Aquatic Food Production Systems
Wild Fishing
Aquaculture
Types of fishing
Environmental Impacts
Reducing Impacts
Controls
Intensive Vs Extensive
Impacts and Reducing Impacts
Demersal Trawling
Demersal Long Lining
Pelargic Trawling
Pelargic Long Lining
Pelargic Drift Nets
Purse Seining
Shellfish Trap
Used to catch solitary fish.
Quite effective.
Non-species selective
Cod, Haddock, Plaice.
Less effective then trawling
Slightly more selective
Cod, Haddock.
Used to catch shoals
Very effective
Quite selective only predetors are by-catch
Herrings, Mackerel
Less effective
Can be quite specific.
Squid, tuna.
Known as the wall of death
Quite effective.
Non-selective
Tuna, Herring
Quite effective, can be selective if around a shoal.
Non-selective towards predetors.
Tuna, Herring, Sardines
Quite effective
Selective to shellfish but not to the species of shellfish
Crabs, Lobsters, Crayfish
By-catch
Population Decline
Ghost Fishing
Habitat Destruction
Quotas
Equipment Design and Use
Restricting Efforts
Abiotic Factors
Species Selection
Breeding
Gender Control
Competition
Pests and Disease
Nutrition
Lice
Escapes
Antibiotics
Habitat Loss
Organic Waste Pollution
Salmon
Shrimp
Oysters
Aquaponics
Integrated Multi-trophic Aquaculture
Polyculture
Drift-nets
Sharks, Turtles, Dolphins, Whales
Pelargic Long Lines
Albatross
Pelargic Trawling
Porpoises
Demersal Trawling
Wide vareity and large amounts.
Shrimp fishing
Shrimp, crab, sea urchins, starfish
This occurs when young fish or too many fish are removed and the natural birth rate falls below the mortality rate.
Species which reach maturity late or past the size of fishing will be more likly to be overfished.
This is when discarded or broken nets catch fish.
Dead or dying fish can also attract predetors which can also het caught and die.
Sea Bed Damage
Coral Reef Impacts
Dynamite Fishing
Food-Web Impacts
Seagrass Beds
This is a nursery for young fish. It also holds sand together and can easily be disturbed and then die.
This stunns fish and makes them easier to catch. It does destroy the structure of the coral.
Fishing one species has an effect on all other fish in the food web.
It is illegal in most countries but some remote areas still practice it.
Bottom trawling destorys everything and crushes corals. It also mixes aerobic and anaerobic sediments.
Coral polyps are sensitive and will have damage if pushed into the corallite which attaches them. This makes it very easy to damage.
Common Fishing Policy (CFP)
The rules through which European fishing fleets and fishing stocks are managed,
Started in the 1970s and was reformed in 2014.
Gives all european fishing fleets equal access to EU waters to create fair competition.
Aims to balance maximising catches with conserving fish stocks.
Exclusive Economic Zones (EEZ)
Extends 200 nautical miles from the coastlines each respective country can control this area how they wish.
However the CFP only allows for 12 nautical miles to be privetly owned.
The EEZs are ignored and the EU seen as one. It is calculated from the maximum sustainable yield. Quotas were worked out by looking at the amount of fish that were caught before the CFP. Then national governments provide the quota for each boat.
Mesh Size = increasing the size of the mesh means only larger fish are caught.
Mesh Design = When a net is pulled by a trawler the holes move into a diamond shape. Using a fixed square means fish can escape more easily.
Turtle Exclusion Devices (TED) = Large spring loaded escape pannels which allow turtles to escape.
Acoustic deterrent devices = High frequency sounds which defer dolfins or animals.
Cut down fishing days only allow a certain number of days to be fished.
Limiting the size and power of boats.
Drift nets banned in certain ares.
Demersal trawling is also banned inareas with protected corals.
No Take Zones = Allows snorkelling, boating and diving but fishing and coral collectign are banned.
They filter planktonic organisms from the sea water so they find their own food.
Breeding
Fish are chosen for their characteristics.
Roe and milt are taken from the fish and the young are placed in a seperate tank
Young hatchlings are removed and fed.
When they are 12-18 months old they become smolt and have to be moved.
Limiting factors to be controlled.
Dissolved O2 added through aeration
Temperature meaning fishing only occurs in certain regions.
Flow rates this makes more muscle.
Pests means added pesticides or antibiotics.
Light done artifically to make them smolt faster.
Food salmon are carnivous so have to be fed fish meal.
Extensive.
Intensive
Clean water and oxygen can be added.
500,000 eggs in a hatchery
Snapping their eye stalks to stimulate spawning
Shrimp eat plankton so can find their own food.
Predetors are removed.
Nutrients are added to increase algae growth.
Food pellets can be added
Young oysters are bred from selected adults.
Predetors are removed.
Oyster young are spaced out.
Herbivores are more likely to find their own food.
Predetors need to be fed.
Adults are selected based on: disease resistance, rapid growth rates, appearence.
Roe and milt can be collected and hormones are added to induce spawning.
Fish gender can be controlled by using hormones. Young fish if exposed to hormones will go agaist their genes and become the other gender.
Rainbow trout = females taste better. But if a female fish (by genes) produces milt by hormones only female fish will be produced.
Talapia = Males are larger.
Rarely a problem for indoor fish but outdoor fish may need extra fencing, netting or bird/ seal culling.
The species must be able to survive in the local conditions.
High stock levels may cause disease to spread very quickly.
Water flow control, pesticides and antibiotics can be used to control diseases.
Must be able to be sold in local markets.
Fish make up 50% of all aquaculture, algae 25%, milluscs 15% and crustatceans 10%
Temperature
Oxygen
Daylight
Water flow
Controls reproduction which is seasonal. Artifical light continues the day so increases growth.
Higher temperatures have faster grow rates however this would have a lower dissolved oxygen level.
Different species need different levels of oxygen in the water.
If all fish swim in the same direction then it decreases the chance of collisions and spread of disease.
One way of reducing this would be to move the farms from the migration paths of wild fish towards the shore.
Use of pesticides.
Have the water from from the young fish to the old fish to limit the spread
Addittion of Wresse fish which eat the lice.
Using sterile fish including triploids to reduce the wild fish from breeding with escapes and producing offspring.
Keeping a close monitior on nets and fencing.
Farmer training, proper spacing and assisstance in disease identification can all slow or stop spread of disease.
Disease-free food and vaccines can also help.
Specific flow paths and lower stocking density can also help.
Food levels can be monitored so no extra food is wasted and disgarded.
Bacteria could be introduced so they can break down wastes.
Currents or sewage systems may be introduced to carry away waste materials.
Policies are intoduced to stop or reduce the amount of fish farms and protect some local areas.
The practice of culturing more than one organism in the same pool system
Certain species can have effects on others. Providing each other with specific conditions or food which would be found in the wild.
Combines hydroponics and aquaculture.
Water from the hydroponics is then given to the fish. The water is filled with nutrients from the fish to the plants and aerated by the plants for the fish.
involves cultivating organisms in the way that allows uneaten food, wastes, nturients and by-prducts to be used by other species.
Mimiks natural systems.