Although there are hundreds of different types of seafood, and thousands of different ways to prepare the food, there are five main categories as identified by the International Standard Statistical Classification of Aquatic Animals and Plants and adopted by the Food and Agriculture Organisation. These categories contain several subgroups and then even more species within these, and are; fish, molluscs, crustaceans, other aquatic animals and aquatic plants. The data includes both seafood caught in the wild and those raised through the practice of aquaculture.
The most popular of the types of Seafood in terms of tonnes consumed fish can be split into five subgroups. The first of these is marine pelagic, which are fish that live and feed near the bottom of the sea and include fish such as; tuna, swordfish and smaller fish like herring and sardines. The next group are known as marine demersal and are very similar to the pelagic fish in terms of where they live and feed, however they are much less active than the pelagic fish and differ in their appearance by their white flesh, compared to the red flesh of the pelagic fish. The difference in colour of the flesh is due to the fact that the pelagic fish are more active than the demersal, and as such the red flesh is a characteristic of the more powerful swimming muscles that they need. Another group is the diadromous which are fish that inhabit fresh water and the sea and include fish such as salmon and eels.
The final sub group in the fish category is the freshwater fish, which – as their name suggests – inhabit fresh water like rivers and lakes. Some common examples of fresh water include carp, bass and trout. Due to their location fresh water fish find themselves being fish farmed more readily than their counterparts.
Molluscs are invertebrates with soft bodies, two of the subgroups are protected by a shell, whilst the third is not. The first of this group is the bivalves, which refers to the two hinged shells, such as; oysters, scallops and mussels. This subgroup is very popular, especially in finer dishes, they usually bury themselves on the seabed or against rocks and hard surfaces to keep themselves safe from predators. Oysters were favoured by the ancient Romans and are very popular in Ireland, where it is very normal to buy oysters as a bar snack to go with a pint of Guinness – this tradition doesn’t feature in the rest of the UK and can be quite a surprising combination to come across. Gastropods are the other category that have a protective shell, although this is in a single piece as opposed to the bivalves and popular gastropods include limpets and whelks. The final subgroup in this category are cephalopods, which don’t have a shell at all and are generally of higher intelligence than their two counterparts in this category. Octopus ad squid are both examples of this group which are eaten around the world, both of which require delicate preparation to be safely consumed.