Biology and management of deepwater snappers of Hawaiian Archipelago

Marine Fisheries Review, Spring, 1993 by Wayne R. Haight, Donald R. Kobayashi, Kurt E. Kawamoto

Somerton and Kobayashi(12,13) explored the possible consequences of increasing the minimum size limit for opakapaka from 1 to 3 pounds or initiating a 1-3 month seasonal closure of the fishery. Their results from computer simulation indicated that both management strategies could substantially benefit the fish population in terms of increasing the spawning stock biomass. The potential increases ranged from 15-300% after a time period of 5-10 years, depending on the initial condition of the stock. Maximal benefits are attained if sublegal fishing mortality is minimal (i.e. small fish are avoided or released alive) in the case of a size limit increase, and if a seasonal closure effectively reduces the total annual fishing mortality (i.e. there is no compensatory increase in fishing effort during the open season). It is unlikely that the long-term equilibrium yield would increase; however, the population would be less vulnerable to recruitment overfishing and the associated catastrophic stock decline. The State of Hawaii is currently evaluating these and other management options (e.g. bag limits, areal closures) in response to concerns of deepwater snapper overfishing, primarily in the MHI.

Research Needs Pertaining to Management

Details of the reproductive biology are minimally adequate for most of the primary Hawaiian deepwater snapper species. More age and growth studies are needed, particularly for the younger and smaller fish, with enough data to better define the magnitude of growth variability. Discrepancies in growth estimation due to methodological differences in aging (e.g. Morales-Nin and Ralston, 1990; Radtke, 1987; Smith and Kostlan, 1991) need to be addressed and resolved, as this information forms the foundation for cohort/ virtual population analysis, or stock synthesis assessment models. Movement patterns of adults and the extent of egg and larval dispersal need further study to clarify the identity of individual stocks, which would help determine the temporal and spatial scale for effective management. (1) (WPRFMC) Western Pacific Regional Fishery Management Council. 1991. Annual bottomfish and seamount groundfish report, 85 p. (2) S. Ralston and K. E. Kawamoto. 1985. A preliminary analysis of the 1984 size structure of Hawaii's commercial opakapaka landings and a consideration of age at entry and yield per recruit. U. S. Dep. Commer.. NOAA, Natl. Mar. Fish. Serv., Southwest Fish. Cent., Admin. Rep. H-85-1, 9 p. (3) (WPRFMC) Western Pacific Regional Fishery Management Council. 1988. 1986 annual report of the fishery management plan for the bottomfish and seamount groundfish fisheries of the western Pacific region, 150 p. (4) S. Ralston and K. E. Kawamoto. 1987. An assessment and description of the status of bottom fish stocks in Hawaii. U. S. Dep. Commer., NOAA, Natl. Mar. Fish. Serv., Southwest Fish. Cent. Admin. Rep. H-87-7, 55 p. (5) R. B. Moffit and F. A. Parrish. In review. Temporal and spatial utilization of habitat by juvenile Hawaiian pink snapper, Pristipomoides filamentosus. (6) D. A. Ellis, E. E. Demartini, and R. B. Moffitt. 1992. Bottom trawl catches of juvenile opakapaka, Pristipomoides filamentosus (F. Lutjanidae), and associated fishes, Townsend Cromwell cruise TC-90-10; 1990. U. S. Dep. Commer., NOAA, Nat]. Mar. Fish. Serv., Southwest Fish. Sci. Cent. Admin. Rep. H-92-03, 33 p. (7) S. Ralston and K. E. Kawamoto. 1988. A biological assessment of Hawaiian bottom fish stocks, 1984-87. U. S. Dep. Commer., NOAA, Natl. Mar. Fish. Serv., Southwest Fish. Cent. Admin. Rep. H-88-8, Honolulu, Hawaii, 60 p. (8) D. A. Somerton and D. R. Kobayashi. 1990. A measure of overfishing and its application on Hawaiian bottomfishes. U. S. Dep. Commer., NOAA, Natl. Mar. Fish. Serv., Southwest Fish. Sci. Cent. Admin. Rep. H-90-10, 18 p. (9) J. R. Beddington and J. G. Cooke. 1983. The potential yield of fish stocks. FAO Fish. Tech. Pap. 242, 47 p. (10) D. A. Somerton, B. S. Kikkawa, and A. R. Everson. 1989. Biological assessment of the Hawaii bottom fish stocks and the southeast Hancock Seamount armorhead stock, 1988. U. S. Dep. Commer., NOAA, Natl. Mar. Fish. Serv., Southwest Fish. Cent. Admin. Rep. H-89-6, 34 p. (11) D. Kobayashi, Natl. Mar. Fish. Serv. Southwest Fish. Sci. Cent. 2570 Dole Street Honolulu, Hawaii 96822, unpublished data. (12) D. A. Somerton, and D. R. Kobayashi. 1990. Some effects of increasing the minimum commercial size limit of opakapaka, Pristipomoides filamentosus. U. S. Dep. Commer., NOAA, Natl. Mar. Fish. Serv., Southwest Fish. Cent. Admin. Rep. H-90-3, 10 p. (13) D. A. Somerton, and D. R. Kobayashi. 1990. Some effects of a seasonal fishing closure on opakapaka, Pristipomoides filamentosus. U. S. Dep. Commer., NOAA, Natl. Mar. Fish. Serv., Southwest Fish. Cent. Admin. Rep. H-90-16,9 p.