Reduced nutrient input can negatively affect fish populations

Agricultural runoff often leads to increased nutrient enrichment and thus eutrophication of lakes. However, reducing nutrient inputs to water to prevent eutrophication can have a negative impact on fish populations, as the productivity of lakes is limited by low nutrient availability.

Nº 19


  • Freshwater Resources
  • Reduction of Freshwater Pollution
  • Controlling Nutrient Levels
some attempts made
past case
Region-1
Region-2
Region-3
Region-4
ongoing case
no attempts made

Reduced nutrient input can negatively affect fish populations

Agricultural runoff often leads to increased nutrient enrichment and thus eutrophication of lakes. However, reducing nutrient inputs to water to prevent eutrophication can have a negative impact on fish populations, as the productivity of lakes is limited by low nutrient availability.

All of the Great Lakes in North America, except Lake Erie, are characterised by phosphorus levels in the offshore regions – parts of the water with a minimum depth of twenty metres – that are below the US-Canada target for lake water quality. Policies to reduce nutrient leaching can therefore result in phosphorus deficiencies, which can limit fish populations. This has implications for all trophic levels in these ecosystems, including reduced production of top predator fish. Impacts are greatest in Lake Huron and Lake Michigan, where fisheries have experienced declines in maximum yield.

  • Facilitated the efforts to address the initial problem; The problem-shift had no effect on the efforts to address the initial problem
  • Cascading (far-reaching effects following each other)

Simroth, E. (2020, August 21). Offshore Decline: Great Lakes fish populations at risk from low nutrient levels. Great Lakes Now. https://www.greatlakesnow.org/2020/08/offshore-great-lakes-fish-populations-nutrient-levels/

Gerwing, T. G., & Plate, E. (2019). Effectiveness of nutrient enhancement as a remediation or compensation strategy of salmonid fisheries in culturally oligotrophic lakes and streams in temperate climates. Restoration Ecology, 27(2), 279-288. https://doi.org/10.1111/rec.12909

Simroth, E. (2020, August 21). Offshore Decline: Great Lakes fish populations at risk from low nutrient levels. Great Lakes Now. Retrieved March 29, 2023, from https://www.greatlakesnow.org/2020/08/offshore-great-lakes-fish-populations-nutrient-levels/

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