One of Okinawa’s most popular products on the Japanese mainland is kuruma tiger shrimp (Penaeus japonicus, locally called kuruma ebi) produced by Epoch Prawn Farms in mineral-rich, deep-sea water pumped to the surface by the Okinawa Deepsea Water Research Institute.
Before cooking, you can differentiate kuruma shrimp from other tiger shrimp by the distinct blue in their tails. The prawns are nearly translucent with stripes that give them their English name tiger shrimp.
The shrimp are initially hatched at a centralized location near the research institute before being distributed to several farms. The shrimp are active at night and spend their days buried in the sand on the bottom of the growout ponds.
In June, at Epoch Prawn Farms, the water is drained from the tanks and the sand at the bottom is exchanged with new sand, and any shrimp that were not harvested the previous year are collected. Exchanging the sand is a difficult and expensive process, but important for producing high-quality shrimp. If the sand is not replaced, the shrimp have a softer color and less flavor.
The shrimp eggs near the deep-sea water institute hatch in September. They are cultured through their larval stages and then transferred to the shrimp farms. Around 400,000 postlarvae are stocked in each pond. Epoch has three ponds.
The prawns grow slowly during the cold winter months, but they have a better taste and more amino acids than prawns grown in the summer, when they grow more quickly.
To ensure the highest quality, Epoch feeds the shrimp daily with a proprietary mix of vitamins, squid, ground fish and other ingredients imported from mainland Japan. The feed is expensive, but ensures that the shrimp develop the right color. Every day, divers patrol the pools to ensure the shrimp are eating and that no debris has entered the tanks from the sea. Water is exchanged daily.
Utilizing lights and bait, shrimp are trapped at night because that’s when they are active. A simple funnel net allows the shrimp to enter the trap and keeps them from escaping. Small shrimp can easily escape from the traps. In the morning, the shrimp are transferred to cold-water containers and transported directly to a processing facility.
At Epoch, the shrimp are sorted by size and then the shrimp with no damage to their appendages are separated for live shipment. About 1% of the shrimp has soft shells, which are very popular. Once sorted, the shrimp are weighed and boxed. They can live two to three days if kept cold, and can be shipped live all over Japan.
Most Okinawa tiger shrimp are sent to Tokyo and other large cities in Japan, where high-end restaurants purchase them at auctions. Some shrimp are also flash frozen for distribution during non-peak seasons. Shrimp are especially popular as gifts (esebo), given at the end of the year.
Epoch Tiger Prawns produces high-quality shrimp. Many farms throughout Okinawa also produce tiger shrimp, but the close proximity to deep-sea water and careful control allow Epoch to produce truly superior shrimp. Depending on size, its shrimp sell for between $31 and $45 a pound.
Source: The Ultimate English Guide to Kumejima [Okinawa]. Tiger Prawns [車エビ]. No date, discovered on May 21, 2013.