Chapter 5 - Oceans and fisheries Flashcards
What are eight resources that come from the ocean?
Food, chemicals and building materials, wave and tidal energy, tourism, transport and the potential for safe drinking water
What is food as a resource from the ocean?
Food can come from the oceans in the form of animals such as fish or shellfish.
The main fisheries are located on continental shelves in the euphotic zone as there is an abundance of light and oxygen and upwellings bring nutrients from the sea floor. This allows the growth of phytoplankton which fish depend on.
What are chemicals and building materials as a resource from the ocean?
Materials can be eroded from land or broken down by wind and water. These particles and dissolved substances are carried into the oceans through rivers. Some of these materials include salt from seawater, magnesium, gold, tin, titanium and diamonds. Sand and gravel are also mined from the sea floor for construction. Oil is extracted from the sea floor by offshore drilling rigs.
What is wave and tidal energy as a resource from the ocean?
Waves and tides occur because of the gravitational pull of the moon and the sun. The waves create a large amount of energy when they break on the shore. Tides come onto the land and then later recede which can be harnessed to generate electricity.
What is tourism as a resource from the ocean?
The oceans are significant tourist attractions. People of MEDCs are drawn to marine sites of natural beauty such as coral reefs or islands such as the Maldives. The ocean also allows diving, snorkeling and cruise industries to attract tourists.
What is transport as a resource from the ocean?
Vessels such as large ships are essential to transport people and goods across the oceans. However, ocean travel is becoming less popular due to technological advancements and an increase in aviation. Pleasure cruises are still an important economic sector.
What is the potential for safe drinking water as a resource from the ocean?
Due to the salt content of ocean water, it needs to be desalinated before it is potable.
What are surface currents?
Surface currents are the movement of the surface water of the sea in a constant direction. They are caused by prevailing winds.
What are prevailing winds?
Prevailing winds are the direction from which the wind nearly always blows in a particular area.
How do currents in the southern hemisphere travel?
Currents in the southern hemisphere travel anticlockwise.
How do currents in the northern hemisphere travel?
Currents in the northern hemisphere travel clockwise.
Where are cold currents located?
Cold currents are located near the north and south poles.
Where are warm currents located?
Warm currents are located near the equator and the tropics.
Describe the distribution of major fish populations
Major fish populations are found in the continental shelves in the euphotic zone due to the abundance of phytoplankton. There is an abundance of phytoplankton here due to there being sufficient, oxygen, light and cold currents that bring an upwelling of minerals and nutrients from the sea floor allowing them to grow. Fish eat these phytoplankton so they are mostly found in the same areas of the phytoplankton.
How do ocean currents and continental shelves affect the distribution of marine fisheries?
Ocean currents bring an upwelling of nutrients from the sea floor for producers, bring food supply for consumers and the cold and warm currents mix. The continental shelves are shallow which allows light to penetrate and there is an inflow of nutrients from rivers and the sea floor which leads to rapid photosynthesis. Phytoplankton are producers therefore will attract fish and make fisheries more accessible.
What are upwellings?
Upwellings are areas where minerals and nutrients from the ocean floor and brought to the surface by currents.
What is overfishing?
Overfishing is when the number of fish that is caught is greater than the rate at which the fish reproduce, leading to a fall in the fish numbers in an area.
What is El Niño Southern Oscillation?
El Niño Southern Oscillation is the change in the prevailing winds that leads to a change in the pattern of currents in the oceans of the south pacific. The upwelling of cold, nutrient rich water is disturbed by the prevailing winds which leads to an upwelling of warm, nutrient poor water. No nutrients means that phytoplankton won’t grow well so there will be less food available for fish. This negatively impacts the fishing industry.
Describe how the effects of El Niño reduce the fish catch along the Pacific coast of South America
The warming in sea surface temperature prevents upwelling of nutrients. This reduces the available nutrients for phytoplankton and reduces rates of photosynthesis. Therefore, there will be less food for the fish and they will have to migrate.
Suggest the effects of a reduction in fish catch on the people living along the Pacific coast of South America
There will be fewer fish to eat so they will have to alter their diets. There will be a reduction in exports of fish or fish related products which will cause the local economy to collapse. There will be a reduction in work, leading to poverty and forced migration.
What are the three causes of overfishing?
Demand for fish as food due to an increasing world population as it is now easier to find fish using technological advancements such as sonar and detailed weather data.
Economic gain as most fisheries focus on gaining the most profit instead of being able to fish sustainable. Sustainable fishing involves monitoring how many fish are left in order to provide the next generation of fishermen and their customers.
Creation of huge nets that scoop up everything in an area including unwanted fish which is discarded as bycatch.
What is bycatch?
Bycatch is any animals caught by the fishermen that are not the intended target of their fishing effort.
What are five impacts of overfishing on marine species?
Reduced catch leading to a loss of jobs and reduction in food supply.
The size of fish gets progressively smaller, increasing the demand for food.
Increase in fishing efforts.
Harvesting of untargeted, protected or endangered marine species that are discarded as bycatch.
Reduction in marine biodiversity, leading to a disruption of the food chain.
What is a solution to overfishing?
Fish farming in controlled environments. Due to the increasing human population, the increased demand for fish as food is above the production capacity of oceans and seas. Overexploitation of the fisheries leads to a decline in wild fish populations.
What is aquaculture?
Aquaculture is the farming of freshwater fish.
What is mariculture?
Mariculture is aquaculture practices in marine environments.
What are five advantages of farming fish in controlled environments?
It reduces pressure on the wild population, allowing their populations to increase, the production of farmed fish is constant, there is no bycatch and no erosion of the seabed.
What are two disadvantages of farming fish in controlled environments?
They are more prone to diseases and it is less likely to be successful due to pollution from waste products.
What are seven ways to manage the harvesting of marine species?
Changing net types and mesh sizes, using other species specific methods, implementing quotas, implementing closed seasons, protecting specific areas, creating conservation laws and implementing international agreements.
How does changing net types and mesh sizes manage the harvesting of marine species?
If the mesh size is too small, it will catch juvenile fish which reduces the number of fish that can grow to maturity and reproduce. A diamond shaped mesh catches fish more easily so using a square shaped mesh allows the smaller fish to escape.
How does using other species specific methods manage the harvesting of marine species?
Rather than using fish aggregation devices (FADs) which bait all the fish together, use a large net to collect everything and leads to a large bycatch of juvenile fish, you can use the pole and line method which is very selective on which fish it catches and leads to almost no bycatch.
Use the diagram to explain how dolphins escape from a net fitted with a DED (3)
net has escape hole / hood;
is big enough for dolphins;
floats keep the escape hole open;
grid prevents dolphins getting trapped in narrow part of net / directs dolphins to escape hole;
Suggest the effect this gravel extraction has on the marine ecosystem (3)
damage to seabed;
loss of habitat;
death of / damage to, marine plants / (named) marine organism;
disruption to food chain;
noise / activity, scares off some organisms;
