Estimators of discards using fishing effort as auxiliary information with an application to Iberian hake (Merluccius merluccius) exploited by the Portuguese trawl fleets

► New statistical methodology to estimate discards by weight. ► New statistical methodology accounting for difficulties in random deployment of observers on-board commercial vessels. ► Identification of high influential observations on discards' estimates. ► Quantification of hake discards by the Portuguese trawl fleets operating off the Portuguese continental shelf.