Stejneger’s Beaked Whales in the Aleutian Islands

Compiler*: Debra G. Corbett | Nanutset Heritage | *Originally presented in “From the Wildside” USFWS / Alaska Maritime National Wildlife Refuge / Aleutian Islands Unit November 2013 Newsletter.

Stejneger's beaked whale. Drawing by Al Denbigh.

Stejneger’s beaked whale. Drawing by Al Denbigh.

Mesoplodon stejnegeri

A male Stejneger’s beaked whale, also known as a Bering Sea beaked whale or saber-toothed whale, washed ashore near the outlet of Airport Creek on Adak Island November 2013.  These whales are mysterious and described in the literature as poorly known, but every few years one or more strand on Adak’s beaches. Between 1975 and 1999 there were five individual and seven mass stranding events involving 2-4 animals. Much of what is known about the species has been learned from studying whales found on Adak.

1994 stranding of four pregnant females in Kuluk Bay. USFWS file photo.

1994 stranding of four pregnant females in Kuluk Bay. USFWS file photo.

Stejneger’s are the northernmost species of beaked whale. They are found in the cold northern waters of the North Pacific Basin, from central California and the Sea of Japan, north to the Bering Sea. They are small, reaching lengths of only about 17-18 feet as adults. Stejneger’s feed primarily on squid in deep (200-4,000 feet deep), dark waters, using echolocation to hunt.  They can stay down for up to 85 min and reach depths of 6,230 feet. Beaked whales have a unique feeding mechanism: rather than capture prey with their teeth, they suck it up. Longitudinal grooves along the underside of the throat stretch and expand as the tongue suddenly retracts, creating a pressure drop that sucks prey in with the water.

The most noticeable characteristic of adult male Stejneger’s beaked whales is a pair of massive flattened tusks, near the middle of the lower jaw. These tusks are the only teeth in most species of beaked whales, and only males have them.  Males presumably use them when fighting for females—note the parallel scars in the drawing above, evidence of males ramming each other with the paired tusks. Females may select mates based on the size and shape of male tusks.  For more information check out the Alaska Department of Fish & Game description.

Strandings

Most individual strandings involve single animals weakened by old age, disease, injury, rough weather, or other causes. Mass strandings are more complicated and not fully understood. Every year hundreds of whales beach themselves. Most are toothed whales that normally inhabit deep waters and live in tightly knit groups. Sick leaders may draw a herd into shallow water, the healthy animals following because they are responding to distress signals from the debilitated animal. Storms, strong magnetic anomalies, predator avoidance, and human activities such as sonar operations, seismic testing, and warfare have all been linked to mass strandings. Other ideas abound but the question remains unresolved.

Because Stejneger’s beaked whales are not well studied, any animal coming ashore has the potential to provide researchers with extremely valuable data. Anyone finding a stranded beaked whale can report it to the Alaska Marine Mammal Stranding Network at 877-925-7773, or 877-9-AKR-PRD.  Other numbers are Protected Resources Offices in Juneau 907-586-7235, or Anchorage 907-271-7325, or the Alaska Sea Life Center at 888-774-7325.  These offices ask you to report any injured, entangled or dead sea mammals in the water or on the beach.  The most important information to collect is the date, location (including latitude and longitude), number of animals and species.  Remember—don’t move or touch the animals. Visit the Alaska Marine Mammal Stranding Network page to learn more and download the Stranding Network iphone app: alaskafisheries.noaa.gov/protectedresources/strandings.htm.

 

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