For many years, stock assessments for pelagic species relied heavily on catch data collected in UK ports, but a significant proportion of pelagic catches are landed outside the UK and not available to be sampled by the traditional onshore sampling programme.
Without access to information from these catches, scientists were working with an incomplete picture of the distribution and age composition of the fishery catches. In short, the quality of information being used for stock assessments had room for improvement.
In 2018, the Scottish Pelagic Fishermen’s Association, Shetland UHI and Marine Scotland came together to develop a new approach where fishermen would become an integral part of the data collection process.
Seven vessels initially joined a voluntary self-sampling pilot scheme, collecting biological information directly from their catches while still at sea. The success of the pilot quickly demonstrated the value of the approach, and participation expanded to include 20 of Scotland’s 21 pelagic fishing vessels.
During every fishing trip, crews collect samples from each haul, measuring the length and weight of fish and recording the location and timing of the catch along with additional environmental variables. A random selection of trips are also targeted for additional sampling, where a sample of fish are frozen at sea and returned to fish laboratories so that their age, sex and maturity can be determined. The data gathered are supplied to the International Council for the Exploration of the Sea (ICES), where it contributes directly to annual stock assessments.
Developing this system required close collaboration. Fishermen worked with scientists to design sampling methods that were practical to carry out during normal fishing operations, while organisations including Shetland UHI, Marine Scotland, SPFA and the Scottish Fishermen’s Federation helped oversee training, quality assurance, logistics and data management.
What started as a pilot involving seven vessels became a nationally adopted approach. Since 2021, scientific data on pelagic catches are collected directly the crews on pelagic vessels and includes those landing in the UK or abroad. The new sampling programme, called the Scottish Pelagic Industry Science Data Collection Programme is now an integral part of Scotland’s National Sampling Programme. It provides a more representative understanding of the herring, mackerel and blue whiting fisheries, contributing to better knowledge on the stock status and sustainability.
The programme strengthened relationships between industry and science. Their involvement has helped build trust in the data, confidence in the process and a shared understanding of the challenges facing the fishery. This positive working relationship has facilitated collaboration on new areas of pelagic science too.
By combining scientific expertise with practical experience at sea, the project is helping ensure that management decisions are informed by the best possible evidence — and that the future of Scotland’s pelagic fisheries is built on a more complete understanding of the stocks they depend upon.
