A Narrative by Bill Webber

Before I get into the explanation of Ike Jime, let me start off by saying this is not a new process but is a time proven process that has been used in many countries for many years on many different species of fish. Ike Jime is not a brand or region of origin, it is a method of processing. The technique originated in Japan but is now in widespread use throughout better fisheries around the world.


Being that the anatomy is different in fish species harvested world-wide and the fact that I am just a salmon guy, I will focus this discussion on the research I have personally found relating to the Genus Oncorhynchus (salmon). I will describe how I implement Ike Jime into my operations in my never-ending quest to purvey a well harvested and handled salmon. I have adopted these stringent at sea processes to increase quality with the sole purpose of passing on a rich and flavorful dining experience to my patrons.


If you were to do a Google search on Ike Jime, you will find many articles about this process and procedure. Much of the knowledge base in this writing is borrowed from many websites and will help guide me as a quality minded individual, fisherman and engineer in achieving my personal end goal of producing a high-quality product.


I have compiled what I have found to be pertinent to the at sea processing that I do at the point of harvest. Ike Jime is performed just after capture. The process of Ike Jime is how to kill the fish properly to realize the benefit of this process and shut down all bodily and autonomic processes.


I plan to make and implement new tools to automate and mechanize these processes and procedures to increase production efficiencies relating to small vessel salmon processing operations. Working on a small boat platform with a strict quality protocol and approach, it is imperative that those who adopt vertical integration in their commercial fishing business and move beyond the traditional model, make this Paradigm Shift to purvey the perfect salmon for discerning high-end markets.


Ike Jime - a flesh preserving and taste enhancing Japanese method of paralyzing the salmon, minimizing the pain and suffering, and short circuiting the pain and stress response of the salmon. Ike Jime methods are described by some as “Killing the fish without the flesh knowing that it is dead”.



There are two processes one can use in salmon, the Brain Spike and the Spinal Cord Destruction as defined below.



Ike Jime, the brain spike method paralyzes the salmon to maintain the quality of its flesh.  This method involves the insertion of a spike quickly and directly into the hindbrain, located slightly behind and above the eye, thereby causing immediate brain death. When spiked correctly, the salmon fins flare and then the salmon relaxes, immediately ceasing all motion. Destroying the brain and the spinal cord of the salmon will prevent reflex action from happening, such muscle movements would otherwise consume adenosine triphosphate (ATP) in the muscle, and as a result produce lactic acid, making the salmon flesh sour.


The Spinal Cord Destruction (SCD) Ike Jime method is passing a wire down the spinal column of the salmon. This severs the nerves and stops impulses from the spinal column, much like pulling the plug from a network of computers. Having performed SCD, this renders a total shutdown of all bodily and autonomic processes.

You’ve done it right if the salmon shimmies as the wire goes through the spinal cord. No shimmy? You did it wrong. Run the wire only once, don’t keep moving the wire up and down to make the salmon move. More extended insertion of the wire depletes ATP which you are trying to preserve.

One must be careful with this method of Ike Jime for sushi, sashimi and ceviche style salmon as there is a great potential to introduce pathogens up the spinal column and into the salmon that won't be eliminated with cooking.

In our operation, minimizing the spread, proliferation and introduction of pathogens into our salmon is accomplished by using an injected and metered Chlorine Dioxide (ClO2) in our onboard process water system. To meet and exceed FDA regulations and food safety requirements, all our work surfaces, cutting and piercing tools are continually rinsed with this sanitized water supply, which is just another way we set the quality bar at a higher level. The beauty of using ClO2 in our process water is, once it does its job of killing pathogens, ClO2 reverts into sodium chloride - table salt. No harsh chemicals are used on the fish or put into the ocean.

These Ike Jime processes will definitely kill the salmon quickly which will aid in maintaining a better-quality salmon, far above the commodity product. Many of the best practices in purveying a very high-quality product has to do with pre-rigor processing at the point of harvest while still at sea.


Stress during capture, whether from overcrowding, struggling in a net, being lifted into the air, or even the long-term stress from poor handling practices, results in more exhausted salmon. The muscles of exhausted salmon have a lower pH (due to lactic acid production in the muscle). That low pH enhances the action of enzymes present in the muscle that break down protein. One study even claims that stress increases the amount of the enzymes present in addition to making them more effective. Higher stress also leads to more stress-related compounds in the blood, which some studies show degrade muscle. Finally, tired and stressed salmon have less available ATP in their muscles. ATP is the energy source that makes biological systems run. After an animal dies, its muscles remain pliable for as long as it has some reserves of ATP.

Once the ATP is used up, the muscles tense and will not loosen, this is called rigor-mortis. Rigor-mortis in salmon can be strong enough to rip apart the connections between muscle fibers, leading to mushy meat. Muscles from stressed salmon with low ATP reserves go into rigor-mortis faster and harder than muscles from rested, unstressed salmon with more ATP. Eventually rigor-mortis contractions soften as the connections between the muscle fibers break down.

Even if you decapitate a salmon, the muscles in its body might continue to undergo stress due to the action of its autonomic nervous system. The autonomic or involuntary nervous system keeps running even if the brain is absent. The spinal cord keeps sending messages to the muscles. The muscles continue to use ATP, and the salmon goes into rigor faster and harder than if we stopped those messages by destroying the spinal cord or brain using Ike Jime.


Image showing muscle damage due to stress.



Breaking the gills and rapidly dropping internal temperatures to <40F is essential for high quality, safe handling of salmon. If the salmon can be headed, gutted and rinsed, the temperatures will drop much faster, while the salmon is in a pre-rigor mortis state. Paradigm Seafoods maintains safe handling procedures and preserves mother nature’s intrinsic quality of the salmon we harvest through these well-researched and applied quality specifications.

The less trauma a salmon goes through before and during processing, the higher the quality of the flesh, simple as that. Compared to red meat and poultry, salmon muscle is delicate. It needs all the structure it can get. So unlike red meat, where we like a little protein breakdown to enhance tenderness, anything that breaks down the structure of salmon muscle is bad.

Once the Ike Jime method is performed, the blood in the salmon flesh retracts to the gut cavity, which produces a better colored and flavored fillet if left intact for a short period of time.

In Paradigm Seafoods’ Processed at Sea operation, the dorsal aorta is exposed when cutting off the head. An Intravenous Pressure Bleed procedure is started in this main artery, evacuating up to 99% of the blood from the venous and arterial systems exiting through the post cardinal artery of the salmon. This bleeding process is performed while the salmon is in a pre-rigor state.

Pre-rigor processing minimizes the stress on the salmon and reduces the production of adrenaline. High levels of residual adrenaline in a dead salmon will result in a slightly bitter/sour flavor and vastly shorten the shelf life of the fresh salmon.

Processing the salmon quickly and immediately after capture delays the rigor mortis process when compared to salmon that are left to die by slower methods such as merely bleeding-out and chilling. With the complete destruction of the brain and in particular, the hind brain, there is no movement from the salmon and therefore any energy remaining in the muscle tissue is used to maintain cellular structure of the flesh post-harvest.

Ike Jime delays the rigor mortis process and the enzymic degradation of the muscle tissue. It results in a far superior flesh quality compared to conventional methods, where the energy reserves are depleted very shortly after capture.

Leaving a salmon flopping on a deck or merely thrown into an ice bin, can often take several minutes for the salmon to die, during which time the salmon reacts by a normal adrenaline inducing escape response behavior which consequently depletes the energy reserves in the muscle tissue.

The texture and taste are also affected, as the flesh may have a softer feel to the tooth, and possibly a stronger 'fish' taste due to a build-up of lactic acid, remaining blood, and other secretions because of stress during death. In addition, methods that cause stress in a slow dying salmon also cause quality issues such as reduced shelf life, flesh gaping, softness, and blood spotting of the flesh.

The Ike Jime methods, on the other hand, ensures that death is quick and relatively stress-free. The salmon enters rigor mortis much slower, as much as 24 hours later.

The rigor is less extreme, so the flesh does not tend to tear away from bone and connective tissue. The texture is improved, being almost crispy yet still supple. The taste of an Ike Jime salmon is more refined, with complex subtleties that bring out the true flavor and taste of the fatty oil laden salmon.  



Good bleeding processes at the point of harvest are essential to the visual appeal and taste of well-handled and cared for salmon flesh. Some studies show that compounds in the blood of some fish soften muscle tissue or flesh. This is discernably a bad thing.

Much of the commodity salmon harvested and sold in Alaska have a measurable amount of blood still left in their body. If the salmon wasn’t well cared for by bleeding and chilling, the remaining blood left in the body deteriorates much faster than the flesh and turns rancid leaving a foul finish on one’s pallet or it can even smell fishy before preparing to cook it. This is evidence of poorly handled salmon.

Below is a corrosion cast view of a salmon’s venous and arterial system.


Understanding the labyrinth of the venous and arterial system shows how much blood can be retained and/or removed from a fish’s body using the techniques outlined in my narrative titled, “Understanding the Importance of Bleeding Salmon”. I wrote this narrative some 12 years ago on the best practices, expectations, bleeding protocols and techniques currently used in the Alaska salmon industry. This narrative summarizes the processes and expectations of each method employed at the point of harvest. The fisherman literally owns the quality responsibility and sets the quality bar in each salmon they catch and handle. A well bled salmon can only happen at the point of harvest, before death and not hours later or post rigor at a shoreside processing facility.


All research points to the importance of immediate gutting. Leaving the guts in a salmon creates some very acidic enzymes. Pre-rigor processing totally removes any enzymic degradation of the salmon and does not even allow it to occur as the guts have been removed. This in-itself resets the shelf life window of a salmon handled with adherence to these strict protocols and procedures.

Filleting is a different story. If you fillet before rigor, the muscles will not be damaged as much because they won’t have the skeleton to react against, but the fillets aside from being firmer, will be smaller and denser. Pre-rigor fillets are almost crunchy when eaten as sashimi.

If you like pre-rigor salmon, Ike Jime is the optimum technique because it increases the window you have to serve the salmon in a pre-rigor state.

I prefer to eat salmon after they have gone through rigor mortis and of course are handled and processed in the manner I have outlined. For people like me who prefer post-rigor salmon, Ike Jime delays rigor substantially. Salmon processed this way aren’t ready to eat as quickly as salmon processed using typical western techniques. When Ike Jime salmon do come out of rigor, however, they are much better than conventional commodity processed salmon.

It takes practice to figure out how to time the processing of different fish. Some fish are best after one day, some after two or more. When eaten as sashimi, the benefits of Ike Jime are clear. The more you cook the salmon, the less obvious the benefits, obviously because of over cooking. With transit times being as they are in moving salmon from Alaska, the rigor mortis stage has generally past and our salmon product is simply ready for a rich dining experience.

I have had some of our customers report that they have received their shipments still in rigor mortis; this is because of our at-sea-processing and a well-managed cold chain. That does not happen in the commodity product arena – period. This is a huge confirmation to me that the many things we do in our at sea operations are in fact done right and done well.

In short, Ike Jime is not just marketing hype, it is the real deal in purveying the best eating salmon, shows respect to the salmon and recognizes that it is as curated by Bill Webber, a piece of fish of higher value.