Hector’s dolphin faces serious pressures from human activities given its limited coastal distribution. The main threat to the species in general is entanglement in gillnets (Dawson 1991; Slooten and Lad 1991; Dawson and Slooten 1993; Martien et al. 1999; Secchi 2006; Slooten 2007; DOC and Mfish 2007), with trawl fisheries also causing some mortality. Amateur gillnetting (as opposed to commercial gillnetting) is a significant part of the problem (Dawson and Slooten 2005). Sixty percent of all dead Hector’s dolphins for which cause of death could be determined, had died as a result of gillnet entanglement (DOC and Mfish 2007). Risk analyses for Hector’s and Maui’s dolphins indicate that recent levels of mortality are unsustainable (Slooten and Lad 1991; Martien et al. 1999; Slooten et al. 2000; Burkhart and Slooten 2003; Slooten 2007; DOC and Mfish 2007). This conclusion is robust to the uncertainty in abundance, mortality, and vital rates (Slooten et al. 2000; Slooten 2007). The most recent population viability analysis indicates continued population declines (Slooten 2007). Additional threats include pollution, disease, vessel traffic, and habitat modification (Stone and Yoshinaga 2000).
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