Marine crustaceans dwelling in the North Sea remain a puzzle for researchers - The catch numbers for these crabs show a significant decrease

In the chilly waters of the North Sea, a mystery has been unfolding for several years. The catches of North Sea shrimp, a crucial component of the marine food chain and the most valuable catch for German coastal fishing, have been dwindling. This decline, as recent as 2024, saw the North Sea shrimp catch amount to only one-third of the average catch from 2000 to 2015.

This trend has not gone unnoticed. Dr. Lara Kim Huenerlage, a marine biologist, is now focused on understanding this phenomenon at the Thuenen Institute for Sea Fisheries in Bremerhaven. Her research endeavours extend beyond the North Sea, as she previously conducted studies on bioluminescent shrimp (krill) in the Arctic Ocean.

The cause of the North Sea shrimp's dwindling numbers is multifaceted. Rising water temperatures, a common symptom of climate change, are putting pressure on the North Sea ecosystem and affecting the shrimp population. Warmer winters can accelerate embryonic development, leading to premature hatching and potential negative consequences for the new cohort.

New predators, such as jellyfish and squid, are also appearing in the North Sea, posing a threat to the shrimp's larvae. These factors, combined with the short lifespan of the North Sea shrimp, make it vulnerable to environmental changes.

To unravel this mystery, Dr. Huenerlage and her colleagues collect biological data, consult with fishermen, and collaborate with international working groups. The Thuenen Institute for Sea Fisheries in Bremerhaven is part of an International Council for the Exploration of the Sea working group aiming to make shrimp fishing more predictable through improved population forecasting models.

The research on North Sea shrimp is complex and of economic importance. The low catches have led to increased prices for crab sticks and some retailers no longer offering crab products. In 2024, the North Sea shrimp made up more than half of the total earnings for fishing companies in Lower Saxony and Schleswig-Holstein.

Despite the efforts of researchers like Dr. Huenerlage, the life plan of North Sea shrimp remains largely unknown. The question of why there are sometimes more and sometimes fewer young shrimp along the coast remains unanswered. The population of North Sea shrimp fluctuates greatly, and its development cannot be reliably predicted.

The research on North Sea shrimp is likely to continue beyond the currently planned project period of 2027. The stakes are high, not just for the fishing industry, but for the entire North Sea ecosystem. As climate change continues to alter our oceans, understanding and addressing these changes is crucial for the future of marine life and our planet.