585 



Abstract — Much of the information 

 available on the population status of a 

 harvested fish species is obtained from 

 landings data. When fishing restric- 

 tions are in place, fishery-dependent 

 data are reduced and assessments 

 rely more heavily on fishery-indepen- 

 dent data. Stock assessments of red 

 porgy iPagrus pagrus) have shown a 

 declining population and have led to 

 a number of management measures, 

 including a moratorium on fishing 

 this species. To investigate how a lack 

 of fishery-dependent data during a 

 moratorium would affect stock assess- 

 ment results for red porgy. we con- 

 ducted simulations representing a 

 range of periods of moratorium. As 

 data were removed from the model, 

 stock status indicators and projec- 

 tions became increasingly variable. 

 Projections estimated that a 12-year 

 moratorium would be needed for stock 

 rebuilding, but simulations showed 

 that uncertainty surrounding stock 

 assessment estimates would increase 

 after three years without fishery- 

 dependent data. Unless additional 

 data are collected during periods 

 of strict fishing regulations, it may 

 be difficult to accurately assess the 

 length of time needed for the stock 

 to rebuild and to assess the popula- 

 tion status. 



Effects of a simulated fishing moratorium on 



the stock assessment of red porgy iPagrus pagrus) 



Michelle L. Davis (contact author) 



Department of Fisheries and Wildlife Sciences 

 Virginia Polytechnic Institute and State University 

 100 Cheatham Hall 

 Blacksburg, Virginia 24061-0321 

 Email address: midavisl gvt.edu 



Jim Berkson 



National Marine Fisheries Service RTR Unit 

 Virginia Polytechnic Institute and State University 

 100 Cheatham Hall 

 Blacksburg, Virginia 24061-0321 



Manuscript submitted 28 March 2005 

 to the Scientific Editor's Office. 



Manuscript approved for publication 



19 January 2006 by the Scientific Editor. 



Fish. Bull. 104:585-592(2006). 



For commercial or recreational fisher- 

 ies, a large portion of the information 

 available for assessment of the popu- 

 lation status of a species is obtained 

 during harvesting operations. When 

 harvest restrictions are in place, fish- 

 ery-dependent data are reduced and 

 assessments become more reliant on 

 fishery-independent data. During a 

 moratorium, harvest ceases completely 

 and new methods may be required to 

 assess the status of the stock. It is 

 assumed that stock assessment results 

 accurately portray the current popula- 

 tion and that these results are used in 

 policy decisions affecting future stock 

 status. However, stock assessment 

 results are not solely a product of the 

 population being assessed, but are 

 also a function of stock status, data 

 sources, and sample size. Although 

 most stock assessments include close 

 evaluation of data sources, few assess- 

 ments include the quantification of 

 potential effects of changes in fish- 

 ery-dependent data as a byproduct 

 of changing harvest restrictions. We 

 therefore investigated the effects of 

 the reduced availability of fishery- 

 dependent data on stock assessment 

 results and management decisions. 



To accomplish this goal, we con- 

 ducted model simulations for red 

 porgy (Pagrus pagrus) that is found 

 off the coast of the southeastern 

 United States from North Carolina 

 to Florida. This reef-associated fish is 

 an important resource for commercial 

 and recreational fisheries (Huntsman 



et al.. 1978; Low et al., 1985). Red 

 porgy have an extensive native range 

 and inhabit coastal waters on both 

 sides of the Atlantic Ocean in both 

 hemispheres (Pajeulo and Lorenzo, 

 1996; Labropoulou et al., 1999; Hood 

 and Johnson, 2000). They are associ- 

 ated with live-bottom reef habitats on 

 rocky outcroppings and therefore have 

 a patchy distribution off the south- 

 eastern United States (Grimes et al.. 

 1982). Red porgy are protogynous 

 hermaphrodites; females dominate 

 the smaller size classes, and males 

 occur at all ages (Manooch, 1976). Fe- 

 males generally reach maturity from 

 age-1 to age-2 at approximately 300 

 mm total length, and the majority of 

 red porgy age-5 and older are mature 

 males (Hood and Johnson, 2000). 



Red porgy have been harvested ex- 

 tensively by three major fisheries (Fig. 

 1): commercial, recreational, and a 

 fishery comprising large-scale charter 

 boats called "headboats" (Huntsman 

 et al., 1978). All three fisheries use 

 mainly hook-and-line gear and target 

 a wide variety of temperate reef fishes 

 (Chester et al., 1984), not exclusively 

 red porgy. In the early 1980s, the red 

 porgy stock began showing signs of 

 decline (Collins and Sedberry, 1991; 

 Vaughan et al., 1992). As the stock 

 decline became more evident, the 

 minimum size limit was raised (Table 

 1) by the South Atlantic Fishery Man- 

 agement Council (SAFMC), the group 

 mandated with managing red porgy 

 and other fish off the coast of North 



