"ikejime ...technique used to ensure that fish stays fresh and delicious.First you drain the blood by cutting under the gills and at the base of the tail.Fish can be shipped in good condition if the blood that causes it to stink is drained from the body. After that, a wire is inserted in the backbone to remove the nerves and the fish is killed right away. Freshness can be preserved by delaying rigor mortis"
Source: The Allure of Ingredients
No 8, 2012. page 9