© Dr. Ulrike Schückel
MEKUN: Protecting the oceans
Watt'n Hummer – Research for biodiversity and species protection
Searching for clues in the Wadden Sea: The European lobster was long considered to be almost extinct. Unexpected finds in the Schleswig-Holstein Wadden Sea National Park now give cause for hope – and raise new questions. The HUSAWA project is scientifically investigating these clues.
The European lobster – a native giant in danger
The European lobster (Homarus gammarus) belongs to the order Decapoda and is the largest native crustacean in the North Sea. Female lobsters grow more slowly than males and do not reach sexual maturity until they are 4-6 years old. Each female produces up to 20,000 eggs annually, but only a tiny fraction of these survive.
The lobster is now considered highly endangered in the North Sea. Its once abundant stocks have declined sharply since the 1960s – a decline most likely caused by overfishing, climate change, pollution, and destruction of its habitat. Despite various conservation measures, stocks have not yet been able to recover.
European lobster Profile
Lat. name: Homarus gammarus
Size: up to 60 cm
Weight: up to 6 kg
Age: more than 60 years
Distribution: from the Lofoten Islands (northern Norway) to Morocco and the Mediterranean Sea
Habitat: rocky sea beds, up to 60 m water depth
Diet: nocturnal hunters – mussels, snails, worms, fish, carrion
Reproduction: sexually mature at 4–6 years; females carry several thousand eggs; larvae hatch after 10–12 months and go through three stages in open water before transitioning to life on the seabed in the fourth stage
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Why is habitat so important?
Lobsters prefer rocky sea beds where they can hide in crevices or under rocks. They are considered extremely sedentary and usually only stray a few hundred meters from their burrows. However, the sea beds of many coastal regions have been severely altered over decades, partly due to the use of bottom trawls, causing lobsters to lose important refuges.
Wind farms and resettlement: hope for lobsters
The expansion of offshore wind farms could have a positive effect by creating new habitats on the otherwise soft seabed, providing potential refuges for lobsters. Wind farm areas are also closed to bottom trawling. Initial studies in the Riffgat wind farm have shown that lobsters are present in these areas. Whether lobsters remain in wind farm areas permanently or migrate remains unclear and is still being researched.
Another important contribution to stabilizing lobster stocks is the reintroduction project on Heligoland, which began in 1999. For this purpose, egg-bearing females are caught, their larvae are raised, and the young lobsters are released into the wild at the age of one year. Since 2018, the project has been continued by Reefauna. Initial successes can be seen in the recovery of about ten percent of the released lobsters, which indicates a slow growth of the population around Heligoland.
Catches in the Schleswig-Holstein Wadden Sea National Park
The unexpected discovery of lobsters in the national park during monitoring trips – far away from the known stocks around Heligoland – prompted further investigations. In recent years, a total of 24 lobsters have been caught using lobster pots. The catches were mainly concentrated off Pellworm and in the Hörnum Tief off Sylt – regions with stony sediments. Old males and egg-bearing females among the catches indicate that these are not just migratory animals, but a small but well-established lobster population in the Wadden Sea – and that was the impetus for the HUSAWA project.
© Dr. Ulrike Schückel
Female lobster with eggs
FUN FACTS
Claw handedness
Lobsters are left- or right-handed, depending on which side their powerful claw is on.
Powerhouses
The shears can generate over 90 kg/cm² of pressure – comparable to the bite force of a bull shark.
Formerly “poor people's food”
Lobsters were once considered cheap food for workers, slaves, and prisoners.
Blue blood
Lobsters have blue blood—because of the copper in the blood pigment hemocyanin.
Endless growth
Lobsters molt and grow—throughout their entire lives.
HUSA... what? HUSAWA!
The HUSAWA (Hummer–Sandkoralle–Wattenmeer) project is investigating whether an independent lobster population may have developed in the Wadden Sea. To this end, mitochondrial genomes of lobsters from the Wadden Sea, Helgoland, and wind farms are being sequenced to study gene flow and connectivity between populations.
The larval phase also poses a mystery: lobster larvae live pelagically in their first weeks – that is, freely in the water column. Despite intensive sampling, they have hardly been detected in classic net catches to date. To get to the bottom of this phenomenon, the project combines classic and modern methods: plankton nets and genetic techniques such as metabarcoding are used to search specifically for lobster DNA in water and plankton samples.
In addition, the captured lobsters are equipped with color markings and acoustic transmitters to provide information about their distribution, population size, and whereabouts. This data is crucial for establishing targeted conservation measures in the future.
“Kurs Natur 2030” – Schleswig-Holstein's biodiversity strategy
The Kurs Natur 2030 biodiversity strategy in Schleswig-Holstein aims to preserve biological diversity and protect endangered species. In the marine sector in particular, 30 percent of coastal and marine areas are to become ecologically valuable. This includes measures such as the renaturation of seagrass beds, the protection of migratory fish species, and the reduction of human intervention. The aim is to make ecosystems more resilient and preserve their natural functions so that they can provide long-term habitats for animals and plants. For this reason, the HUSAWA project is also being funded as part of the biodiversity strategy.
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