Small-boat surveys and DNA profiling of M?ui dolphins (Cephaloryhnchus hectori maui) in 2020
Rochelle Constantine, Debbie Steel, Emma Carroll, Cara Hansen, Garry Hickman, Kristina Hillock, Mike Ogle, Pearson Tukua, C. Scott Baker
Here, we report on the first year of a two-year project intended to replicate the 2010-2011 and2015-2016 genotype mark-recapture surveys of Māui dolphins. From the 11th – 27th February 2020, we conducted a total of 11 small-vessel surveys along the west coast of
the North Island from south Kaipara, in the north, to the Mokau River, Taranaki in the south. During 1,569.5km of survey effort we encountered a total of 26 groups of Māui dolphins, with an average of 2.4 groups per day (ranging from 0-5 groups per day). Group sizes ranged from 1-9 dolphins (average of 3.7-4.2 dolphins using minimum and maximum estimates). Dolphins were encountered between South Kaipara and south of Port Waikato. A total of 50 biopsy samples were collected (ranging from 0-14 samples per day; average of 4.5 per day). Consistent with previous years, the dolphins showed little behavioural response following the biopsy event. DNA profiling of the 50 samples identified 47 samples of 30 individual Māui dolphins (haplotype ‘G’) and three samples of two individual Hector’s dolphins; a female (haplotype ‘Jb’) first identified in 2010, and a male (haplotype ‘Ca’) not previously sampled. Including this newly identified male, we have now found four living Hector’s dolphins associated with Māui dolphins. Further analysis, including a two-sample, closed population estimate of abundance for comparison to previous surveys, will be undertaken once the 2021 field season is complete.