Abstract
The use of light-emitting diodes (LEDs) is increasingly used in fishing gears and its application is known to trigger negative or positive phototaxis (i.e., swimming away or toward the light source, respectively) for some marine species. However, our understanding of how artificial light influences behavior is poorly understood for many species and most studies can be characterized as trial and error experiments. In this study, we tested whether exposure to white LED light could initiate a phototactic response in Antarctic krill (Euphausia superba). Trawl-caught krill were used in a controlled artificial light exposure experiment conducted onboard a vessel in the Southern Ocean. The experiment was conducted in chambers with dark and light zones in which krill could move freely. Results showed that krill displayed a significant positive phototaxis. Understanding this behavioral response is relevant to development of krill fishing technology to improve scientific sampling gear, improve harvest efficiency, and reduce potential unwanted bycatch.
Highlights
Light-emitting diodes (LEDs) are increasingly used in commercial fisheries
The measurements of the LED light in air was characterized by a wavelength ranging between 400 and 800 nm with two distinct intensity maximum peaks (Fig. 2)
We found that krill displayed a positive phototactic response to LED light by actively swimming toward the light source under controlled conditions
Summary
Artificial light in commercial fishing gear applications can increase catch rates, contribute to reduced bycatch levels, and decrease energy costs (Nguyen and Winger 2019). In their natural environment, euphausiids use ambient light to adjust their position in the water column to preferred isolume levels, and they have developed advanced bioluminescent photophores that likely trigger responses from their conspecifics (Warner et al 1979). Knowledge about species-specific behavioral responses to artificial light varies, but depending on the particular taxon’s response pattern, such information can be highly relevant to the development of efficient and low impact fishing technology. Increased ethological understanding of the species, catch technology development and data processing development will contribute to evolve a management system adapting to future consequences of increased catches and a changing ecosystem
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