4.3 Aquatic food production systems

what can occur as a result of unsustainable use of aquatic ecosystems

environmental degradation and collapse of wild fisheries

what does aquaculture provide the potential for

increased food production

where are the highest rates of productivity found in aquatic systems

near the coast or in shallow seas where upwellings and nutrient enrichment of surface waters occurs

why is harvesting some species considered controversial

ethical issues arise over biorights, rights of indigenous cultures and international conservation legislation

what have developments in fishing equipment led to

dwindling fish stocks and damage to habitats

how can unsustainable exploitation of aquatic ecosystems be mitigated

through policy, legislation and changes in consumer behaviour

what are some issues around aquaculture

loss of habitats, pollution, antibiotics and other medicines added to the fish, spread of diseases and escaped species

what are some examples of marine ecosystems

oceans, mangroves, estuaries, lagoons, coral reefs, deep ocean floor

why do marine ecosystems often have high stability and resilience

they are usually very biodiverse

where is one half of marine productivity found

in coastal regions right about the continental shelf

why do deep ocean ecosystems have low productivity

light does not reach so the only food sources are chemotrophs and dead organic matter that comes from above

what is the continental shelf

the extension of continents under the seas and oceans, where they exist it creates shallow water

why are continental shelves important

it has 50% of oceanic productivity but 15% of its area, upwellings bring nutrient rich water up to the continental shelf, light reaches the shallow seas so producers can photosynthesize, countries can claim it as theirs to exploit and harvest

what is the average width of the continental shelf

80km

how wide is the siberian shelf

1600km

how deep is the north sea on average

150 meters

what did UNCLOS designate in 1982

that the continental shelves belong to the country from which they extend and that the 200 nautical miles from the low water mark of the shore is considered the exclusive economic zone belonging to that country

why is fishing in international waters impacted by their legal status

it affects who is allowed to fish there, who controls it and who cleans it up when there is a pollution problem

what are phytoplankton

single celled organisms that can photosynthesize and are the most important producer in the oceans

how much of primary productivity is from phytoplankton in oceans

99%

what are zooplankton

single celled animals that eat phytoplankton and their waste

what are the two types of marine organisms

benthic, pelagic

what does benthic mean

living on or in the sea bed

what does pelagic mean

living surrounded by water from above the seabed to the surface

what percentage of fishery activity is in the oceans

90%

what do fisheries include

shellfish, eels, tuna etc

how many people make their livelihoods in fisheries

half a billion people

how many people get 20% of their protein intake from fish

three billion

how much of our protein intake is from fish

about 15%

describe fish nutritionally

high in protein, low in saturated fats, contain vitamins A, B, D

what percentage of the worlds fisheries are fully exploited, in decline, seriously depleted or too low to allow recovery

70%

is the global fish catch increasing

no

when does a fishery exist

when fish are harvested in some way, it includes capture of wild fish and aquaculture or fish farming

what is aquaculture

the farming of aquatic organisms in both coastal and inland areas involving interventions in the rearing process to enhance production

how many kilograms of fish does the average person eat each year

20kg

how many kg of meat does the average person eat per year

8kg

how many tonnes of farmed fish were produced in 2012

60 million tonnes

what are some ways in which fish farming is becoming more sustainable

fishmeal uses more trimmings and scraps which would have been wasted in the past, livestock and poultry processing waste is substituted for fishmeal

what percentage of the worlds farmed fish is produced by china

62%

how is most fish farmed in china

they are grown in rice paddies and their waste provides fertilizer for the rice

what are shrimp and salmon fed on in aquaculture

fishmeal or fish oil produced from wild fish

how much of the mangroves have been lost in the Philippines in the last 40 years

two thirds

what are the impacts of fish farms

loss of habitats, pollution, spread of diseases, escaped species including genetically modified organisms which may survive to interbreed with wild fish, escaped species may outcompete native species and cause the population to crash

what are two reasons we are overfishing the oceans

there is a high demand for seafood, there is a lack of effective regulation

why has the world fish catch stalled

overfishing, climate change, environmental degradation, inaccurate data and management, illegal, unreported, and unregulated fishing

what actions can be taken to reverse overfishing

implementing sustainable fishing practices, establishing marine protected areas, promoting responsible consumer choices, combating Iuu fishing, supporting sustainable aquaculture, improving fisheries management, educating and involving local communities

where do wild atlantic salmon live

in the North Atlantic and Baltic Seas

why did the commercial market for wild salmon crash

due to overfishing at sea and in rivers where they go to spawn

where are atlantic salmon now farmed

in fish farms

why do salmon farms create pollution

the fish are kept in high densities and their uneaten food, faeces and chemicals used to treat them enter the ocean

what pest are a problem in salmon farms

sea lice

what happens when farmed salmon interbreed with wild salmon

it reduces the genetic fitness of the wild stock as farmed salmon are bred for fish farm life so the ability to survive of the salmon in the wild is reduced

what has happened as wild stocks of many fish species decline

fish farming has increased

what percentage of fisheries are under threat of over-exploitation

75%

what technologies are used to help commercial fishing

satellite technology to find fish

how long can modern fishing fleets stay at sea

for weeks and even the whole season

what does indiscriminate fishing gear do

take all organisms in an area whether they are the target species or not

what do trawlers do

drag huge nets over the seabed essentially clearcutting it

what caused the "cod wars" between britain and iceland

in the 1970s, Iceland banned all foreign vessels from fishing in Icelandic waters

what was the turbot war between canada and spain

canada fired upon and captured the crew of a spanish fishing boat, the spanish boat cut its trawl net when it was being pursued but the canadians recovered it and found it had a net with a mesh size smaller than that permitted and this caught the smaller fish, this resulted in increased regulation of fisheries

what is the annual world fish catch

90 million tonnes

how much of the global catch goes into fish meal and fish oil products

about a quarter

how much of the world fish catch is by catch

about 20 million tonnes

what happens to the by catch

it is thrown back into the oceans from the fishing boats, most are dead or dying when they are thrown bacck into the sea

how many people were employed at the peak of the newfoundland cod fishery in 1968

40,000

owhy did the stocks of the newfoundland cod fishery plummet

overharvesting and habitat damage

when did the newfoundland cod fishery close

1992

have the fish stocks at the newfoundland cod fishery recovered

no

in the North Atlantic Ocean, what percentage do fisheries catch of what they did 50 years ago

50%

what species of fish are near collapse in the North Sea and to Scotland's west

cod

can the deterioration of oceanic fisheries be reversed

yes

how can the deterioration of oceanic fisheries be reversed

by granting fishers an ownership stake in fish stocks, eg, fishers in Iceland and New Zealand have used marketable quotas to allow them to sell catch rights

why are some scientists pushing for management of whole ecosystems rather than single species

because marine ecosystems are highly complex

what can help replenish an overfished area

well positioned and fully protected marine reserves, known as fish parks

what is an example of fish reserves working

a network of reserves off St Lucia in 1995 has raised the catch of small scale fishers by up to 90%

how can consumers promote healthy fishery production

by eating less fish and buying seafood from well managed abundantly stocked fisheries

what is the capacity of the world's fishing fleet in comparison to the sustainable yield of fisheries

double

how much may global fish catch need to be reduced to prevent additional collapses

by half

how much do industrialized nations subsidise their modern fleets by

50 billion dollars a year

what is a good example of the tradgedy of the commons

exploitation of the oceans

what is The United Nations Convention on the Laws of the Sea

an international agreement written over decades that attempts to define the rights and responsibilities of nations with respect to the seas and marine resources

what are internal waters according to UNCLOS

next to a countries coastline where foreign ships may not travel and the country is free to set its own laws and regulate use

what are territorial waters according to UNCLOS

up to 12 nautical miles from the coastline where foreign ships can transit on innocent passage but not spy, fish or pollute (in island states, a boundary line is drawn around the whole archipelago)

what is beyond the territorial waters according to UNCLOS

another 12 nautical miles of contiguous zone where a state can patrol smuggling or illegal immigration activities

what is the exclusive economic zone according to UNCLOS

the state has sole rights to exploit all natural resources, foreign nations may overfly or navigate through this zone, if a countries continental shelf is greater than 200 miles from its coast, it also has exclusive rights to exploit this

what organization monitors seabed exploitation in internationl waters

the international seabed authority

what is the maximum sustainable yield

the highest possible use that the system can match its own rate of replacement or maintenance

what does the carrying capacity for each species depend on

its reproductive strategy, its longevity, the indigenous resources of the habitat

what is the equation for sustainable yield

SY = total biomass at time t +1/energy - total biomass at time t/energy

what is a simpler equation for sustainable yield

SY = annual growth and recruitment - annual death and emigration

what does harvesting the maximum sustainable yield usually result in in practice

population decline

why does harvesting the maximum sustainable yield usually result in population decline

the population dynamics of the target species are normally predicted rather than measured, it is often impossible to be precise about the size of a population, estimates are made on previous experience, disease may strike the population

which approach is safer than harvesting the MSY

harvesting the optimal sustainable yield

what are fishing quotas often set as