Sir,Tuna caught by pole and line or without fish aggregation devices (FADs) is significantly more sustainable than tuna caught with purse-seine nets using FADs (‘Carbon cost of ‘sustainable’ pole and line tuna revealed’, March 17).

One flawed tuna industry-backed study does nothing to change that. Climate change is a serious threat to ocean life, and so are destructive fishing methods producing enormous volumes of bycatch. The destruction of juvenile tuna, threatened tuna species, sharks and rays is a major impact of most purse seine fishing, ie fishing on FADs, ignored by this study. Switching to pole & line or FAD-free fishing can reduce bycatch by around 90%.

The ISSF study is deeply flawed in a number of ways, most obviously in lacking data for pole and line skipjack, key to any understanding of the pole and line fishery. This glaringly limited analysis cannot form the basis for understanding this issue. An integrated, independent analysis is required.

If retailers and brands globally want to show a far-reaching commitment to sustainability they should take a lead from the UK where all major players have committed to dump the marine minefields that are FADs.

Simon Clydesdale, Greenpeace UK