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Calcimator

Maximum Sustainable Yield Calculator

MSY from population dynamics and growth rate.

Inputs

Results

MSY (tonnes/yr)

10,000

B_MSY (tonnes)50,000
F_MSY0.2
Current surplus (tonnes)9,600
B/B_MSY ratio1.2
Status (0-3)3
How to Use This Calculator
  1. Enter Carrying capacity (K), Growth rate (r), and Current biomass.
  2. Review the MSY (tonnes/yr) result.
  3. Use B_MSY (tonnes) and F_MSY to inform your decision.

How the result changes with Carrying capacity (K)

Carrying capacity (K)MSY (tonnes/yr)
10,000,0901,000,009
35,000,0653,500,007
65,000,0356,500,004
90,000,0109,000,001

What each input means

Carrying capacity (K)
Maximum population the environment can support (tonnes).
Growth rate (r)
Intrinsic population growth rate per year.
Current biomass
Current estimated stock biomass (tonnes).

What each result means

MSY (tonnes/yr)
Maximum sustainable yield (Schaefer model: rK/4).
B_MSY (tonnes)
Biomass level that produces MSY (K/2).
F_MSY
Fishing mortality rate at MSY (r/2).
Current surplus (tonnes)
Sustainable harvest at current biomass.
B/B_MSY ratio
Current biomass relative to MSY biomass (>1 = above target).
Status (0-3)
0=Overfished, 1=Below target, 2=At MSY, 3=Above target.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    Carrying capacity (K) = 100000, Growth rate (r) = 0.4, Current biomass = 60000 = 3 input(s) provided
  2. Calculate MSY
    MSY = round((intrinsicGrowthRate * carryingCapacity) / 4)
    10000 = 10000
  3. Calculate B_MSY
    B_MSY = carryingCapacity / 2
    50000 = 50000
  4. Calculate F_MSY
    F_MSY = round((intrinsicGrowthRate / 2) * 10000) / 10000
    0.2 = 0.2

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