Skip to main content

The Dolphin with the Damaged Fin

When we first saw the little dolphin with a large injury to its dorsal fin in 2013, we called it “DD” for “damaged dorsal”. It had a big chunk of flesh missing, we think from a close-call with a boat propellor. It is shown above with Square Notch (its mum) and the fresh wound in May 2013.

DD Right Side and Mum [Square Notch] August 2013

By August that year, DD’s wound had largely healed leaving a prominent scar. It was a good sign that the calf was in otherwise healthy and Square Notch a good mother.

Six years later, in November 2019, we found an older DD seemingly fine and active in a group of sub-adult common dolphins near Mornington.

DD Right Side 2019

If you look closely at the above images you can see a good match for the location and size of the scar on the right side of the dorsal fin, making an almost certainly DD.

One of our challenges with identifying dolphins from fin-ID photos is that the shapes and marks on their fins change with time. This is quite obvious if you compare the changes to Square Notch’s fin between May to August 2013 in the top two images. (DRI researchers have taken over 100,000 fin-ID images during three decades of study).

DD Left Side 2019

The image of DD’s left side shows how the injury distorted its fin.

Usually, it’s hard to ID young dolphins with “clean fins” so we need to look for close associations with adults as in the above images with DD and Square Notch. Then we need to wait until they get nicks in the back of their fin, so we can ID them. Fortunately, DD is an odd example!

DD is now about 6 years old and part of a group of sub-adult (teenage) common dolphins living in Port Phillip. We don’t know if DD is male or female as it’s quite hard to tell their sex without seeing their abdomen.

DD and Square Notch are part of a remarkable community of common dolphins that came into Port Phillip in 2006 and stayed. It’s the only bay in the world where common dolphins have left the open ocean to permanently live.

Remember to respect dolphins by obeying the Marine Mammal Regulations. Don’t approach closer than 100m for boats or 300m jetskis. DETAILS HERE

In another 3 to 5 years DD will be of an age where it can mate. I wonder if its offspring will also be so accident prone!

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.