Caprazli Fisheries Mortality Index (FMI)

A visualization framework for fisheries exploitation status with life-history-specific threshold calibration

---

Author

Kafkas M. Caprazli
📧 caprazli@gmail.com
🆔 ORCID: 0000-0002-5744-8944

---

Overview

The Caprazli Fisheries Mortality Index (FMI) plots fishing mortality (F) against natural mortality (M) on log-log axes. Unlike the traditional Exploitation Rate (E = F/Z), which compresses information into a single dimension, FMI preserves two independent dimensions:

1. Status — Position relative to the F=M isocline (Gulland threshold)
2. Magnitude — Distance from origin representing biological turnover

The F=M line is mathematically equivalent to E=0.5:

F = M  →  E = F/(F+M) = 0.5

This anchors FMI to the Gulland (1971) heuristic while providing superior visual discrimination across life histories.

---

Validation Results

Validated on 209 stocks (10,565 stock-years) from the RAM Legacy Database.

Performance

Approach	Sensitivity	Specificity	PPV	AUC
Universal (threshold 1.25)	89%	39%	54%	0.72
Stratified	76%	69%	66%	0.71–0.85

Life-History-Specific Thresholds

Life History	M Range	Optimal Threshold	AUC
Long-lived	< 0.2	4.91	0.79
Medium	0.2–0.4	2.15	0.79
Moderate turnover	0.4–0.8	2.45	0.85
Fast turnover	≥ 0.8	0.45	0.71

Key finding: Stratification improves specificity from 39% to 69% (+30 percentage points).

---

Quick Start

Prerequisites

install.packages(c("dplyr", "tidyr", "ggplot2", "purrr", "pROC", "cli"))

Run Validation

& "C:\Program Files\R\R-4.5.1\bin\x64\Rscript.exe" R\sliding_window_validation.R
& "C:\Program Files\R\R-4.5.1\bin\x64\Rscript.exe" R\stratified_roc_analysis.R

---

Repository Structure

caprazliFMI/
├── R/
│   ├── RAM_validation_candidates.R      # Extract F+M stocks
│   ├── sliding_window_validation.R      # Main validation
│   ├── stratified_roc_analysis.R        # Life-history ROC
│   └── investigate_false_negatives.R    # Diagnostic analysis
├── output/
│   ├── sliding_window/                  # Validation results
│   └── stratified_roc/                  # Stratified analysis
├── docs/
│   ├── VALIDATION_sliding_window.md     # Results documentation
│   ├── FUTURE_dynamic_FMI.md            # Paper 2 roadmap
│   └── FUTURE_life_history_thresholds.md
├── data/                                # RAM Legacy (not in git)
├── CLAUDE.md                            # Project intelligence
└── README.md

---

Data Source

RAM Legacy Stock Assessment Database v4.65
DOI: 10.5281/zenodo.7708834

Ricard, D., Minto, C., Jensen, O.P., and Baum, J.K. (2012). Examining the knowledge base and status of commercially exploited marine species with the RAM Legacy Stock Assessment Database. Fish and Fisheries 13(4): 380-398.

---

Citation

@software{caprazli_fmi_2025,
  author    = {Caprazli, Kafkas M.},
  title     = {Caprazli Fisheries Mortality Index (FMI)},
  year      = {2025},
  publisher = {Zenodo},
  doi       = {10.5281/zenodo.17844169},
  url       = {https://github.com/capraCoder/caprazliFMI}
}

---

License

MIT License — see LICENSE for details.

---

Contact

Kafkas M. Caprazli
📧 caprazli@gmail.com
🆔 ORCID: 0000-0002-5744-8944