Caïman

Three mother-calf fin whale pairs have already been observed in the Marine Park this season. Among them is one individual very familiar to researchers: the one they call Caïman. Making her debut in the catalogue in 1986, this female fin whale has been identified 32 summers over the past 35 years, a record in terms of fidelity! She has also been a valuable breeder. If she continues to be observed with the newborn, it would help confirm that Caïman has given birth for at least the fourth time!

In fin whales, it is not always so easy to identify the mother of a calf. Calving take place between November and January, and nursing lasts 6 or 7 months. That means that calves are nearly weaned by the time they arrive in the St. Lawrence, and can therefore be observed swimming with other adults. It is only through repeated observations that researchers can confirm the kinship. In 2004, for example, Caïman was only seen once with a calf, so it is not possible to determined whether or not it was her own.

Caïman gets her name from a resemblance not to a reptile, but to another fin whale nicknamed U2. These two individuals both show a similar notch at the base of their dorsal fins, a similarity that gave rise to an untranslatable play on words in French and, in turn, Caïman’s moniker.

By Camille Bégin Marchand

Caiman (Bp034) can be recognized by its dorsal fin which has a notch at the base. However, this fin whale is not the only one to bear this mark. It can be distinguished from its look-alikes by the irregular contours of the end of its dorsal fin. Moreover, if it arches its back enough, one can see scars at the end of its peduncle. Caiman is a female fin whale known since 1986. She has been observed almost every year since her first identification. In fact, it is the rorqual whale (including fin whales, blue whales and humpback whales) most often seen in the Saguenay-St. Lawrence Marine Park: 30 years out of 33! For many years, Caïman was known to have only one flank. A photo of its two flanks during the same observation session allowed us to see that this individual had a double identification. These photos made it possible to join the two individuals into one.

Photo-identification is a technique used since the 1930s. It consists in using the natural marks (pigmentation, coloration pattern, scars) of individuals to identify them. This technique is used on several animals: whales, seals, giraffes, chimpanzees, zebras, etc. Each species has its own unique characteristics that allow us to distinguish each individual from its congeners. It is very practical in cases where human-made markings such as tags, tattoos or collars cannot be easily applied. Although the steps of this technique seem simple, each photo requires many hours of laboratory analysis. The photos are compared with those of several individuals and matched according to rigorous criteria. The digitization of photos allows us to see even more details. We can sometimes wonder if computer programs could not accelerate the work, but, until now, the human eye remains the most efficient tool to perform this tedious work. This technique also has other uses. Thanks to photo-identification, the research team of the Mingan Islands Cetacean Research Station (MICS) has identified a blue whale (B105) at 30-year intervals on each side of the Atlantic, in the Gulf of St. Lawrence in 1984 and in the Azores in 2014. In 2015, this same blue whale was back on the east coast of North America, recognized once again through photo-identification. It is the photo-identification that allowed us to confirm this 3900 km “migration”.

With the notch at the base of her dorsal fin, Caïman has several look-alikes, including U2 and Bp086. It is the irregular contours of the tip of this fin that make it possible to differentiate Caïman from her fellow fin whales, and, if she arches her back enough, the scars at the end of her peduncle are also diagnostic.

In 2017, Caïman visited the Marine Park with her calf. She was also accompanied by offspring in 1989 and in 2000. In 2004, we observed her just once with calf in tow, which is not enough to affirm that it was necessarily her own. In fin whales, females are believed to be sexually mature by the age of six and reproduce every three years for the rest of their life.

To date, Caïman is thought to be the most commonly identified fin whale in the Marine Park. She was first observed back in 1986! At the time, she already appeared to be an adult.

Longevity in fin whales is estimated to be around 90 years, but older individuals have already been discovered, such as one specimen found in Antarctica that was determined to be 111 years old. Techniques for estimating the age of baleen whales are based on post-mortem counting of the growth layers of various persistent tissues, and not on the layers of wax accumulated in the ears, as was the case in the past. For example, the layers of proteins accumulated in the lens of the eye and the growth of certain bones are two methods used.

A rather general rule of thumb for all cetaceans: the smaller the species, the shorter its lifespan. In the St. Lawrence, harbour porpoises live for 15 to 20 years. Conversely, blue whales live between 85 and 100 years. There are exceptions, however. Bowhead whales might live for over 200 years, making them the longest-living of all mammals. Their secret: bowheads are believed to have the ability to repair their DNA and effectively fight cancer and age-related diseases.

Also, in killer whales and long-finned pilot whales – which form tightly knit matriarchal societies – females live longer than males and well beyond menopause that sets in around the age of 40, which is very rare in mammals. These old females play an essential role in passing down knowledge to the next generations. The entire group benefits from the experience and assistance of the elders, which increases their chances of survival and reproduction.

The well-known Caïman enters the Marine Park at last. This female fin whale differs from other individuals by its dorsal fin, the tip of which is quite irregular. This is what allows us to differentiate her from her lookalikes: U2 and Bp086. Additionally, several pale lines can be seen below her dorsal fin. Caïman also has a few scars at the end of her peduncle. This fin whale is a regular visitor to the Marine Park.

On the morning of August 30, at 7:18, Caïman was fitted with a telemetric tag, 6 nautical miles off of Cap de Bon-Désir. During the tracking, the animal was observed with five other fin whales, two blue whales and a humpback within a radius of approximately 150 metres. All of them were surface feeding. After just over 8 hours of tracking, the telemetric tag fell off of Caïman’s back while she was opposite the mouth of the Saguenay Fjord, near the K54 buoy. Following a two-week break in early August, the Large Rorqual Telemetric Monitoring Project co-led by Fisheries and Oceans Canada, the GREMM, and Parks Canada ends its activities this week. Results will soon be published on the Whales Online website

The gash at the bottom of Caïman’s dorsal fin is a trait shared by many fin whales, such as U2 and Bp086. What helps differentiate her from her look-alikes are the irregular contours of the tip of her dorsal fin. If she arches her back enough just as she dives, a few scars can be seen at the end of the right side of her peduncle.

Caïman was observed on July 28, 2015, 3.5 nautical miles off of Cape Granite and has been seen at least through July 31, 2015. Since she was first observed in 1986, she has been seen almost every year, making her the most observed fin whale in the history of the Saguenay-St.-Lawrence Marine Park. She has also been seen more than once with young.

Male fin whales reach sexual maturity between 8 and 12 years of age and females, between the ages of 6 and 10. Mating takes place in temperate waters between December and January. Gestation lasts between 11 and 12 months. Calving takes place between November and January of the following year, also in warmer waters. Nursing lasts 6 to 7 months. Newborns measure on average 6.4 m and weigh 1.9 t. Females can give birth every 3 years. When calves arrive with their mothers at their feeding grounds such as the St. Lawrence River, they may or may not already be weaned. Caïman was observed with a calf in 1989 and 2000. In the 2004 season, she was seen just once with a young, meaning we are unable to determine whether or not it was her own. A mother-young relationship can be speculated only after multiple observations of the two animals side by side throughout the summer. A genetic test conducted through a biopsy allows such speculations to be confirmed.

Caïman was observed by the GREMM team on July 22 at 11:30, 5 nautical miles off the coast of Cap Granite.

Caïman is most easily identified by her left flank. At the very end of its peduncle on the right side is a scar, although it is rarely visible unless Caïman strongly arches her back before diving.

Another fin whale, U2, strongly resembles Caïman, with a V-shaped gash on his dorsal fin (he has a white spot on the left side). But U2 was last observed in the Estuary in 2011.

Caïman was seen with a young at her sides in 2004. However, with a single observation of this calf that season, it cannot be said whether or not it was Caïman’s.

For the migration of North Atlantic fin whales, a mystery was revealed with a study released in late 2013 in the journal PLOS ONE. Satellite monitoring of 12 fin whales was conducted during their spring journey from the Azores to southeastern Greenland. This trip seems to be less direct than one would think, and it is not made on an empty stomach. En route, these fin whales made hunting stops, especially at mid-latitudes. Hence they alternate periods of active travel and feeding periods. In travel mode, the paths taken are straight lines, while during hunting, movement is multi-directional and travel is slower.

Regions south of the 48° N parallel, less rich than those farther north, are deemed insufficient to meet the needs of the great cetaceans. But plankton density measurements north of the Azores have revealed that these regions were of interest to them, representing a positive ratio between the energy the whales expend on hunting and the energy they gain from the prey they capture.