1400 



1.200 



cr 



< 1,000 



_j 



4001- 



200 



o o DOLLARS 



o o POUNDS 



-J_ 



_L. 



_L- 



1959 I960 1961 1962 



1963 



1964 



1965 



1966 



1967 



1968 



Figure 9. — Estimated weight and value of bait shrimp catch from Galveston Bay, Tex., 1959-68. 



Effects of fishing intensity. - - To approach 

 the second problem, we have expanded our 

 use of the commercial landing statistics. Re- 

 cent changes in the size and efficiency of 

 fishing vessels have been so large that effort 

 statistics over the last 12 years are not com- 

 parable. To standardize the effort statistics, 

 we calculated the relative fishing power of 

 numerous shrimp vessels (defined as the ratio 

 of a boat's catch per unit of effort to that of a 

 standard boat fishing the same area at the 

 same time) and described the relations between 

 this statistic and various vessel charac- 

 teristics. During our initial study, we com- 

 puted the mean power factors for 211 commer- 

 cial shrimp vessels in the Tortugas fishery in 

 January and February 1965. We examined the 

 data to find possible relations between fixed, 

 measurable characteristics of the vessels, 

 such as length, horsepower, and weight, and 

 the power factors. 



The most significant relation was between 

 power factors and vessel length (fig. 12). A 

 subsequent study of 33 vessels fishing in sta- 

 tistical area 19 off the Texas coast in August 

 and September 1967 indicated that the relation 

 between power factors and vessel length did 

 not differ significantly (at the 95-percent level) 

 from that calculated for the Tortugas fishery. 

 With these relations we plan to standardize 

 our effort data so that data on catch per unit 

 of effort are comparable from year to year 

 despite changes in the size of vessels. Changes 



in catch per unit of effort from year to year 

 can then be examined critically to evaluate the 

 effects of long-term changes in fishing in- 

 tensity. 



Richard A. Neal, Project Leader 



The Growth and Distribution of Juvenile 

 Pink Shrimp in the Estuaries of 

 Everglades National Park 



Studies were begun on the growth and distri- 

 bution of pink shrimp in the Whitewater- Coot 

 Bay estuary of Everglades National Park in 

 July 1968. 



Distribution .-- We studied the four main 

 basins in Whitewater Bay and established 

 trawling stations in each. We selected eight 

 stations so that each area had within it a 

 shallow and a deep trawling location (fig. 13). 

 Odd-numbered stations were in water 0.7 to 

 1.1 m. (2.5 - 3.5 ft.) deep, and the even- 

 numbered ones were in water 1.7 to 2.1 m. 

 (5.5 - 7.0 ft.) deep. 



Regular monthly sampling with a modified 

 2-m. (6.6-ft.) roller frame trawl began in 

 September 1968. We scheduled trawling trips 

 near the time of the new moon and included 2 

 nights of sampling at each station. Seven trawl 

 drags each about 100 m. (330 ft.) long were 

 made on each station visit. For each drag the 

 trawl was pulled for 1.5 minutes at a standard 



16 



