Using delta generalized additive models to produce distribution maps for spatially explicit ecosystem models

•We develop a delta GAM to predict functional group distribution in ecosystem models.•This GAM is used to create maps for an OSMOSE ecosystem model of the Gulf of Mexico.•We demonstrate our approach for pink shrimp (Farfantepenaeus duorarum) in summer.•Using a delta rather than a negative binomial GAM saves significant computation time.•GAMs fitted for OSMOSE correctly predict low- and high-abundance areas qualitatively.