Shortening the growing time of mussels - FINAL REPORT / Shortening the growing time of blue mussels on long lines
The main objective of the project was to develop and evaluate a method for the cultivation of mussel shells on seaweeds that yields at least a year earlier than the traditional cultivation method. The sub-goals were to assess the stock size and recruitment capacity in the experimental small shellfish fishing areas in Hvalfjörður and the uptake of cadmium in mussels after transport and in further cultivation.
The summary conclusions of the project are as follows:
a) The stock size assessment of mussels in Hvalfjörður revealed a fairly large fishing stock and based on a 10% fishing quota of stock size, it would be possible to fish 1,500 tonnes annually in the fjord. The mainstay of the population in most areas are large shells that are not suitable for cultivation.
b) The collection of wild small shells (approximately 20-30 mm) for soaking and rearing of hangers (rotating) in the sea yields a harvest at least a year earlier than the traditional cultivation method.
c) Small shells can be fished, transported, socked and released in cultivation areas away from fishing grounds. However, the size of the shells has a lot to say about the possibilities for further cultivation, as their mobility seems to decrease from 25 mm shell length. In the study, a crop of lines of caught and plucked shell was about 5 kilograms of marketable shell per meter of length.
d) This cultivation method can be useful in addition to conventional cultivation. Being able to pick up wild mussels can be very important, especially if traditional larval collection has been destroyed for some reason. The results of the current project will potentially be useful for more than shortening the growing season and can play a key role in the development of mussel farming around the country.
e) Uptake of cadmium in mussels can be a problem after transport and in further cultivation and it is important to monitor the concentration of cadmium in mussels before it is placed on the market.
This report presents results from a research project funded by AVS year 2009. The main aim of the project was to evaluate whether it would be possible to shorten the growing time of blue mussels so that they reach market size more rapidly. The following technique was tested; harvesting of natural stocks of blue mussel in two fjords in West Iceland where small individuals were sorted out from the catch (<40 mm) and put into socks to grow to market size in hanging culture. > <40 mm) and put into socks to grow to market size in hanging culture. Using this technique, small mussels between ca 20-30 mm in shell length reach market size (45mm +) in hanging culture in one year, while using traditional methods (spat collection and growth) this takes 2-3 years. This technique thus offers possibilities to utilize an unexploited natural stock of mussels and shorten considerably the growing time to market size.