ISO 16663-2:2003

Overview

ISO 16663-2:2003 specifies a standardized test method for determining the mesh length of fishing nets using a ruler. Applicable to passive fishing gears (for example gill nets, entangling nets and trammel nets), the standard defines sample conditioning, measurement procedure, calculation rules and reporting requirements to ensure repeatable, comparable mesh size data for quality control, compliance and research.

Key topics and technical requirements

• Scope: Measurement of mesh length (Part 2) for passive fishing gear; complements ISO 16663-1 (mesh opening).
• Conditioning / atmosphere: Dry specimens must reach equilibrium in the standard atmosphere per ISO 139 (typically 24 h for man‑made fibres).
• Wet testing: Two options:
  • Immersion in tap water at (20 ± 2) °C for ≥ 12 hours, or
  • Immersion in a wetting‑agent solution at (20 ± 2) °C for ≥ 1 hour.
• Measurement principle: Manually straighten netting in the N‑direction and measure the distance from the first knot or joint (inclusive) using a ruler with 1 mm accuracy.
• Calculation rule: Measured length (five consecutive meshes) is divided by 5 to obtain single mesh length. Perform at least 10 single measurements per netting piece unless otherwise agreed. Average mesh length is rounded up to the next millimetre.
• Statistics: Determine the coefficient of variation and confidence interval for the set of measurements.
• Test report contents: Must state conformity to the standard and include date, netting description (material, yarn type, knotted/knotless, nominal linear density per EN ISO 1107), average mesh length (mm), number of measurements, net state (dry/wet), coefficient of variation, confidence interval and any deviations.

Applications and typical users

• Manufacturers - quality control and product specification of nets and panels.
• Testing laboratories - standardized methods for certification and verification.
• Fisheries managers and regulators - enforce mesh size regulations for selectivity and conservation.
• Researchers - compare gear performance and biological selectivity across studies.
• Procurement and inspection - ensure delivered gear meets contractual mesh-size requirements.

Using ISO 16663-2 promotes consistent mesh size measurement, supports regulatory compliance, reduces disputes over gear specification, and improves reproducibility in fisheries science.

Related standards

• ISO 16663-1 - Fishing nets: Method for determination of mesh size - Part 1: Opening of mesh
• EN ISO 1107 / ISO 1107 - Fishing nets: Netting basic terms and definitions
• ISO 139 - Textiles: Standard atmospheres for conditioning and testing

Keywords: ISO 16663-2, mesh length, fishing nets, mesh size measurement, passive fishing gear, gill net, trammel net, test method, standard atmosphere.