Mortality Flashcards
How is mortality expressed?
as an instantaneous loss rate → rate of change in stock size at a particular moment (not over one year, one day, etc.)
How would you describe this equation?
What is Z represent?
typically used to denote the total instantaneous loss rate
Instantaneous loss rate →
current population numbers can be described as the exponential decay of previous population numbers
N1/N0 is an expression of what?
Survival (S)
Survival
annual proportion of population that survives
What does this expression interpret?
Relationship between instantaneous mortality and annual survival rates
What are the two components of mortality?
F & M
F
instantaneous fishing mortality rate
M
instantaneous natural mortality rate
Z =
F+M
F Includes
all deaths from fishing activities
Direct removals: fish caught & kept
Indirect removals: fish that are not kept but are still killed from fishing activities (discards, cryptic mortality)
M includes
mortality from many sources (starvation, disease, senescence, spawning stress, predation, abiotic factors, etc.)
Often assumed constant over life of fish
Explain Baranov’s catch equation:
WHy is Baranov’s catch equation so useful?
Links things that we observe (catch) with things we want to know about but don’t have numbers. Does this base on the exponential decay model.