Paper short abstract:

The paper highlights the migration of the invasive Chinese mitten crab in North Sea coastal waters during the early twentieth century. Hydraulic infrastructures, as dams and sluices, mediated animal mobility and serve as an analytical lens to unveil complex interactions between humans and crabs.

Paper long abstract:

In the early decades of the twentieth century, an unknown invasive species with hairy claws appeared in the North Sea estuaries. The Chinese mitten crab (Eriocheir sinensis) spread from southeastern China to European coastal waters by hitching rides in the ballast water of commercial freighters. As shoals of crabs invaded the Ems, Weser, and Elbe rivers, anxieties spread among coastal societies. Fishermen and engineers worried that the crab would disrupt the balance of native ecosystems, harm commercial fisheries, and damage hydraulic infrastructures through its burrowing behavior.

However, the new freshwater habitats were already engineered with dams and sluices, blocking the crab’s upstream movement. These hydraulic infrastructures played a pivotal role in structuring the mobility of this non-human species. In my paper, dams and sluices serve as an analytical lens to highlight complex interactions between humans and crabs throughout their migration. When swarms of crabs circumvented these physical barriers, fisheries scientists had the chance to study their biology, while fishermen – and their wives, the "Fischweiber" – countered "crab invasions" by setting traps and developing harvesting schemes to turn this pesky crustacean into a valuable commodity for gastronomy or livestock feeding. The perspective on hydraulic engineering also reveals unforeseen consequences of attempts to control migrating crabs, which rarely interacted with these technological solutions as fishermen, scientists, and engineers had expected. To narrate this entangled history between human practices, technological changes, and animal mobilities along German watercourses, the paper incorporates a more-than-human-perspective – offering a crab’s-eye view – into its envirotechnical analysis.