Diel and Seasonal Occurrence of Pink Shrimp, 

 Penaeus duorarum Burkenroad, in 

 Two Divergent Habitats of 

 Tampa Bay, Florida 



By 



CARL H. SALOMAN, Fishery Biologist 



Bureau of Commercial Fisheries Biological Laboratory 

 St. Petersburg Beach, Fla. 33706 



ABSTRACT 



Pink shrimp, Penaeus duorarum , were sampled for 17 months in two divergent 

 habitats in Tamp Bay, Fla. Information was obtained on size and sex of the shrimp, 

 water temperature, salinity, light transmission, and activity in relation to moon 

 phase. Catches were larger during darkness and rose as temperature decreased 

 from about 30° C. to 14° C. Larger shrimp were caught in darkness than in daylight 

 throughout the period. Larger shrimp were also caught at the station having lowest 

 salinity and incidence of transmitted light. In dark phases of the moon greater 

 numbers of shrimp were caught than during light phases. The size of shrimp 

 reached a peak in April and May after an average increase in length of about 1 mm. 

 carapace length per month. Female shrimp were larger than males in all samples 

 except two. 



INTRODUCTION 



The pink shrimp, Penaeus duorarum , is one 

 of three principal penaeids caught in the Gulf 

 of Mexico and along the southeastern coast of 

 the United States. It supports a sizable bait- 

 shrimp fishery in Tampa Bay, Fla., and is 

 occasionally harvested offshore near the Bay 

 (Saloman, 1965). This report results from 

 ecological investigations in Tampa Bay and 

 concerns some of the habits of pink shrimp 

 and their abundance in relation to biological 

 and hydrological factors. The importance of 

 understanding inshore behavior and develop- 

 ment of young shrimp lies in the fact that 

 estuaries serve as nurseries for shrimp 

 which as adults support offshore commercial 

 fisheries. The significance of the estuary in 

 the life cycle of certain penaeid shrimp is 

 widely recognized. 



Diel sampling was undertaken at two Tampa 

 Bay stations representing different types of 

 habitat. The Egmont Key station (fig. 1) is in 

 relatively clear water, has a depth of 4 to 

 6 m., and swift tidal currents (1.5 knots; U.S. 

 Coast & Geodetic Survey, 1951). Mean salinity 

 was 33.2 p.p.t., and the range was 29.3 to 

 35.2 p.p.t. Attached vegetation ( Thalassia 

 testudinum and Syringodium filiforme) was 

 abundant in each sampling period, but the 

 plants became partially defoliated during the 

 winter. Bottom sediments were a fairly uniform 



Figure 1.-- Sampling stations in Tampa Bay, Fla.-- Egmont 

 Key (triangle) and Old Tampa Bay (star). 



