Herring larvae in the North Sea (IHLS)

Herring is one of the most important commercial fish species, including for the North Sea fisheries. Its management must be sustainable in order to protect the resource for future generations. A good knowledge of the stock structure is essential for optimal management, as this is the only way to prevent over-exploitation or under-exploitation of the stock.

The objective of the International Herring Larval Survey (IHLS) is therefore to assess the herring stock throughout the North Sea by recording the abundance and distribution of herring larvae in the North Sea spawning grounds during annual research cruises. As the number of newly hatched herring larvae is related to the number of parents that have participated in the spawning activities, we can gain important information about the size of the spawning stock (parental biomass).

Research on the abundance of herring larvae has a long tradition in the North Sea. Larval survey programmes to determine the abundance and reproductive success of herring have been carried out since the beginning of the 20th century, but were initially limited to the southern North Sea.

In its current set-up, the IHLS has been carried out since 1972 and is coordinated by the International Council for the Exploration of the Sea (ICES).

Currently, the Netherlands and Germany participate in the research, with two areas of the herring larval stations being sampled by each nation, and the other two areas being shared or covered in turn. Due to the prevailing weather conditions, larger research vessels are usually used, such as the fisheries research vessel "Walther Herwig III" and the research vessel "Tridens".

As a contribution to the International Herring Larval Survey (IHLS), we compile the collected data on the occurrence of herring larvae in the North Sea for Germany within the EU Data Collection Framework (DCF). The results are used within ICES for the calculation of scientific catch quota recommendations.