Effects chain – Example presentation from the ‘fisheries’ action field | Umweltbundesamt

Climate changes relevant to the action field

State: Air temperatures

Climate change has resulted in air temperatures rising. In the period from 1881 to 2022 temperatures in Germany rose by 1.7 °C thus amounting to 0.6 °C above the global mean (see 'Mean values of climate changes'). In the course of the past 50 years, the speed of temperature rise has distinctly increased in Germany: Looking at the entire period from 1881 to 2022 temperatures increased every decade by 0.12 °C, and since 1971 the warming rate of 0.38 °C per decade has resulted in making this value three times as high.

Impacts of climate change

Impact: KM-I-1 Water temperature in the sea

As air temperature rises, sea temperature rises too. The seas are getting warmer thus changing the ecosystem conditions for fish communities and all other sea life. The annual mean surface temperature of the North Sea has been rising by 0.26 °C. The annual values are subject to natural fluctuations.

Impact: FI-I-2 Herring larvae in the Greifswalder Bodden

The increasing water temperatures result in herring spawning earlier in the western part of the Baltic Sea, and their larvae consequently needing external food earlier too. However, this food is not available or not available in sufficient quantities at this early stage thus leading to the starvation of larvae. Consequently, the recruitment success of herring stocks has declined drastically since the late 1990s.

Adaptations – activities and results

Response

In order to maintain herring stocks in the western part of the Baltic Sea, it is crucial to reduce fishing pressure on this species and to identify the sources of their natural mortality with the objective, where possible, to minimise the impact of such sources. The more adult fish are able to spawn, the greater their recruitment success, provided that the herrings, in the early stages of their life, are able to benefit from favourable environmental conditions. In past years, the fishing quotas for these stocks have already been reduced significantly. The ICES (see Cluster Fisheries) had recommended a fishing ban for each year between 2019 and 2023. This recommendation has meanwhile been extended to the duration of 2024.