WIREDGOV

The review of scientific evidence that has been used to inform the development of proposals to close fishing for sandeel in all Scottish waters.

Aim of this Report

This report provides a review of the available scientific evidence on the potential effects of sandeel fisheries management on the marine environment. It includes information on the drivers of sandeel distribution and abundance, the importance of sandeel to other fish species, seabirds and marine mammals, and the potential effects of sandeel fisheries management measures upon these species. The report's focus is not on the provision of advice on whether sandeel fisheries management measures should be put in place.

Sandeel

Sandeel are part of the Ammodytidae family, consisting of small eel-like fishes, and represent the most abundant species group in the North Sea (around 15% of the total fish biomass, Sparholt, 1990), playing a key role in North Atlantic marine food webs. This key role is associated with the structure of North-Atlantic food-webs, often described as a having "wasp-waist" structure, where a relatively low diversity of forage i.e., prey fish (including sandeel and clupeids) form the intermediate trophic link between a large diversity at both lower trophic levels (phyto/zooplankton) and higher trophic levels (predatory fish, marine mammals, and seabirds). In accordance, variations in the abundance and availability of sandeel or other forage fish can have important effects on both ends of marine food web (top-down regulation of lower trophic levels and bottom-up effects on marine predators) and disrupt the energy transfer across the whole food-web (Lynam et al. 2017).

Sandeel in the North Atlantic and the North Sea refers to a complex of species of which the most abundant is the lesser sandeel (Ammodytes marinus), which supports the largest single-species fishery in the North Sea. The lesser sandeel is a winter-spawning species which lay eggs on the sand in winter months, with planktonic larvae occupying the water column from hatching in February – April to settlement in May – June. Settlement marks a key transition in the sandeel life cycle, after which they form pelagic feeding schools (targeted by marine predators) during the day, burying into the sand at night. Following the summer feeding season, sandeel remain in the sand day and night for the overwintering period, apart from a short spawning period in December – January, until emergence from the sand the following spring. These aspects of sandeel life cycle, particularly this life-long attachment to a sand bank, are important determinants of their distribution.

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