Minke Whale
Order Cetacea : Family Balaenopteridae : Balaenoptera acutorostrata Lacepede

Description. Smallest of the baleen whales in the Gulf of Mexico, adult minkes only reach up to 10.2 m in length and 10 metric tons in weight. As with all baleen whales, females are slightly larger than males of comparable age. Minke whales have a very narrow and pointed rostrum and a broad white band on the dorsal surface of the flippers. Coloration is dark gray to black above and white below. The baleen plates are yellowish-white, or cream, colored. The dorsal fin, located in the latter third of the back, is tall and falcate and the throat grooves end just beyond the flippers.

Distribution in Texas. Worldwide in distribution, minke whales are the most numerous of baleen whales. They are not listed as endangered. Known in Texas on the basis of a single stranding from Matagorda Peninsula on March 29, 1988.

Habits. As with most other baleen whales, minke whales tend to be highly migratory and move to cold temperate and polar waters in spring and then return to warmer waters in autumn. The movements of minke whales in the North Atlantic are heavily influenced by spawning concentrations of capelin, upon which they feed. Also, seasonal segregation by sex and age is pronounced in these whales. Mature males tend to migrate farther north in spring and summer than do females and immatures.

Minke whales feed on krill; fish, including sand lace, sand eel, salmon, capelin, mackerel, cod, coal fish, whiting, sprat, wolffish, dogfish, pollack, haddock, and herring; and squid. Capelin are the dominant food item of North Atlantic minkes.

Although baleen whales are generally thought incapable of echolocation, minke whales are known to produce a variety of sounds including narrow band pulses suitable for echolocation. Such sounds are described as "series of clicks" and may aid in locating food concentrations. Other sounds of these whales are described as "grunts, pings, zips, ratchets, and clicks."

In the North Atlantic, mating occurs from October to March. Females give birth to a single calf in early winter. The gestation period is about 10 months. Newborn minke whales are 2.4-2.7 m in length and the lactation period is 4-5 months. Age at sexual maturity is approximately 6 years for males and 7 years for females.

Remarks. The minke whale that stranded on the Texas coast was an immature female that was alive when first observed. This not only was the first of its kind known for Texas, but its physical features were particularly interesting in that the white bands usually present on the dorsal surface of the flippers were absent, and the baleen plates were partially black and numbered only approximately 240 per side. Typically, minke whales have about 300 baleen plates on each side of the mouth and they are cream-white in color. These features initially caused confusion in the identification of the whale; however, measurements of the tympanic bullae confirmed that, indeed, it was a minke whale.

Ilustration credit: Pieter A. Folkens.