Chalky Halibut is an unfortunate reality that the entire seafood industry must deal with. Similar to 'Jelly' Chilean Sea Bass, Chalky Halibut is an internal denaturation of protein that is not detectable when looking at a Whole Fish so it often goes unnoticed until the product is cut into.
Below is some information provided by the International Pacific Halibut Commission that we want to bring to your attention:
Chalky halibut has been recognized for decades, although until recently the problem was limited to summer fisheries in the southern fishing areas off Washington and Oregon. Until 1995, landings in most areas have occurred during short fisheries in the early and late summer, and most product was frozen. Since 1995, fisheries occur throughout the open period, and a majority of the product is sold fresh. This, combined with an increased awareness of chalkiness by the marketplace...
IPHC research, both in the 1960s and in the late 1990s, have shown chalkiness to be directly associated with a buildup of lactic acid and resulting lowered pH in post-mortem flesh. The condition is specifically associated with a denaturation of muscle proteins resulting in an increased drip loss and a sometimes startling loss of translucence in the flesh. In extreme cases, the flesh gapes, and has little use as a food product. Our research has associated chalkiness with two areas of the coast during late summer and early fall, and male halibut tend to be chalkier than females. It is likely that the areas with the highest rate of chalkiness are associated with high bottom temperatures (12-14 degrees C), which are near the upper thermal limit for the species distribution....
As described above, when Halibut are caught they fight and release into their blood/muscles a level of Lactic Acid that will damage the internal structure of the meat if they die before they are able to release the buildup. Tuna exhibit similar characteristics when they are caught; if Tuna fight too long and die before they are able to secrete the Acid, their bodies heat to a level that negatively affects the quality of the meat ... their 'blood boils'.
Unfortunately, not all Halibut look as beautiful as the fillets shown in the picture above, and on occasion we - like the rest of the Seafood Industry - go through runs or 'batches' of Halibut that contain the slightly common 'Chalky' appearance when processed. We understand this is not desired and are always willing to replace any product that shows signs of Chalkiness. We also do our best to recognize regions and periods of the season that tend to develop more 'chalky' fish than others. When recognized, to the best of our ability we will avoid the region and notify our suppliers.
This is an ongoing issue that the entire industry faces. Thankfully J.J. partners with organizations that provide funds and time to study issues like this, ultimately hoping to find a solution!