1956 Study Linked Smelt to Lake Trout Decline in Lake Superior

Invasive fish outcompeted lake trout and ate their young, officials said 70 years ago.

Published on Feb. 18, 2026

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A 1956 study by district fisheries biologist John Hale found that the growing population of smelt in Lake Superior was contributing to the decline of lake trout by competing for food and eating the trout's young. The study also cited the increasing lamprey infestation as another factor impacting the lake trout population.

Why it matters

The findings from this 1956 study highlight the long-standing ecological challenges facing Lake Superior, one of the most important and iconic freshwater ecosystems in the United States. Understanding the historical factors that have impacted the lake's delicate balance is crucial for informing modern conservation and restoration efforts.

The details

Hale's 1956 study found that the invasive smelt were outcompeting the native lake trout for food sources and also directly preying on young lake trout. This double threat was seen as a major contributor to the declining lake trout population at the time. The study also noted the growing lamprey infestation as an additional pressure on the lake trout.

  • The 1956 study was conducted by district fisheries biologist John Hale.
  • The findings were published in the Duluth News-Tribune on February 17, 1956.

The players

John Hale

A district fisheries biologist who conducted a 1956 study linking the invasive smelt population to the decline of lake trout in Lake Superior.

Lake Superior

One of the largest and most ecologically important freshwater lakes in the United States, facing historical challenges from invasive species and other threats.

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The takeaway

This 70-year-old study highlights the long-standing ecological challenges facing Lake Superior, and underscores the importance of continued research and conservation efforts to protect this vital natural resource.