SALT WELL WATER FACILITIES 



AT THE BUREAU OF COMMERCIAL FISHERIES 



BIOLOGICAL LABORATORY, HONOLULU 



By Eugene L. Nakamura, Fishery Biologist 



Biological Laboratory, Bureau of Commercial Fisheries, Fish and Wildlife Service, 

 U.S. Department of the Interior, Honolulu, Hawaii 



Abstract. — A salt well water system was developed in Honolulu to maintain skipjack 

 tuna (Katsuwonus pelamis) in captivity. Problems encountered with the system in- 

 eluded accumulation of rust from the cast-iron casing in the well, inability of the well 

 to provide sufficient water for additional fish pools, inaccessibility of the aeration trays 

 for cleaning, necessity of frequent cleanings of the fish pool due to algal growth, and 

 inability to observe the fish closely because of wind ripples. (Tliese problems were rem- 

 edied by drilling a larger well with an asbestos-cement casing, by building a new 

 aerator with trays spaced farther apart and easily accessible, and by enclosing the new 

 pool in a building. 



A salt-water system was developed at 

 the U.S. Bureau of Commercial Fisheries 

 Laboratory's dock site in Honolulu in 1958 

 to maintain skipjack (Katsuwonus pela- 

 mis), a pelagic tuna, in captivity. Salt 

 water from a well was used because of its 

 freedom from sediments, pollution, dilu- 

 tion by rains, and fouling organisms (bar- 

 nacles, mollusks, annelids, etc.) . The sys- 

 tem comprised a well, a pump, an aerator, 

 a sump on which the aerator rested, and a 

 fish pool (fig. 1). Poly vinyl-chloride 

 pipes were used. The well, properties of 

 the water, and the development of a suit- 

 able aerating device have been described 

 in detail by Strasburg [preceding article 

 in this collection]. While skipjack were 

 being kept in the pool (Nakamura, 1960), 

 certain shortcomings of this original sys- 

 tem became apparent. These problems 

 and their remedies are described in this 

 report. 



The casing of the w^ell Avas a 3i/2-inch 

 cast-iron pipe. Rust from this casing w^as 

 deposited within the plastic pipes and on 



the perforated trays of the aerator. A 

 layer of rust up to a millimeter thick lined 

 the pipes after 18 months of use. Al- 

 though rust was believed not to be harm- 

 ful to the fish, it Avas undesirable because 

 it reduced the bores of the pipes and the 

 perforations in the trays and indicated de- 

 terioration of the well casing. 



The limitations of the well's capacity 

 became apparent w^ien over 100 gallons 

 per minute were pumped, for the water 

 level in the well then dropped below^ the 

 foot valve, which was 6 feet below the sur- 

 face. This inadequate flow precluded the 

 installation of additional fish pools. 



It thus became apparent that a new well 

 was required with a noncorrosive and non- 

 toxic casing and of a capacity which 

 should accommodate planned expansion. 



The aerator was originally constructed 

 so that the trays could be removed for 

 cleaning. After about a year and a half 

 of intermittent use, however, warping of 

 the trays and swelling of the wood sep- 

 arating the trays made removal impos- 



169 



