Allowing for environmental effects in a management strategy evaluation for Japanese sardine

作者：Hurtado Ferro Felipe^*; Hiramatsu Kazuhiko; Shirakihara Kunio

来源：ICES Journal of Marine Science, 2010, 67(9): 2012-2017.

DOI：10.1093/icesjms/fsq126

• catch rules
• environment-based management
• Japanese sardine
• management strategy evaluation

The Japanese sardine (Sardinops melanostictus) is a valuable, but highly variable, resource. After record catches during the late 1980s, a 4-year recruitment failure, coupled with overfishing, resulted in severe stock depletion. TAC-based management was introduced in 1997, but the trend has not been reversed and the biomass is now 2 orders of magnitude below the value in 1987. Although a strong correlation exists between winter sea surface temperature (SST) in the nursery area and recruitment, uncertainty about future environmental effects is not explicitly considered in the management. We evaluate the robustness of three catch rules to environmental uncertainty, as captured by three stock-recruitment models (one without an environmental factor and two based on correlations between recruitment and SST for two datasets), in terms of the risk of further depletion, average biomass, and average catch: a constant fishing mortality (CF), a strategy that follows the Japanese guidelines (JG), and a more conservative strategy (ENV) that uses a temperature threshold as a proxy for regime shifts to switch between alternative catch rules. ENV and JG performed better than CF, with ENV displaying better performance in the long term, but differences were negligible in the short term.