Photo-ID is the heart of whale research

Photo-ID has been around for decades: it allowed researchers to study the marine mammal populations and opened the door to awesome whale research worldwide. So what exactly is photo-ID, why is it important, and how can you gain skills in this discipline? Find out in this post.

A picture says more than a thousand words

Whales and dolphins’ broad distributions, underwater lifestyles, and migration patterns make them challenging subjects to study. Populations are constantly changing; group compositions keep shifting, and individuals are frequently on the move. One of the techniques cetacean scientists use is photographic identification (photo-ID) to study what is happening to marine mammals.

With Photo-ID, researchers identify individual animals by comparing photos to existing databases. Each image brings the researchers a step closer to understanding associations, group compositions, population sizes, and a myriad of other important information.

photo-id whales
Credit: Anaïs Remili

How does photo-ID work?

Photos are among the essential types of data cetacean researchers collect when they go on boat surveys. For dolphin studies, the critical element to capture is the dorsal fin. The fin is as unique as a fingerprint; each has a particular shape, pigmentation, scars, nicks, and notches. Some individuals have very distinctive marks, while others with “clean” fins are more challenging to distinguish (check out the Figure below to see how different fins can be!). When whales are the study subjects, the photo-target is the unique pattern on their characteristic tails or the side of their bodies.

After the photoshoot, it’s analysis time. By matching the photos to a catalog of individuals that have been sighted before within an area, the researchers can determine whether the individual on the new photos has been photographed before. Photo-ID catalogs generally consist of pictures of the left and right sides of dorsal fins (and the tail for some whales) and a codename for each individual. The codename is usually the species abbreviation plus a number, but sometimes the individuals also receive “real” names. After all, it’s easier to remember that a dolphin is called Jessica than to recognize it as TT508.

Photo-ID requires a lot of patience

Although looking through photos of marine mammals undeniably sounds fun, photo-ID also requires a lot of patience and an eye for detail. Some catalogs contain images of hundreds or even thousands of individuals, so matching can require countless office hours. Nowadays, the software can help automatically find individual matches. However, manual checking is still inevitable to ensure that the software does not make mistakes.

Why is photo-ID useful?

Despite being a relatively simple technique, photo-ID yields an impressive variety of information. Researchers can find out which individuals associate with each other, where they live and how far they travel. Furthermore, we can learn about personality differences by analyzing the behavior of individuals identified through photo-ID. Additionally, bioacoustic analyses paired with photo-ID studies can show communication variations, such as group dialects or individual characteristic whistles.  Over the long term, photo-ID studies can also reveal life spans, calving intervals, life history characteristics and provide population size estimates.

How you can practice your skills

Photo-ID is a crucial element in many marine mammal studies, so gaining relevant skills will give you a considerable step ahead if you want to pursue a career in cetacean science. For example, borrow a DSLR camera to familiarize yourself with photography. Not everyone has whales in their backyard, unfortunately, so practice on other wildlife, your pets, or even go to the pool with your friends and pretend they are regularly surfacing cetaceans (maybe don’t say you are comparing them to whales, though).

There are also plenty of citizen science projects that need your help with analyzing data; this is a great way to practice your photo-ID matching skills while making a valuable contribution to research! You can email researchers/universities/institutes to ask if they require any photo-ID volunteers. They usually have loads of work so they will be happy to receive your help. Bonus: this allows you to make connections, plus it looks great on your CV. Alternatively, you can check out the links below for online photo-ID projects of a range of marine mammal species.

Lastly, getting an internship can help you improve your photo-ID skills. We have a post dedicated to finding internships here:

How to find an internship / volunteering experience?

Eline van Aalderink is a recent MSc Marine Biology graduate from the University of Groningen (the Netherlands), where she specialised in marine mammal ecology and conservation biology. She is currently working as a marine mammal research assistant/supervisor at Archipelagos Institute of Marine Conservation in Greece.

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