400 
Fishery Bulletin 96(3), 1 998 
Numbers-at-length were converted to numbers-at- 
weight for each species by means of simple allomet- 
ric relationships. 
sustainable basis. SPR is a fraction expressed as the 
ratio of exploited spawning stock biomass in rela- 
tion to the equilibrium unexploited SSB 
Assessment of exploitation effects 
The REEFS model was configured to assess two fish- 
ery management decision-making endpoints, yield- 
per-recruit (YPR) and spawning potential ratio 
(SPR). Fishery management endpoints are relatively 
robust measures of potential yields and recruitment. 
As such, they help to focus on biological (size) and 
fishing (intensity) controls for managing current and 
future fishery production. Because biomass B(a,t) is 
the product of numbers-at-age multiplied by weight- 
at-age, yield in weight Y w from a given species s was 
calculated as 
Y w (F,L',t) = F(f)J B(L\a,t)dL = 
v 
L r (9) 
F(m N(L\a,t)W (Lja,f)dL . 
L' 
Yield-per-recruit (YPR) is then calculated by scaling 
yield to average recruitment from the right-hand side 
of the above equation. Spawning stock biomass (SSB, 
in metric tons [t] ) is a measure of the stock’s repro- 
ductive potential or capacity to produce newborn, 
ultimately realized at the population level as suc- 
cessful cohorts or year classes. Spawning stock bio- 
mass is obtained by integrating over individuals be- 
tween the minimum size of first maturity, L , and 
maximum reproductive size (here assumed to be the 
maximum size L, ) in the stock 
Li 
SSB{t)= j B(L\a,t)dL. (10) 
L 
The size of first capture, L \ is that regulated by re- 
gional fishery management. The modeled fishing 
mortality rate of headboats (and “viewing power” of 
divers) was assumed to remove (and sight) fish with 
a “knife-edged selectivity pattern” (see Gulland, 
1983) over the range of exploitable sizes 
JO if L\a < L' 
{ F(t) if L\a>L ' ' 
( 11 ) 
SPR = 
BSB exploited 
B B B u n f . x pl oit e d 
( 12 ) 
Resultant estimated SPRs are then compared to the 
U.S. Federal standards which define 30% SPR as the 
“overfishing” threshold (Rosenberg et al., 1996). Lin- 
ear regressions of estimated SPRs for snapper and 
grouper were made on 1996 average exvessel prices 
obtained from voluntary Monroe County dealer re- 
ports (NMFS 4 ). Because sale of jewfish was prohib- 
ited, a theoretical 1996 jewfish price was estimated 
as 0.438 of the price of gag grouper on the basis of 
historical average annual price ratios (1987-90). 
Management analyses 
This assessment focuses on 35 reef fish species in 5 
families: groupers, Epinephelinae; snappers, 
Lutjanidae; grunts, Haemulidae; the hogfish, 
Lachnolaimus maximus , Labridae; and the great 
barracuda, Sphyraena barracuda, Sphyraenidae. 
These are the primary targets of the recreational, 
commercial, and headboat fleets. Population dynam- 
ics parameters for each of these fish used in the 
analyses were gleaned from summaries in Claro 
(1994) and taxa-specific literature (Tables 2 and 3). 
The hogfish was grouped with snappers for analyti- 
cal purposes. 
The assessment used the following 7 steps (Fig. 2): 
Step 1 : Conduct visual survey for the reef fish com- 
munity in year t and intercalibrate diver 
sampling efficiency by species, site, and 
year. 
Step 2: Begin management analysis for species s 
using intercalibrated visual survey data to 
compute within-year estimates of L and 
associated 95% confidence intervals from 
the size and abundance data, by species, 
integrated over the range of exploitable 
sizes. 
Step 3: Compute a statistically independent set of 
annual mean estimates of L using fishery- 
dependent headboat data and compare 
these with visual survey estimates. 
Spawning potential ratio (SPR) is a contemporane- 
ous management endpoint that measures the stock’s 
potential capacity to produce optimum yields on a 
4 NMFS. 1996. Fishery Statistics Div., Southeast Fisheries Sci. 
Center, Natl. Mar. Fish. Serv., NOAA, 75 Virginia Beach Dr., 
Miami FL 33149-1003. 
