Introduction to stock assessment
Unit 2.1: Types of data
Field technician fishing.
Photo credit: DFO
Each category plays an important and complementary role in stock assessments.
Fishery-dependent data
Fishery-dependent data collected by commercial, recreational, and Indigenous FSC fisheries include:
- catch
- fishing effort
- size (length and weight), number, and species of fish caught
- bycatch and discards
Sources of fishery-dependent data collected by commercial, recreational, and Indigenous FSC fisheries can include:
- landing records
- commercial sampling
- logbooks
Where possible, the following indices may be estimated from fishery-dependent data:
- catch per unit effort
- abundance, biomass, and spawning stock biomass
- population metrics (for example, age structure and sex ratio)
- recruitment
- metrics of individual fish condition (for example, weight-to-length ratios)
- fishing mortality
- gear selectivity
Fishery-dependent data can be collected over time to produce valuable data time series for stock assessment. For example, information on total catch over time is a common and key input to many stock assessment models.
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