Deaths in fishing nets were previously considered to be the most serious threat (responsible for more than 95% of the human-caused deaths in Māui dolphins), with currently lower level threats including tourism, disease, and marine mining. Research of decreases in mitochondrial DNA diversity among hector's dolphin populations has suggested that the amount of gill-net entanglement deaths likely far surpasses that reported by fisheries. Population simulations estimated that the current population is 30% of the 1970 population size estimate of 50,000 dolphins, based on their estimated capture rate in commercial gillnet fisheries.