The effects of varying the percentage of herring versus salmon protein in manufactured diets on the survival, meat content, hepatosomatic index and meat sensory quality of adult red king crab Paralithodes camtschaticus held in captivity

The current study investigates whether it is possible to increase the meat content of captive king crab by feeding manufactured diets in which the protein component consisted of varying percentages of either ‘herring’ or ‘salmon’ meal (the total protein content in the diet remained at approximately 50% regardless of the protein source). The latter has been shown to be a cheaper and more accessible source of dietary protein in Norway. A 9week trial was undertaken with groups of king crabs held in 12 land-based holding tanks and fed the Nofima manufactured king crab diet. The protein composition of the experimental diets varied with 0, 25, 50 and 100% salmon meal replacing the respective percentage of herring meal in diets 1–4 respectively. An initial, 4week and final 9week census were conducted to measure the average meat content and mortality of the experimental crabs. The hepatopancreas body index and sensory samples were also collected at the final census. The results showed that at the conclusion of the experiment there were no significant differences in the percentage meat content in the crabs fed the various diets (Diet 1: 50.1%, Diet 2: 50.0%; Diet: 3 45.3%; and Diet 4: 43.4%). On average there was a 1% increase in meat content per week during the experiment. There were no significant differences in the hepatopancreas body index, or in taste quality between crabs fed the different feeds during the experiment, or between king crabs that were fed the artificial diets and those collected from the wild at the conclusion of the experiment. The results of the experiment show it is possible to maintain, and enhance, the meat content of king crab held in captivity for periods up to 9weeks using the Nofima manufactured diet on a commercial scale. Secondly, the Nofima manufactured diet can replace herring meal, which has been used previously, with the cheaper salmon meal, without significant loss in meat gain, or sensory quality in the resulting king crabs.