Current State of the Art:
In commercial fish farming, such as the breeding of Atlantic salmon, fish roe is artificially fertilized in special containers. After 24-48 hours, a representative number of eggs is randomly selected, removed and treated with diluted acetic acid to assess the resulting fertilization rate per incubator. Through this treatment, the eggs lose their natural opacity, become transparent and can be examined under a light microscope. Until now, this inspection has been done manually, and is heavily dependent on the individual experience and knowledge of the operator. Additionally, the acetic acid treatment leads to a change in the internal structure of the eggs (denaturation), which can lead to interpretation errors in the microscopic evaluation.
A fully automated device for the non-destructive examination of fish eggs by means of Optical Coherence Tomography (OCT) allows capturing tomographic image data similar to Computer Tomography within a matter of seconds. The scanned fish eggs remain viable and can be examined in their natural state. To this end, the eggs are transferred into a water filled sample container, which is designed to let the eggs slide into fixed positions for measuring. The OCT probe above the sample container is positioned fully automatically above the egg to be tested. The camera integrated in the probe detects blastodiscs in the fish eggs and provides the coordinates for the subsequent OCT measurement. The data obtained are then evaluated and logged online. With the help of the determined fertilization rate, it is then possible to calculate the expected number of hatching eggs per incubator.