overfishing Flashcards
overfishing
increased intensity and efficiency of modern fishing is having a highly negative effect on the populations of some marine organisms
what are the consequences of using small mesh sizes during overfishing?
smaller, juvenile fish which are not sexually mature are unable to escape nets
reduces the future breeding population
over time this leads to fewer offspring
reduces genetic diversity
what are the effects of overfishing on other wildlife?
drift nets can catch non-target species such as turtles or dolphins
can catch organisms that are the prey of other species - e.g. catching capelin which is eaten by cod or krill which is eaten by some whales, seals, penguins squid and fish, which can affect whole food webs
trawling damages the sea floor habitat of organisms such as some molluscs - e.g. clams
what controls can be used to reduce the impact of overfishing?
impose quotas on catches so only a certain mass of fish can be landed
what additional problems can imposing quotas for overfishing lead to?
too many fish are still caught but those over quota are discarded
why is it important to ensure mesh sizes of nets are large enough to let young fish escape?
ensure the young fish can grow and become sexually mature and then reproduce
what control can be used to reduce the impact of overfishing in certain zones?
enforcement of exclusion zones
what areas and at what times of year should fishing boats be unable to fish?
areas where fish breed (breeding grounds) and during (spawning) the breeding season
give 2 other controls that can be used to reduce the impact of overfishing
legislate size of fishing fleets and number of days at sea
encourage consumers to eat sustainably sourced fish
what main source can be used to overcome the problem of overfishing?
fish farming
