Morphology & Biology
Pilchards, or sardines, are generalised terms commonly used to describe small members of the herring family Clupeidae. These terms are not precise and can refer to up to 15 different species. Specifically, the term ‘sardine’ should refer to the juvenile form of a pilchard. Sardina pilchardus, the European Pilchard or Atlantic-Iberian Sardine, is the only representative of its genus Sardina, named after the island of Sardinia.
The European pilchard possesses cylindrical body, and rounded belly in adults, and is coloured with a darker blue dorsal area and white belly that is typical in countershading. Some faint black vertical stripes amongst the blue make the fish distinct. Its caudal fin is forked, adapted for manoeuvrability and acceleration, its anal fins and dorsal fins are enlarged and its pectoral fins are greatly reduced. They are most commonly around 20cm in length, to a maximum of 27cm, and have been recorded living up to 15 years of age.
European pilchards form large schools, which migrate throughout their range for breeding and feeding. They also undergo diel vertical migration, whereby their schools move from deep waters in the day (25-55m) to shallow waters at night, in unison with the zooplankton they feed on. Pilchards and their relatives in Clupeidae are known as ‘forage fishes’, which are vital for the marine ecosystem. By feeding directly on planktonic organisms, they convert energy from the lowest trophic level into a food source for larger predators, like mackerel, tuna, cetaceans, seabirds and sharks.
They do not reach sexual maturity until the age of two to three, or an estimated length of 14.8cm. They are broadcast spawners, producing 50,000-60,000 eggs at a time, and in unison with one another, to increase the chances of survival. The breeding season is September through to June in the Mediterranean, and June to August in the Black Sea.
Pilchards are a highly adaptable species, and can occur in brackish, marine and fresh water. Sardina pilchardus distributed widely in the Atlantic, from Iceland and the North Sea to off the coasts of Senegal and Morocco and is very common throughout the Mediterranean Sea. Their distribution within a region is at least partly determined by oceanographic processes, such as upwelling and sea surface temperature. As a result, pilchards exist in small metapopulations, that exist in separate areas with limited overlap and interaction.
The European Pilchard is a widely exploited fish in commercial fisheries. It is currently listed as Least Concern by the IUCN Red List of Threatened Species, but in some regions, it is considered over-exploited due to heavy landing and fishing. Morocco has been highlighted as such a region, where the pilchard is the main target species of the country’s pelagic fisheries, making up 70% of total small pelagic catch. Portugal altered its small pelagic fishery target species when sardine abundance dropped. Most commercially fished stocks have been evaluated as being fully exploited.
Studies in the Iberian Peninsula show that high levels of pilchard recruitment have increased the total catch size in the past, but overexploitation reduced the productivity of the population dramatically and it did not recover.
Fisheries & Aquaculture
The pilchard does not have a high market value and is eaten, used as bait or ground into fishmeal for aquaculture. In Morocco, Mauritania and around the Sahara, they are a highly important commercial species.
Catches have been increasing steadily since records began in the 1950s, with substantial peaks in 1976 and 1990. Purse seine nets, beach seine nets, gillnets, small drift nets, high-opening bottom trawls and light fishing are all used to fish them, mostly within coastal areas. Purse seine nets target schools of young pilchards particularly.
Pilchards, herring, sprats and other small fish species have been overexploited in Europe since the advent of industrial fishing in the 19th century. It has been suggested that this persistent extreme pressure on these ecologically vital species over the past two hundred years has had a negative impact on the marine environment across European waters. Large marine mammals and sharks are now a rarity in our waters, and it is thought the overexploitation of the base of the marine food chain is at least partly responsible for their declines and decrease in size. Common dolphins, for example, are specialist predators of the pilchards.