O. mero is the most documented New Zealand Opisthoteuthis species, with over 100 reference specimens.

[1][5] The type locality of O. mero is: 36°52'S, 176°19'E, 510 m, on the northern end of New Zealand.

This species was originally found in virtually all waters surrounding New Zealand.

[4] O. mero is listed as Endangered by the IUCN due to the effects of commercial deep-water trawling upon population size.

The longevity of Opisthoteuthis species along with their low fecundity and slow growth (primarily within embryonic development which may take 1.4-2.6 years among other species in the genus) have made many species easily susceptible to precipitous population declines, and slow recoveries.