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Lobsters have a soft spot for microalgae

Lobster under study
Credit: Nathalie Rose Lefrançois
Lobster under study
  • Lobster under study
  • Experimental platform intended to study
  • Lobster fishing trap
  • Microalgae-based bait
Lobsters have a soft spot for microalgae

As was explained early last year in this article, commercial fishing for lobster (Homarus americanus) in Québec is facing a significant obstacle: the mackerel and herring stocks traditionally used as bate are in decline. My Biodôme research team in physiology, aquaculture and conservation was approached by players in the biotechnology industry to evaluate different microalgae-based bait formulations, an eco-responsible alternative for commercial lobster fishing in eastern Canada.

New behavior analysis platform

To study the American lobster’s food-seeking behavior, we set up an experimental platform consisting of four superimposed water lanes with ramp lighting, video surveillance and a cooling, ventilation and water circulation system. After a few weeks of setup and fine tuning (no more light seeping in, fluctuating noise levels and unsatisfactory hydrodynamics), we finally obtained consistent preliminary results.

Thanks to this experimental platform, we observe, only at night, the entire palette of lobster foraging behavior: detection, orientation, locomotion, handling and ingestion. With a little luck we’ll get the opportunity to observe the lobster’s ultimate hoarding behavior. In that sequence, the lobster leaves its shelter, makes its way to the bait (artificial or not) located two meters in front of it, grabs hold and returns with it quickly to its shelter, like a triumphant thief with its loot at the tip of its pincer, in order to savor it out of sight.

Positive results

An interesting fact: during our tests and with a little insight, we noticed that lobsters’ feeding behavior was strongly influenced by their sex. Indeed, according to scientists from Fisheries and Oceans Canada, between 60 and 80 percent of catches in traps are males, and only between 2 and 10 percent of lobsters that venture into traps will in fact end up being caught in one. Females, whether egg-bearing or not, generally prove to be less attracted to the promises of baited traps.

In the course of repeated tests under controlled conditions, preliminary results obtained by our team indicate good responsiveness, with the new lab-tested microalgae-based formulation getting lobsters to move slightly more often than what is observed with traditional bait (whole mackerel pieces).

Microalgae: hope for a green revolution

The Canadian lobster fishing industry has been seeking an alternative for a number of years. Efforts to this point seem inconclusive, and above all have failed to solve problems related to the use of limited aquatic resources, production costs, the markets’ perception, available volumes and their stability (price and availability).

This “green” approach, assuming it materializes, would reduce fishing pressure on vulnerable pelagic fish populations and would meet the expectations of Canada’s commercial fishing industry in an exemplary way. Optimization of the microalgae formulation is under way, and sea trials are scheduled for the 2024 season.

 

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