FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



their interest in the project and willingness to 

 cooperate. In Febrnary 1959, the same organiza- 

 tions signed another contract with almost identi- 

 cal conditions, except that the Bureau of Commer- 

 cial Fisheries was to bear the additional cost of 

 the water and electricity used in the plant. 



A former horse and mule stable at Paia was se- 

 lected for use as a tilajiia hatchery and its recon- 

 ditioning and convei'sioii began early in December 

 1957, and was completed in all major respects in 

 January 1958. A biologist was stationed at the 

 hatchery from January tlirough December, 1958, 

 and from February through December, 1959. 



This report describes tlie results obtained at 

 the Paia hatchery during the "2 years of its opera- 

 tion. It is hoped that this review of the problems 

 encountered, the methods employed, and the eco- 

 nomic aspects of the operation will prove of value 

 and interest to fishery scientists and to members 

 of the tuna industries who are concerned with the 

 problem of obtaining an adequate supply of live 

 bait. 



The production of bait-size tilapia under 

 natural conditions in two types of ponds, located 

 in the Honolulu area, is described in the appendix. 

 In a brackish-water pond where many natural 

 predators were present, production and survival 

 of young fish were essentially zero. In a fresh- 



water pond with few predators but prevalent can- 

 nibalism, bait-size fish were produced in limited 

 quantities. 



The interesting breeding habits of T. mos- 

 ■tamiica have been well described by Chen (1953) 

 and other investigators. The adult male in breed- 

 ing condition establishes a territory in which he 

 digs a saucer-shaped depression, if the bottom is 

 of sand or uuid, or clears a circular area of algae, 

 stones, or detritus, if the bottom is of hard clay or 

 rock. He then maintains constant vigil over liis 

 ■'nest," chases away any other males that approach 

 too closely, and attempts to herd females into the 

 nest area. If a female can l>e encouraged to 

 spawn, the eggs are extruded over the nest, ferti- 

 lized by the male, and are immediately taken into 

 the mouth by the female. The female then moves 

 away or is cha.sed away by the male. The male 

 remains to guard the nest and to court other 

 females. The eggs hatch in about 60 hours, but 

 the female continues to carry the j'oung in her 

 mouth cavity for another 5 to 8 days. When the 

 young are finally released by the female they form 

 a tight little school near the surface of the water 

 where they are easily dipnetted. If not dipnetted 

 during their first day of freedom they sink to the 

 bottom or middle layers of the tank where they 

 are more difficult to capture. 



Figure 1. — Former stable at Paia, Maui, before being remodeled for use as a tilapia-rearlng plant. 



