Seafood is any form of sea life regarded as food by humans. Seafood prominently includes fish and shellfish. Shellfish include various species of molluscs, crustaceans, and echinoderms. Historically, sea mammals such as whales and dolphins have been consumed as food, though that happens to a lesser extent in modern times. Edible sea plants, such as some seaweeds and microalgae, are widely eaten as seafood around the world, especially in Asia (see the category of sea vegetables). In North America, although not generally in the United Kingdom, the term "seafood" is extended to fresh water organisms eaten by humans, so all edible aquatic life may be referred to as seafood. For the sake of completeness, this article includes all edible aquatic life.
- Types of seafood
- Texture and taste
- Health benefits
- Health hazards
- In religion
The harvesting of wild seafood is usually known as fishing or hunting, and the cultivation and farming of seafood is known as aquaculture, or fish farming in the case of fish. Seafood is often distinguished from meat, although it is still animal and is excluded in a strict vegetarian diet. Seafood is an important source of protein in many diets around the world, especially in coastal areas.
Most of the seafood harvest is consumed by humans, but a significant proportion is used as fish food to farm other fish or rear farm animals. Some seafoods (kelp) are used as food for other plants (fertilizer). In these ways, seafoods are indirectly used to produce further food for human consumption. Products, such as fish oil and spirulina tablets are also extracted from seafoods. Some seafood is feed to aquarium fish, or used to feed domestic pets, such as cats, and a small proportion is used in medicine, or is used industrially for non-food purposes (leather).
The harvesting, processing, and consuming of seafoods are ancient practices with archaeological evidence dating back well into the Paleolithic. Findings in a sea cave at Pinnacle Point in South Africa indicate Homo sapiens (modern humans) harvested marine life as early as 165,000 years ago, while the Neanderthals, an extinct human species contemporary with early Homo sapiens, appear to have been eating seafood at sites along the Mediterranean coast beginning around the same time. Isotopic analysis of the skeletal remains of Tianyuan man, a 40,000-year-old modern human from eastern Asia, has shown that he regularly consumed freshwater fish. Archaeology features such as shell middens, discarded fish bones and cave paintings show that sea foods were important for survival and consumed in significant quantities. During this period, most people lived a hunter-gatherer lifestyle and were, of necessity, constantly on the move. However, where there are early examples of permanent settlements (though not necessarily permanently occupied) such as those at Lepenski Vir, they are almost always associated with fishing as a major source of food.
The ancient river Nile was full of fish; fresh and dried fish were a staple food for much of the population. The Egyptians had implements and methods for fishing and these are illustrated in tomb scenes, drawings, and papyrus documents. Some representations hint at fishing being pursued as a pastime.
Fishing scenes are rarely represented in ancient Greek culture, a reflection of the low social status of fishing. However, Oppian of Corycus, a Greek author wrote a major treatise on sea fishing, the Halieulica or Halieutika, composed between 177 and 180. This is the earliest such work to have survived to the modern day. The consumption of fish varied in accordance with the wealth and location of the household. In the Greek islands and on the coast, fresh fish and seafood (squid, octopus, and shellfish) were common. They were eaten locally but more often transported inland. Sardines and anchovies were regular fare for the citizens of Athens. They were sometimes sold fresh, but more frequently salted. A stele of the late 3rd century BCE from the small Boeotian city of Akraiphia, on Lake Copais, provides us with a list of fish prices. The cheapest was skaren (probably parrotfish) whereas Atlantic bluefin tuna was three times as expensive. Common salt water fish were yellowfin tuna, red mullet, ray, swordfish or sturgeon, a delicacy which was eaten salted. Lake Copais itself was famous in all Greece for its eels, celebrated by the hero of The Acharnians. Other fresh water fish were pike-fish, carp and the less appreciated catfish.
Pictorial evidence of Roman fishing comes from mosaics. At a certain time the goatfish was considered the epitome of luxury, above all because its scales exhibit a bright red color when it dies out of water. For this reason these fish were occasionally allowed to die slowly at the table. There even was a recipe where this would take place in garo, in the sauce. At the beginning of the Imperial era, however, this custom suddenly came to an end, which is why mullus in the feast of Trimalchio (see the Satyricon) could be shown as a characteristic of the parvenu, who bores his guests with an unfashionable display of dying fish.
In medieval times, seafood was less prestigious than other animal meats, and often seen as merely an alternative to meat on fast days. Still, seafood was the mainstay of many coastal populations. Kippers made from herring caught in the North Sea could be found in markets as far away as Constantinople. While large quantities of fish were eaten fresh, a large proportion was salted, dried, and, to a lesser extent, smoked. Stockfish, cod that was split down the middle, fixed to a pole and dried, was very common, though preparation could be time-consuming, and meant beating the dried fish with a mallet before soaking it in water. A wide range of mollusks including oysters, mussels and scallops were eaten by coastal and river-dwelling populations, and freshwater crayfish were seen as a desirable alternative to meat during fish days. Compared to meat, fish was much more expensive for inland populations, especially in Central Europe, and therefore not an option for most.
Modern knowledge of the reproductive cycles of aquatic species has led to the development of hatcheries and improved techniques of fish farming and aquaculture. Better understanding of the hazards of eating raw and undercooked fish and shellfish has led to improved preservation methods and processing.
Types of seafood
The following table is based on the ISSCAAP classification (International Standard Statistical Classification of Aquatic Animals and Plants) used by the FAO for the purposes of collecting and compiling fishery statistics. The production figures have been extracted from the FAO FishStat database, and include both capture from wild fisheries and aquaculture production.
Fish is a highly perishable product. The fishy smell of dead fish is due to the breakdown of amino acids into biogenic amines and ammonia.
Live food fish are often transported in tanks at high expense for an international market that prefers its seafood killed immediately before it is cooked. This process originally was started by Lindeye. Delivery of live fish without water is also being explored. While some seafood restaurants keep live fish in aquaria for display purposes or for cultural beliefs, the majority of live fish are kept for dining customers. The live food fish trade in Hong Kong, for example, is estimated to have driven imports of live food fish to more than 15,000 tonnes in 2000. Worldwide sales that year were estimated at US$400 million, according to the World Resources Institute.
If the cool chain has not been adhered to correctly, food products generally decay and become harmful before the validity date printed on the package. As the potential harm for a consumer when eating rotten fish is much larger than for example with dairy products, the U.S. Food and Drug Administration (FDA) has introduced regulation in the USA requiring the use of a time temperature indicator on certain fresh chilled seafood products.
Fresh fish is a highly perishable food product, so it must be eaten promptly or discarded; it can be kept for only a short time. In many countries, fresh fish are filleted and displayed for sale on a bed of crushed ice or refrigerated. Fresh fish is most commonly found near bodies of water, but the advent of refrigerated train and truck transportation has made fresh fish more widely available inland.
Long term preservation of fish is accomplished in a variety of ways. The oldest and still most widely used techniques are drying and salting. Desiccation (complete drying) is commonly used to preserve fish such as cod. Partial drying and salting is popular for the preservation of fish like herring and mackerel. Fish such as salmon, tuna, and herring are cooked and canned. Most fish are filleted prior to canning, but some small fish (e.g. sardines) are only decapitated and gutted prior to canning.
Seafood is consumed all over the world; it provides the world's prime source of high-quality protein: 14–16% of the animal protein consumed worldwide; over one billion people rely on seafood as their primary source of animal protein. Fish is among the most common food allergens.
Iceland, Japan, and Portugal are the greatest consumers of seafood per capita in the world.
The UK Food Standards Agency recommends that at least two portions of seafood should be consumed each week, one of which should be oil-rich. There are over 100 different types of seafood available around the coast of the UK.
Oil-rich fish such as mackerel or herring are rich in long chain Omega-3 oils. These oils are found in every cell of the human body, and are required for human biological functions such as brain functionality.
Whitefish such as haddock and cod are very low in fat and calories which, combined with oily fish rich in Omega-3 such as mackerel, sardines, fresh tuna, salmon and trout, can help to protect against coronary heart disease, as well as helping to develop strong bones and teeth.
Shellfish are particularly rich in zinc, which is essential for healthy skin and muscles as well as fertility. Casanova reputedly ate 50 oysters a day.
Texture and taste
Over 32,000 fish species of many more marine invertebrate species have been described. However, only a small number of species are commonly eaten by humans.
Research over the past few decades has shown that the nutrients and minerals in seafood can make improvements in brain development and reproduction and has highlighted the role for seafood in the functions of the human body.
Doctors have known of strong links between fish and healthy hearts ever since they noticed that fish-eating Inuit populations in the Arctic had low levels of heart disease. One study has suggested that adding one portion of fish a week to your diet can cut your chances of suffering a heart attack by half. Fish is thought to protect the heart because eating less saturated fat and more omega-3 can help to lower the amount of cholesterol and triglycerides in the blood – two fats that, in excess, increase the risk of heart disease. Omega-3 fats also have natural built-in anti-oxidants, which are thought to stop the thickening and damaging of artery walls. Regularly eating fish oils is also thought to reduce the risk of arrhythmia – irregular electrical activity in the heart which increases the risk of sudden heart attacks.
10–12% of the human brain is composed of lipids, including the omega-3 fat DHA. Recent studies suggest that older people can boost their brain power by eating more oily fish, what with regular consumers being able to remember better and think faster than those who don't consume at all. Other research has also suggested that adding more DHA to the diet of children with attention-deficit hyperactivity disorder can reduce their behavioural problems and improve their reading skills, while there have also been links suggested between DHA and better concentration. Separate studies have suggested that older people who eat fish at least once a week could also have a lower chance of developing dementia and Alzheimer's disease.
Including fish as a regular part of a balanced diet has been shown to help the symptoms of rheumatoid arthritis – a painful condition that causes joints to swell up, reducing strength and mobility. Studies also show that sufferers feel less stiff and sore in the morning if they keep their fish oil intake topped up. Recent research has also found a link between omega-3 fats and a slowing down in the wearing of cartilage that leads to osteoarthritis, opening the door for more research into whether eating more fish could help prevent the disease.
Fish is high in minerals such as zinc, iodine and selenium, which keep the body running smoothly. Iodine is essential for the thyroid gland, which controls growth and metabolism, while selenium is used to make enzymes that protect cell walls from cancer-causing free radicals, and helps prevent DNA damage caused by radiation and some chemicals. Fish is also a source of vitamin A, which is needed for healthy skin and eyes, and vitamin D, which is needed to help the body absorb calcium to strengthen teeth and bones.
Fish and shellfish have a natural tendency to concentrate mercury in their bodies, often in the form of methylmercury, a highly toxic organic compound of mercury. Species of fish that are high on the food chain, such as shark, swordfish, king mackerel, albacore tuna, and tilefish contain higher concentrations of mercury than others. This is because mercury is stored in the muscle tissues of fish, and when a predatory fish eats another fish, it assumes the entire body burden of mercury in the consumed fish. Since fish are less efficient at depurating than accumulating methylmercury, fish-tissue concentrations increase over time. Thus species that are high on the food chain amass body burdens of mercury that can be ten times higher than the species they consume. This process is called biomagnification. The first occurrence of widespread mercury poisoning in humans occurred this way in Minamata, Japan, now called Minamata disease.
Shellfish are among the more common food allergens. A common misconception is a cross-reactivity between seafood and iodinated radiocontrast agents.
A 2013 study by Oceana found that one third of seafood sampled from the United States was incorrectly labelled. Snapper and tuna were particularly susceptible to mislabelling, and seafood substitution was the most common type of fraud. These practices can harm both the consumers' wallet and pose health risks. Another type of mislabelling is short-weighting, where practices such as overglazing or soaking can misleadingly increase the apparent weight of the fish. The detection of water retention agents helps identify the fraud and its origin.
Research into population trends of various species of seafood is pointing to a global collapse of seafood species by 2048. Such a collapse would occur due to pollution and overfishing, threatening oceanic ecosystems, according to some researchers.
A major international scientific study released in November 2006 in the journal Science found that about one-third of all fishing stocks worldwide have collapsed (with a collapse being defined as a decline to less than 10% of their maximum observed abundance), and that if current trends continue all fish stocks worldwide will collapse within fifty years. In July 2009, Boris Worm of Dalhousie University, the author of the November 2006 study in Science, co-authored an update on the state of the world's fisheries with one of the original study's critics, Ray Hilborn of the University of Washington at Seattle. The new study found that through good fisheries management techniques even depleted fish stocks can be revived and made commercially viable again.
The FAO State of World Fisheries and Aquaculture 2004 report estimates that in 2003, of the main fish stocks or groups of resources for which assessment information is available, "approximately one-quarter were overexploited, depleted or recovering from depletion (16%, 7% and 1% respectively) and needed rebuilding."
The National Fisheries Institute, a trade advocacy group representing the United States seafood industry, disagree. They claim that currently observed declines in fish population are due to natural fluctuations and that enhanced technologies will eventually alleviate whatever impact humanity is having on oceanic life.
For the most part Islamic dietary laws allow the eating of seafood, though the Hanbali forbid eels, the Shafi forbid frogs and crocodiles, and the Hanafi forbid bottom feeders such as shellfish and carp. The Jewish laws of Kashrut forbid the eating of shellfish and eels. In the Old Testament, the Mosaic Covenant allowed the Israelites to eat finfish, but shellfish and eels were an abomination and not allowed. In ancient and medieval times, the Catholic Church forbade the practice of eating meat, eggs and dairy products during Lent. Thomas Aquinas argued that these "afford greater pleasure as food [than fish], and greater nourishment to the human body, so that from their consumption there results a greater surplus available for seminal matter, which when abundant becomes a great incentive to lust." In the United States, the Catholic practice of abstaining from meat on Fridays during Lent has popularized the Friday fish fry, and parishes often sponsor a fish fry during Lent. In predominantly Roman Catholic areas, restaurants may adjust their menus during Lent by adding seafood items to the menu.