Bp955, a.k.a. “Ti-Croche”

Distinctive traits

It hook-shaped dorsal fin is strongly curved toward the rear. However, it is the resemblance of Bp955’s dorsal fin with that of the late Capitaine Crochet that earned it the nickname “Ti-Croche”.

It story

The shape of it dorsal fin reminds us of Capitaine Crochet (Bp050), whose death in 2013 represented a great loss. Thanks to a photo-ID follow-up, researchers were able to conclude in May 2018 that Capitaine Crochet is indeed the mother of Ti-Croche. A particularly clear photo of Ti-Croche taken by a GREMM collaborator on May 27, 2018 made it possible to compare it chevron to that of the calf accompanying Capitaine Crochet in a photo taken in 2009. Interestingly, Capitaine Crochet was always one of the first fin whales to arrive in the season. Ti-Croche seems to continue this trend.

In 2016, Bp955, a.k.a. Ti-Croche, had not yet reached it full adult size.


 

Taken from the newsletter Portrait de baleines, July 7, 2017

Last summer, an unknown fin whale made a noteworthy entrance into the Estuary. Its hook-shaped dorsal fin sparked a wave of general hope amongst captains and naturalists in the region. This particular physical attribute evoked the great disappearance of 2013: that of Capitaine Crochet (Bp050). In no time, the new visitor came to be called “Ti-Croche”, especially since this newcomer had not yet quite reached its adult size. But is Bp955 (its identification number) really the offspring of the late Capitaine Crochet?

Separation of a sample of fat and skin © GREMM

The alleged death of the famous fin whale Capitaine Crochet had caused quite a stir both within the Marine Park’s whale-watching community as well as amongst researchers and the general public. As readers might recall, this female had been spotted emaciated and dragging a crab trap, and attempts to rescue her failed to produce the desired results; Capitaine Crochet left the Marine Park, never to return.

She owes her moniker to her dorsal fin, which was strongly arched backwards. But even if the resemblance between Capitaine Crochet’s dorsal and Bp955’s encourages quick conclusions, it is best to err on the side of caution: the shape of a fin is not a sufficient criterion for determining family relationships. For example, Bp955’s dorsal fin resembles that of another individual identified in the GREMM catalogue, Bp910.

In fact, there is only one technique that can be used to obtain reliable genetic data for identifying kinship: biopsies. A sample of a few milligrams of skin and fat is taken using a dart and then analyzed in the lab, where the DNA is extracted. Therefore, in the absence of a biopsy, we are unable to confirm (or infirm!) that Bp955 is the calf of Capitaine Crochet!

Learn more:

Fin whale data sheet