The waters surrounding Midway Atoll National Wildlife Refuge are home to at least 266 species of fish, including seven pelagic species; some are endemic to the Northwestern Hawaiian Islands (NWHI) or very rare in the Main Hawaiian Islands (MHI). Fish diversity in Refuge waters isn’t as high as that found in the MHI, perhaps because Midway is near the northern extent of the NWHI and its waters are much cooler.
Overall, fish biomass is higher in the NWHI than that found in the MHI. Compared to other NWHI locations, reef fish populations are lower at Midway, likely due to years of human activity, including fishing, at the atoll.
Key priorities for coral reef research at Midway Atoll National Wildlife Refuge have included surveys to document frequency and abundance of different species and studies to assess shallow reefs of the NWHI for biodiversity, status and management issues. Some of the interesting discoveries at Midway Atoll have included:
- The Hawaiian grouper (hapu’upu’u, Epinephelus quernus) typically occurs at much greater depths elsewhere in the NWHI and MHI (up to 300 feet at MHI); at Midway and Kure Atolls, divers encountered them at shallow depths, sometimes in assemblages with masked angelfish and knifejaws.
- Jacks, called ulua in Hawaii, were less common at Midway than elsewhere in the NWHI. At least 17 species in the “jack” (Carangidae) family have been recorded at Midway; the Hawaiian thick-lipped jack (Pseudocaranx dentex) is among the most common.
- The whiskered boarfish (Evistias acutirostris) and knifejaws (Oplegnathus spp.) are rare elsewhere in the Hawaiian archipelago, except at Kure and Pearl and Hermes; researchers observed them under many of the overhangs.
Other species commonly seen in Midway Atoll’s waters include:
- Fantail filefish / o’ili’uwi’uwi (Pervagor spilosoma)
- Spotted cardinalfish / ‘upapalu (Apogon maculiferus)
- Hawaiian dascyllus / ‘alo’ilo’i (Dascyllus albisella)
- Saddle wrasse / hinalea lau-wili (Thalassoma duperrey)
- Oval chromis (Chromis ovalis)
- Spectacled parrotfish / uhu uliuli (Chlorurus perspicillatus)
- Convict tang / manini (Acanthurus triostegus)
- Yelloweye damselfish (Stegastes fasciolatus)
For more detailed information, check out:
- The USFWS Checklist of Reef Fishes of Midway (information about distribution and abundance of fish in Midway’s waters)
- Coral Reef Ecosystems of the Northwestern Hawaiian Islands (interim results from surveys in 2000)