In an effort to continue to improve environmental processes while making systems safer and more effective, the European salmon industry has started to use cleaner fish to sustainably control salmon sea lice in aquaculture environments. Cleaner fish introductions can have impact, however, and the extent has been largely unknown outside of visual observation.
The overall aim of one study was to investigate fish behaviour using an HTI Acoustic Tag System. This system allows for 2D/3D tracking of fish behavior in fine-scale (to 20 cm), allowing researchers to better understand the activity and potential impacts of the cleaner fish placed in the aquaculture net-pens.
Tagged wild ballan wrasse and tagged farmed lumpfish were stocked in net-pens with Atlantic salmon. The Acoustic Tag System provides unique fish identification, and recorded strong species specific behaviour in the net pens. Lumpfish spent most of their time (80%) at the top of the pens day and night, compared to 15% and 30% respectively for the ballan wrasse.
The real-time 3D data
suggested patterns of increased delousing activity for both species when water temperatures were rising.
Monitoring day-night variations in the vertical distribution of salmon shed light on potential overnight creel recaptures. The practical implications of monitoring behavioural trends provided much insight as to how fisheries managers may be able to better control or influence species interaction. Scientists also discovered that there were differences in swimming speeds between the species (an unexpected outcome that was previously based on morphology) and that artificial light altered behaviour and impacted the delousing potency.
Scientists have a better understanding of cleaner fish activity in fish farms using acoustic tags. They continue to be an effective tool for monitoring the fish while taking into account origins, history, seasonal, environmental, and stocking conditions.
HTI is honoured to work with aquaculture teams in the UK including: Eric Leclercq, Benjamin Zerafa, and Herve Miguad. To learn more about this study, read the Fish Farmer January 2016 article or contact us at support@HTIsonar.com.
|Remotely accessing real-time data that is tracking fish behaviour in 3D.
|Example of 3D track from top-view and depth profile of an individual ballan wrasse over 48 hours.
"The 3D Tracking System performed extremely well
given that it was
tested for the first time
challenging farm conditions,
salmon densities, tidal flow,
and salinity variations,
as well as
from seal scarers & boats."
- Study Team, University of Stirling Institute of Aquaculture
"The development of novel methods
for the control
sea lice on farmed salmon
to the future
of the industry."
- Sainsbury's Spokesperson
This project funded by Sainsbury's,
the Scottish Aquaculture Innovatoin Centre,
& Marine Harvest, Scotland