Can community size-based indicator management protect both forage species and large predators in the system?


The ratio of small to large fish abundance on Georges Bank: Showing a healthy system from the 1960s to the mid 1980s with about 20 times more small fish than large fish; excess forage fish in the 1990s; and decline of forage species in recent years (as their natural predators were not fished, leading to too many large fish in the system given the base of small fish.)

The Sustainable Fisheries Framework (SSF) aims to maintain a healthy ecosystem by not over-exploiting any species, with special considerations made for forage (prey) species that have implications for predators in the system. Communities of forage fish usually consist of an assemblage of several species, the composition of which changes over time. Therefore, managing forage fish as individual species is difficult because of their large natural variability. This project will develop a forage fish management approach that considers their collective role in the ecosystem as predator food, and attempts to find a balance between the abundance of forage fish and predators. Because marine ecosystems are strongly size structured (big fish eat little fish), this project will examine a range of potential size-based indicators during known times of ecosystem health or stress in order to identify which size-based indicators are most useful for informing fisheries management, and determine an acceptable ratio between prey and predators.

Program Name

Strategic Program for Ecosystem-based Research and Advice (SPERA)



Principal Investigator(s)

Daniel Duplisea

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