Meet the Rice's Whale
Neptune's Note XI
Name: Otherwise known as the ‘Gulf of Mexico whale’, scientists are somewhat divided on exactly what the Rice’s whales’ name should be. Though first scientifically discovered in 1965 by cetologist, Dale Rice, who declared it a local population of the closely related Bryde’s whale, it was only recently1 confirmed to be a completely separate species. What is most likely the first documentation of a Rice’s whale occurred in 1790 when the whaling ship Keziah reported multiple ‘finback’ encounters. These sightings were later dismissed, as fin whales, along with blue, sei and common minke whales, only occasionally visit the Gulf of Mexico but the Rice’s whale is endemic. Hence, some argue that while the scientific name remains Balaenoptera ricei, it should commonly be known as the ‘Gulf of Mexico whale’. Scientists from the New England Aquarium felt so strongly about it, in 2022 they wrote a letter arguing a threefold case as to why it should be named as such. Firstly, they believe specifying a geographic origin within the name encourages a greater awareness of the species’ endangered status. Secondly, the few species in the Bryde’s whale complex2 are inconsistently named after people. And thirdly, promoting a trend of naming whales in honour of people risks glorifying a potentially problematic namesake. Those opposing this argument continue to use the common name ‘Rice’s whale’ to honour Dale Rice for discovering the whales’ existence and celebrating his 60 years of work for marine mammal science. I, remaining as impartial as possible, will continue to use ‘Rice’s whales’ simply because I heard it first.
Family: Balaenopteridae. All nine rorquals, aka the largest group of baleen whales, make up the Balaenopteridae family from the largest known animal to have ever lived, the blue whale, to the smallest of the rorquals, the northern minke whale.
Genus: Balaenoptera. From the Latin balaena meaning ‘whale’ and the Ancient Greek πτερά meaning ‘fin’.
Location: The Rice’s whale is the only baleen whale endemic to the northern Gulf of Mexico, remaining here year-round. They inhabit a particular stretch off the coast of western Florida but have occasionally been sighted throughout the Gulf.
Status: Recently assessed and declared critically endangered and decreasing by the IUCN Red List.
Population: The Rice’s whale is on the brink of extinction, alongside its Gulf of Mexico neighbour, the Vaquita, and is considered one of the most endangered cetaceans in the world. Population estimates say there are 33 individuals left, 16-26 of which are mature.
Weight: As they’re a somewhat elusive species, data for the Rice’s whale is limited. However, an average of the recorded measurements suggest they can weigh up to 30,000kg but it could be as much as 60,000kg.
Length: As an intermediate-sized rorqual, they can grow up to 12.65 metres3.
Anatomy: The streamlined body of the Rice’s whale has a uniformly dark charcoal grey colouring on the upper body with a paler, sometimes pinkish hue on their belly. One of the most distinctive characteristics of the Rice's whale is the presence of three prominent ridges along the top of its flat and pointed head, a trait shared only with members of the Bryde's whale complex. They are almost identical in outward appearance to the Bryde’s whale, however, the Rice’s whale can be distinguished internally by the shape of the nasal bones. They also lack white chevrons down their back and any pigmentation on their lower jaw, a common trait among other members of the Balaenopteridae family. They have a comparatively large dorsal fin with a strong curve, located around two-thirds of the way down their back and around 40 to 50 ventral pleats stretching along the underside of their mouth. These are the creases seen on baleen which allow them to expand the inside of their mouth to consume large quantities of prey in a single gulp.
Diet: The feeding behaviour and diet of Rice’s whales remains largely enigmatic, with limited data available. One tagged individual gave some insight into their habits and it was revealed they have a diel vertical diving pattern. This means they spend most of their day feeding at or near the seafloor and swim closer to the surface at night. Although their exact diet is unknown, lanternfish and hatchetfish are suspected prey due to their abundance in waters where Rice’s whales live. It’s thought that like other baleen whales they may consume more microscopic organisms too such as plankton, krill and copepods but for now, their diet remains a mystery.
Social habits: Rice's whales are generally solitary creatures, often observed alone or in pairs. However, on occasion larger groups of Rice's whales have been sighted and it is believed that these aggregations might be related to feeding activities as is the case in some other whale species.
Unique facts:
They’re known as the newest species of whale in the world as scientists only identified characteristics which distinguished them as a new species in 2021.
Their population is currently less than 100.
Threats they face:
With so few Rice’s whales left they are likely the most endangered whale in the world. Facing the threats that so many cetaceans face across the ocean, they also live in an area heavy with shipping traffic and famous for its oil spills.
Predators: While there are no recordings of any predation on Rice’s whales, their main predator is most likely Orca. Orca are known to frequent the Gulf of Mexico and have been spotted attacking sperm whales and dolphins and are the only known natural predator of the closely related Bryde’s whale too. We also know that Orca are the bravest cetacean of them all so there’s a good chance they have their sights set on the poor little Rice’s whale as well. Large whales under attack from a pod of Orcas will usually try to outrun the pod as a form of escape but because Rice’s whales are endemic they might be more vulnerable to predation.
Oil Spills: As we know, the Gulf of Mexico is prone to frequent oil spills, with 46 incidents releasing nearly one thousand barrels of oil between 2011 and 2013 alone. The 2010 Deepwater Horizon oil spill, the largest in world history, had a devastating impact on the Rice's whale population. The spill covered almost half of their main habitat and reduced the population by 22%. 17% of Rice’s whales were killed from this single event and 22% of females suffered reproductive failure. With the Rice's whale population already critically endangered another oil spill could prove fatal for the species.
Vessel Collisions: Rice's whales are particularly susceptible to vessel collisions as they spend the majority of their nighttime hours within 15 metres of the surface, which puts them at the greater risk of colliding with ships. Although documented ship strikes on Rice's whales are rare, this may be due to underreporting and the species' overall rarity. In 2019 one whale was spotted with a severely deformed spine from what looked like a vessel collision and another deceased whale washed up on shore with severed vertebrae, lung damage, and internal bruises most likely from a ship strike. With busy shipping lanes passing through their habitat, vessel collisions remain a major anthropogenic threat.
Plastic ingestion: The ingestion of plastic debris has been documented as a growing cause of mortality in Rice's whales. The holotype USNM 594665 is the only recorded case of death due to plastic ingestion, where a sharp piece of plastic lacerated the whale's gastric organ, causing internal bleeding and ultimately leading to the whales’ death. While the NOAA considers plastic ingestion a low threat to Rice's whales, the rarity of the species and potential underreporting of such incidents may mask the true extent of this threat.
Ocean Noise: Human activities in the Gulf of Mexico, such as shipping traffic and seismic airgun surveys to source oil and gas fields, generate underwater noise that overlaps with the hearing range of Rice's whales. As the species likely relies on hearing for critical functions, including communication, navigation, finding mates, locating prey, and predator avoidance, increased ocean noise levels can lead to habitat degradation and disruption of these functions. This, in turn, can result in adverse physical and behavioural effects, further threatening an already critically endangered population.
With so few of these lovely whales remaining, we must act now to protect them. By supporting conservation efforts, we can create safer and healthier oceans to give the Rice's whales a fighting chance at survival.
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Amie 🐋
In 2021.
Species which due to a lack of research and data scientists cannot determine as an official separate species.
41.5 feet.
I feel very sorry for the beleaguered little whales..they're born iñto such a dangerous world!