In response to multiple stressors, coral reef health has declined in recent decades,
with reefs exhibiting reduced living coral and structural complexity, and a concomitant
rise in the dominance of algal resources. Reef degradation alters food availability
and reduces the diversity and density of refuges for prey. These changes affect predator–prey
interactions and can have cascading impacts on food webs and fisheries productivity.
We use a size‐based ecosystem model of coral reefs that incorporates the influence
of structural complexity, benthic primary production and detrital recycling to explore
how predator–prey interactions and fisheries productivity respond to a gradient of
We show that fisheries productivity overall may be robust to initial stages of reef
degradation because the benefits of increased resources outweigh the costs of moderate
refuge decline. However, the assemblage composition and size structure of reef fish
will differ on degraded reefs, with herbivores and invertivores contributing relatively
more to productivity.
More significant losses of refuges associated with the erosion of structural complexity
correspond to fisheries productivity losses of at least 35% compared to healthy reefs.
Synthesis and applications. Our model provides fisheries managers with quantitative predictions about how fisheries
productivity may change in response to the ongoing degradation of coral reefs. We
predict an initial increase in productivity at intermediate reef degradation, followed
by a drastic decline when structural complexity is lost. We also capture subtle changes
to potential catch composition and fish size, including increases in smaller herbivorous
and invertivorous fish from degraded reefs, which will undoubtedly impact fisheries
value. On the one hand, our results reassure for continued productivity in the short
term, but on the other, we warn against complacency. Management must change to capture
any potential benefits to fisheries, and long‐term sustainability still depends on
the maintenance of complex coral reef habitats.