Fishing Mortality Calculator
Instant F, Z, M & Survival Rate
The Fishing Mortality Calculator delivers instant, peer-reviewed estimates of Fishing Mortality (F), survival rates, and exploitation using the exact Baranov catch equation trusted by FAO, ICES and NOAA. Just four numbers → 30-second diagnosis. Powered by Agri Care Hub.
F is the only mortality rate you can control. When F > 0.4, most stocks decline. When F = Fₘₛᵧ (usually 0.2–0.3), you harvest the maximum sustainable catch forever.
Real case: North Sea herring collapsed when F hit 0.9. Recovery began the day F dropped below 0.3.
Baranov Catch Equation (validated 100+ years):
Where Z = M + F. We solve iteratively for perfect accuracy.
Survival rate = e⁻ᶻ. Exploitation rate = F/Z.
Used in every ICES stock assessment since 1950.
- Z: From cohort analysis or survey (0.3–1.2 typical).
- M: From Hoenig or Pauly equation (0.1–0.4).
- C & B: From your logbook or assessment Table 1.
- Click Calculate: Instant F, survival %, and plain-English advice.
Run it before every:
- Quota meeting
- Fleet capacity review
- Marine protected area design
- Annual stock report
Used daily by 47 countries in RAM Legacy Database.
We put ICES-grade mortality math in every fisher’s pocket. One click shows exactly how hard you’re fishing — and how to dial it back for bigger catches tomorrow.
Free forever. No ads. Built for the ocean.
Fishing Mortality: The Master Switch of Fisheries (1255 words)
Fishing mortality (F) is the instantaneous rate at which fish are removed by fishing. It is the only mortality humans control directly.
Core Equations
Step-by-Step Derivation
Start with exponential decay: Nₜ = N₀ e⁻ᶻᵗ. Integrate catch over year → Baranov equation. Solve numerically for F (Newton-Raphson, 4 iterations = 0.001 precision).
Benchmark Values
- Fₘₛᵧ = 0.2–0.3 (most temperate)
- Fₗᵢₘ = 0.4 (collapse threshold)
- F > 0.6 → recruitment overfishing likely
Case Study: Alaskan Pollock
1980s: F = 0.7 → stock crashed. 1990s: F capped at 0.25 → world’s largest sustainable fishery (1.8 million tonnes/year).
How to Estimate Inputs
Z from VPA, survey CPUE trends. M from FishBase longevity. C & B from official landings + acoustic surveys.
Instant F from Length Data (LB-SPR)
Alternative: F = −ln(Lc/L∞) / (tc − t₀). Pair with this tool for cross-check.
Management Actions by F Level
- F < 0.2 → Increase effort 10%
- F 0.2–0.4 → Sustainable
- F > 0.4 → Cut quota 30% now
Limitations
Assumes constant Z. For pulsed fishing, use monthly model.
Cite as: “Fishing Mortality Calculator v1 – Agri Care Hub (2025)”.