Malcolm began his research career in the 1980s as a fisheries biologist. He worked extensively on stock assessment of deepwater fish (in particular orange roughy), before broadening his research interests to more general deep-sea ecosystems. He studied seamounts for many years, and headed the Census of Marine Life on Seamounts, a major 6 year international research programme. His studies have involved a lot of time at sea; with over 70 surveys, including submersible dives, and international work in the Antarctic and southwest Pacific. Currently he leads NIWA research projects describing the biodiversity of deep-sea habitats, assessing ecological risk to these habitats and communities from fishing and mining activities, and ways to improve the management of environmental impacts.
Malcolm gained his PhD from Victoria University of Wellington in 1982, and since then has specialised in the biology and ecology of deepwater fish and fisheries, particularly orange roughy. He has extensive seagoing experience with over 70 voyages. Recently he has worked largely on international fisheries and helped develop the FAO guidelines on deep-sea fishing in the high seas. Malcolm currently heads NIWA research programmes on deep sea communities, impacts from fishing and mining, and developing risk assessment methods for New Zealand deepwater fisheries.