TS 5421

TS 5421 is a terminology standard for fisheries that defines the language used in population dynamics. It brings together the core terms used to describe how fish stocks change over time, including age, size, mortality, catch, growth, and reproductive output.

Why population-dynamics terminology matters

Population dynamics is the branch of fisheries biology that explains why the abundance of a stock rises or falls. Concepts such as abundance by age or body weight, total annual mortality, fishing removal, consumption by carnivorous fish, disease-related mortality, and individual growth rate are fundamental to stock assessment. Clear definitions help scientists, managers, and industry users apply the same concepts consistently across studies and reporting systems.

The standard also includes expressions related to density-dependent fecundity or production. In general technical terms, density dependence describes how crowding, competition, and environmental limits can influence survival and reproduction in a stock. This standard therefore serves as a controlled vocabulary for population analysis rather than a method standard that prescribes assessment procedures.

• Terms for stock abundance by age and body size
• Concepts for annual and age-specific mortality
• Losses due to fishing, predation, and disease
• Expressions for growth rate and reproductive output
• Density-dependent production and fecundity terminology