Lenfest Ocean Program

Supporting Science and Communicating Results

Published Paper

Tambora and the Mackerel Year

Phenology and fisheries during an extreme climate event

Alexander, K. E., Leavenworth, W. B., Willis, T. V., Hall, C., Mattocks, S., Bittner, S. M., Klein, E., Staudin, M., Bryan, A., Rosset, J., Carr, B. H., Jordaan, A. (2017). Tambora and the mackerel year: Phenology and fisheries during an extreme climate event. Science Advances, 3(1). doi:10.1126/sciadv.1601635.


  • Bottom line: A volcanic eruption that brought chaos to New England coastal fisheries 200 years ago may offer lessons for modern-day resource managers in responding to climate change. In particular, this study suggests that temporary changes in ecosystems may lead to permanent and unexpected shifts in the use of natural resources.
  • Background: 
    • On April 5, 1815, an Indonesian volcano named Tambora erupted. It was one of the largest eruptions in recorded history, spewing about 24 cubic miles (100 cubic kilometers) of ash into the stratosphere. The ash reduced incoming sunlight, dropping global temperatures approximately 1.5 degrees Celsius. In 1816, New England experienced crop failure and famine, in what came to be known as the “year without a summer.”
    • The climatic shift also altered the timing of fish returning from the ocean to spawn in New England rivers and streams. Among these anadromous fish, the earliest to spawn is alewife, which many residents relied on for food, fertilizer, and livestock feed.
  • Methods: To study the effects of the Tambora eruption on New England fisheries, Lenfest Ocean Program grantee Adrian Jordaan and colleagues used Complex Adaptive Systems (CAS) theory, an approach that offers simple ways to study system-level transformations that emerge from changes in the individual behavior of agents, in this case people and fish.  To distinguish Tambora’s climate effects from anthropogenic influences, they examined other events including the War of 1812, human population growth, dam construction, and modifications in fishing gear. The researchers focused on impacts to fish catch, using data on the export of several fish species. All the information was found in historical records, including fish inspectors’ reports, chronologies of human population growth, and even a journal kept by a Massachusetts doctor who recorded the temperature four times a day for 40 years.  
  • Findings:
    • The abnormally low daily temperatures affected fisheries differently according to the species migration routes, spawning patterns, and temperature tolerances. Alewives suffered most, from disrupted spawning, increased natural mortality, and greater fishing mortality, owing to New Englanders searching for alternative food after the massive crop failure. The alewife fisheries faltered in 1816 and collapsed by 1817.
    • Fishermen were forced to move offshore and target mackerel, the next species to arrive in abundance along the coast. This earned 1816 another nickname: “the mackerel year.”
    • This shift from river-based to ocean-based fishing was rapid. New England created new fishing gear, canal systems, railroads, and factories. Although alewife fisheries recovered from Tambora in a few decades, the larger “coupled human and natural system” remained focused on mackerel and expanded to other oceanic species.
    • There are parallels between the Tambora climate event and modern climate change, including the potential for famine, increases in extreme weather, and the difficulty in forecasting the local effects of global change. The researchers argue that studying the past and understanding how our adaptive responses can lead to unexpected consequences may help advance human resilience.

The full publication is available here:


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