Wednesday, 13 February 2013

Week 8: Sardine (Sardina pilchardus)


The sardine was @SpeciesofUK from 20th to 26th January, 2013.

Sardines are named after the island of Sardinia in the Mediterranean, where they traditionally occurred in large numbers.

The sardine species Sardina pilchardus, which is found around the UK, is distributed across the NE Atlantic, from Iceland in the NW to the northern coast of Africa and as far south as Senegal.1 This species has a particular concentration around the British Isles and the North Sea, making it a true UK species.2

Sardines
[Source: Etrusko25]

What is a sardine?

Good question. I'll try to explain but you'll probably wish you hadn't asked...

'Sardine' is a common name given to several species in the Clupeidae family which also includes herring, shads, hilsa and menhaden. The UN's Food and Agriculture Organisation lists a total of 21 species that it permits to be called 'sardines' in canned food products.3

In the UK, the term sardine is most often used to refer to one species in particular, Sardina pilchardus, otherwise known as the European Pilchard. (This is the species we'll focus on in the remainder of this blog.)

Drawing of Sardina Pilchardus
[Source: Les poissons Gervais, H.]

It's also useful to understand what a pilchard is. Like sardine, 'pilchard' is a word that can be used to describe several species. But in the UK, people usually use sardine and pilchard interchangeably to describe Sardina pilchardus. According to one common definition, if a Sardina pilchardus is longer than 15cm it's called a pilchard; if it's less than 15cm, it's called a sardine.

Historically, pilchards suffered from a poor image in the UK and didn't sell well. Since 2004, however, one very successful fishery, the Cornish Sardine Management Association, has found a clever way of marketing them. They have re-branded pilchards as "Cornish sardines," and successfully marketed them as a sustainable, high quality alternative to sardines. So today, you're unlikely to see a pilchard called a pilchard in a UK shop anymore, but you will find “Cornish sardines” which are the same thing! There is a good article in the Independent that explains this better than I can.

Of course, just to add to the confusion, other species do still get called pilchards! One example of this is the Pacific Pilchard, Sardinops sagax, which is readily available in UK supermarkets alongside the more common Sardina pilchardus.

Suitably confused? Well, from now on, when I use the word 'sardine' just assume I'm referring to Sardina pilchardus.

Identifying a sardine

Sardines are small, near-cylindrical fish, but with a rounded belly. The juveniles are more compact.

They are metallic green or olive-coloured along the back with golden flanks and pearlescent silver shading on the belly.


Sardina Pilchardus
[Source: Citron]

Sardines often have a series of dark spots on their upper flanks, sometimes with a second or even third series below.

Behaviour

Sardines are coastal. You won’t find them way out in the open ocean, although they do stray several hundred kilometres from the coast in the North Sea.4

They are also pelagic fish. Pelagic means they live near the surface (as opposed to near the bottom or on reefs). They usually keep to between 25-55m from the surface during the day, or as deep as 100m. At night they can rise to just 10m from the surface.5

Sardines spawn in batches, near the coast or in the sea, producing 50,000 to 60,000 eggs in total, each about 1.5mm in diameter.7 Batch spawning means eggs are shed more than once in a season. (The opposite to batch spawning is fractional spawning, meaning all eggs are shed in a short period.)

Sardine are planktivores, meaning they feed on plankton, tiny organisms in the sea, and they especially favour planktonic crustaceans.

Sardine schools

One of the most impressive sights in the ocean is a school of sardines. It's a shimmering, elegant, magnificent creature.

Sardines school together for protection from predators. It's thought that fish moving in schools easily confuse predators that rely on vision to pick out individual prey. It's sensory overload. Another theory is that in a school, sardines literally have more eyes, enabling better collaboration in spotting and reacting to predators.

School of Sardina Pilchardus
[Source: Etrusko25]

Sardine predators include: tuna, salmon, dolphins, sharks, swordfish, seals and sea gulls. The reduction in many of their predator fish has allowed the sardine population to soar in recent years.8

The most famous schooling sardines are found off the coast of South Africa, where they migrate in the famous "sardine run." You simply must watch a video of this, it's incredible!

Sardine fisheries

Since the 1950s, catches of sardines have steadily been increasing, reaching peaks in 1976 and 1990.9

Sardines are a reasonably sustainable fish to catch. They are low in the food chain so have a low concentration of pollutants, they shoal so there is little chance of by-catch, and they are fast growing so rapidly replace stock.10

Catch of Sardines
[Source: Daniel Ventura]

Some sardine fisheries, such as the one in Cornwall, have now secured Marine Stewardship certification for being sustainable.11

A common way to catch sardine is with a Purse Seine. Gillnets, beach seines, trap nets and bottom trawls are also used.12

A purse seine is a net that is literally purse-shaped and closed with a draw-string type rope. It’s a favoured method for catching fish that school near the surface, like sardines. Purse seines are great for sustainable fishing because they focus on the school of sardine and limit by-catch of other species.13

Sardines as food

Sardines are a popular foodstuff because they are rich in Omega-3 fatty acids. Omega-3 reduces incidence of heart diseases, reduces the likelihood of Alzheimer’s, helps brain development and memory, can reduce cancer risk, and fights depression.14 Omega 3 has strong evidence to back it up, particularly in terms of boosting heart health.15

Far and away the best source of Omega 3 fatty acids is oily fish, such as sardines.

Fresh sardines are usually cooked whole. They are great oven-baked or even on the barbeque.16

I
n the UK, however, sardines are often sold in cans, either in an oil or sauce. They are great on toast!

Strange but true...

Sardines breed at different times of the year depending on their location. In the English Channel, they breed in April. In the North Sea and Black Sea, in June-August. In the Mediterranean, from September-May.6

3http://www.newworldencyclopedia.org/entry/Sardine
12http://www.fao.org/fishery/species/2910/en
16http://www.goodfishguide.co.uk/fish/sardine-european-pilchard-187

1 comment:

  1. Hi, thanks for the great sardine info!
    Where can I find more information about the strange but true remark:
    "Sardines breed at different times of the year depending on their location. In the English Channel, they breed in April. In the North Sea and Black Sea, in June-August. In the Mediterranean, from September-May."

    Followed your citation but in FAO webpage can't find anything about breeding timeframes.

    ReplyDelete