Gut content data for round gobies at Guldborgsund in 2011, including (a) the percentage occurrence of taxa groupings in gut content of (n = 297 fish) and (b) the overall BA effect estimates for Guldborgsund for all taxa (from the full site model), as well as present and absent subsets of taxa (with 95% credibility intervals). ‘Other’ taxa found in gut contents were primarily mobile taxa that are poorly detected in HAPS core data (e.g. Palaemon adspersus, Palaemon elegans) and fish (Gasterosteus aculeatus, round goby scales).