Photography I³S

One of the biggest problems we have encountered in estimating the population was how to make sure we do not count the same individuals again. Each fish is a living organism, it moves and could be counted twice. Another clue was whether we met them at exactly the same spot. Particularly important information, since we would understand their spatial distribution, whether they stay / reside at the same place.
From studying the bibliography we found out about tiny tags that can be attached with a thread. This method was easily rejected because it was impossible for our big hands, while wearing gloves, to achieve such a delicate process. The threads could also have an effect on their wellbeing during growth. This method is better not applied to vulnerable species.
Another idea was marking them with a tiny dot of a different color, with the use of an underwater marker. We contacted Edding Hellas, who supplied us with appropriate markers, which worked underwater. But their chemical composition contained ingredients that could be toxic to the seahorses, so this idea was abandoned as well. That is why we ended up using a free licensed software – I³S (Interactive Individual Identification System). This software is designed to identify and recognize the detailed “footprint” of their bodies, through an algorithm. More specifically, the area identified is the side view of the seahorses head. To run the software, seahorses had to be photographed at a very close range (macro photograph), so that their “pattern” was distinct, as in the example below.

An example of the seahorse’s head – profile impression Macro photographs for identifying them through the I³S program  Macro photographs for identifying them through the I³S program Macro photographs for identifying them through the I³S program Macro photographs for identifying them through the I³S program  Macro photographs for identifying them through the I³S program Macro photographs for identifying them through the I³S program  Macro photographs for identifying them through the I³S program Macro photographs for identifying them through the I³S program  Macro photographs for identifying them through the I³S program  Observation that arose after a closer look at the photograph – notice the parasitic “lice”