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Calcimator

Bycatch Rate Calculator

Calculate bycatch ratio, discard rate, BPUE, and fleet-wide bycatch estimates from fishing operation data for fisheries management.

Inputs

Results

Bycatch ratio (%)

13.79

Discard rate (%)10.34
BPUE (kg/hr)8
CPUE (kg/hr)50
Fleet bycatch estimate (t)400
Gear selectivity (%)86.21
Retained Bycatch Kg200
Bpue Per Set40
How to Use This Calculator
  1. Enter the total catch weight or count for the fishing trip or set.
  2. Input the bycatch weight or count (non-target species discarded or retained).
  3. Review the bycatch rate as a percentage of total catch and the bycatch ratio.
  4. Compare to fishery-specific bycatch limits or observer data benchmarks.
  5. Report bycatch data to your observer program or fishery management authority as required.

How the result changes with Target catch (kg)

Target catch (kg)Bycatch ratio (%)
1,000,0000.08
3,500,0000.02
6,500,0000.01
9,000,0000.01

What each input means

Target catch (kg)
Weight of the intended target species caught.
Total bycatch (kg)
Weight of all non-target species caught (both retained and discarded).
Discarded catch (kg)
Weight of catch returned to the sea (dead or alive). Must be ≤ total bycatch.
Fishing effort (hours)
Total hours of active fishing (trawling, soaking, etc.) for this sample.
Number of sets/hauls
Number of individual fishing events (trawl hauls, net sets, longline sets).
Fleet total effort (hours)
Total annual fishing effort for the entire fleet, used to extrapolate bycatch estimates.

What each result means

Bycatch ratio (%)
Bycatch as a percentage of total catch (target + non-target).
Discard rate (%)
Discards as a percentage of total catch.
BPUE (kg/hr)
Bycatch per unit effort — kilograms of bycatch per fishing hour.
CPUE (kg/hr)
Catch per unit effort for target species.
Fleet bycatch estimate (t)
Extrapolated annual fleet-wide bycatch in metric tonnes.
Gear selectivity (%)
Target catch as percentage of total catch. Higher = more selective gear.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Target catch (kg) = 5000, Total bycatch (kg) = 800, Discarded catch (kg) = 600, Fishing effort (hours) = 100 = 6 input(s) provided
  2. Calculate Bycatch ratio
    Bycatch ratio = bycatchRatio * 100
    13.79 = 13.79
  3. Calculate Discard rate
    Discard rate = discardRate * 100
    10.34 = 10.34
  4. Calculate BPUE
    BPUE = bycatchKg / effortHours
    8 = 8

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