The edible portion of the sea urchin is the reproductive glands, or the gonads, which contain the milt or roe depending on if it is a male or female. The gonads of the Ezo horse-dung sea urchin feature a deep orange color, while the kita purple sea urchin has a bright yellow color. To contrast the two, they are referred to as the red sea urchin and white sea urchin.
The Ezo horse-dung sea urchin has a rich, creamy taste, while the kita purple sea urchin has a lighter more refined taste. In the past, both types of sea urchin could be harvested in just about every part of Hokkaido, but changes in the environment have resulted in many fishing grounds only able to harvest either type and not both.
■Fertile konbu kelp grounds have a large stock of sea urchin
Statistics on the sea urchin catch by municipality for 2012 showed that Nemuro City caught the most Ezo horse-dung sea urchin, while Hakodate City caught the most kita purple sea urchin. Rishiri Island and Rebun Island also had a large catch, and viewing the fishing grounds of both islands as one because of their close proximity would make this area one of the largest sea urchin harvesting grounds in Hokkaido.
Sea urchins are omnivorous and the Ezo horse-dung sea urchin and kita purple sea urchin of Hokkaido both eat konbu kelp. This is why the Rishiri and Rebun areas are a major harvesting area because of their well known konbu kelp crop. Visitors are encouraged to taste both types of sea urchin to compare.
■Map / Main municipalities with fishing grounds
・Ezo horse-dung sea urchin
Nemuro City, Rebun Town, Rishiri Fuji Town, Rishiri Town, Hakodate City
・Kita purple sea urchin
Hakodate City, Rebun Town, Rishiri Town, Rishiri Fuji Town, Setana Town, Haboro Town, Shakotan Town
Surrounded on all four sides by ocean, Hokkaido’s sea urchin harvesting grounds migrate to each part of the prefecture depending on the season. To protect the stock, fishermen only harvest sea urchin in designated waters during the pre-set season, but some municipalities have concentrated efforts on aquaculture like Hamanaka Town, making it possible to enjoy fresh, raw sea urchin nearly throughout the year. Sea urchins are caught off Rausu Town on the Shiretoko Peninsula under the sea ice and in the calm summer waters along the coast of the Oshima Peninsula from Shiribeshi using nets. During the season, fishermen-run canteens pop up cross Hokkaido where you can eat fresh uni kaisen-don during the short fishing season.
In addition to handheld fishing nets, in some regions fishermen dawn wet suits to dive underwater to harvest sea urchin. There is also a type of drift net fishing used where a net with steel frame is sunk to the bottom and towed behind a boat.
Most places ban sea urchin harvesting in October during the spawning season, and since the meat is not very plump during November immediately after the spawning season, the season spans from December to the following September. By region, the season can be broken down to Hidaka in the spring, Shiribeshi in the summer, and spring/summer for Northern Hokkaido and winter to spring for Eastern Hokkaido. Ezo horse-dung sea urchin grown on aquaculture farms in Hamanaka Town are shipped from September to the following March.