It is possible the Ike Jime process is being used commercially in Japan, but I have not heard of its being used elsewhere. That is not to say it is not being used. The North Atlantic Fisheries College, Shetland investigated the system for farmed salmon and it might b worth contacting them for more information. Thy have a web site. The system is also included in a current EU funded project on humane ways of killing fish. The Japanese claim the procedure delays the onset of rigor in fish by perhaps 12-24 hours, but as I understand the literature the total time into/through rigor is no longer in Ike Jime fish than in the control fish. The reason Ike Jime prolongs time into rigor is that the fish does not struggle when dying. The same effect is seen if fish are anaesthetised prior to killing by, say, a blow to the head. Ike Jime does not result in high quality in the fish. The claim is that rigor is delayed and for some speciality Japanese products, the fish should be eaten in the pre-rigor condition. For this market, Ike Jime ensures a high quality product. In my view, Ike Jime has no advantage for the quality of the product as far as non-Japanese markets are concerned, but might be adopted on the grounds that it is a more humane way of killing fish than others. (I am not convinced of this.) Following is a bibliography; you might find an explanation of the biochemistry/physiology in this.
M., Banno, A., Haitani, M., Hirai, H., Nakagawa, T. & Makinodan, Y. (1996)
Influence on post- mortem rigor in fish body and muscular ATP consumption
by the destruction of spinal cord in several fishes.
Fisheries Science, 62, 796-799
N.S., Wilson, N.D., Jerrett, A.R. & Hall, B.I. (1984)
Effects of brain destruction on post harvest muscle metabolism in the
fish kahawai (Arripis trutta). Journal of Food Science, 49, 177-179
M., Yamanaka, H., Abe, H., Ushio, H., Watabe, S. & Hashimoto, K.
(1988) ATP and creatine
phosphate breakdown in spiked breakdown in spiked plaice muscle during storage,
and activities of some enzymes involved. Journal
of Food Science, 53, 1662-1665
S. & Sato, A., (1996) Effects
of various killing procedures on post-mortem changes in the muscle of chub
mackerel and round scad. Nippon
Suisan Gakkaishi, 62, 3453-457
T., Goto, E., & Ooi, A., (1996) Observation
of characteristic muscle structure related to delay in red sea-bream rigor
mortis by spinal cord destruction. Fisheries
Science, 62, 977-984
T., Matsuhisa, M., Yamaura, M., Sumiyoshiyama, T. & Ooi, A., (1997)
Delayed example in rigor mortis of spinal cord destroyed plaice detected
by measurements of isotonic contraction and isometric tension.
Fisheries Science, 63, 830-834
T., Ooguchi, N. / Ooi, A., (1996) Change
in rigor mortis of red sea-bream dependent on season and killing method.
Fisheries Science, 65, 284-290
T., Toyoda, T. & Ooi, A., (1996) Delay
in rigor mortis of red sea-bream by spinal cord destruction. Fisheries Science,
H., Ohno, K., & Ninomiya, J. (1990) Changes in texture during cold storage
of cultured yellowtail meat prepared by different killing methods.
Nippon Suisan Gakkaishi, 56, 1673-1678