744 



Fishery Bulletin 92(4). 1994 



Results of the SPM suggest that the Belize fishery 

 is capable of further expansion in most areas but that 

 Jamaican fishing areas are overfished. Current lev- 

 els of effort in Belize seem to be only 10% of the lev- 

 els that would maximize landings of prime commer- 

 cial species. Landings are presently at about half of 

 MSY for this group (Table 5). This is not surprising 

 because many Belizean fishermen report that this 

 fishery is virtually incidental to their lobster fish- 

 ery. In Jamaica, on the other hand, present fishing 

 effort is 41% above the level that would maximize 

 the catch of prime commercial species, but effort is 

 below the level predicted to maximize total fish land- 

 ings. However, the low present catch of prime com- 

 mercial species in Jamaica relative to their appar- 

 ent potential (21% of MSY) is clearly due to the ef- 

 fects of overfishing rather than to under-exploitation. 



Y = 2.74 f- 0.69 flog (() 

 MSY = 1 05t/km 2 



Log effort (hook h/km 2 yr) 



15 



Y = 2.52 f - 0.67 f log (f) 

 MSY = 0.64 t/km 2 



Log effort (hook h/km 2 yr) 



Figure 4 



The relationship offish yield (F) to fishing effort (/) 

 for reef fishing grounds in Belize (B) and Jamaica 

 (J). (A) The relationship for total yield of reef fish; 

 (B) the relationship for prime commercial species. 



The model's predictions must be regarded with 

 caution, however, because of the poor fit of the SPM 

 data. The relationships of CPUE and /"within coun- 

 tries were nonsignificant but positive (Table 4). When 

 the relationship between CPUE and f is non-nega- 

 tive, MSY cannot be estimated: the relationship of 

 yield (Y) with effort (/) continues to increase rather 

 than attain a maximum. Although a negative slope 

 might be obtained if particular data points were re- 

 moved, there was no objective basis for doing this. 

 Thus, when data from Belize and Jamaica were 

 pooled, the negative slope of the regression between 

 CPUE and /"was predominantly based upon the re- 

 lationship between countries. This decreases the ef- 

 fective number of degrees of freedom and diminishes 

 confidence in the estimate of MSY. The estimate may, 

 therefore, serve to establish initial levels of MSY, but 

 if time series of catch and effort are developed in the 

 two countries, the present relationship is likely to 

 be modified and should be reevaluated for each fish- 

 ery and country as data allow. 



The lack of significant relationships between CPUE 

 and /'within the Jamaican and Belizean reef fisheries 

 may arise from several factors: heterogeneity of the 

 fishery among areas; mixing of fish stocks between 

 fishing areas or migration offish into or out of these 

 areas; and disequilibrium of the fisheries in the dif- 

 ferent areas. All of these factors appear to be present, 

 although their relative importance is unclear. 



Heterogeneity is apparent from the differences in 

 composition of the catches within countries as well 

 as between them. Heterogeneity was noted when land- 

 ings were classified at familial or broader taxonomic 

 groupings and likely is greater at the species level. 



Movements of fishes among areas were noted par- 

 ticularly in the Belizean fishery, which is based upon 

 a mix of targeted fishing on spawning aggregations 

 and fishing on the nonspawning, more dispersed 

 phase of the populations. CPUE may be expected to 

 vary between these two phases of the fishery, thereby 

 confounding the use of a spatially based surplus pro- 

 duction model. Separation of these two phases of the 

 fishery is difficult. CPUE is a function of both the 

 degree of aggregation (or behavior) of the fish and of 

 their abundance, which is presumably affected by 

 total f. Therefore, data cannot be used from only one 

 phase of the fishery. Furthermore, the catchability 

 of a particular gear — and hence its impact per unit 

 of /upon fishing mortality — presumably varies be- 

 tween the different phases of a fishery. It may there- 

 fore be necessary to standardize each gear type be- 

 tween different phases of the fishery, as well as to 

 standardize among gears. 



Jamaican, and perhaps Belizean, reef fisheries may 

 be in a state of flux, which violates the model's as- 



