740 



Fishery Bulletin 92(4), 1994 



fishermen noted their fishing grounds on a chart in 

 relation to the cays, and the fishing grounds were 

 assumed to extend to the reef crest. The areas of these 

 grounds were then measured with a planimeter. 



In Jamaica, four line transects orthogonal to the 

 shoreline from nearshore to the shelf edge were car- 

 ried out in each of three areas: Old Harbour Bay, 

 Farquhars Beach, and Great Bay (Fig. 1A). Transects 

 within each area were approximately 2 nmi (=3.7 km) 

 apart. The mean depth of the south Jamaican shelf 

 is 20 m ( Woodley and Robinson, 1977), and the dropoff 

 is at about 50 m (Nicholson and Hartsuijker, 1982); 

 observations of bottom type were made with a glass- 

 bottomed viewing box deployed over the side of a 

 small vessel. Observations were carried out at 4-km 

 intervals of the dominant substrate material (i.e. 

 sand, grass, coral, or mud). The proportion of shelf 

 represented by each substrate type was estimated 

 from the proportion of stations at which the particu- 

 lar substrate type was dominant. The results of these 

 surveys were compared with historical surveys of the 

 Jamaican shelf (Nicholson and Hartsuijker, 1982). 



Data analysis 



Catch and effort data were summed by area, gear 

 type, and species group. Totals were standardized 

 by proportions of the fishing year and of the popula- 

 tion of fishermen surveyed. Fishing effort in a SPM 

 must be expressed in a common unit. Hook-and-line 

 effort (hook h/km 2 ) was selected as the common unit 

 of effort because our surveys indicated that it was 

 the dominant fishing gear in Belize (in terms of inci- 

 dence of use and yield obtained) and the most widely 



used gear overall. Fishing effort from other gear types 

 (i.e. bottom gill net, trap, weir, and spearing) was 

 standardized to hook-and-line gear by using the 

 weighted mean of the ratio of catch rates from the 

 particular gear to the hook-and-line catch rate within 

 each area. Effort was then summed within each area. 

 Catch and effort for each area were standardized 

 per square kilometer of fishing ground. Log-trans- 

 formation of the catch-per-unit-of-effort (CPUE) data 

 (the Fox [19701 variant of the SPM) did not improve 

 the fit, so it is not presented. However, the relation- 

 ship between CPUE and effort (/") was highly nonlin- 

 ear; therefore, the relationship is presented both 

 without transformation and with effort data log- 

 transformed, which linearized the relationship be- 

 tween CPUE and f. 



Results 



Catch and effort 



Annual catch was estimated to be more than four- 

 fold higher off the south coast of Jamaica (998 tonnes) 

 than off the coast of Belize (240 tonnes) (Table 1). 

 When landings were normalized to the area of pro- 

 ductive fishing ground (Tables 1 and 2) (i.e. the por- 

 tion of shelf estimated to be coral and sea grass), yield 

 per unit of area from Jamaican waters (552 kg/km 2 ) 

 was 39% higher than off Belize (340 kg/km 2 ). How- 

 ever, this difference was not statistically significant 

 in a comparison of mean yield from the different fish- 

 ing areas in the two countries (Kruskal-Wallis [KWJ 

 one-way ANOVA: x 2 =0.33, « = 13,P>0.2). 



