Saltwater Recirculation System and Laboratory at the 



Exploratory Fishing and Gear Research Base 



Pascagoula, Mississippi' 



By 



DONALD A. WICKHAM, Fishery Biologist 



National Marine Fisheries Service 



Exploratory Fishing and Gear Research Base 



Pascagoula, Mississippi 39567 



ABSTRACT 



An approximately 10,000-gal capacity saltwater recirculation system and lab- 

 oratory were built to conduct controlled behavioral studies of the responses of fish 

 to harvesting gear. This facility consists of an 18-ft diameter by Ay.t-ft deep pool, 

 a 4-ft deep by 15-ft long rectangular tank, and several water tables. Design com- 

 promises resulting from space limitations and construction of the laboratory in an 

 existing one-story structure are discussed- Techniques using a commercial swim- 

 ming pool diatomaceous-earth filter for removing iron precipitate from the subsur- 

 face salt water and particulate matter from the high salinity wedge river water 

 used to supply the system are described. The system's components and operation 

 are also briefly described. 



A saltwater recirculation system and a lab- 

 oratory were built at the National Marine Fish- 

 eries Service (NMFS) Exploratory Fishing 

 and Gear Research Base, Pascagoula, Miss., in 

 1969. These facilities were erected to study 

 controlled behavioral responses of fish to har- 

 vesting gear. This system and laboratory are 

 described because the medium size (about 

 10,000 gal), moderate cost, and the approach 

 to problems in design and operation may be 

 of value to others. 



Guidelines for the design were taken from 

 Marvin and Wheeler (1961), Clark and Clark 

 (1964), and Marvin and Proctor (1964). 



The saltwater system and laboratory were 

 built within a one-story concrete block struc- 



^ Contribution No. 213. 



ture adjacent to the net-storage shed at the 

 Base's dock site on the Pascagoula River (Fig- 

 ure 1). Construction of a saltwater labora- 

 tory in the 800 ft' of floor space available re- 

 quired considerable design compromises. Space 

 limitations prohibited the construction of large 

 storage tanks used in most recirculation sys- 

 tems. Maximum utilization of available space 

 was possible by designing a dual-capacity sys- 

 tem — combining experimental pool and water 

 reservoir. 



Construction of the recirculation system on 

 an existing ground level concrete slab pre- 

 vented placing a sump below the experimental 

 tanks; therefore, a modified sump was incor- 

 porated to permit isolation of the pool-reser- 

 voir during experiments. This sump was 



