Missing catch data are a big problem in achieving sustainability of world fisheries (Nature 519, 280–282; 2015). The accuracy of catch data is also important — particularly for endangered fish species.

Take the common skate (Dipturus batis), now classified as critically endangered in the Red List of the International Union for Conservation of Nature. In 2009, the European Union put a total ban on fishing for this species and made it illegal to retain these fish on vessels, exchange them between boats, or land them.

We were therefore surprised to learn that official landing records of D. batis in 2014 by UK vessels in the United Kingdom and Europe, and by foreign vessels in UK ports, showed commercial catches totalling 1.8 tonnes. In 2011–13, the total recorded catch was even higher at 7.8 tonnes (all data by written request from the UK Marine Management Organisation).

The reliability of these figures is unclear, however, given that catch totals are compiled from assorted data collected at numerous UK ports. Local inaccuracies might be perpetrated through systematic errors in species identification, for example, or by mistakes in the codes allocated at market.

It is essential for the future of vulnerable species that catch data are properly checked by the authorities to monitor adherence to bans, and that punitive action is taken against contraventions.