Figure 9. — Catches of postlarval pink shrimp entering 

 Little Shark River and Buttonwood Cannal, July 1966 to 

 June 1967. 



the relations among spine count, season, moon 

 phase, and area. It appears that older shrin-ip 

 (i.e., those with more spines) occur in winter 

 and that there is a lunar cycle in their 

 occurrence which may be related to the number 

 of hours of night flood tides in excess of night 

 ebb tides. 



Programs have been written for recording 

 catch and environmental data on tapes and for 

 summarizing the physical and biological 

 measurements. Analysis of the data by using 

 multivariate statistics after appropriate trans- 

 formations will begin after the completion of 

 field and sorting work. These programs were 

 developed for work on juvenile shrimp data, 

 and should require little modification for use 

 with postlarval catch data. 



C. P. Idyll and M. A. Roessler 

 Project Leaders 



Institute of Marine Sciences, 

 University of Miami 

 (Contract No, 14- 17-OOOZ- 187) 



highest peak of abundance in July was followed 

 by an abrupt drop to a low level in August. A 

 minor peak appeared in September, and there- 

 after abundance remained low. In the firsthalf 

 of 1967 a minor peak occurred in February 

 and abundance was increasing in June (fig. 10). 



At Joe River station, there were three 

 periods of high relative abundance during 1966. 

 The first and smallest was in January, the 

 second was in June, and the third and largest 

 was in September. In the first half of 1967, the 

 pattern was similar to that in 1966; a peak 

 occurred in January and a period of high 

 abundance was developing in June (fig. 10), 



A comparison of the abundance at the two 

 stations shows that periods of abundance in 

 Buttonwood Canal correspond reasonably well 

 with those in Joe River, except that peaks 

 may occur at the latter station 1 month before 

 they do in Buttonwood Canal. 



A comparison of the mean monthly sizes 

 of shrimp at the two stations shows that shrimp 

 were consistently larger in Joe River than 

 in Buttonwood Canal. On an annual basis (July 

 1966 to June 1967), shrimp from Joe River 

 averaged 2.5 mm. (0.1 inch) carapace length 

 larger than shrimp from Buttonwood Canal. 

 Mean sizes differed by as much as 4.8 mm. 

 {O.Z inch) carapace length in some months. 



Analysis of the data for 1966 provides the 

 first opportunity to compare the abundance of 

 shrimp at the two stations with the commercial 

 catch of small shrimp on an annual basis. 

 Periods of abundance in Buttonwood Canal 

 corresponded, in general, to subsequent peaks 

 of abundance in the commercial catch, but this 

 relation was not as apparent as in earlier years. 

 The data from Joe River, however, showed a 

 good relation to the commercial catch. Three 

 periods of high abundance were observed which 

 corresponded well with three subsequent 

 periods of increased abundance of small shrimp 

 on the grounds. Lag periods for the Joe River 



VARIATIONS IN ABUNDANCE OF JUVENILE 



PINK SHRIMP EMIGRATING FROM THE 



EVERGLADES NATIONAL PARK ESTUARY 



TO THE COMMERCIAL CATCH 



The relative abundance of emigrating juve- 

 nile pink shrimp was determined in the past 

 by sampling at a single station in Buttonwood 

 Canal with a channel net. After extensive tests 

 with several types of gear, we learned that 

 reliable subsamples of the migrants could be 

 taken with light, mobile "wing nets." The 

 development of this gear made it possible to 

 establish a second sampling station in upper 

 Joe River (the major outlet in the estuary) in 

 the western outlet of Whitewater Bay, and 

 thereby improve the accuracy of the abundance 

 estimates. 



The relative abundance of juvenile shrimp 

 in Buttonwood Canal varied during 1966, The 



o o BUTTONWOOD CANAL 



• • JOE RIVER 



Figure 10. — Relative abundance of juvenile pink shrimp 

 emigrating from two stations in the Everglades National 

 Park estuary. 



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