Wednesday, April 18, 2018

Sperm Whale Dies from Eating Trash

A young sperm whale (Physeter macrocephalus) washed up dead on the southeast coast of Spain in February.  Not an unusual event in itself, but when scientists performed a necropsy on the whale, they found more than sixty pounds of plastic trash in his gut.  Unable to digest or expell the detritus, he died of slow starvation.  He weighed just 13,000 lbs at his death--emaciated for a mammal that can reach 120,000 lbs as an adult.  The tragedy demonstrates how serious the ocean's plastic pollution problem is.  Although sperm whales dive thousands of feet in pursuit of their favorite food, squid, they loitter at the surface to recover from their exertions.  There they are exposed to plastic debris that can be mistaken for food or simply accidentally ingested.  The sperm whale is highly social and has the biggest brain of any cetacean.

Plastic decomposes very slowly in seawater.  Patches of floating debris can be found in all the world's oceans.  The Great Pacific Garbage Patch is estimated to contain 87,000 tons of plastic and other debris such as discarded fishing nets and equipment.  The 2011 tsunami that destroy the Fukushima nuclear facility alone swept 5 million tons of debris into the Pacific. In a study published this month, researchers say the patch is 4 to 16 times larger than previously estimated and is growing exponentially.  Once thought to be a region primarily of microplastic debris, it actually contains larger pieces of trash.  Once these larger pieces breakdown in microplastic particles, it will be much more difficult to remove from the water.  This chart shows the increase in plastic trash concentration from 1962 to 2018.

Sperm whales were almost hunted to extinction in the 19th century for their oil and ambergris.  The peak of sperm whale hunting occurred in the 1840s and 1960s.  They have been fully protected but international convention since 1985, but whale recovery has been slow, especially in the South Pacific where breeding age males suffered a heavy death toll.  They are currently listed as vulnerable by the IUCN.  The whales dying of trash ingestion has been detected before.  In 2008, two sperm whales stranded in northern California.  One died of a ruptured stomach and the other of gastric impaction.  Both had large amounts of debris in their stomach included discarded nets and fishing gear.  One hundred and thirty four different types of plastic nets were counted.  No longer hunted, an has found yet another way to kill whales.