The Sei Whale Of Port Arthur, Texas (Balaenoptera Borealis)
- ThePersaudCatalog
- 6 days ago
- 8 min read
Updated: 2 days ago
This month's article series will be discussing... Port Arthur, Texas! Port Arthur is a small town on the Northeast coast of Texas. Port Arthur is approximately 90 miles (144.841 kilometers) east of Houston, & 317.1 miles (510.32298 kilometers) south of Dallas.
The town is extremely economically important to Texas, as Motiva Oil Refinery, the largest oil refinery in the U.S, is located in Port Arthur.
As the town is located directly on the coast, the town is only approximately 7 feet (2.1336 meters) in elevation.
Due to this low elevation & proximity to the Gulf of Mexico, the town is extremely susceptible to hurricanes.
The town is primarily located in Jefferson County, however, it does have a small strip of land in the neighbouring Orange County. The town census-designated area is approximately 144.1 square miles (373.21729 square kilometers), 46.61% of which is covered in water.
The town's coastlines have a very high amount of marine mammals, which have been written about in the town's newsletter. These marine mammals can be seen around the port or prancing off the coast in the ocean. One of these marine mammals is the Sei Whale.
The Sei Whale is a species of baleen whale found all around the globe. They tend to live in deeper offshore waters, & prefer to stay away from polar regions. The Sei whale is the third largest Balaenopterid whale on the planet, following after the Blue & Humpback Whale, which was previously covered in The Persaud Catalog on April 10th of 2023.
The name “Sei” is very unusual, & comes from the Norwegian word for Pollock. The origin of the word is currently believed to be due to the Sei whale's migration patterns. You see, Sei whales migrate to Norway around the same time that the prime Pollock fishing season starts, meaning that both are seen by Norwegian fishermen at about the same time. As such, they are associated with pollock, & earned this name.
The Sei whale has previously had many issues with whalers, which led to them being put on the endangered species list. They are currently internationally protected to help their populations recover, meaning that it is illegal to harvest Sei whales in most cooperating jurisdictions, with a fine of up to 10,000$ per whale in the United States.
Like the majority of whales, they have a life span that is about the same as humans, between 65 & 74 years.
In this article, we will discuss the discovery & life, the mating procedures, habits, tactics, practices, & strategies, the distribution, & the scientific details of the Sei Whale. With that being said, let us delve into this behemoth.
The Discovery & Life Of The Sei Whale
The Sei whale was discovered by René-Primevère Lesson, a French surgeon, naturalist, & herpetologist, in the year 1828.
The Sei whale is approximately 44,092.452437 pounds at adult size, & 14.2 meters (46.58793 feet) long. Some Sei whales can be as small as 12.2 meters (40.02625 feet), while the largest ever recorded was 20 meters (65.6168 feet). They do not grow for their entire lives, & have a set stopping point.
As said in the introduction, the Sei whale is the third-largest species of whale in the Balaenoptera genus. The lifespan of the Sei whale is 70 years on average, but it can go up to 74 years. Since this is a cetacean, it is extremely intelligent. They do display some level of intelligence, but in contrast to a bottlenose dolphin or an orca, they are not very smart. However, in contrast to the majority of other oceanic animals, they rank extremely high. They are, in fact, some of the best communicators of the ocean. They are often solitary aside from breeding, & they do communicate with other whales. Occasionally, they can also be found in very small groups of 2 to 5.
With all current fossil records, it can be estimated that this species has existed for at least 13.65 million years.
Sei whales are not dangerous to humans or human vessels, & tend to just stay away from humans in general. They used to be captured by humans for their meat & oil; however, with their international endangered status, whalers generally avoid them. Sei whales are not territorial, as they migrate & do not maintain one steady area.
Sei whales can swim by moving their lower body up & down, & propelling themselves forward. Their flippers are used for steering, similar to the steering wheel of an automobile. Their buoyancy is maintained by their blubber, as the blubber is generally less dense than the water surrounding it. Being one of the fastest swimming whales, they are able to swim at a maximum of 30 miles per hour.
Like the majority of other Cetaceans, they are only able to sleep by turning off half their brain at a time. They tend to “sleep” near the surface, not to drown.
These whales primarily feast on krill, copepods, & small fish that can fit through their baleen plates. To maintain their body weight, they have to eat 2,000 pounds (907.1847 kilograms) of food per day. They hunt diurnally, in 5 to 20 minute dives. Their primary means of locating food is echolocation, similar to that of bats. Due to their behemoth size, they have extremely few predators. Their main predators are larger sharks, & large killer whales, though parasitic crustaceans are common amongst these whales.
The Sei whale is dark grey, with a cream coloured underside. Additionally, they have a small protruding dorsal fin about 2/3rds of the way down their back.
As of 2025, they have an estimated population of 50,000. In the mid-20th century, 300,000 sei whales were killed for their meat & oil, which led to the massive population decline. Thankfully, their population trend is now considered to be increasing.
The Mating Procedures, Habits, Tactics, Practices, & Strategies Of The Sei Whale
The Sei whale breeds via sexual reproduction. This species is not hermaphroditic, & has two distinct sexes. All Sei whales tend to become reproductively mature at 8 to 10 years of age. Their breeding system is polygynous, as one male will mate with multiple females in each breeding season. Breeding occurs during the winter, in temperate oceanic regions, usually in the southern hemisphere.
Once the females & the males initiate copulation & complete the mating ritual, the males will not have any involvement in the calf’s life. Their gestation takes 11 to 13 months. One pregnancy tends to only yield 1 child, as the children are so large at birth that the mother has to go through extreme physical strain to gestate more than one. The calf will be 15 feet (4.572 meters) long, & 1,500 pounds (680.3886 kilograms) at birth.
The mother will nurse the baby for 6 to 9 months. During the later months, the baby will learn to eat solid foods such as copepods & krill, so that it can get used to that diet. Once the mother is getting ready to stop breastfeeding, she will migrate with the child to one of the optimal food grounds. After the baby departs from the mother to begin a life of its own, the mother most likely won’t have another child for at least a year to recover, & rest.
The Sei Whales' breeding interval depends upon the individual whale, however, it generally doesn’t last longer than 2 years. Interestingly, researchers have noted that there has been a recent increase in pregnancy. It is unclear why exactly this is, but a new hypothesis has emerged dictating that this increase is in response to human predation.
The Distribution Of The Sei Whale
The Sei whale is found all across the globe, except for in Hudson Bay, Baffin Bay, the Mediterranean Sea, & Antarctic regions. The Sei whale is sporadic in its migrational patterns, as it may visit a certain area, & then not visit for many years after that.
Generally, they are observed in deeper waters, though they can occasionally be seen leaping out of the water. It is rare to see them from the coastline, so much so that it is normal not to see Sei whales in a certain location for 2 to 3 years. It is unclear where exactly they breed, as tracking them is extremely difficult.
The Scientific Details Of The Sei Whale
Possibly the most interesting thing about the Sei Whale, or whales in general, is their blowhole located atop their skull. What is not often known is that the blowhole on a whale, is that it is their nostril. Since they have a hole atop their head, they do not need to get completely out of the water to breathe. This helps them preserve energy & sleep properly. They use their blowhole by taking breaths of air at the surface, then contracting the muscles around the blowhole so that the blowhole is tightly closed. They close it while underwater so that water does not get into the whales' lungs. When they blow their blowhole, the resulting water stream can be up to 13 feet high.
Their bones are not hollow but instead are somewhat thin. Since they are baleen whales, they have tooth plates that they use to strain krill. Additionally, they have frills around their teeth that will catch any debris & dirt from entering the whale's mouth. The sei whale will have 219 to 400 baleen plates in total. These teeth plates are made from keratin, similar to that of a human hair. These teeth are dark in colour, & their frills are white.
As of 2025, we are unable to find any records of their fossils that are available to the public domain.
Unfortunately, the Sei whale is one of the most understudied baleen whales, so we don’t know very much about their movements, skeletons, or very much of anything else.
Their phylum is Chordata, meaning that they developed these 5 characteristics. All species under the phylum of Chordata develop 5 similar characteristics either in adulthood or as juveniles. The characteristics that they develop include, a notochord, dorsal hollow nerve cord, endostyle or thyroid, pharyngeal Slits, & a post-anal tail. & three middle ear bones.
Their class is Mammalia. Their order is that of Artiodactyla, which are even-toed ungulates. Species categorized under Artiodactyla are ungulates, hoofed animals which bear weight equally on two of their five toes; these toes are the third & fourth toes. The other three toes are either present, absent, vestigial, or pointing posteriorly.
Their infraorder is that of Cetacea. Key characteristics of this infraorder are their fully aquatic lifestyle, streamlined body shape, often large size & exclusively carnivorous diet. Another characteristic is their incredible social intelligence. There are roughly 90 species categorized under Cetacea.
Their family is that of Balaenopteridae. All family members have a series of longitudinal folds of skin running from below the mouth back to the navel. These furrows allow the mouth to expand & unhinge in a way when feeding, permitting them to suck in large amounts of food & swallow in one gulp. There are currently 10 species categorized under this family.
Their genus is Balaenoptera. There are currently 8 species categorized under this genus. Their binomial name is Balaenoptera Borealis.
Directories / Credits
Citation No. 1: “Sei Whale”, Written by Unknown, & Published at an Unknown Date. Published by World Wildlife. Retrieval Date: November 22nd, 2023.
Citation No. 2: “Balenoptera Borealis: Sei Whale”, Written by Nancy Shefferly, & Published at an Unknown Date. Published by the Animal Diversity Web. Retrieval Date: November 22nd, 2023.
Citation No. 3: “AnAge: The Animal Ageing & Longevity Database”, Written by Unknown, & Published at an Unknown Date. Published by AnAge. Retrieval Date: November 22nd, 2023.
Citation No. 4: “Sei Whale”, Written by Unknown, & Last Updated on October 30th of 2023. Published by the National Oceanic & Atmospheric Administration Fisheries. Retrieval Date: November 22nd, 2023.
Citation No. 5: “Sei Whale: Balaenoptera Borealis”, Written by J. G. Cooke, & Last Updated on June 25th, 2018. Published by the International Union for Conservation of Nature. Retrieval Date: November 22nd, 2023.
Citation No. 6: “Sei Whale”, Written by Unknown & Published at an Unknown Date. Published by Animalia. Retrieval Date: November 22nd, 2023.
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