Cod is a key species in the Barents Sea; it is arguably one of the most ecologically and economically important species in the North Atlantic. Despite the Northeast Arctic cod stock being in good condition as well as harvested sustainably, it is under threat from the effects of global climate change.
Climate change is often thought of and studied as the single effect of increased temperature. However, the effects of climate change are more wide-reaching than that and can affect the cod in unknown ways.
An understudied combined effect of climate change is changing food availability for the cod. The cod’s normal food, like capelin and herring may change in abundance and distribution affecting the cod’s diet. Furthermore, the Barents Sea may become home to an increased number of invasive species, like the snow crab and red king crab, potentially disrupting the environment and relationships between cod and their normal food.
A crucial question therefore is, how do changes in temperature and food availability affect cod at both the individual and population level?
In this young research talent project, we have the unique opportunity to use rare and extensive long-term datasets, combined with innovative modelling tools to investigate the impacts of increased temperature and changing food availability on Northeast Arctic cod.
A kick-off meeting took place in May 2024 held at the University of Oslo attended by all participants, over two days. Several scientific presentations were made by the participants with led to productive and stimulating discussions for planning and conducting the research ahead.
Two manuscripts have been published as part of the project so far. The first focuses on the effects of biomass reduction effects on the role of climate fishing and recruitment on fish population dynamics, testing across 54 marine fish species. This manuscript was led by Joël Durant, work package leader in Oslo and co-authored by the P.I, Rebecca E. Holt. The strongest changes were found in pelagic habitats. These species exhibited increased sensitivity to changes in external drivers like climate and fishing at biomass levels concurrent with a pre collapse period compared with post collapse biomass levels.
The second manuscript focusses on the predator-prey dynamics between cod and haddock in response to climate warming. This publication was led by Joël Durant, work package leader on the research project and co-authored by the P.I. The research found that the distribution and increased abundance of cod may limit the expansion of haddock to new areas in the Barents and North Seas.
Many studies focus on a single driver within global climate change, primarily temperature, but fail to consider the wider implications of environmental change at the individual and population level. In this project, we will develop and apply a multifaceted innovative modelling approach, combined with extensive high-resolution long-term data to evaluate the potential impacts of changing food environment (through prey availability, prey composition, diet: prey type, energy content and digestibility) and temperature on the economically and ecologically important Northeast Arctic cod (Gadus morhua) in the Barents Sea
We will use extensive unique spatio-temporal datasets, including the NEA cod stomach content database, spatiotemporal prey abundance datasets that reflect NEA cod diet, and environmental datasets for temperature in the Barents Sea. These data sources together with existing empirical knowledge will be used to quantitatively analyse past and present changes in predator-prey dynamics, prey availability and NEA cod diet (WP 1 & 2).
This vital information will be used to parametrise, and develop, novel trait-based models to examine the effects of changing temperature and spatio-temporal food environment on important population characteristics, such as survival, growth, reproduction, mortality, and productivity of NEA cod (WP3).
We will use a mechanistic approach, focusing on the well-known respiratory physiology mechanism allowing us to provide predictions of temperature- and food-environment-induced adaptations for life-histories and behaviour at the population level, allowing for an innovative study on the synergistic effects of external stressors on arguably one of the most ecologically and economically important species in the North Atlantic, Northeast Arctic cod.