Lumpfish Glow Ultraviolet Biofluorescence Journal Of Fish Biology Colours Camouflage

Scientists have observed biofluorescence in lumpfish (Cyclopterus lumpus) for the first time. They found that individual lumpfish were illuminated with a certain lighting for photography. 

The study describing the findings has been accepted for publication in the Journal of Fish Biology. 

All the juvenile lumpfish that had been photographed exhibited green biofluorescence. Light emissions were found to have the greatest intensity along the tubercles of the high crest (part of the dorsal fin emerging from the snout and head) and the three longitudinal ridges. 

The study marks the first documentation of biofluorescence in fish produced within a commercial aquaculture operation. 

What Are Lumpfish?

The lumpfish considered in the study are found in temperate waters, where the temperatures range from four to 12 degrees Celsius. These fish are produced commercially for controlling sea lice in Atlantic salmon farming operations in North Atlantic countries. These unique creatures have a rough, scaleless skin with a variable colour pattern that is sexually dimorphic in adult specimens. Sexual dimorphism refers to the differences between males and females of the same species. 

Important Findings Of The Study

According to the study, the species changes colour for camouflage. The body of lumpfish is covered with multiple rows of knobby protuberances called tubercles. The most pronounced tubercles are found along three longitudinal ridges along the length of the body. 

Since the fish are constantly subject to osmotic pressure and mechanical abrasion in the environment, their skin should have integrity and function well to ensure good health and welfare.

Due to biological control on salmon farms, lumpfish are in high demand. The use of living organisms to suppress pest populations is known as biological control. 

The fish come in a variety of colours, which change as the fish age, according to an article published by The New York Times. Scientists believe that fluorescent green is the true colour of the fish. 

Lumpfish are funny-looking fish and solitary creatures. They spend most of their lives on the seafloor and latch themselves onto rocks and seaweed.

According to the NYT article, biofluorescence occurs when an organism absorbs ultraviolet rays that are usually invisible to people, and re-emits them as colours that humans can see. These colours could be red, orange or green. Biofluorescence is different from bioluminescence, in which organisms produce their own light through a chemical reaction. 

Elizabeth Fairchild, a researcher at the University of New Hampshire, said the fish may use its biofluorescence to attract prey. They can have any rainbow colour as hatchlings. When they become juveniles, they change their skin colour to match their surroundings. This helps them hide from predators. 

Upon reaching adulthood, they develop pale-gray to light-blue skin. During the breeding season, the males turn orange-red and females turn blue-green.

According to the study, an effective method that can help scientists understand subclinical stress in lumpfish through non-invasive methods focusing on the skin is yet to be determined. 

In the study, the authors have documented biofluorescence in juvenile lumpfish and characterised the type of biofluorescence observed under aquaculture conditions. Though biofluorescence has been observed in other marine fishes in the past, the study marks the first known documentation of biofluorescence in a commercially produced fish species.