A long-standing collaboration between DTU Aqua and the Danish Pelagic Producers Organisation (DPPO) on collecting data on the mackerel stock in the North Sea has developed into an important contribution to the ICES stock assessment.
In this year’s survey, around 42% of the total recorded biomass and as much as 63% of the young mackerel were found in the area of the North Sea surveyed by DPPO member vessel Ceton as part of the International Ecosystem Summer Survey in the Nordic Seas (IESSNS).
The Northeast Atlantic mackerel stock assessment is based largely on extensive international surveys at sea. Since 2018, Denmark has contributed to extending these surveys into the North Sea through close collaboration between DTU Aqua, DPPO and scientific institutions across the North East Atlantic.
The Danish mackerel survey began as a pilot study in 2018. Following the positive results, the survey was carried out again in 2019, and since then data on the distribution and occurrence of mackerel in the North Sea have been collected year after year.
The project is coordinated by DPPO, co-funded by the EU and carried out in collaboration with DTU Aqua and fishing company Gifico.
After several years of continuous data collection, the significance of the Danish contribution has become increasingly clear. In this year’s International Ecosystem Summer Survey in the Nordic Seas (IESSNS), around 42% of the recorded mackerel biomass was found in the part of the North Sea surveyed by Ceton.
Even more striking was the result for recruitment to the stock: 63% of the recorded young mackerel were found in the Danish survey area. For DPPO, the results underline the value of long-term collaboration between the fishing industry and the scientific community.
‘When we began this work several years ago, the aim was to contribute more and better data on mackerel in the North Sea. We can now really see the value of the continuity that has been established. When such a large proportion of both the biomass and the young mackerel is recorded in the area surveyed by Ceton, it shows just how important the Danish contribution has become,’ said DPPO chief scientific officer Claus Reedtz Sparrevohn.
The mackerel survey is an extension of the international survey of mackerel in Nordic waters. The international survey provides fisheries-independent data that form part of the scientific basis for assessing the Northeast Atlantic mackerel stock. The Danish contribution ensures that the North Sea is included in this data basis.
For DPPO, the project provides a concrete example of what can be achieved when the fishing industry’s vessels, practical experience and resources are combined directly with scientific methods and expertise.
‘This is exactly the kind of collaboration between industry and science that we want to invest in. Fishers have the vessels and an enormous amount of practical knowledge of the sea and the fishery, while scientists bring the scientific methods and analysis. When we combine the two and do so consistently over many years, we can create knowledge that has a real impact on the stock assessment and, ultimately, on fisheries management,’ said DPPO CEO Esben Sverdrup-Jensen.
This year’s results also underline the importance of maintaining long time series. It is not the individual survey alone, but the continuous collection of comparable data year after year that makes it possible to track changes in the stock’s distribution and development.
For DPPO, it is an important milestone that a project in which the industry has invested for several years is now making an increasingly important contribution to scientific knowledge about one of the most important pelagic stocks.
