1) What are the most important characteristics of the mussel?
2) What is the best time for the consumption of fresh mussels?
3) Where are mussels cultivated?
4) How are mussels cultivated?
5) What are the "red tides"?
6) What is the control of bio-toxins?
What are the most important characteristics of the mussel?
The Mussel (Mytilus galloprovincialis) is a bivalve mollusc whose shell is composed of two valves symmetrical, elongated and triangular, calcium carbonate, covered externally by a layer of bluish colour. In its shell can be observed a few concentric lines called striations of growth, which is observed, as it has been occurring growth.
Feeds filtering particles of matter in suspension and phytoplankton found in water so its growth is subject to the availability of these. The gills are highly developed, and are used both for breathing and feeding. It is a large filter feeder; under normal conditions a medium-sized Mussel filters out 4 to 5 litres of water at the time, being able to efficiently capture particles with diameters between 2-5 microns. A string of Mussel can filter more than 700,000 litres of water in a day and a "batea" (production raft) can consume 180 metric tons of organic matter in a year.
Differentiation by gender of the mussels can be observed at a glance once cooked by their colour: darker in colour, orange or reddish parts are females and the paler are males, although these tones may be more or less accused on the basis of the diet that provides the mussel in the marine environment. Lorbé Mussel is characterized by being clearer than in other areas for this reason. [return]
What is the best time for the consumption of fresh mussels?
Due to the particular conditions of its cultivation and food, the time in which the mussel begins to find itself in an optimal state is from the months of June / July because, starting in the spring, there is availability of food in the water. These optimal conditions are extended during the second half of the year and even during the first months of the following year while the harvest is not exhausted. The end of winter and early spring is the worst time to eat fresh mussels.
Production of frozen mussels, in brine or pasteurized, allows the consumption of mussels in their prime all year round the year. [return]
Where are mussels cultivated?
The Galician estuaries are optimal zones for cultivation due to its special geographic and oceanographic conditions. The main reason for being an ecosystem with as high productivity is the outcrop: ascent to the surface of cold water from deep areas that drag a lot of nutrients. Harnessing this potential of the estuaries enables a shorter time period for growth than in other places.
There are approximately 3,400 production rafts across the estuaries of Ares - Betanzos, Muros, Arosa, Pontevedra and Vigo in Galicia. There is an anecdotal presence in Balyona y Corme. This crop production is a strategic sector of great importance in the Galician economy and diet. [return]
How are mussels cultivated?
It is traditionally grown in floating rafts called "bateas" which consist of a gridiron of eucalyptus wood which are mounted on floats of iron coated polyester and fiberglass. A maximum of 500 ropes of 12 meters in length, in which the mussel is held by its byssus (filament to fix to rocks, ropes or almost any substrate) can hang this artefact. These rafts are placed within the polygons of cultivation in previously determined positions in the interior of the estuaries.
The mussel cultivation cycle begins with the harvesting of breeding or seed in the rocks or collectors placed strategically and prior to fixing this breeding, which has some early stages of its life in water (pelagic stages) free. It is planted in the initial string with the help of surround gauze that holds the mussel till it secretes the byssus, which is going to fix it to the rope. After approximately 6 months it is a split of the initial string into two or three new strings to reduce the density and allow the growth to continue. Finally and after about 12 months time it is ready for commercialization.
Production cycle of Mytilus galloprovincialis. Source: FAO
What are the "red tides"?
At certain times of the year the mussel is susceptible to an accumulation of certain substances called "bio-toxins", containing some species of phytoplankton that feeds, and they are known as "red tides". In case of high concentrations of these species of phytoplankton in the water, to be part of the diet of mussels, it can accumulate these substances giving rise to toxicity if consumed, although it does not cause damage to the mussel.
There are currently systems established by the Administration and executed by them and also by companies to ensure the safety of these products, as far as marketing is carried out through the legal channels. Galicia is a world reference in the control of the bio-toxins because of the structure that has been developed. [return]
What is the control of bio-toxins?
Local Galician Government exercises an initial monitoring in three aspects differentiated as preventive measures. In a first step, controls the oceanographic conditions to know when there are the best ones for the development of plankton species that may contain bio-toxins. A second part of the control consists of the investigation of the presence in water of these potentially toxic species of plankton. The third part, which is the final for toxicity data, consists of the analysis of Mussel.
Marketing companies, as responsible for products placed on the market, have at their disposal and use the information generated by the Administration and also conduct their own analytical controls to ensure the wholesomeness of their products.
Depending on the risk, companies and Administration perform the analysis with greater or lesser frequencies. [return]