YIELD PER RECRUIT MODELS OF SOME REEF FISHES OF 

 THE U.S. SOUTH ATLANTIC BIGHT 



Gene R. Huntsman,' Charles S. Manooch III, 1 and Churchill B. Grimes 2 



ABSTRACT 



Yield per recruit models for red porgy, Pagrus pagrus; vermilion snapper, Rhomboplites aurorubens; white 

 grunt, Haemulon plumieri; red snapper, Lutjanus campechanus; black sea bass, Centropristis striata; gag, 

 Mycteroperca microlepis; scamp, M. phenax; snowy grouper, Epinephelus niveatus; and speckled hind, E. 

 drummondhayi, the most important species to both recreational and commercial fishing off North Carolina 

 and South Carolina, are strikingly similar, and suggest that there is a single strategy for managing reef fishes 

 in the South Atlantic Bight For all species, yield per recruit at median recruitment ages increased rapidly in 

 response to increasing F (instantaneous fishing mortality rate) until F = 0.3-0.4. Thereafter, only small 

 increases in yield resulted from large increases inF. Major gains in yield at all but very small values of F (F < 

 0.15), resulted if recruitment to the fishery was delayed to age 3 or older. The value of M (instantaneous 

 natural mortality rate) affected the magnitude of yield/ recruit but had little effect on the shape of the re- 

 sponse surfaces. 



The annual total recreational and commercial catches of reef fishes provides a preliminary estimate of max- 

 imum sustainable yield if the following assumptions are accepted: 1) F > 0.3, 2) recruitment ages approx- 

 imate those required to produce maximum yield per recruit, and 3) recruitment is sufficient to saturate the 

 available habitat. Preliminary estimates of the relative fishing power (per day) of different components of the 

 fishery are headboats, 1.0; commercial handline boats, 1.3-1.5; and reef trawlers, 3.8-5.2. 



In this paper we examine the implications of yield per 

 recruit models to management of the reef fishery in 

 the South Atlantic Bight. We examined models for 

 each of the several important species in this fishery to 

 determine if there was a single pattern of yield re- 

 sponse that, in turn, would allow development of a 

 coherent management philosophy. 



The Fishery 



Warm Gulf Stream-influenced water and irregular 

 rocky substrates allow occupancy of the outer con- 

 tinental shelf of the U.S. South Atlantic Bight (Cape 

 Hatteras to Cape Canaveral) by a community of 

 primarily Caribbean, deep reef fishes. Principal 

 species include groupers (Mycteroperca and Epi- 

 nephelus), snappers (Lutjanus and Rhomboplites), 

 porgies (Calamus and Pagrus), and grunts (Hae- 

 mulon) (Huntsman 1976a). The black sea bass, Cen- 

 tropristis striata, is abundant at more temperate reefs 

 nearer shore. 



Reef fishes support both recreational and commer- 

 cial fisheries in the area. About 40 headboats, about 



'Southeast Fisheries Center Beaufort Laboratory, National 

 Marine Fisheries Service, NOAA, Beaufort, N.C. 28516-9722. 



! Southeast Fisheries Center Beaufort Laboratory, National 

 Marine Fisheries Service, NOAA, Beaufort, N.C; present address: 

 Department of Horticulture and Forestry, Blake Hall, Cook College, 

 Rutgers University, P.O. Box 231, New Brunswick, NJ 08903. 



260 charter boats (usually six passengers or fewer), 

 and numerous private boats operate in the rec- 

 reational fishery. The last two groups exert a greater 

 fraction of the fishery effort in Georgia and Florida 

 than in the Carolinas. The commercial fishery has 

 two main segments — handline vessels and trawlers. 

 Traps are also used occasionally, especially for black 

 sea bass. Handline fishing is with hook and line re- 

 trieved by hydraulic or electric reel. Trawling is 

 relatively new in the area and had little acceptance 

 until Sea Grant programs in South Carolina and 

 Georgia introduced the "high-rise" trawl in 1975 

 (Ulrich et al. 1977). When used by knowledgeable 

 snapper fishermen skilled in fathometer reading, the 

 high-rise trawl can be exceptionally effective in tak- 

 ing reef fish. 



The magnitude of the recreational catch is only partly 

 known. Headboats landed about 773 t annually from 

 1972 through 1974 at North Carolina and South Car- 

 olina ports (Huntsman 1976a), and the catch for the 

 entire bight averaged 972 t from 1976 through 1980.' 

 Catches by charter and private boats are unknown, 

 except for an estimate by Manooch et al. ( 1 98 1 ) of the 

 1978 charter boat catch in North Carolina (about 

 91 t). 



Manuscript accepted Mav 1983. 



FISHERY BULLETIN: VOL. 81, NO. 4. 1983. 



'Unpublished data, Southeast Fisheries Center Beaufort Labora- 

 tory, National Marine Fisheries Service, NOAA, Beaufort, NC 



28516-9722. 



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