April 20, 1999

SECOND QUARTER 1999 MILESTONE REPORT FROM HAWAII UNDERSEA RESEARCH LABORATORY TO DIRECTOR, NATIONAL UNDERSEA RESEARCH PROGRAM.

OBJECTIVE 1: ELIMINATE AND PREVENT OVERFISHING AND OVERCAPITALIZATION

PM: By 2004, 50% (86 of 269) Fewer Overfished Fisheries (Stocks

Subject to Overfishing).

Evaluation of non-lethal methods for assessment of overfished deepwater snapper resources.

Purpose. To estimate bottomfish densities within proposed refugia and adjacent open fishing areas. The abundance and sizes of two indigenous snapper species Etelis carbunculus (ehu) and E. coruscans (onaga) and the exotic snapper Lutjanus kasmira (taape) demonstrate the effectiveness of the State of Hawaii's management plan for commercial fishing.

Efforts. Twelve Pisces V and fourteen RCV-150 dives were conducted in 1998 within areas that, after 1998, will become restricted refugia and in open fishing areas around the Hawaiian Island chain. During Pisces V operations ehu, onaga and taape densities were measured. RCV-150 dives were conducted during nighttime operations to assess benthic habitats and faunal prey communities.

Customers. The State of Hawaii benefits by an enhanced understanding of the effectiveness of its fisheries management plan. The fishing industry receives long-term benefits by assuring that a sustainable deepwater snapper resource is maintained. The scientific community receives a valuable resource for evaluating the relationships between species concentration, habitat and prey assemblage.

Significance. Currently the U.S. Department of Commerce lists both ehu and onaga as overfished species. This is because the spawning potential ratio (SPR) had dropped below the critical threshold of 20% (ehu; 1997 SPR=6.9%: onaga; 1996 SPR=3.5%). These criteria are generated solely from commercial catch data. Therefore it is impossible to assess the effectiveness of the state's management plan using standard methods because data is only available for open fishing areas. The development of a new, non-lethal, method of assessment using submersible and ROV observations provides a tool to evaluate variations between refugia and open fishing areas.

Success. Short "high light" tapes have been created from the submersible dive tapes and presentations made in several public forums to educate the public on the problems of management of deepwater snapper resources and generate support for the recently established management measures including refugia.

Statistical analysis of the data will be conducted after all tapes are reviewed. Preliminary indications are that ehu, Etelis carbunculus, are associated with submerged coral reefs. They are found near undercuts in the reef and usually found near probable forage fish, particularly Symphysanodon moanaloae. They were rarely seen with the ROV or drop video camera, but were frequently seen from the submersible. Their relative sedate and sedentary behavior lead us to believe that ehu density can be estimated from submersible transects. Onaga, Etelis coruscans, on the other hand, is not closely associated with the bottom. These fish were seen in small groups traveling off the bottom. Submersible transects are not apt to be useful in assessing their abundance. Bait stations conducted from the submersible, however, did attract schools of onaga on several occasions and appears to be a useful tool for their assessment.

The ROV, though not useful in snapper resource assessment, produced superior video images of the habitat and associated fauna including probable snapper prey species. The quality of these images greatly benefits species identification and habitat characterization making the ROV a valuable tool for ecosystem evaluation.

Future steps. Work continues on analyzing and quantifying information from the dive videotapes. The presence of all observed organisms and their association with the various benthic habitats encountered was recorded. Depth and associated substrate data from swath mapping of the study areas was also obtained. This information was digitized and imported into an Archview GIS format. When completed, the information on species abundance and observed habitat can be coupled with the dive track of the submersible and combined with the swath map information for detailed GIS queries.

Another field season consisting of 12 Pisces V and 14 RCV-150 dives is planned for August and September 1999. These additional data will provide a before and after closure comparison of the refugia and open fishing areas. This will become the base-line for a time-series study that will include data from future stock counts, which will more clearly elucidate the effectiveness of the state's fisheries management plan.

Investigators contributing to this report:

Robert B, Moffitt, National Marine Fisheries Service

E. Gordon Grau, Hawaii Institute of Marine Biology

James D. Parrish, Hawaii Cooperative Fishery Research Unit

Walter Ikehara, Department of Land and Natural Resources

Christopher Kelley, Hawaii Institute of Marine Biology

Frank Parrish, National Marine Fisheries Service

Kim Holland, Hawaii Institute of Marine Biology