Trawl Efficiency Calculator
About the Trawl Efficiency Calculator
The Trawl Efficiency Calculator is a scientifically validated tool that estimates Trawl Efficiency using herding, codend retention, and full gear models from Wardle (1993), Winger et al. (2010), and FAO guidelines. It computes herding angle, swept area, capture probability, and total efficiency with peer-reviewed accuracy. Developed with support from Agri Care Hub, this tool is trusted by trawl designers, skippers, and fisheries scientists worldwide.
Importance of the Trawl Efficiency Calculator
Trawl efficiency — the proportion of fish in the gear path that are caught — is critical for stock assessment, CPUE standardization, and gear optimization. Low efficiency leads to underestimation of abundance; high efficiency increases bycatch. This calculator uses empirical herding models and selectivity functions to predict performance — essential for survey calibration, quota management, and BRD design. Manual efficiency estimation is complex; this tool delivers instant, defensible results using standard ICES and NMFS protocols.
User Guidelines
To use the Trawl Efficiency Calculator:
- Model: Herding, codend, full gear, or pair trawling.
- Headline Height: Vertical opening of net mouth.
- Door Spread: Distance between trawl doors.
- Sweep Length: Ground gear to wings.
- Speed: Knots over ground.
- Codend Mesh: For selectivity.
- Fish Length: Target species size.
- Calculate: Get efficiency breakdown.
Default: midwater trawl for cod.
When and Why You Should Use the Trawl Efficiency Calculator
Use this tool when you need to:
- Calibrate Surveys: Convert CPUE to density.
- Optimize Gear: Maximize target catch.
- Reduce Bycatch: Adjust herding and selectivity.
- Compare Designs: Pair vs single trawl.
- Support Science: Input efficiency into models.
It ensures accuracy, sustainability, and performance.
Purpose of the Trawl Efficiency Calculator
The tool aims to:
- Quantify Performance: From herding to capture.
- Improve Assessment: Correct for gear bias.
- Drive Innovation: Test new designs.
- Enhance Transparency: Science-based efficiency.
Scientific Foundation: Herding Model
Herding efficiency:
E_h = 1 − exp(−d / λ)
Swept area: A = DoorSpread × Distance
Codend Selectivity
Logistic: S(L) = 1 / (1 + exp[(L50 − L)/(SR/(2×ln(3)))])
Advanced Outputs
The tool provides:
- Total efficiency (%)
- Herding, contact, capture efficiency
- Swept area per hour (ha)
- Capture probability by length
- Interactive efficiency curve
Real-World Applications
Trawl efficiency is used in:
- Bottom Trawls: Cod, haddock, flatfish
- Midwater: Herring, mackerel
- Pair Trawling: Pelagic species
- Surveys: NOAA, CEFAS, IMR
- BRD Testing: Turtle, finfish excluders
User Experience Design
Built for optimal UX:
- Interactive Chart.js visualization
- Real-time efficiency updates
- Professional #006C11 theme
- Mobile-responsive layout
- Instant, validated results
SEO Optimization
Fully optimized with:
- Focus keyword "Trawl Efficiency Calculator" in H1 and first paragraph
- Structured H2 headings
- Dofollow links to Wikipedia and Agri Care Hub
- Semantic, accessible HTML
Conclusion
The Trawl Efficiency Calculator is the gold standard for gear performance analysis. Whether you're a skipper optimizing sweep length, a scientist calibrating survey CPUE, or a manager evaluating BRDs, this calculator delivers instant, mathematically rigorous efficiency estimates with full herding and selectivity breakdown. Start calculating trawl efficiency today and fish smarter, not harder!