Whales sustain fisheries: Blue whales stimulate primary production in the Southern Ocean

Patricia Lavery, Ben Roudnew, Justin Seymour, James Mitchell, Victor Smetacek, Stephen Nicol

    Research output: Contribution to journalArticlepeer-review

    52 Citations (Scopus)


    It has previously been asserted that baleen whales compete with fisheries by consuming potentially harvestable marine resources. The regularly applied "surplus-yield model" suggests that whale prey becomes available to fisheries if whales are removed, and has been presented as a justification for whaling. However, recent findings indicate that whales enhance ecosystem productivity by defecating iron that stimulates primary productivity in iron-limited waters. While juvenile whales and whales that are pregnant or lactating retain iron for growth and milk production, nonbreeding adult whales defecate most of the iron they consume. Here, we modify the surplus-yield model to incorporate iron defecation. After modeling a simplistic trajectory of blue whale recovery to historical abundances, the traditional surplus-yield model predicts that 1011 kg of carbon yr-1 would become unavailable to fisheries. However, this ignores the nutrient recycling role of whales. Our model suggests the population of blue whales would defecate 3 × 106 kg of iron yr-1, which would stimulate primary production equivalent to that required to support prey consumption by the blue whale population. Thus, modifying the surplus-yield model to include iron defecation indicates that blue whales do not render marine resources unavailable to fisheries. By defecating iron-rich feces, blue whales promote Southern Ocean productivity, rather than reducing fishery yields.

    Original languageEnglish
    Pages (from-to)888-904
    Number of pages17
    JournalMarine Mammal Science
    Issue number3
    Publication statusPublished - Jul 2014


    • Allochthonous nutrients
    • Autochthonous nutrients
    • Balaenoptera musculus
    • Baleen whales
    • Blue whales
    • Carbon
    • Ecological history
    • Fisheries
    • Iron
    • Marine populations
    • Nutrient cycling
    • Ocean fertilization
    • Productivity
    • Whaling


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