Fisheries and Fishery Management Flashcards
What are some consequences of fishing?
Declines of individual target species
Declines of entire functional groups
Pushing frontiers further, longer and deeper
Ecosystem impacts
Name some example of large population declines due to fishing
Western Atlantic Bluefin Tuna - Declined from >200,000 to ~20,000 over a 20 year period
Canadian Atlantic Cod almost collapsed to local extinction
How many countries account for ~20% of all landings on the high seas?
4
Taiwan
South Korea
Spain
China
What are by-catch species?
Non target species that are caught by accident when fishing - they rarely survive
When do by-catches often exceed landings (target species)?
When targeting small species such as shrimp and prawns
What is the total area of ocean trawled greater than?
Area of forests ever cut down
What did Thomas Henry Huxley conclude?
There was no conceivable way in which fishing could seriously impact fish populations
What is maximum sustainable yield?
The maximum amount of a given fish population that you can catch every year, without driving the population to extinction
Where is MSY attained?
Around 50% of virgin biomass
What are total allowable catches?
Set total limit on amount of a population that can be caught, aiming for MSY
Can be divided into individual quotas which limit the catch of individual boats
What MPAs?
Marine protected areas
Areas of the sea set aside for long-term conservation aims
Different MPAs can have different levels of protection
Do MPAs work?
Yes
Biomass typically triples within reserves
Density increases ~40%
Larger fish e.g. dharks benefit more from protection
What are the 5 features of effective MPAs?
NEOLI
No take
Enforced
Old
Large
Isolated
How many NEOLI characteristics do succesful MPAs need? Is this reflecting current conservation?
4-5 characteristics - anything less is indistinguishable from unprotected sites
10% of MPAs investigated had 4-5 characteristics
84% had 1-2
