Work Package 2: Environmental stochasticity, trophic interactions and choice of harvest strategies

Leader: Aline M. Lee, NTNU

A central challenge in ecosystem management is to separate the effects of harvest from the influences of changes in climate on the population dynamics. Here we propose that this requires a change in the choice of harvest strategies, moving from a prime focus on maximizing the mean annual yield to reducing the effects of harvesting on the population variability to maximize the cumulative yield over a longer time period (12).

This will require an integrated approach that involves a multi-species approach across trophic levels (e.g., 47), as well as an understanding of how environmental stochasticity affects the population dynamics at different trophic levels. In this WP we will apply a three-step approach to derive principles for developing such robust harvest strategies.

  • First, we will explore how differences in the structure of the environmental noise should influence the choice of harvest strategy by, e.g., requiring more information about autocorrelation structure in the previous vital rates.
  • Second, we will examine the potentially additive effects of environmental stochasticity on the population dynamics of harvested species, in particular focusing on interactions between environmental noise at different trophic levels.
  • Third, we will use these patterns to produce stochastic multispecies harvest models using extensive stochastic simulations, with different strategies and varying parameters defining the harvesting rate.

This will provide valuable insights in how multivariate environmental noise will affect the dynamics as well as the temporal mean and variance of the yield as function of different harvest strategies (12).