Shellfish Farming Overview

COMING SOON - An overview of European Shellfish Farming

 

What is Aquaculture?

"Aquaculture is the farming and marketing of freshwater or marine plants and animals in a controlled environment avoiding the harmful effects of nature. Due to the depletion of world fisheries stocks, aquaculture is today the only alternative to make a significant contribution to the world’s aquatic food supply and to become an important provider of food for the world’s growing population. Aquaculture also has a social dimension providing for an alternative livelihood and thus has an important role in the alleviation of poverty in the world. Consequently, in the same way that agriculture has replaced the gathering of wild plants and livestock breeding has replaced hunting, aquaculture is supplementing fishing in order to save the endangered seas."Source - Aquamedia

Extensive Mussel Farming

The rearing of mussels is always done in extensive conditions.  The young mussels are collected from the sea and can be cultured using a number of different techniques:

   1. ‘Bouchot' culture - which uses a series of wooden poles as supports, onto which the mussels are transplanted for on-growing
   2. Suspended rope culture - where ropes, covered with mussel seeds kept in place by nylon nets, are suspended either from rafts, wooden frames or from Iong lines of floating plastic buoys.
   3. Bottom culture - which depends on the harvesting of young  mussels and spreading them out on specially prepared protected  growing plots.

The shores of the north-western Atlantic have two indigenous blue mussel species, Mytilus galloprovincialis and Mytilus edulis. In Norway , Sweden , Denmark , Germany , Netherlands , France and the United Kingdom the farmed species is Mytilus edulis.  In Galicia in NW Spain Mytilus galloprovincialis is cultured.

A number of different methods to culture mussels are used in Europe . Traditionally, mussel culture consisted of collecting seed (20 mm long) and the subsequent grow-out to commercial size (4-7 cm) in 1-3 years. In France , mussels are cultured by tying coconut fibre ropes filled with seed to poles placed on the beach near the low water line. In areas in the UK , the Netherlands and Germany seed is spread on bottom plots. In Spain , west Ireland , Sweden and Norway , where the sea is too deep for bottom culture, raft and long-line systems dominate. This involves placing seed mussels in stockings attached to vertically suspended ropes. The M. galloprovincialis industry in Spain is mainly concentrated in estuaries (Rías) on the Galician coast and is the main mariculture activity in Spain . The culture method consists of grow-out of wild seed on culture ropes suspended from rafts situated in nutrient-rich and sheltered environments inside the estuaries. Market size is reached in ± 1½ year, depending on several micro- and macro-scale factors, such as the site and depth of cultivation, the position of the culture ropes within the rafts, and the source of seed.

Dredging wild seed beds is the traditional source of seed in the Netherlands and the UK . Collecting seed on man-made substrates is traditionally practiced in Bouchot culture in France . Ropes from coconut fibre are placed on frames in bays where heavy settlement of mussel larvae occurs. Two different methods to procure wild seed are used in Spain : (1) scraping of juvenile muss els from intertidal beds on exposed rocky shores and (2) hanging spat-collecting ropes from rafts in the estuaries. Although considerable spatial and temporal fluctuations in mussel larvae abundance occur, in Spain there is no shortage of seed from collector ropes or intertidal beds. Recent investigations showed that collecting seed on vertically suspended ropes could be an important addition to the catch from wild beds for bottom culture of muss els in the Netherlands and Germany. Several Dutch companies are now collecting mussel seed in pilot scale long-line farms. The seed is being used on bottom plots. With the exception of Spain , collecting sufficient and predictable amounts of mussel seed each year is extremely difficult. Large quantities of seed are needed. Thus, securing a reliable supply of spat and seed is a major challenge to the majority of European blue mussel farmers.

 

 

Links to Aquaculture Information

 

Aquamedia is a focus for accurate and up-to-date information about aquaculture.
To take a virtual tour of a Clam farm CLICK HERE
Sustainable Aquaculture in Europe - Consensus project www.euraquaculture.info