Population Dynamics of Marine Forage Fish

Forage fish are small to medium-sized species that occupy a central role in marine food webs, transferring energy from planktonic producers to higher predators. Their population dynamics are shaped by a balance of bottom-up forces, such as plankton availability and temperature-driven productivity, and top-down pressures, including predation and fishing. Seasonal and interannual variability in growth, recruitment and spatial distribution often reflect shifts in oceanographic conditions, regime changes and anthropogenic impacts. Many forage stocks exhibit boom-and-bust cycles or prolonged low phases following collapse, with recovery trajectories influenced by life-history traits, prey–predator interactions and ecosystem context. Understanding these dynamics is essential for predicting the responses of forage communities to climate change, for designing ecosystem-based management strategies and for safeguarding both ecosystem functioning and the viability of commercially and ecologically important species.

Research from Nature Portfolio

Recent studies have applied spatiotemporal models to assess the capacity of fish populations to recover spatially after environmental perturbations. One investigation evaluated cold-water anomalies over several decades for two flatfish species and found that, following a cold period, one species’ distribution expanded back northwards with warming while the other remained displaced southwards. These findings demonstrate nonlinear and species-specific responses to temperature forcing and suggest that some distributional changes may be effectively irreversible, emphasising the need to consider lasting spatial shifts in the management of forage-like assemblages.

Population Dynamics of Marine Forage Fish publication trend

The graph below shows the total number of articles in population dynamics of marine forage fish across all publications each year (not limited to Nature Index journals).

Technical terms

Forage fish: Small to medium-sized schooling species that link planktonic producers with higher trophic levels.

Trophic cascade: A series of indirect interactions in a food web initiated by changes in the abundance of a top predator or primary producer.

Condition factor: A metric of fish health or robustness, typically derived from weight-to-length ratios to indicate body reserves.

Regime shift: A rapid and sustained change in ecosystem structure and function driven by environmental or anthropogenic forces.

Bottom-up regulation: Population control arising from resource availability, such as food supply or primary production.

References

1. A regime shift in the Southeast Greenland marine ecosystem. Global Change Biology (2022).
2. Lagged recovery of fish spatial distributions following a cold-water perturbation. Scientific Reports (2021).
3. Indexing starvation mortality to assess its role in the population regulation of Northern cod. Fisheries Research (2022).
4. Comparative Modeling of Cod-Capelin Dynamics in the Newfoundland-Labrador Shelves and Barents Sea Ecosystems. Frontiers in Marine Science (2021).