Distribution and Abundance of Introduced Fishes on Shallow and Mesophotic Reefs of the Hawaiian Islands
Aquatic organisms are often accidentally or intentionally transported to new habitats through anthropogenic activities. In Hawai‘i, the Bluestriped Snapper (Lutjanus kasmira), Blacktail Snapper (Lutjanus fulvus) and Peacock Grouper (Cephalopholis argus) were introduced to the island of O‘ahu in the 1950’s to enhance recreational and commercial fishing. Here, we investigated the current distributions and abundances of these introduced fishes on shallow (≤30 m) and mesophotic (>30 m) reefs of the Hawaiian archipelago using fish data collected from 2007 to 2017.
Introduction
Aquatic organisms are often accidentally or intentionally transported to new habitats through anthropogenic activities. In Hawai‘i, the Bluestriped Snapper (Lutjanus kasmira), Blacktail Snapper (Lutjanus fulvus) and Peacock Grouper (Cephalopholis argus) were introduced to the island of O‘ahu in the 1950’s to enhance recreational and commercial fishing. Here, we investigated the current distributions and abundances of these introduced fishes on shallow (≤30 m) and mesophotic (>30 m) reefs of the Hawaiian archipelago using fish data collected from 2007 to 2017.
The present study showed
- varying degrees of spread of the three introduced fishes, and
- their limited occurence on the mesophotic reefs of the Northwestern Hawaiian Islands, especially on the northwestern end of the island chain.
This limited occurrence on the mesophotic reefs indicates potential effects of physical factors and habitat preference on their vertical and horizontal distributions.
Shallow (0-30 m) surveys were performed during summer months from 2007 to 2017 on shallow hard-bottom reefs of the Hawaiian Islands. At each site, one or two pairs of divers simultaneously performed a reef fish survey using a stationary point count (SPC), with each diver identifiying, sizing and counting all fishes inside an SPC cylinder 15 m in diameter.
Methods (Shallow)
Shallow (0-30 m) surveys were performed during summer months from 2007 to 2017 on shallow hard-bottom reefs of the Hawaiian Islands. At each site, one or two pairs of divers simultaneously performed a reef fish survey using a stationary point count (SPC), with each diver identifiying, sizing and counting all fishes inside an SPC cylinder 15 m in diameter.
Mesophotic (30-100 m) surveys were performed during summer months from 2010 to 2016 on mesophotic hard-bottom reefs of the Hawaiian Islands. At each site, a single diver identified, counted and estimated size of all conspicuous, diurnally-active fishes along a 25 × 2 m belt transect.
Methods (Mesophotic)
Mesophotic (30-100 m) surveys were performed during summer months from 2010 to 2016 on mesophotic hard-bottom reefs of the Hawaiian Islands. At each site, a single diver identified, counted and estimated size of all conspicuous, diurnally-active fishes along a 25 × 2 m belt transect.
Shallow reefs
Main Hawaiian Islands
All three species - present at all islands
Northwestern Hawaiian Islands
L. kasmira - present up to Kure Atoll
L. fulvus - absent
C. argus - present up to French Frigate Shoals (FFS)
Mesophotic reefs
Main Hawaiian Islands
L. kasmira - present & relatively abundant at Hawai‘i Island
L. fulvus & C. argus - rarely observed
Northwestern Hawaiian Islands
L. kasmira - present up to FFS + 1 individual at Lisianski (37 m depth)
L. fulvus & C. argus - absent
Results
Shallow reefs
Main Hawaiian Islands
All three species - present at all islands
Northwestern Hawaiian Islands
L. kasmira - present up to Kure Atoll
L. fulvus - absent
C. argus - present up to French Frigate Shoals (FFS)
Mesophotic reefs
Main Hawaiian Islands
L. kasmira - present & relatively abundant at Hawai‘i Island
L. fulvus & C. argus - rarely observed
Northwestern Hawaiian Islands
L. kasmira - present up to FFS + 1 individual at Lisianski (37 m depth)
L. fulvus & C. argus - absent
Atsuko Fukunaga1,2, Randall Kosaki2, Brian Hauk1,2
1 Joint Institute for Marine and Atmospheric Research
2 NOAA Papahānaumokuākea Marine National Monument
Authors thank the officers and crew of the NOAA ship Hi‘ialakai for logistic support and field assistance. J. Leonard, D. Wagner, K. Keogh, H. Owen, S. Harris, J. Cousins, E. Kehn, K. Lopes, T. Brown, J. Hansen, C. Kane, G. McFall, R. Boland, A. Montgomery, Y. Papastamatiou, C. Clark, R. Pyle, R. Whitton, S. Matadobra, S. Annandale, L. Giuseffi, M. Winston, J. Copus, R. Coleman, D. Pence and B. Greene provided field support for mesophotic surveys. University of Hawai‘i Marine Option Program interns assisted with shallow-water data collection. S. Godwin coordinated numerous cruises for shallow-water surveys. Partner agencies contributing to shallow-water surveys include NOAA Pacific Islands Fisheries Science Center’s Ecosystem Science Division, US Fish and Wildlife Service and State of Hawaii Department of Land and Natural Resources.
