Interactions between small pelagic fish and young cod across the north Atlantic

Area of Science:

• Marine Ecology
• Fisheries Science
• Population Dynamics

Background:

• Large-scale marine species interactions are challenging to study.
• Lack of interaction data impedes holistic fisheries management.

Purpose of the Study:

• Estimate interaction strength and direction between Atlantic cod and pelagic fishes.
• Test if small pelagic fish reduce early-life cod survival, delaying cod population recovery.

Main Methods:

• Utilized separate and hierarchical Bayesian models.
• Analyzed time series data across the North Atlantic range of Atlantic cod.
• Estimated interactions between cod and Atlantic herring, mackerel, sprat, and capelin.

Main Results:

• A negative relationship between Atlantic herring and cod recruitment was found in 8 of 14 regions (94% probability).
• Most regions showed no significant interaction between Atlantic mackerel and cod recruitment (68% probability of negative interaction).
• Weak or no relationships were observed with sprat and capelin, though a negative interaction with sprat increased when autocorrelation was considered.

Conclusions:

• The impact of pelagic fish on young cod varies by species but is consistently negative for Atlantic herring.
• These species interactions, particularly with herring, must be considered for depleted cod population recovery strategies.
• The Bayesian modeling approach is applicable to studying species interactions using time series data in various systems.