Dead Sperm Whale Washes Ashore

By Allan Schreiber

Beached sperm whale. Photo: Keary Sorenson

On a Saturday in mid-March, at a beach north of Pt. Reyes, an unusual beaching event occurred. An adult male sperm whale was found washed ashore. Measured at over 50 feet long (15.6 m), it probably weighed over 40 tons. Sperm whales are rarely seen in shallower waters such as those off Pt. Reyes, and finding one on this beach was a matter of interest and concern.

The following day, a crew from the Marine Mammal Stranding Network arrived with representatives from The Marine Mammal Center (TMMC), California Academy of Sciences, NOAA and the National Park Service. Accompanying Ray Bandar, of Cal Academy, was Beach Watch volunteer Keary Sorensen. Dr. Frances Gulland, Director of Veterinary Science at TMMC and also a Beach Watch volunteer, conducted the necropsy.

The sperm whale (Physeter macrocephalus) is a toothed whale found world wide in deep ocean waters. It formerly was hunted for its spermaceti, a high quality oil stored in the snout. It is this reservoir  which gives sperm whales their distinctive large, squarish heads.

They also were prized for ambergris, which was once a primary ingredient in the manufacture of expensive perfumes. Although large-scale hunting of sperm whales was halted in 1979,  Dr. Gulland’s necropsy showed that other human actions are still threatening these magnificent animals.

In the stomach of the Pt. Reyes sperm whale, the necropsy team found a huge mass of fishing net. This wad measured over 6 feet by 9 feet (2m x 3m) and weighed 440 pounds (200kg).  In her message to TMMC volunteers, Dr. Gulland described it as a mixture of monofilament line,  2-inch net and braided rope.

Wrapped within this accumulation were assorted bits of plastic waste including a child’s comb and plastic bags.  One bag was still full of the garbage it had contained when it was dumped.

Sperm whales food of choice is squid, including the deep-water giant squid. Perhaps in the search for this food, sperm whales may forage close enough to the sea bottom to ingest such non-food items as this lethal mass of netting.

In her press release on this event, Dr. Sarah Allen of Pt. Reyes National Seashore describes a 2004 beaching of a sperm whale at Pt. Reyes, also with a stomach full of fish net. Aside from a couple of newborn sperm whales, these two recent events were the first stranding of sperm whales in decades. Dr. Allen mentions the speculation that the whales may be following the Humboldt squid which have been moving into waters off central California in recent years.

Regardless of what has brought sperm whales to Sanctuary waters, the cause of death was probably derelict fishing gear and other debris resulting from human carelessness. The Sanctuary and FMSA are currently planning a marine debris action program to locate certain kinds of abandoned gear. The effort hopes to prevent such tragedies from happening in the future.

 

All photos: Keary Sorenson