The larvae play an important role in DTU Aqua’s research
The tiny larvae play an important role in DTU Aqua’s research project NOW LUMP, which is supported by the charitable organisation Seabreak. The project aims to improve our understanding of lumpfish biology and investigate the environmental conditions the species needs to thrive.
Why the species is struggling in Denmark
Lumpfish populations are declining in Danish waters, making it important to understand the pressures affecting the species.
Fishing has most likely had a significant impact on lumpfish stocks. There are also indications that the current condition of the marine environment is detrimental to the species. However, important knowledge gaps remain regarding the lumpfish’s life cycle, migrations and vulnerability to changes in its environment.
Scientists know that adult lumpfish depend on both the open waters of the North Atlantic and the coastal waters of Denmark during the spawning season, when they lay their eggs on stones and vegetation on the seabed.
However, how changing environmental conditions affect the growth and survival of lumpfish at different stages of their life cycle remains an open question.
Additional expertise to investigate the crucial early life stages
To help answer these questions about lumpfish biology, the NOW LUMP project will gain additional expertise in September with the arrival of two PhD students.
With successful spawning and the hatching of eggs into viable larvae, everything suggests that these young researchers will have the opportunity to work not only with adult lumpfish, but also with the species’ early life stages.
“This is highly significant, because the early life stages are often the most sensitive to changes in the surrounding environment,” says Jane Behrens.
The researchers’ hypothesis is that fishing pressure, together with climate change, rising sea temperatures, marine heatwaves, and increasingly frequent and prolonged periods of oxygen depletion, has placed such severe pressure on lumpfish that the population has declined dramatically in recent years.
On 1 January 2025, a complete ban on lumpfish fishing was introduced on the basis of advice from DTU Aqua.
A miniature replica of the adult fish
At an early stage, the tiny lumpfish larva is a remarkably faithful miniature version of the adult fish. One distinctive feature, however, is its bright green colouration. Within a few minutes, it can change colour and become completely dark in order to camouflage itself.
From the moment it hatches, the young lumpfish has a fully functional suction disc on its underside, which it uses to attach itself to surfaces on the seabed.
While the male lumpfish guards and cares for the eggs, the female loses interest in them immediately after spawning. Nevertheless, she has provided well for her offspring: the larvae hatch with a nutrient-rich yolk sac, which serves as their first food supply.
You can see lumpfish and learn more about the researchers’ work on the species at Denmark’s four major public aquariums – Kattegatcentret, Nordsøen Oceanarium, Den Blå Planet and Øresundsakvariet – as results from the project begin to emerge.