In the More Information section for each tin you can see the method used to catch the fish and the rating the Marine Conservation Society has given the fish in its Good Fish Guide. 

The canneries we work with subscribe to sustainable fishing practices such as pole-and-line fishing, which reduces by-catch and does not damage the sea bed, and purse seine, which allows smaller fish to swim free and replenish ocean stocks. Olasagasti and Zallo catch their tuna and anchovies in an MSC-protected area of the Bay of Biscay for instance. Yurrita, too, works with the MSC. We also work with canneries, such as Pinhais, that use smaller quantities of fish so that the best can be hand-picked and tinned, and which pack the tins by hand rather than machine, thus reducing their carbon footprint. Canneries like Olasagasti and Angelachu and others catch the fish seasonally for a limited amount of time so as to avoid overfishing and depleting ocean stocks. 

As well as working with suppliers who protect the oceans, we use recyclable, minimal packaging wherever we can. Some components of the hampers are made from the boxes the tins are shipped in. And tinned fish, of course, has a long shelf-life, so waste is likely to be reduced.