BY CAM RENAUD
So, it’s that time of year again when thousands of whales perform the longest marine migration from cold northern waters to the tropics to give birth. They start arriving in Cabo around mid-November and are pretty much gone by the end of March.
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The migration is up to 5000 miles and 1/5th of the distance around the world. At an average speed of 5 mph (8 km/h) that works out to about 100 days of travel just to get down here.
Typically, the younger males arrive first, and the moms and mature males show up by mid-December. Prime birthing time is January after an 11-month gestation period. Late birthing can be problematic as whale moms need to make sure junior is big and strong enough to make the journey back north in the spring. Newborn calves are from 10-16 feet long (3.5 to 5 metres) and weigh about a ton. Although they stay with mom for their first year, this timing also means moms will mate again a month or two after birthing, while still here.
The most frequently seen whale in Cabo waters is the Humpback; followed by Gray whales and then Blue whales – the largest mammal on earth – are a distant 3rd. Humpbacks and Grays are similar in several ways including size and weight, up to 50 ft and 35 tons (16,000 kgs), and a maximum lifespan of up to 70 years.
When I found out humpbacks are also common in Hawaii, I wondered if the pods would debate – “Well we went to Mexico last year let’s do Hawaii this year” – but that’s not the case. The Pacific Ocean has 3 distinct populations of Humpbacks: the West Coast population, the Central North Pacific population and the Western North Pacific population. Each of these groups will spend a season feeding on Krill (small shrimp) and Herring in the North Pacific. They fatten up for the migration, eating as much as 2 tons a day since they typically do not eat during the entire round trip migration period.
The Humpbacks all start heading south, but the West Coast group comes to Mexico or as far south as Costa Rica, the Central North Pacific whales head to Hawaii and the Western North Pacific whales head to waters south of Japan.
Once I knew the West Coast Humpbacks were regulars, I wanted to know how I could tell the difference between a Humpback and a Gray whale. The first thing you usually see when looking for whales is the spout of water, and that is one way to distinguish them. The shape of the blowhole in the top of a Gray whale’s head is rounder than a Humpback’s, a Gray whale’s spout will be about 8-10 ft high and rounder in shape than the 15 ft vertical column a Humpback will make. If you catch a glimpse of the whale’s tail, you’ll see another difference- Grays have a smaller rounder paddle-shaped tail while humpbacks have a larger ‘V” shaped tail. Gray’s also don’t have a Dorsal fin on their back, whereas a Humpback has a nubby dorsal fin. The Humpback’s pectoral (side) fins are also distinctive and the largest appendage of any animal, sometimes over 8 ft (3.5 mts) in length.
Both types of whales exhibit similar behaviours, more or less, including breaching, spy hopping, logging, lob tailing, tail slapping and fin slapping. Breaching is always spectacular to see, likely by a Humpback, as Grays typically stay in the water and only breach when coming up from deep water to breathe, breaking the surface with upward momentum. The humpbacks will breach by achieving a speed of 18 mph (25 km/h) assisted by a final push with those large pec fins. Technically, a breach is defined as at least 40% of the whale’s body clearing the water, otherwise, it’s simply referred to as a jump. Breaching requires a huge amount of energy and is a sign of a very healthy whale as the old and sick need to conserve their energy to simply survive the migration. Spy hopping is when a whale sticks its head out of the water to look around, largely a curiosity move practiced by moms, especially if they have a little one with them. Logging is lying on the surface napping in the warm surface waters. Lobtailing is where a whale will pound its tail on the surface of the water, as an indication of displeasure or warning. Fin slapping may also denote displeasure or can simply be mom playing with junior.
Males and females may do similar things but for different reasons. Big males will breach, tail slap, and fin slap to ward off other males especially when the big guys are trying to hook up with a lady friend.
Humpback males are also famous for their songs while in Cabo – understood to be used for swooning the ladies. The songs can last up to 20 minutes and can be heard as far as 20 miles away. Julio Iglesias has nothing on these guys. Whales are known to have a specific vocabulary, and researchers have been recording the songs to figure out what the different sounds mean. Interestingly, the 3 Pacific populations share the same language unlike other whale populations elsewhere.
At the end of the season, the whales start to head back north. Junior, after consuming their mother’s milk with up to 50% fat for the past couple of months, has packed on about 100 lbs a day. There will be perils along the way. Pods of Orcas will happily make a meal out of junior, which is why a young female will accompany the mom, with the calf swimming between the two for safety.
Sadly, in the past, commercial whaling was the greatest peril. Large-scale commercial whaling was outlawed in most places in 1986 however Iceland and Norway continue limited whaling, and Japan is still doing large-scale commercial whaling. These days the whale population is still only 35% of what it was at its peak, but it is growing at about 5% per annum.
Hopefully, you’ll find time to enjoy and appreciate these visitors while they’re still here. Cheers!
