Multivariate environment-fish biomass model informs sustainability and lost income in Indian Ocean coral reefs

Low optimal fisheries yield creates challenges for sustainability in a climate refugia

“…For example, fisheries yields in the Caribbean are reportedly low (i.e., <1.5 tons/km 2 /year) and associated with lower physical energy in terms of tidal range ($0.2 m), waves, and currents (Koslow et al, 1994). Influences on production appear to vary at many spatial scales according to environmental conditions that are currently only partially understood (Gove et al, 2015;McClanahan, D'Agata, et al, 2023;McClanahan, Darling, et al, 2023). Yield potentials will vary even when the variability in effort and capture rates are not considered.…”

“…Given the variability, further research will be needed to evaluate the causes and consequences of variable production. Estimating production has been difficult but provides critical information for improving subsequent yields, food security, and income estimates (McClanahan, D'Agata, et al, 2023;McClanahan, Darling, et al, 2023). Kenya's ocean-exposed fringing reef to the north of our studied bay has an estimated MSY between 5 and 7 tons/ km 2 /year, which suggests <4 years to recover biomass to MSY in the absence of fishing in these overfished fisheries .…”

“…Thus, resistance may be either unrelated or possibly inversely related to recovery (McClanahan et al, 2012). This makes it challenging to evaluate climate resilience as a single compositive variable but rather as having elements of avoidance, resistance, and recovery (McClanahan, D'Agata, et al, 2023;McClanahan, Darling, et al, 2023). Similarly, high diversity appears to be associated with low productivity contrary to the positive diversity-productivity hypothesis (Hooper et al, 2005).…”

“…A priority for modern resource policy is to improve management in climate sanctuaries or refugia (Myers et al, 2000;Van Woesik et al, 2022). Climate refugia are locations having the properties of high biodiversity and the capacity to either avoid, resist, or quickly recover from climate change disturbances (McClanahan, D'Agata, et al, 2023;McClanahan, Darling, et al, 2023;West & Salm, 2003). Once refugia are identified, there is a need to evaluate their status and manage them to avoid losses of diversity and ecological services arising from local human impacts.…”

“…Therefore, most estimates of yields are based on landed catch and not stock and production, which has produced controversy over the accuracy of sustainability metric options (Pauly et al, 2013). Fish production is expected to vary with environments and yet environment-production relationships are poorly known (McClanahan, D'Agata, et al, 2023;McClanahan, Darling, et al, 2023). Large disparities in estimates of r for coral reefs are the result.…”