Post provided by ASTA AUDZIJONYTE, Heidi Pethybridge, Javier Porobic, Rebecca Gorton, Isaac Kaplan, and Elizabeth A. Fulton

Increased Demands on a Crowded Ocean

Multiple demands on, and uses of, the ocean. ©Frank Shepherd

The ocean was once a limitless frontier, primed for exploitation of fish and other marine life. Today, a scan of the coastline (in our case off Australia and the US) shows an ocean landscape dotted with aquaculture pens, wind farms, eco-tours, and oil rigs, as well as commercial and recreational fishing boats. This presents marine and maritime managers with the huge challenge of balancing competing social, conservation, and economic objectives. Trade-offs arise even from success stories. For example, seal and sea lion populations are recovering from centuries of hunting, which is great. But now they’re preying heavily on economically valuable species like salmon and cod, creating potential tensions between fisheries and conservation communities. Ecosystem-based management is one way that we can start to address these trade-offs.

New Tools for Ecosystem-based Management

Ecosystem-based management for marine systems is an approach that incorporates species interactions, multiple drivers, and trade-offs. This approach is usually spatially explicit, including detailed mapping of overlap between species, threats, and human users. For instance, how are fish stocks shifting under climate change, and does this put them out of range of fishers?

How will climate change effect fish stocks? ©Matthew T Rader

A key component of ecosystem-based management is evaluating multi-species dynamics in space and time. This approach also lets us test management strategies that account for, and adapt to, change. In our experience (from research in over 20 countries), we desperately need tools that support such evaluations and handle a diverse array of ocean drivers. Methods to address a single issue – like those involving only one predator-prey interaction – can often be coded up de novo by individual scientists. But a concerted international effort is vital for more complex problems.

Methods: Atlantis Ecosystem Model

To support ecosystem-based management we created Atlantis. Atlantis is a spatially structured end-to-end marine ecosystem model written in C and available for all major operating systems. It’s based on dynamically interacting physics, biology, fisheries, management, assessment and economics sub-models. This Atlantis code base has been actively developed by CSIRO (Australia) for almost 20 years and shared extensively worldwide.

To date, Atlantis has been applied in assessing:

  • alternative fishery management strategies
  • historical impacts of harvesting
  • compliance with fishery regulations
  • robustness of ecological indicators
  • impacts of global change
  • effects of changes in fish body size on ecosystem dynamics.

In ‘Atlantis: A spatially explicit end‐to‐end marine ecosystem model with dynamically integrated physics, ecology and socio‐economic modules’ we formally document this code base and make it accessible to new users. For existing users, it documents assumptions, equations, and best practices. We’ve provided an installation guide and example application files, along with information on how to access the code and updates. The detailed Atlantis user manual should be a huge help to anyone using the model. There’s also loads of user support, including a wiki and Google group.

Benefits of Collaboratively Modelling the Future Ocean

At a minimum, Atlantis represents the bio-physical portion of the system, but most applications evaluate aspects of harvest, assessment, and/or economic and social drivers.

As human demands on the ocean increase and the effects of climate change become more apparent, integrated ecosystem modelling tools like Atlantis will be increasingly important. There are already over 30 model applications worldwide and more in development. We hope that the publication of this article and user manual enhances the use of Atlantis as a robust ecosystem-based management tool. It will also encourage new collaborations with those who work across different marine fields. These won’t only include physics, biology, and fisheries stock assessment, but also human behaviour, economics and social science.

To find out more about Atlantis, read our Methods in Ecology and Evolution article ‘Atlantis: A spatially explicit end‐to‐end marine ecosystem model with dynamically integrated physics, ecology and socio‐economic modules’ (No Subscription Required)