In summarizing the data for each month, the 

 number of hours fished was tabulated by sub- 

 subareas that measured 10 minutes of latitude 

 and 10 minutes of longitude. 



The monthly subsubarea totals were summed 

 on the basis of the geographical subarea 

 previously described. Since coverage for ef- 

 fort within the north-central Gulf was in- 

 complete, the estimated total number of hours 

 fished by all vessels every month in each 

 subarea (E) was calculated from information 

 obtained through canvasses by the formula: 



E = Nit 



where N = total number of trips by all vessels 

 in the subarea; and x" = average number of 

 "standard" hours fished per trip in the sub- 

 area by all canvassed vessels. 



Effort statistics used in this study were 

 calculated on the premise that all trawlers 

 were equally efficient; i.e., all vessels had 

 a simple linear relation between traveling 

 time and corresponding catch. 



Size and Distribution of Catch and Effort 



Annual landings varied only slightly from 

 an average of 39,500 tons during 1959-61 

 (figure 3, table 1). Landings in 1962 rapidly 

 increased to a record of more than 48,000 

 tons but returned to the average level in 1963, 

 During 1959-63, annual fishing effort on the 

 grounds fluctuated markedly between 63,000 

 hours in I960 and about 106,000 hours in 

 1962 (figure 3, table 2). 



on both near shore and offshore grounds. It is 

 apparent, however, that the sharp rise in total 

 landings for 1962 was the result of increased 

 effort on both fishing grounds. Catch and ef- 

 fort continued at a high level on the same 

 grounds in 1963. The average effort for the 

 5 years was 23,500 hours, with a maximum 

 deviation of 69 percent. The average annual 

 catch for the same period was 11,000 tons. 



East of the Delta, annual landings remained 

 comparatively stable from 1959 through 1962, 

 averaging 31,600 tons, but declined to about 

 25,000 tons in 1963. A severe reduction in 

 the effort expended offshore was apparently 

 responsible for the decreased catch. Effort 

 expended annually in nearshore and offshore 

 areas (combined) averaged 57,000 hours, or 

 71 percent of the total, with a maximum de- 

 viation from the 5-year mean of 32 percent. 

 Seventy-three percent of the total catch for 

 the 5 years was made east of the Delta. 



Separation of catch and effort data into 

 monthly units of time showed definite patterns 

 of annual and seasonal change within each 

 fishing area (figure 4, tables 3 and 4). 



West Delta-offshore - -Annual bottomfish 

 production ranged from about 10,000 tons 

 (1959) to nearly 3,000 tons (1961) indicating a 

 downward trend during the 3-year period. A 

 threefold increase in production in 1962 was ap- 

 parently due to a measurable upswing in effort. 



It is evident that, seasonally, maximum pro- 

 duction usually occurred early in the year 

 between January and April, whereas minimum 

 production occurred during June through Au- 

 gust. 



125 



100 



75 



o 50 



25 



WEST OF DELTA 



EAST OF DELTA 



TOTAL 



□ -Effort 

 H- Londings 



i 



UfflM 



III 



m 



1959 I960 1961 1962 1963 1959 I960 1961 1962 1963 1959 I960 1961 1962 1963 



Year 



Figure 3. — Effort expenditure and total commercial landings by industrial bottomfish 

 trawlers operating in the north-central Gulf of Mexico, 1959-63. 



Annual landings from grounds west of the 

 Mississippi River Delta declined by more 

 than one-half from 1959 to 1961. This drop 

 was due to a significant reduction in effort 



East Delta-offshore --Production increased 

 sharply from 9,400 tons in 1959 to 14,600 

 tons in 1960, and remained relatively stable 

 through 1962. The catch declined to a low of 



