Information on the fish stocks is collected from three main sources:
- Statistics on the quantities of each species landed are collected in fishing ports by officers of Marine Scotland Compliance.
- Biological data on the size and age of the fish caught are obtained by sampling catches directly. Marine Scotland scientific staff regularly visit fish markets around Scotland, and sail on more than 60 commercial voyages each year.
- Research vessel surveys are conducted to determine the abundance of fish, including those too small to be caught by fishermen. Special surveys are also organised to examine the abundance of pelagic fish such as mackerel, sprats and herring and shellfish such as Norway lobsters ( Nephrops) and scallops.