Eels are the largest freshwater fishes found in New Zealand, and their life cycle spans thousands of kilometres, linking our lakes and rivers with the open waters of the Pacific Ocean. Yet for all we know about them in freshwater, a central part of the tuna story remains a mystery: where do they spawn? Tagged eels have been tracked towards the Pacific Islands before losing their tags - or getting eaten. Also, larval shortfin eels have been observed in the Pacific, but the exact location of spawning is unknown, no eggs have been seen, and certainly no spawning has been observed.

This post was inspired by the 'Infinite Monkey Cage' podcast on the European Eel, which is similarly mysterious, yet widespread. If you're interested to know more, see the comments section below for a link to a recent paper that dispels the long-held belief that New Zealand eels spawn 'near Tonga' or 'east of Samoa' - well worth the read!