Kudoa Images (Prevalence of Kudoa in Puget Sound salmon net pens)

The goal of this study is to assess the extent that net pen salmon in Puget Sound are infected with the Kudoa parasite. Farming Atlantic salmon is a major aquaculture operation in Washington state, and it is the most abundant commercial aquaculture species in the West Coast of North America. In the state of Washington, this non-native species was introduced in the mid-20th century for commercial farming, and has been developed into a multimillion dollar industry. Texture of the muscle is one of the most important sensory attributes for farmed Atlantic salmon.

The effect of genetic factors, the composition of diet, feeding pattern, and farming conditions on the structure, biochemical composition, and characteristics of the muscle have been considered in several works (Johnston et al, 2007). The most prominent textural deficiency in farmed Atlantic salmon is the softness of the muscle. This softness was found mainly due to classical gaping that may or may not be related to postmortem changes or induced by the protease activity of parasite such as Kudoa spp. (Whitaker et al, 1997). Often, the affected fillets are also susceptible to gaping upon moderate bending, and overall texture of the fillets are frequently characterized as soft and/or mushy. In the worst case, the muscle becomes semi-liquid and will start flooding upon filleting.

The textural problem due to protease activity from Kudoa spp. is widespread in the salmon industry in the West Coast of North America. In the state of Washington, more than a million dollars of income loss due to claims are reported annually. (Cook A., Personal communication 2012). Often, the affected fish are identified only after they reach the customer, and the loss of confidence in the products is a major setback to the development of the industry in the state, as the main foreign competitors (e.g., Chile) do not have this problem (Cook A., personal communication 2012). Spectrometry data