The impact of density-dependent changes in individual life histories on marine population dynamics
André M. de Roos Institute for Biodiversity and Ecosystem Dynamics University of Amsterdam, The Netherlands
Thursday, October 5, 2017 4:00 PM Fishery Sciences Building, Room 102 Open advising about undergraduate programs hosted in FSH lobby from 3:30-4:00 pm
Historically, models describing the dynamics and management of marine populations are based on assumptions that poorly reflect the ecology of and the complex interactions between individual organisms and their environment. For example, the most often used multi-species models of fish communities only take into account the negative effect of predator-prey relations between fish species, that is, the mortality impact on the prey, but ignore the benefits of predation, the increase in mass of the predator. With an increasing demand for ecosystem based management this discrepancy between the models and the ecology becomes important to address. In this presentation I review how current fisheries models account for ecological processes. Subsequently, I will introduce a class of size-structured population models based on individual energetics that explicitly account for ecological interactions of individual fish. Analysis of models of this kind will be shown to not only increase our understanding of the mechanisms shaping fish community dynamics, but also make counterintuitive predictions about the outcome of fisheries management strategies. More specifically, it will be shown how intermediate levels of harvesting prey fish may promote rather than demote persistence of piscivores. Lastly, I will show how the same type of size-structured population models based on individual energetics can also be applied more generally, for example, to explain the persistent population oscillations that have been observed in Antarctic krill.
Bio: André de Roos’ research focuses on the relationship between individual life history and the dynamics of populations and communities. Whereas the main body of theory concerning population dynamics and community structure is based on the analysis of unstructured, Lotka-Volterra type population dynamic models, which ignore differences between individuals altogether, the defining feature of biological organisms is that they grow and develop throughout their life from the moment they are born till the moment they die. In between these individuals might reproduce, but the majority generally does not. Hence, after mortality ontogenetic development and growth in body size can be considered the most prominent life history processes, which furthermore commonly results in individuals playing a different ecological role in the different stages of their life history. Using a special class of physiologically structured population models, André de Roos theoretically explores the often counter-intuitive effects of density dependence in ontogenetic development on the dynamics and structure of marine communities.
The Data Management Specialist 2 (Natural Science) will assist the Alaska Fisheries Science Center’s (AFSC) Fisheries Monitoring and Analysis Division (FMA) with data management. The position is located at the Alaska Fisheries Science Center, 7600 Sandpoint Way N.E., Seattle, Washington. The job duties of this position will be to assess, track and ensure that data collected by fisheries observers meets data quality standards.
This position reports to the Debriefing Services Supervisor and is primarily responsible for:
Serving as an inseason advisor for fisheries observers deployed to commercial fishing vessels.
Conducting mid-cruise debriefings of fisheries observers during their deployment to commercial fishing vessels.
Conducting final debriefings of fisheries observers at the completion of their deployment to commercial fishing vessel.
Ensuring the data collection methods used by fisheries observers are consistent with the programs’ established procedures.
Ensuring that all data collected by fisheries observers meets the program’s data quality standards.
Assisting fisheries observers to resolve data collection and recording problems.
Assisting in the briefing of fisheries observers prior to their deployment.
Interacting with members of the fishing industry to assess whether their vessel meets Federal requirements for fisheries observer sample stations.
Working and communicating with FMA staff to ensure data integrity and consistency.
Pay is $21.12/hour, expected start date is June 5, 2017 and application close date is 5/16/2017.
The acidification of the ocean expected as seawater absorbs increasing amounts of carbon dioxide from the atmosphere will reverberate through the West Coast’s marine food web, but not necessarily in the ways you might expect, new research shows.
Dungeness crabs, for example, will likely suffer as their food sources decline. Dungeness crab fisheries valued at about $220 million annually may face a strong downturn over the next 50 years, according to the research published Jan. 12 in the journal Global Change Biology. But pteropods and copepods, tiny marine organisms with shells that are vulnerable to acidification, will likely experience only a slight overall decline because they are prolific enough to offset much of the impact, the study found.
“What stands out is that some groups you’d expect to do poorly don’t necessarily do so badly – that’s probably the most important takeaway here,” said Kristin Marshall, lead author of the study who pursued the research as a postdoctoral researcher at the University of Washington and NOAA Fisheries’ Northwest Fisheries Science Center. “This is a testament in part to the system’s resilience to these projected impacts. That’s sort of the silver lining of what we found.”Marine mammals and seabirds are less likely to be affected by ocean acidification, the study found.
FishWise is a sustainable seafood consultancy that promotes the health and recovery of ocean ecosystems through environmentally and socially responsible practices. FishWise uses market-based approaches to achieve responsible business practices and create change on the water. This science-based and business-friendly approach has allowed FishWise to build partnerships and strong working relationships with industry, government, and NGOs.
We are seeking a Project Manager to advance social responsibility and protect human and labor rights within seafood supply chains. The Project Manager will be responsible for research, development, and execution of work plans on human rights, under the direction of the Project Director – Human Rights Lead. Work plan goals are threefold: 1) to create tools and recommendations that help the seafood industry improve traceability and eliminate products that are harvested illegally, or associated with human rights abuses, from their supply chains; 2) to facilitate discussions between key players to find novel solutions to human rights, labor, and social compliance challenges; and 3) to communicate progress and updates to a core group of NGOs, industry, and other stakeholders. The Project Manager will achieve these goals by building strong relationships with the seafood industry, government, academia, and NGOs.
Reporting: This position reports to the Project Director – Human Rights Lead.