Find the Truth!

• Mortality caused by fishing may be replaced by juveniles that would not otherwise been recruited to the adult population.

• Fishing above the MSY is overfishing and will cause a decline in juvenile biomass.

• Overfishing can often be detected by reduced catches, a reduction in average age of adult fish and slower growth of the fish that do survive.

Find the Truth!

• Mortality caused by fishing may be replaced by juveniles that would not otherwise been recruited to the adult population.

• Fishing above the MSY is overfishing and will cause a decline in juvenile biomass.

• Overfishing can often be detected by reduced catches, a reduction in average age of adult fish and slower growth of the fish that do survive.

So what impact d

oes fishing have on fish

populations?

What are the environmental impacts of fishing?

What are the environmental impacts of fishing?

What is By-catch? Organisms that are caught unintentionally. They usually dieTypes include;• fish that are too small to sell• Surplus to quotas• Species of no commercial value

Albatrosses caught in long linesWhales/dolphins caught in drift nets

species inadvertently caught in trawl nets

• Ghost fishingFish, lobsters etc caught by discarded or lost fishing gear

• Seabed damageCoral reefs damaged by nets.

• Foodchain effectsSome species become more common if their predators are over-exploitedReduced food supply for predators, increased food supply for competitors.

Other Environmental Impacts

The Crown-of-Thorns is a , carnivorous predator that preys on reef coral polyps. They climb onto reef structures, and then extrude their stomach onto the coral. This releases digestive enzymes that allow the starfish to absorb nutrients from the liquefied coral tissue.

Overpopulation of Crown-of-Thorns has been blamed for widespread reef destruction.

The Giant Triton (a mollusc) and the harlequin shrimp attack and feed on Crown-of-Thorns starfish. Some large reef fish, particularly Humphead wrasse, may also prey on the starfish.

Decline in predator populations (through overharvesting, habitat destruction) has also been offered as an explanation for increasing outbreaks of Crown-of-Thorns starfish.

What is the threat from crown of thorns starfish?

The Crown-of-Thorns is a , ___________________that preys on reef coral polyps. They climb onto reef structures, and then extrude their stomach onto the coral. This releases digestive enzymes that allow the starfish to absorb nutrients from the liquefied coral tissue.

Overpopulation of Crown-of-Thorns has been blamed for widespread reef destruction.

The _____________(a mollusc) and the ____________attack and feed on Crown-of-Thorns starfish. Some large reef fish, particularly__________________, may also prey on the starfish.

Decline in _________________(through overharvesting, habitat destruction) has been offered as an explanation for increasing outbreaks of Crown-of-Thorns starfish.

What is the threat from crown of thorns starfish?

What are the environmental impacts of fishing?

Seabed damage

Bycatch

Food web effects

Ghost Fishing

Effects on fish stocks

examplesexplanation

Complete a spider diagram to summarise the impacts. Include evidence and explanation