- ze'oo N 



SS'OO 



26»00 



ZS'OO 



flO°00 



25°00 



ATLANTIC 

 OCEAN 



83»00 W. 



82'00 



8I'00 



80*00 



Figure 1. — Geographic location of the Sanibcl and Tortugas pink shrimp trawhng grounds. 



fishery. A few vessels trawl in the area throughout 

 the year. Catches are landed at Fort Myers, Fort 

 Myers Beach, Punta Gorda, Placida, or Naples, 

 Fla. 



The Tortugas grounds comprise about 10,000 

 km. 2 (3,000 square nautical miles) of trawlable 

 bottom west of Key West, Fla. A'lost fishing is 

 between the 18- and 55-m. depths. The fishery 

 began in 1950 and has produced about 5,442,000 

 kg. (tails) of pink shrimp annually. Peak catches 

 occur from October through March each year, 

 and 300 to 500 vessels participate in the fishery 

 (Iversen and Idyll, 1959). Some trawhng occurs 

 on the Tortugas grounds throughout the year. 

 Catches are landed at Key West, Marathon, 



Everglades, Fort Myers, Fort Myers Beach, or 

 Tampa, Fla. 



DATA REQUIREMENTS AND DESIGN OF 

 EXPERIMENTS 



To obtain the information required to estimate 

 mortality rates, a group of animals is drawn from 

 the standing crop, marked, and returned to the 

 former environment. We assume that subsequent 

 observations of the marked group are applicable 

 to the population of which the group is believed 

 to be part. Requirements for a successful experi- 

 ment are that: (1) the e.xperimental animals either 

 are imaffected by the capture-mark-release proc- 

 ess, or the effect is accurately measured and 



492 



U.S. FISH AND WILDUFE SERVICE 



