Jump here, not there: Helping control sea lice infestations in Atlantic salmon populations
Infestations of sea lice in Atlantic salmon farms cause health problems for fish and economic problems for producers. But researchers from the University of Melbourne and the Institute of Marine Research in Norway have discovered a new way to manipulate the behavior of Atlantic salmon and keep fish safe from sea lice. Their research was published in the December issue of the Journal of Animal Science.
In Atlantic salmon farms, the pens where fish live can act as “reservoirs” for sea lice and spread the harmful lice among the wild populations of salmon and trout. Sea lice feed on the skin and blood of Atlantic salmon and trout populations, resulting in unhealthy fish and a loss of profits. Many believe the current treatments (medicated feed and chemical baths) are inefficient. A new, more efficient, and more cost-effective treatment for sea lice was needed to help the commercial Atlantic salmon populations, and, in turn, the wild populations.
The researchers for this study administered sea lice medication by taking advantage of a natural fish behavior. Salmon need to jump so they can swallow air and refill their swim bladders. Already, some salmon producers administer sea lice medication by spreading oil-infused medication on the surface of the water. When the fish jump through, they are coated in the medication that kills sea lice. The medication is effective, but the researchers for this study wanted a way to administer it more efficiently.
Salmon in the experimental group were not allowed access to the water’s surface for up to 48 hours. This restriction was not harmful to fish, but because of this restriction, the fish were very motivated to jump and swallow air once they got the chance. Knowing this, the researchers then allowed fish to jump in a small area of the pen. If used in a commercial setting, the water surface of the chosen area would be covered with the oil-infused medication, so the fish would be coated with the anti-sea lice treatment as they jumped out of the water.
Observations recorded by video cameras showed that the fish did jump more frequently when only allowed to jump for a short period of time.
“By combining the increased jumping behavior induced by this technique with a floating, oil-infused treatment, efficiency of sea lice treatments may be improved and treatment chemicals can be re-collected, thus decreasing environmental pollution,” wrote the researchers.
Encouragingly, the treatment may be effective for fish that are heavily infested with lice because they jump with a greater frequency than un-infested fish.
Dr. Paul Brown, professor of Fisheries and Aquatic Science at Purdue University, was intrigued by the study. He said the research may be a preliminary step to improvements in the Atlantic salmon industry. With this technique, sea lice populations could decline and lessen both environmental and economic concerns.
“The authors should be lauded for their novel method of exposing fish to therapeutics,” said Brown.
The study was titled “Modifying Atlantic salmon (Salmo salar) jumping behavior to facilitate innovation of parasitic sea lice control techniques.” It can be read in full at http://journalofanimalscience.org/
ASAS Scientific Communications Associate
MadelineMS@asas.org / 217-689-2435