Going eye to eye with this Robust Clubhook Squid is one of the many experiences that await visitors who tour Moss Landing Marine Labs. Large squid are favorite snacks of sperm whales, as the artist’s rendering on the wall suggests. You’ll notice that the sperm whale doesn’t have any teeth on its upper jaw. How did MLML grad Mariah Boyle use this fact to keep the peace between villages in Fiji? Find out in The Case of the Missing Sperm Whale Teeth!
Posts Tagged ‘whales’
By Gillian Rhett, Invertebrate Zoology & Molecular Ecology Lab
If you saw Nate’s post last month, you may have wondered: where does a whale carcass go? Sometimes it will wash up on a beach, which is lucky for us because that means we can collect all kinds of samples and information that help us learn more about how whales live and die.
But most whale carcasses don’t wash up on beaches. Initially, the gases that are a byproduct of the decomposition process build up inside the carcass and it floats, providing food for surface-dwelling animals such as seabirds. But when the remaining tissues and bones sink to the seafloor, that’s not the end of the story!
Graduate student Scott Gabara caught this fantastic photo while out in the field with PISCO. This humpback was putting on a great display for the eyes with its enthusiastic breaching. MLML student Casey Clark is currently conducting research on humpback whales – check out his student profile to learn more!
Each year, humpback whales migrate between their feeding areas in high-latitude places such as Alaska, California and Antarctica to their breeding areas in more tropical regions such as Mexico, Hawaii, Central America, and the South Pacific. This means that during the winter, all of the animals should be in the breeding area and none should be in the feeding area. It turns out that this isn’t true. All around the world, people have seen humpback whales in feeding areas during the winter when they are expected to be in the breeding area. This leads to the following questions: Who are these animals that spend their winters in the feeding area? Are they mostly males? Females? Juvenile animals? Why would they give up their chance to reproduce for the year?
It was these questions that led me to choose my project. For my master’s thesis at Moss Landing Marine Labs, I will attempt to answer at least some of them. To do this, I will look at the animals off the coast of central California, an important feeding area for humpback whales that breed off the coast of Central America. I will be looking at the sex-ratio (the number of males present compared to the number of females present) and the proportion of juvenile animals (the number of young animals compared to the number of adult animals) in this area throughout the year. By seeing how the sex-ratio and the proportion of juvenile animals change from summer to winter, I will be able to determine who is using the area in the winter. For example, if the sex-ratio is 1:1 in the summer (1 male present for every 1 female present) and 1:2 in the winter (1 male present for every 2 females present), I will know that there are more females than males using this area in the winter.
The different sexes and age groups of humpback whales are known to migrate to the breeding area at different times. Adult males are the first to begin the migration to the breeding area, followed by non-pregnant females, juvenile animals and finally pregnant females. This pattern would suggest that female animals in the late-stages of pregnancy remain in the feeding area longer than most other whales. This theory is supported by observations from the feeding area and during migration, but it has never been confirmed that pregnant females remain in the feeding area longer than most other members of the population. I will test this theory by determining the pregnancy rates of females found in the feeding area in the late fall and early winter. If a greater proportion of these females are pregnant than would be expected, this theory would be confirmed. The identification of this area as critical habitat for these pregnant whales would have profound implications for their conservation and management.
Stay tuned to find out how I find the whales, and then collect samples with a crossbow!
by Mariah Boyle, Ichthyology Lab
December 2008: Our boatload of kai vulagi (visitors) are heading towards Survivor Island (the one they used in Survivor: Fiji) for some exploring. All of a sudden, a whale spouts only about 50 yards away from our tiny boat. The whale is small, a juvenile. We follow it for a while – it is breathing often and doesn’t dive even when we are close. I know it is stressed. I can’t get a great look at it but notice its blowhole is offset to the side a bit.
I snap a bunch of photos to send back home to my marine science friends. I’m an ichthyologist, after all – I study fish, and I was out of my element trying to identify this whale in Fiji!
After returning home from the trip I looked up pictures of whales that live in the waters around Fiji and tried to identify it. Before finding a definitive answer, I got an email from Fiji: the whale had died and washed up on shore. A friend emailed me a Fiji Times article on the whale, which reported that upper teeth were not found in the whale, while the bottom 40 were removed using a ladder because the whale was so big! A lot of villagers thought that the whale’s top teeth had been stolen very early in the morning, as the teeth are used for tabua in Fiji, a sacred singular whale tooth on a string used for all sorts of formal ceremonies. I’d seen one right before I left Fiji presented to the island’s chief, Tui Mali, asking him to bless the engagement of a couple working on the island.
After reading that article it all clicked: no teeth in the upper jaw meant it must have been a sperm whale, which only have teeth in their bottom jaw! I looked up sperm whales online and sure enough they also have an offset blowhole. I showed the pictures to a friend and she agreed on the identification. I had been getting lots of messages asking me to try to identify the whale, and now I knew what it was! I researched a bit about sperm whales and wrote a blog for our group’s website to tell everyone about the whale. I felt good about identifying the whale and putting to rest the mystery – little did I know how it would be connected to my next visit to the same island… (more…)