This study deals with development of decision support tools for warmwater pond aquaculture. Efforts are directed at refining the POND© software and developing a new farm-level decision support tool. Refinements to POND© focus on general issues related to program maintenance, enhancements to the enterprise budgeting tool within POND©, and a task-oriented interface for assisting users in accompli...

The variability in the factors affecting the sex ratios of Nile tilapia (Oreochromis niloticus) was studied using pair spawns from the Egypt, Ghana, and Ivory Coast strains. Sex ratios from 129 progeny groups were determined by microscopic inspection of the gonads. Of the 12,450 progeny sexed, 54.14% were males; this differed significantly from a 1:1 sex ratio (P < 0.001). Sex ratios from the 1...

Immersion protocols have been unsuccessful in consistently producing all-male tilapia at a high enough ratio for them to be commercially viable. This study explored ultrasound to improve on the results of previous immersion studies. Experiments were carried out to evaluate immersion with ultrasound as a sex-reversal procedure by 1) assessing duration of treatment (one vs. two hours) on the effi...

To assess the risk posed by vertical transmission of viral haemorrhagic septicaemia virus, VHSV, in rainbow trout ova, an experimental challenge study was conducted. Prior to the fertilisation process samples of milt and/or ova were infected with VHSV. Virus was not detected from either the fertilised ova or hatched fry. These results indicate that the risk associated with VHSV vertical transmi...