Another characteristic is that pelagic fish are gutted in the factory, while demersal fish are usually gutted on the sea. Together with high oil/fat content, this contributes to higher pollution levels in the wastewater of pelagic fish processing. Shellfish are processed into many different types of product. One of the characteristics here is that the products are
usually boiled – contributing to higher levels of energy consumption. Fig. 1 provides an illustration of the main types of fish processing taking place in Denmark. It should be stressed that some processes are not included in the illustration, such as ‘traditionally soured’ pickled herring, which is not gutted until after the souring process.