Development Sequence for  GMT^® 

The YY male technology is under constant development. The first GMT^® (and the broodstock to produce them), developed in a pure strain of Nile tilapia (Oreochromis niloticus) from Egypt, was released in 1995. After the development of the first GMT^®, research on crossbreeding identified a number of superior crossbred GMT^® produced using the Egyptian YY males crossed to females from different pure strains. A longer term breeding programme was also initiated using combined selection to produce a female line giving GMT^® with high percentages of males and faster growth rates. This GMT^® was ready for release in early 2001. The following table summarises development and releases of improved GMT^®.

Table 1. Key developments of GMT^®

Figure 3. Crossbred GMT® (Rel. 2.2- only available in North America at present) has excellent growth rates and is deep bodied with a small head.

Figure 4. A YY male used in the breeding programme to produce GMT® in a red tilapia strain (available towards the end of 2001).  This red strain is actually a uniform pink colour with occasional red tints.  Black markings have been virtually eliminated by breeding. 

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