Flotsam and invasive species
An article in Lofoten Posten in North Norway described flotsam that had been found covered in strange animals. It is actually a measuring buoy that monitors wave height and directional currents. There are hundreds of such buoys all over the world and they can travel great distances. Let us have a look at the photograph:
We see a buoy overgrown with greenery with – as the finder describes it – worm-like animals on it. These worm-like animals are goose barnacles, a type of barnacle that does not spawn in Norway, but comes to our coast attached to flotsam moving northwards with the dominating currents.
They are observed relatively frequently on flotsam up as far as Mid Norway, but seldom further north. The buoy in the article was actually found in North Lofoten.
These barnacles thrive in the Bay of Biscay, along the Dutch and Belgian coast, as well as on both of the English coasts.
These areas are considered to be normal places of origin from which invasive species come, with ballast water, as fouling on ship hulls (or attached to buoys or other flotsam as described in this article), and infect new areas. This is true for the skeleton shrimp, Asian sea squirt, wireweed and «sea puke» (a recent invasive colonial sea squirt), just to mention a few.
From Japan to the USA
The tsunami in Japan in 2011 washed up many wrecks, including several boats. Most of them have sunk again, but one was found off the American west coast in 2013. What surprised researchers most was that there were several Japanese species in the boat’s cargo hold, including five fish species, none of which are found on the west coast of the US. The fish can have travelled all the way from Japan, but might also have been picked up around Hawaii where they are also to be found. The boat also contained several species of crustaceans and algae that are not naturally at home in the US. Parts of floating piers covered with colonies of familiar invasive species have also been found in Oregon.
It is therefore not always boat traffic that is guilty of spreading species, but also flotsam, whether human-made or natural. It appears to be impossible to defend oneself against invasions of this kind, but observant fish farmers are actually the first instance in charting the spreading of invasive species.
So if you see anything strange growing on your nets, «Who should you call?» Steen-Hansen!
The most common species. Click icons below
JJohn is Sales Manager at Steen-Hansen. He has worked with nets for an entire generation, among other things as general manager of a service station.
Discussions with John are not limited to the protection of nets and reduction of fouling. He also has a broad knowledge about nets, net materials and the construction of nets.
firstname.lastname@example.org / +47 94010670
Know the Book on Fouling? Get your free copies here >>
Any particular issues you would like us to address?
Seize the moment, and drop us some lines >>