A poisonous delicacy

The Japanese scientist Shiye Zhao studies microplastics, the small particles that plastic bottles, fishing nets, ropes and other plastic rubbish are broken down to by the weather, sunlight, and waves.

He sets out a small trawl, towes it behind the ship and collects what floats close to the surface. After a short period the trawl is hauled up, and the small pieces of plastic in the net collected in small containers.

- The trawl catches plastic particles larger than 300 microns, i.e. 0.3 millimetres. We study these particles more closely, and examine both their chemical and physical properties, says Zhao.

A toy?

There is a surprising amount of plastic in the sea south of Japan, both large and small pieces, and the small ball that the trawl picked up on Saturday could well have been a toy lost on a beach. But the blue and white ball full of spikes was a puffer fish.

There are 188 different species of puffer fish, some are yellow, some brown, some have fine patterns, some are smooth, and the porcupine family has long spines, like the fish that ended up on the deck on board the Statsraad Lehmkuhl.

A delicacy

Zhao was startled when he saw the fish, and pulled it out of the net with a long pair of tweezers.

He was not cautious without reason, most of the puffer fish are extremely poisonous. It is due to the substance tetrodotoxin, which is 1200 times more toxic than cyanide. The poison is produced by bacteria that the fish ingest through the food they eat, and accumulates in the liver, reproductive organs, eyes and skin. There is no antidote.

Despite the poison, pufferfish are considered a delicacy in Japan, China and Korea. They are used in soup, and eaten raw as sushi. Pufferfish is only prepared by experienced chefs, who have spent several years learning how to handle it correctly. Nevertheless, several people die every year from the poison that paralyses the muscles so you stop breathing.

Defense mechanism

The poison makes the fish taste bad, but does not kill, for example, sharks. The pufferfish therefore has another means of defence, it can inflate itself - as the name indicates.

Pufferfish are not particularly good swimmers, so if they are unable to escape when danger threatens, they swallow water. What was a just-right-sized treat quickly ends up as a huge stinging lump in the throat of the hunter, who spits the puffer fish back out.

The fish that Zhao caught in the trawl eventually calmed down in a tub of water. So it was photographed both in tennis ball size and in normal shape, before Zhao released it back into the sea.