Ecosystem Dynamics in Forage Fish Fisheries

Forage fish, typically small, pelagic species such as herring, anchovy and sardine, occupy a pivotal role in marine food webs by channelling primary production to higher trophic levels. Their population dynamics are characterised by strong temporal variability driven by environmental factors—such as sea surface temperature, ocean currents and nutrient availability—coupled with fishing pressure. Fluctuations in forage fish biomass can cascade through ecosystems, affecting the abundance and distribution of predators including larger fish, seabirds and marine mammals. Recent advances in ecosystem modelling and monitoring have revealed complex interactions between recruitment processes, natural mortality rates and harvest strategies. This has prompted a shift from single-species assessments towards holistic, ecosystem-based management frameworks that seek to balance yield optimisation with the maintenance of ecological integrity and trophic structure. Globally, these approaches inform adaptive harvest control rules, ecological reference points and trade-off analyses, ensuring that both commercial benefits and biodiversity conservation objectives are met.

Research from Nature Portfolio

Recent studies have developed stochastic, age-structured frameworks to assess trade-offs between stage-specific harvest strategies for forage species. Analyses of Pacific herring populations demonstrate that fisheries targeting spawned eggs and those targeting adults exert asymmetric influences on stock resilience and predator persistence. These models reveal that ecosystem thresholds established to safeguard predator populations do not necessarily impose more stringent constraints on harvest than conventional, fishery-driven guidelines. The flexible modelling template accommodates environmental variability, quantifies risks of fishery closures and evaluates the probability of exceeding ecosystem thresholds, thereby informing adaptive harvest policies that integrate ecological safeguards with socio-economic objectives.

Ecosystem Dynamics in Forage Fish Fisheries publication trend

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

Technical terms

Forage fish: Small, schooling pelagic species that transfer energy from primary producers to higher trophic levels.

Trophic level: Position of an organism within a food web, determined by the number of energy transfers from primary producers.

Ecosystem-based management: Holistic approach that considers species interactions, environmental variability and human activities to sustain ecosystem health and services.

Ecopath with Ecosim (EwE): Modelling suite combining static mass-balance models (Ecopath) with dynamic simulations (Ecosim) to explore trophic interactions and management scenarios.

Management strategy evaluation (MSE): Simulation framework for comparing fisheries management strategies under uncertainties in stock dynamics, observation and implementation.

Ecological reference point (ERP): Quantitative threshold or target based on ecosystem objectives, used to guide harvest limits that maintain ecological functions and biodiversity.

References

1. Assessing trade-offs to inform ecosystem-based fisheries management of forage fish. Scientific Reports (2014).
2. Recent trends in abundance and fishing pressure of agency‐assessed small pelagic fish stocks. Fish and Fisheries (2022).
3. Considerations for management strategy evaluation for small pelagic fishes. Fish and Fisheries (2021).