Application of geometric morphometrics in the early detection of opercular deformities in intensively reared gilthead sea bream (Sparus aurata)

Study Object: 
gilthead sea bream, a salt water species from the Mediterranean Sea and the western European and African coasts, with a reputation as a highly valued food fish, both in aquaculture and fisheries.
Principal Aim: 
detect the nature of opercular deformations and their possible causes, and to establish a detection protocol for use in aquaculture.
methodology: 
geometric morphometrics, claering and staining, histology, ct-scanning, experimental set-ups.
Researcher: 
Nguyen Phuc Thuong

 

The importance of reared finfish in the Mediterranean area is significant: each year, 40.000 tonnes of marine finfish is produced for consumption. Skeletal deformities, which occur more frequently in reared fish, provide enormous economic losses.

In this thesis, I look for early signs of cranial deformities in gilthead (Sparus aurata). Early detection is essential for the fish farm to improve the quality and quantity of the crop. For this purpose, an experiment was performed in which larvae were reared in five different treatments and this from day one until the age of thirty days. The treatments were: (1) clear water, (2) water in which algae (nanno) or (3) an artificial algae substitution was added, or (4) water in which an antibacterial agent or (5) a green pigment was mixed. At regularly times, samples of fish were taken.

Using pictures, taken from the preserved larvae an outline-based morphometric analysis will be performed to see if there are significant changes that coexist with deformities and to derive if there are significant differences in incidence of cranial and postcranial malformations between the different treatments. Also, a histological look will be taken at the cartilage and bone tissue of some normal and deformed larvae.