How many of us in the tuna industry know about Mushy Tuna Syndrome (MTS)? Perhaps fishing companies and canneries, but who else? It has been a persistent issue for decades that mainly affects skipjack and one researcher wishes to shed more light on this problem.

Soni Peter, who is currently pursuing her PhD at the University of Queensland, is researching the "Proximate Factors of Mushy Tuna Syndrome and an Amelioration Plan for South Pacific Fishers and Processors."

Atuna reached out to Peter to ask her about MTS and why this should concern the tuna sector. “MTS is a condition in tuna where the texture of the muscle becomes pasty/mushy and more evident after cooking. It has been a significant quality problem in the industry for many years, and it causes high rejects on the line because it is not fit for canning and human consumption,” she explained.

For solid or chunk packs, the packing machine cannot make proper cuts because the precooked loins need to have a firm texture.

She said that she is investigating why it is predominant in skipjack as the syndrome is rare in other types of tuna such as yellowfin or albacore. The prevalence of MTS in the various species is also something she will be examining.

Given her background in the processing industry – she worked in the SolTuna cannery in Solomon Islands as Quality Manager– she was able to witness this problem firsthand. Peter highlighted that the condition is not at all evident when looking at the raw material as “the whole fish looks absolutely fine externally” and it can only be seen after cooking.

Another challenge in identifying the breadth of the syndrome is that it is not constant throughout the year. “The percentage of rejects due to MTS can be as low as one percent to as high as 70 to 80 percent in a batch of tuna.” 

Depending on the capability of the processing plant, the rejected fish goes either into fishmeal or is completely discarded, said Peter.

What is the extent?

Since August of this year, the researcher has been reaching out to stakeholders throughout the tuna supply chain – from fishing companies to canneries – to survey them about the extent of this problem. She aims to gather the data by December in order to publish a paper on it early next year to give the industry an idea about the scope of MTS.

“The idea of the survey is to find out how much it is affecting the industry, the quantity [of rejects], which fisheries are being affected, and the economic impact on the canning and fishing sector.”

Up until now, there has not been published research on the reasons behind this syndrome. “We don’t know what it is causing this and what are the factors in the fish that triggers this condition. There have been some studies done on this but there has been no research until now to find what the proximate factors are.”

The survey information will provide indicators to measure the gravity of MTS in the skipjack fishery and form a base for her to carry out a further study into the proximate factors of the condition. For this, Peter has been in collaboration with the Pacific Community’s research center, the SPC, which will be providing her with tissue samples so she can conduct more analyses.

The economic impact for the canneries also needs to be considered given that the fishing company still gets paid even though the fish has been rejected. MTS also impacts countries exporting pre-cooked loins to Europe, which she highlighted.

Peter concluded that her study will also help to contribute to meeting targets 14.4 and 12.3 set by the UN Sustainable Development Goals (SDG). She quoted FAO’s State of World Fisheries and Aquaculture : "It should be emphasized that reducing fish loss and waste can lead to a reduction in pressure on fish stocks and contribute to improving resource sustainability as well as food security."