Wetlands for Northern Pike Recruitment and Nutrient Reduction

• Wetlands are important ecosystems, harbouring biodiversity, capturing nutrients, and providing recruitment habitats for several fish species. The Baltic Sea, among the largest brackish, semi-enclosed seas in the world, is exposed to large amounts of nutrients as well as the overexploitation of several fish species. One measure to counteract eutrophication is to restore or build wetlands for nutrient catchment (phosphorus) or removal (nitrogen). To function optimally for nutrient removal, these wetlands should cover large areas, be shallow, and be covered by vegetation, creating zones of high microbial denitrification. Wetland environments are also suitable spawning and nursery areas for several fish species inhabiting the coastal zone of the Baltic Sea. Pike (Esox lucius) a predatory species that has decreased in abundance in recent decades, use wetlands as recruitment areas during their anadromous life cycle. After restoring wetlands near the coast and opening the waterways towards the sea, pike larval emigration increased from a few thousand to over a hundred thousand individuals. The habitat and food choice, growth and migration of larvae and juveniles were followed over time, revealing that 80–95% left the wetlands within one month (at a size <6 cm). An optimal wetland enriches nutrients and creates a high primary production base for zooplankton that are used as food for pike larvae. Wetlands near the sea can function both as nutrient traps and as recruitment areas for fish.

Publikations- och innehållstyp

vet (ämneskategori)

ovr (ämneskategori)