overfishing Flashcards
why are fish a sustainable resource?
fish stocks are renewable, fish that are lost by deaths are replaced by births
so population of fish can be harvested
what does overfishing cause?
threaten sustainability of fish populations
too much fishing means that numbers within a population cant be maintained leading to a decline in fish fleets
what is the definition of overfishing?
level of fishing where an increased effort leads to a declining catch
how is the impact of overfishing reduced?
6 ways
fishing quotas - these limit how many fish of one species can be caught, fines are given to those who exceed the quota
restricting size of fishing fleets - fewer boats out catching fish
restricting mesh size for fishing nets
exclusion zones
fish farming
how does restricitng mesh size for fishing nets reduce the impact of overfishing?
by making a minimum mesh size only larger fish get caught and smaller ones can escape and breed - so more fish
what is fish farming?
isolate an area of the sea for the purpose of breeding and growing fish in managed conditions
with farms on land animals are fed, treated with chemicals to prevent disease and then they are harvested
what are exclusion zones?
fishing is banned from these zones and fish will remain at a sustainable level in these zones
what does restricting seasons for fishing do?
bans people to fish during breeding seasons
fish should have enough time to replenish during breeding season
what are the problems with additional nutrients being used in fish farming?
can lead to excess nutrients in the area leaking out and causing eutrophication
what are the problems with the overuse of antibiotics used in fish farming?
lead to resistance in pathogenic bacteria
non specific pesticides can leak out affecting marine food chains
what are the problems with overcrowding in fish farming?
fish in the netted off area in fish farming can be overcrowded diseases and pests can spread easily
what are the problems with genetic modification of fish being used in fish farming?
fish in captivity are sometimes genetically modified for fast growth rates and larger sizes
these fish can breed and out compete the others
to try and prevent the problem fish have been engineered to have 3 complete sets of chromosomes
