Don is a freshwater fisheries scientist with a Ph D from Victoria University of Wellington. He leads NIWAs research on freshwater fish and fisheries. His specialist area is on the biology of freshwater eels, which has lead to considerable contract research for the Ministry of Fisheries and hydro companies. He has also been involved in studies of other native fish species, especially lampreys, and has a particular interest in the migrations between fresh and saltwater that are undertaken by many native fish species. He has also carried out research on headwater trout fisheries throughout New Zealand. His research on eels has lead to considerable involvement with Maori, and he is heavily involved within New Zealand and internationally on issues related to eel management.