Fisheries and Population Dynamics Flashcards
What are the 3 main types of fisheries?
-Artisanal, small-scale fishing, often traditional to feed the family
-Recreational, pleasure or competition
-Commercial, commercial profit
Why are fish an important global source?
Fish provide a major source of protein and omega 3 especially for poorer communities who catch the fish
Why are the world’s fisheries in decline?
Most of the world’s oceans are overfished and not sustainable causing rapid decline in fish populations.
How are fish distributions affected by temperature, nutrients and productivity?
-Fish have different tolerances to temperature and may migrate throughout the year
-Nutrients are must be brought to the surface by upwellings for phytoplankton populations
-Primary productivity based on phytoplankton biomass
How does rugosity affect fish diversity?
Rugosity provides shelter, hiding, food and breeding areas allowing more species to co exist.
How does bioaccumulation affect the food web?
The accumulation of a substance increases with each trophic level and depending and can make their way into humans through consumption of seafood.
How do thermal regimes affect fish distribution?
Fish will move to areas that suit their thermal tolerance range.
How reliable is the Lincoln Index?
Not very as it assumes an equal chance of recapture, is not suitable for migratory or pelagic species and effort is not clearly defined.
What are the factors that determine the reliability of fisheries population data?
-sampling techniques (Lincoln Index can be unreliable)
-fish behaviour (Some species are harder to monitor or may be spawning causing over or underestimation)
-temporal and spatial movement (Migration during certain times so move to a different area)
-life history (growth rates and age)
Limitations of the population size data factors
-sample size
-inconsistencies in reports
-localised collection of data
-age of data set
What is an international management agreement for pelagic species?
RFMO, Regional Fisheries Management Organisations, create treaties for countries to follow
MEY vs MSY
The maximum economic yield is the most money a fishery can make from the population whereas the maximum sustainable yield is the balance between sustainable fishing and economic yield, usually half of the carrying capacity.
How have fisheries management shifted?
Fisheries management have shifted from being single species maximum sustainable yield to now ecosystem based fisheries management.
How do MPA’s help with fishery sustainability?
MPAs provide fish with a safe area where they can reproduce and grow. When populations are reaching a sustainable size a spill over effect will occur where the fish will spill over to the non-protected areas where they can be sustainably fished.
What is the Lincoln Index formula?
N=(M*n)/m
Where:
N=estimated population
n=no. caught in second capture
m=no.marked in second capture
M=No. marked in first capture
