Tuesday, 2 August 2011
Happy feet, the mussel
I just recently reread my articles concerning bad sea food choices and they seemed a little bit too much about doom and gloom and not enough about the amazing amount of healthy alternative and cheap choices out there. This has prompted me to write a few short posts about fish and shellfish which are more positive, extolling the virtues of the fish that you can eat. The first oceanic hero that jumped to mind was the mighty mussel (having just recently been treated to some myself).
Mussels are small filter feeding bivalves that anchor themselves to rocks with a muscular foot, they are hardy and reproduce easily and in great numbers. Given the chance, mussel spat (the word for their spawn...it sounds so dirty) will land and colonise pretty much any surface that gets a whiff of salt water. This makes them ideal candidates for food farming, based squarely upon their biology.
The great thing about mussel farming, from the grower's point of view, is that it takes care of itself. The mussels grow for two or three years, filter-feeding on plankton and other microscopic sea creatures which are free-floating in seawater, after which time they are ready to be harvested.
The blue mussel...a table favourite
The blue mussel (Mytilus edulis) is both farmed and wild-caught in the UK. In 2009, while 3,400 tonnes were wild-caught, using mussel dredges (which is not as bad as it seems, much less damaging than a trawl), nearly 32,000 tonnes, worth £30m, were farmed, making mussels the most heavily cultivated shellfish in the U.K.
Mussels are also good for you. In terms of healthy fish oils such as omega threes (the ones that pushy mums are intent to drown their children in), they are up their with the oily fish big boys like sardines and mackerel (1000mg per 100g if you are crunching the numbers).
Mussel farming usually has two main forms; bottom culture, or suspended culture. The Marine Conservation Society ranks bottom cultivated mussels as 2 (on their 1-5 scale; 1 being most sustainable) and suspended cultivation as number 1. So good marks all around.
Bottom cultivation of mussels on the seabed occurs in in sheltered bays with good water quality. One such area is the Menai Strait in North Wales which produces over half of the total UK output of mussels and has Marine Stewardship Council certification (this area is one of our better managed fisheries and I might come back to it as an example of good policy decisions). Mussel production here relies on collected spat from the Irish Sea, which is re-laid in plots in the Strait where the mussels can grow to market (or munchable) size.
Mussel spat are collected when they are roughly one year old using mussel dredges. These dredges skim the spat off and leave the seabed relatively undisturbed (when compared to bottom trawling). This does not reduce the natural stocks of mussels because the unstable beds where the spat are collected are often destroyed by winter storms anyway; known as ephemeral beds. The seasonal nature of spat collection also allows gaps in collecting of up to a year, which gives time for the ecosystem to recover.
Suspended mussel culture...yum
Suspended culture is even better, and is where the mussels are cultivated on suspended ropes or poles driven into the seabed. With these methods the collection of the spat does not involve dredging and the ropes are simply pulled in after they mussels have grown large enough. Mussel farming of this kind has actually been shown to improve habitat structure and boost both crustacean numbers and those of small fish, helping to repair the structure of our damaged marine ecosystems (praise the mighty muscle).
All in all the mussel is an excellent choice, both in terms of health and sustainability. They also go great with a white wine sauce and french fries....