83«W. 



— r— 



82»W. \^ 



DRY TORTUGAS '' 



MARQUESAS 



KEYS 



25»N.- 



o„<,<!,{§5*^„»°'=' MARATHON 



KEY WEST 



25 50 



SCALE OF NAUTICAL 

 MILES 



*- f BOUNDARY OF TORTUGAS SHRIMP GROUNDS 



Figure l.--Map of south Florida showing the Tortugas fishing grounds. 



the Keys from Key West to the Dry 

 Tortugas. Although shrimp occur outside 

 the regularly fished area, fishing is diffi- 

 cult and hazardous because of the presence 

 of loggerhead sponges, coral, and other 

 obstructions. Small clear areas are to be 

 found in the outside regions and these are 

 occasionally trawled with the aid of a 

 lighted buoy set out by the fishermen. 



The exploitation of the Tortugas shrimp 

 population developed rapidly, drawing 

 boats from older grounds in Florida and 

 from many other southeastern and Gulf 

 States. By 1951, the landings were over 

 19 million pounds (heads on) and approxi- 

 mately this quantity has been landed in 

 each succeeding year, except 1952, when 

 only 11 million pounds were landed. The 

 catch has thus been maintained over 9 

 years of the fishery. This does not suggest 

 that overexploitation has occurred, but 

 some persons in the industry are certain 

 that the catch has been maintained only as 

 a consequence of a great increase in fish- 

 ing effort coupled with the use of small 

 sizes of shrimp which were formerly 

 discarded. Information on the sizes dis- 

 carded or kept is difficult to obtain, but 



there is a greater tendency for buyers to 

 accept small shrimp in recent years. 



PURPOSES OF THE STUDY 



The principal purpose of this study was 

 to investigate the relation between the 

 size of shrimp and the depth of water 

 where they occur. Fishermen's observa- 

 tions and research data suggested that 

 pink shrimp on the Tortugas grounds in- 

 crease in size as water depth increases, 

 but details of this relationship were lack- 

 ing. A second purpose was to investigate 

 the extent to which fishermen discard 

 small shrinnp. A wide range of sizes of 

 shrimp are caught in the trawl nets. The 

 smallest sizes are often thrown overboard 

 with the vmusable part of the catch, and 

 the extent to which discarding is done is of 

 importance to an understanding of the 

 fishery. A third purpose was to study the 

 distribution of fishing vessels on the 

 grounds to deternnine whether effort was 

 concentrated in certain areas, and whether 

 seasons, weather, occurrence of seaweed 

 and jellyfish, or other factors influence 

 the distribution of fishing. 



