Evolutionary Response of Smallmouth Bass to Removal Efforts in Adirondack Lake

Introduction

Decades-long efforts to eradicate invasive smallmouth bass from a midsized Adirondack lake have resulted in an unexpected evolutionary adaptation. The bass population rapidly evolved to grow faster and reproduce earlier, leading to an increased number of smaller fish. This case study highlights critical considerations for invasive species management and aligns with several Sustainable Development Goals (SDGs), particularly SDG 14 (Life Below Water) and SDG 15 (Life on Land).

Background

• Smallmouth bass, native to North America, were introduced widely across the Adirondacks in the 1900s.
• The introduction caused declines in native fish species and stunted growth rates in brook and lake trout due to competition for prey.
• Annual removal efforts targeted a quarter of the smallmouth bass population, primarily eliminating larger fish (>12 inches).

Study Findings

A study published on June 9 in the Proceedings of the National Academy of Sciences revealed the following:

1. Despite removal efforts, the population of small bass (5 inches and under) increased.
2. The bass evolved a fast-living, early-maturing life history strategy in response to heightened mortality rates.
3. Genetic analysis showed significant changes in genes related to growth and maturation between 2000 and 2019.

Management Implications

• Preventing non-native species invasions is crucial to avoid ecological disruption (SDG 15).
• Suppression efforts may backfire by inducing evolutionary adaptations that counteract eradication goals.
• Adjusting removal frequency or targeting only a subset of fish may reduce evolutionary pressures, but further research is needed.
• Eradication efforts should be viewed as an evolutionary arms race, requiring adaptive management strategies.

Case Study: Little Moose Lake

Since 2000, boat electrofishing has been used to suppress smallmouth bass in Little Moose Lake:

• Thousands of bass were removed annually, initially causing a population decline.
• Native fish populations and lake trout growth rates initially improved.
• After several years, bass catch rates increased due to an expanding population of young fish.

Genetic and Behavioral Insights

1. Genetic samples collected since 1995 revealed selection pressures affecting three chromosomes linked to growth and maturation.
2. Smallmouth bass exhibited increased skittishness post-removal, possibly due to behavioral adaptation to frequent removals.
3. Ongoing research aims to determine if behavioral changes have a genetic basis.

Ecological and Conservation Significance

• Brook and lake trout face compounded threats from warming waters, oxygen depletion, and competition with bass (SDG 13: Climate Action; SDG 14: Life Below Water).
• Long-term monitoring is essential to understand ecosystem dynamics and the effectiveness of management interventions.
• The study underscores the importance of integrating evolutionary biology into conservation strategies to support biodiversity (SDG 15).

Funding and Collaboration

The project received funding from multiple sources, including:

• Adirondack League Club
• Northeast Climate Adaptation Science Center
• National Science Foundation Extreme Science and Engineering Discovery Environment
• Cornell University Elizabeth Miller Francis ‘47 Summer Research Grant
• Cornell University Kieckhefer Adirondack Fellowship

Conclusion

This study demonstrates that invasive species removal efforts can drive rapid evolutionary changes, complicating eradication goals. Sustainable management requires adaptive approaches that consider ecological and evolutionary dynamics to protect native biodiversity and aquatic ecosystems, contributing to the achievement of the Sustainable Development Goals.

1. Sustainable Development Goals (SDGs) Addressed or Connected

1. SDG 14: Life Below Water
   • The article discusses the ecological impact of invasive smallmouth bass on native fish species and aquatic ecosystems in Adirondack lakes.
   • It highlights efforts to manage invasive species and protect native aquatic biodiversity.
2. SDG 15: Life on Land
   • The article addresses ecosystem management and biodiversity conservation in freshwater habitats.
   • It emphasizes the importance of preventing invasive species and maintaining ecosystem balance.
3. SDG 13: Climate Action
   • The article mentions warming surface waters and depleted oxygen levels affecting native fish, linking to climate change impacts on ecosystems.
4. SDG 9: Industry, Innovation and Infrastructure
   • The use of scientific research, genetic analysis, and innovative management techniques (e.g., electrofishing) reflects innovation in ecosystem management.

2. Specific Targets Under Those SDGs

1. SDG 14: Life Below Water
   • Target 14.2: Sustainably manage and protect marine and freshwater ecosystems to avoid significant adverse impacts, including invasive species control.
   • Target 14.4: Effectively regulate harvesting and end overfishing, illegal, unreported and unregulated fishing, and destructive fishing practices.
2. SDG 15: Life on Land
   • Target 15.8: Prevent the introduction and significantly reduce the impact of invasive alien species on land and freshwater ecosystems.
   • Target 15.1: Ensure the conservation, restoration and sustainable use of terrestrial and inland freshwater ecosystems.
3. SDG 13: Climate Action
   • Target 13.1: Strengthen resilience and adaptive capacity to climate-related hazards and natural disasters in ecosystems.
4. SDG 9: Industry, Innovation and Infrastructure
   • Target 9.5: Enhance scientific research, upgrade technological capabilities of industrial sectors including environmental management.

3. Indicators Mentioned or Implied to Measure Progress

1. Population Size and Composition of Fish Species
   • Catch rates of smallmouth bass and native fish populations are monitored to assess population trends.
   • Size distribution of fish (e.g., proportion of small bass under 5 inches vs. larger fish) indicates evolutionary changes and population dynamics.
2. Genetic and Life History Traits
   • Genetic markers associated with growth rate and age at maturity are used to measure evolutionary adaptations.
   • Changes in life history traits such as growth speed and early reproduction rates are indicators of population response to management.
3. Behavioral Changes
   • Behavioral traits such as skittishness in fish populations are monitored to understand adaptation to removal efforts.
4. Environmental Conditions
   • Monitoring of water temperature and oxygen levels to assess climate change impacts on fish habitats.
5. Effectiveness of Management Interventions
   • Long-term monitoring of fish populations to evaluate the success of invasive species removal and ecosystem recovery.

4. Table: SDGs, Targets and Indicators

Source: news.cornell.edu