and East Delta grounds. Seasonal trends gen- 

 erally corresponded and annual fluctuations 

 paralleled one another quite closely. The 

 overall trends for the 5 years were also 

 comparable and indicated a slight rise in each 

 of the four subareas. The data therefore sug- 

 gest that the bottomfish present nearshore 

 and offshore were contingents of the same 

 population unit and that the factors governing 

 abundance on one ground operate similarly on 

 the other ground as well. 



To determine how the commercial bottom- 

 fish populations reacted to fishing, an analysis 

 was made of effort and catch statistics as well 

 as of mean annual abundance indices (figure 8). 

 Nearshore and offshore data were combined 

 and trends calculated. Upward trends in com- 

 mercial landings from both the West and East 

 Delta areas were associated with rising trends 

 in fishing effort. Trends in overall level of 

 population size, as indicated by the mean 

 annual catch-per-hour values, were also 



30 



20 



2 10 



WEST OF DELTA 



LANDINGS 



T I I r 



EAST OF DELTA 



— 30 



O 



— 20 



— 10 



60 



o 

 I 



40 



FISHING EFFORT 



i r 



i r 



— 60 



o — 



40 



20 



I I. Oh 



o 

 a 



INDEX OF ABUNDANCE 



I I I I I 



1959 I960 1961 1962 1963 



— I 1 1 1 1 



1959 I960 1961 1962 1963 



1.0 



Figure 8. — Relations between available bottomfish population, landings, and 

 fishing effort in the north-central Gulf of Mexico, 1959-63. 



16 



