlds fisheries to a crisis. Too many fish have been taken out of the ocean, causing the populations of many species to fall to levels below sustainability. Mid 1990's, just over 1 million commercial fishing vessels were harvesting the oceans, in addition to 2 million small boats. Fishing fleets consist of: 1. huge factory freezer trawlers 2. Factory ships 3. Smaller trawlers 4. Support vessels (to provide repairs, fuel, supplies, research and scouting) 4
These fleets have depleted stocks to the extent that some areas are no longer capable of being fished. To combat these trends, maritime countries have extended their legal jurisdiction to 320-km seaward from their coastlines. This EXCLUSIVE ECONOMIC ZONE (EEZ) gives them control of fish stocks and power to grant licenses to foreign fishing vessels. Because of the lack of policing some foreign vessels still fish in other countries EEZ. Fish wars have broken out as traditional fishers protest the harvesting of fish resources by foreign fishing companies. 5