MEPS 667:145-159 (2021)  -  DOI: https://doi.org/10.3354/meps13693

ABSTRACT: The lesser sandeel Ammodytes marinus is a key component of the North East Atlantic ecosystem but little is known about its distribution outside of fished areas. In this study, species distribution models were developed to predict the occurrence and density of sandeels in parts of the North Sea and Celtic Seas regions. A hurdle model was found to be the best fitting model with the highest predictive performance; model evaluation with independent data demonstrated that it had significant discrimination ability across the study region. Percentage silt was the most important variable in predicting occurrence, and percentage sand had a strong influence on density, consistent with past local studies. Slope was also a significant explanatory variable, especially for predicting density, as buried sandeels avoided strongly sloping areas such as the edges of sand banks. A predicted preferred depth range of 30-50 m was consistent with many previous studies, although the depth response did appear partially biased by the depth range investigated in the training data set. Overall, the predicted distribution did not indicate that there were large areas of unexploited habitat. However, some small areas known to be important to sandeel predators were identified by the model. The distribution model helps refine past inferences about sandeel availability to predators and indicates to marine planners potential areas where anthropogenic impacts should be considered.

KEY WORDS: Species distribution model · Ammodytes marinus · Sandeels · Hurdle model · Fish distribution · Spatial management