By Caitlin Scully, naturalist
The past week on the Marietta was as eventful as ever.
Southbound gray whales are still making their way toward their birthing and breeding lagoons in Baja California. Some days we’ve seen nearly 20 whales! Most are traveling individually, though some groups have been observed.
Seeing calves is always a highlight, though the encounters are often brief. We glimpsed very young calves with two mothers that didn’t quite make it to the lagoons before giving birth. Both sets were very reclusive; the mothers barely came to the surface to breathe, and we saw more of the calf than the parent. These calves were very small and one may have still had its fetal creases – horizontal wrinkles along the sides of its body. Fetal creases form when the calf is curled up within the mother for 12 months. They disappear within a week of birth. We made sure these special encounters were brief – just two to three views for our passengers – to ensure that mother and calf weren’t stressed.
Once again we witnessed mating groups. Many were in groups of three to four whales, but we were stunned to witness a group of eight grays that we believe were flirting and mating. The whales were blowing and diving in unison, offering spectacular views of two, sometimes three, sets of flukes at a time. They were rolling and rubbing against each other as they swam. This was a special encounter! A large group of common dolphins sped over to the whales to investigate.
Seeing so many whales in a single day means that we are able to distinguish differences among them. We’ve seen large and small whales, thick and thin, adult and juvenile. We’ve seen flukes raked with orca tooth marks. We’ve also seen whales showing effects of human influence. The flukes, or tails, of whales and dolphins are not made of bone. Instead, they consist of dense connective tissue, similar to our ears. This means these structures can easily be sliced. As the photos show, we have seen whales with slices on their flukes, dents in their tail stocks (the narrow part of their body just before the flukes), and even whales missing parts of their flukes. Boat props or entanglement in fishing gear can cause these wounds. Many of these gruesome wounds heal, but the connective tissue does not fuse back together.
Other interesting encounters this week included Risso’s dolphins, common dolphins, pacific white-sided dolphins, sea lions, and a mola mola. We’re looking forward to next week!