US - Over the past 20 years there have been reports of whales and turtles becoming trapped and dying in mussel farming gear. Although they do seem to be rare events, Scott Lindell, Marine Biological Laboratory, showed that the cases all seem to involve mussel spat collecting ropes, writes Lucy Towers, TheFishSite Editor.
Mussel spat ropes are very fine and flexible ropes when they are first deployed and therefore for a short period of time until they become populated with mussels, they do pose a risk on entanglement.
The deployment of these ropes therefore requires some consideration.
Research by Carol Price, NOAA, also looked into the entanglement risks of mussel farms. As well as spat lines, she also mentioned how buoy and anchor lines can cause a threat, even when made of very strong material. The same goes for other forms of offshore aquaculture.
Ms Price agreed that there are potential interactions between marine life and farming equiptment but did note that the risk seems to be relatively low.
In order to try and prevent entanglements, management options include:
- deploying spat lines before migratory species arrive
- moving spat lines closer to the shore
- keeping buoy lines shorter. For example, 2-4m long pencil buoys used in UK.
- Have fatter buoys on the end and thinner ones in the middle.
- keeping lines and nets taught
- using technology to deter animals approaching the farm
- monitoring occurrences and training staff