Why is the Baltic Sea washing dead seals ashore?

In recent weeks, dozens of dead gray seals—one of the most iconic and protected species of the Baltic Sea—have been found on the shores of Rügen and other Baltic beaches. The mass death has raised concerns among local residents and environmental organizations, which are striving to uncover the cause of this tragic event. Is it the result of human activity, climate change, or natural processes within the ecosystem? Recent studies are beginning to reveal the unsettling details of this case.

Could the seals have drowned?

Groundbreaking findings in the case of the mass death of gray seals have been provided by studies conducted by the German Maritime Museum in Stralsund and the University of Veterinary Medicine Hannover (TiHo). Experts performed autopsies on eleven dead seals found on the shores of Rügen, revealing that drowning is the most likely cause of death.

Although drowning incidents among marine mammals may seem unusual, the research suggests that these animals could have fallen victim to bycatch, meaning accidental entrapment in fishing nets. Another possibility being investigated is deliberate baiting of seals. The telltale signs supporting this hypothesis include hematomas around the head, neck, and flippers; broken vibrissae; abrasions on the head and flippers; and distinctly bloodshot, bulging eyes. Furthermore, histological examinations found food remnants in the lungs, indicating that the animals might have been feeding when they became entangled in nets, ultimately drowning due to their inability to surface for air.

Denkinger, one of the researchers involved in the investigation, points out that the absence of direct evidence, such as seals being found in nets, makes it challenging to definitively confirm bycatch as the cause of death. Nevertheless, the location and timing of these incidents suggest a link to fishing traps in the Thiessow area, which were subject to detailed investigation. While inspections of these traps have so far yielded no conclusive evidence, the increasing number of dead seals in the region hints at a more complex issue.

Sea Shepherd erstattet Anzeige
Obduktionsergebnisse des Meeresmuseums Stralsund weisen auf einen Ertränkungstod hin. Die Organe von 3 untersuchten Robben hätten Verletzungen aufgewiesen, die typisch für Tiere seien, die sich unter Wasser verfangen haben.https://t.co/RJTMeYKIEU

— Robby (@Robby68142735) November 15, 2024

Dozens of dead seals near Rügen

Since October, 44 dead gray seals have been found on German beaches near Rügen—a significant blow to the local population of this species, estimated at around 200 individuals. This means the losses account for 20% of the regional population. Most of the dead animals were discovered in the towns of Haken bei Thiessow, Lobbe, and Zicker on the southeastern coast of the island. The state of decomposition of the bodies indicates that the seals died over an extended period, spanning several days. This tragedy raises serious concerns about the causes behind such a high number of deaths in a short timeframe.

Initial hypotheses – infectious diseases and human impact

Initially, it was hypothesized that the mass death of seals might have been caused by infectious diseases, such as avian flu, or other environmental stressors. Potential causes considered included anthropogenic pressures, such as chemical poisoning or the effects of construction work related to offshore wind farm installations in the Baltic Sea.

However, the Ministry of the Environment dismissed these speculations. According to their reports, autopsy results do not indicate infectious diseases or direct human impacts, such as chemical poisoning or environmental contamination. The causes of the seals’ deaths remain unexplained, fueling concerns and raising further questions about the mechanisms responsible for this tragedy.