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Calcimator

Fish Stock Assessment Calculator

Stock status from catch data and abundance indices.

Inputs

Results

Initial population (N0)

12,500

Remaining stock7,500
Exploitation rate (%)40
Catchability (q)0.01
Status (0=healthy, 1=full, 2=over)1
Avg CPUE50
How to Use This Calculator
  1. Enter Initial CPUE (kg/effort), Final CPUE (kg/effort), and Total catch (kg).
  2. Set Total effort (units).
  3. Review the Initial population (N0) result.
  4. Use Remaining stock and Exploitation rate (%) to inform your decision.

How the result changes with Initial CPUE (kg/effort)

Initial CPUE (kg/effort)Initial population (N0)
10,0005,030
35,0005,009
65,0005,005
90,0005,003

What each input means

Initial CPUE (kg/effort)
Catch per unit effort at start of season.
Final CPUE (kg/effort)
Catch per unit effort at end of season.
Total catch (kg)
Total catch during the assessment period.
Total effort (units)
Total fishing effort in standardized units.

What each result means

Initial population (N0)
Estimated initial stock size (depletion method).
Remaining stock
Estimated remaining population after harvest.
Exploitation rate (%)
Percentage of stock removed by fishing.
Catchability (q)
Catchability coefficient (efficiency of fishing effort).
Status (0=healthy, 1=full, 2=over)
0=Healthy, 1=Fully exploited, 2=Overfished.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Initial CPUE (kg/effort) = 100, Final CPUE (kg/effort) = 60, Total catch (kg) = 5000, Total effort (units) = 100 = 4 input(s) provided
  2. Calculate Initial population
    12500 = 12500
  3. Calculate Remaining stock
    7500 = 7500
  4. Calculate Exploitation rate
    40 = 40

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