overfishing Flashcards
what is overfishing
the rate at which fish are harvested exceeds the rate at which they reproduce
what is drift netting and what is the issue with it
they swim into a net suspended from floats stretched between two boats but with thousands of miles of nets non-target species could be caught like a shark or dolphin
what is trawling
fish that live in deeper water the mid and bottom feeders are caught by a large net which is dragged through the water
catching whatever swims into it equipment used in trawling has damaged the ocean bed destroying the habitats
what are some fishing regulations and what do they help to control
mesh size of nets
quotas
exclusion zones
consumer choice and the use of fish farms may also reduce overfishing
what are the methods to regulate fishing and allow breeding stocks to recover
mesh size of nets must be large enough that young fish can swim through
quotas can be set so that only a certain mass of fish may be brought to land
exclusion zones prohibit fishing in defined areas
consumers may choose to only eat those fish certified by MSC
Legislation controlling size of fishing fleets
legislation controlling the numbers of days spent at sea
fish farming may reduce overfishing
what are the benefits of fish farming
fish convert their food into protein more efficiently
a greater proportion of fishes bodies are edible
fish farming has a lower carbon footprint
what is fish farming the cause of
diseased fish
pollution
escaped fish
resource use
environmental toxins
environmental degradation
fish farming cause of diseased fish
farmed salmon often very densely stocked and so they can easily transmit disease
pollution
the ecological balance of the waterways may be upset
escaped fish
farmed fish have been selected for very rapid growth
if they escape they out-compete wild fish for food, mates and habitat
they also transmit parasites and other infection
resource use
farmed salmon which are carnivorous eat three times their bodyweight in fish feed which is made from other fish
environmental toxins
more concentrated in farmed than iwld salmon although their concentration are so small that their effects do not outweigh the health benefits of eating fish
environmental degradation
the shrimp industry in particular has been blamed for the salinisation of soil and ground water and the destruction pf mangroves
