Quantifying Mesophotic Fish Assemblages of Hawai‘i’s Au‘au Channel: Associations With Benthic Habitats and Depth

Low-light reefs occur in the tropics and subtropics at depths beyond most scientific diving, thereby making conventional surveys challenging.

Towed cameras, submersibles, and mixed-gas divers were used to survey the mesophotic reef fish assemblages and benthic substrates of the Au‘au Channel, between the Hawaiian Islands of Maui and Lānaʻi. 

The patterns in the data suggested two categories of depth populations. One “upper mesophotic” between 53 m and 95 m and the other deeper, possibly part of a “lower mesophotic” assemblage between 96 m and 115 m at the edge of the 'twilight zone' and bottomfish complex.