Research ArticleENVIRONMENTAL STUDIES

Fishers’ response to temperature change reveals the importance of integrating human behavior in climate change analysis

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Science Advances  30 Apr 2021:
Vol. 7, no. 18, eabc7425
DOI: 10.1126/sciadv.abc7425
  • Fig. 1 Ecological and behavioral pathways from temperature to fish catch.

    Climate change projections typically focus on the ecological pathway and how temperature affects fish populations and thereby shapes fish catch. Our analysis also examined a behavioral pathway, through which changing temperature affected (1) fishing effort, including (a) fishing participation (any fishing in the previous week), (b) time spent fishing (person-days), and (c) gear choice (active or passive), to ultimately affect (2) fish catch. Adjusting for multiple dimensions of fishing effort, we then measured how changing temperature and rainfall shapes (3) fish catch to indirectly isolate the ecological effect of temperature on fish populations. Dashed lines represent unobserved phenomena.

  • Fig. 2 Effect of temperature on fishing participation, effort, and gear use.

    Temperatures above the current mean of 28°C reduced (A) fishing participation (any fishing in the previous week), although there is no impact of rising temperatures on (B) fishing effort (person-days) or (C) whether a household used active gear. Plots depict the estimated marginal effect of sustained, single-degree temperature changes across the temperature distribution, accounting for lags and polynomial terms (table S2, models 1 to 3). Dashed lines show 95% confidence intervals. This plot represents a marginal effect rather than a trendline; therefore, this and subsequent plots are interpreted as follows, using (A) as an example: The value at 28°C represents the estimated change in probability of fishing participation when temperatures increase from 28° to 29°C (6% reduction). The value at 29°C represents the change in probability of fishing when temperatures increased from 29° to 30°C (8%). The probability of fishing participation under a two-degree temperature increase from 28° to 30°C is the sum of each single-degree change (14%).

  • Fig. 3 Effect of temperature on fish catch.

    The effects of a sustained 1° increase in temperature above 28°C were (A) mildly negative and statistically insignificant, when taking into account the aggregated “ecological” and “behavioral” effects of temperature on fish catch. Yet, when we controlled for fishing behavior (B), we found a statistically significant increase in fish catch attributable to the ecological effects of rising temperature while holding fishing effort constant, a metric analogous to isolating fish catch (kilograms)-per-unit-effort. However, the potential positive ecological effect on fish availability from warming temperatures is offset by human behavioral responses that reduced fishing effort, and, ultimately, there was no effect on fish catch.

  • Fig. 4 Effect of temperature on other aquatic animal (OAA) and aquatic plant harvest.

    For other aquatic animals, (A) we found that the aggregate ecological and behavioral effect of temperature on other aquatic animal harvest is positive, except at the most extreme temperatures. For aquatic plants, (C) we found that the aggregate ecological and behavioral effect of temperature on aquatic plant harvest is positive and greatest at the highest temperatures. For both (B) other aquatic animals and (D) aquatic plants, when we controlled for harvest effort (we use fishing effort as a proxy for aquatic plant harvesting effort, which was not available), we found a slightly larger increase in harvest attributable to ecological effects of rising temperature while holding effort constant, a metric analogous to isolating harvest (kilograms)-per-unit-effort. This finding suggests reductions in effort as temperature rise is limiting harvest.

Supplementary Materials

  • Supplementary Materials

    Fishers’ response to temperature change reveals the importance of integrating human behavior in climate change analysis

    Kathryn J. Fiorella, Elizabeth R. Bageant, Naomi B. Schwartz, Shakuntala H. Thilsted, Christopher B. Barrett

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    • Extended Materials and Methods
    • Figs. S1 to S5
    • Tables S1 to S3

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