Implementing ecosystem considerations in forage fisheries: San Francisco Bay herring case study

Abstract

Ecosystem based fisheries management is a priority nationally and beyond, yet lack of robust approaches has hampered its implementation. Even though forage fishes are critically important in marine ecosystems, few examples of applied ecosystem-based information exist. We created a multi-pronged approach to ecosystem considerations in fisheries management and applied it to the San Francisco Bay Pacific herring Clupea pallasii fishery as a case history for use in other forage fisheries. The first step of our work used environmental parameters and recruitment indices to predict stock status (Sydeman et al., 2018) for use in setting fishing quotas. The second step, herein, was development of a qualitative predator indicator to further inform quota setting, which consisted of (1) the status of alternative forage species in the ecosystem and (2) predator population “health” and mortality events. This indicator, with “stoplight” management recommendations, is framed in relation to herring population cycles and climatic influences on population dynamics, and can inform potential predator stressors and predation levels on herring. We present a method to apply these metrics to fishing quotas and adjustments, geared toward the annual management cycle and leveraging existing ecosystem status reports. The resulting indicator matrix is flexible to incorporating future environmental and ecosystem change; indeed future research on trophic interactions and climate effects on the herring-based ecosystem is warranted.