Keenan, E. E., Brainard, R. E., Basch, L. V.

Historical and present status of the pearl oyster, Pinctada margaritifera, at Pearl and Hermes Atoll, Northwestern Hawaiian Islands

2006

Atoll Research Bulletin

543

333-344

"Populations of the black-lipped pearl oyster, Pinctada margaritifera, at Pearl and Hermes Atoll in the Northwestern Hawaiian Islands were first reported in 1928 and heavily harvested over the next 2 years. Approximately 150,000 pearl oysters were either exported or killed during the exploitation. An expedition in 1930 to assess postharvest population status found 480 P. margaritifera and determined the population to be severely depleted. Limited surveys in 1994 and 2000 found only a few pearl oysters and led to the conclusion that the population was still depleted. In 2003, the National Oceanic and Atmospheric Administration (NOAA)-led multi-agency marine debris removal team spent several months conducting surveys at Pearl and Hermes Atoll that included quantitative observations of Pinctada margaritifera. Data were collected on location, size, depth, habitat, and orientation of individual pearl oysters on the reef. Analyses of the 1930 and 2003 data sets revealed similar size-frequency distributions of the P. margaritifera population. The population has a spatial distribution within the Atoll similar to the 1930 post-harvest distribution, and some sustained level of reproduction. Density and depth distribution comparisons from the two survey periods suggest that pearl oysters are significantly more abundant in the shallow waters where they were harvested during the fishery but at a similar density overall as they were during the 1930 survey. Although no estimates of absolute population size are available for any time period, the large number of oysters harvested prior to the 1930 survey, together with estimates of oyster density in 1930 and 2003, suggest that the population may never have recovered to its pre-exploitation level."

FY2004 CRCP Project ID 1224; Project Title: Marine Debris Removal from NWHI; Principal Investigator: Rusty Brainard