A world-wide evaluation of the use of environmental information in tactical fisheries management
The Ecosystem Approach to Fisheries Management has for many years been presented as the way to go to ensure fish stock productivity and has been adopted by many governments and international organizations. But to which extent has ecosystem information in fact been included in tactical fisheries management practice?
Figure 1. A suggested framework for including ecosystem drivers of stock production into an adaptive fisheries management framework. (A) First, estimate variance in stock productivity caused by stock abundance and harvest rates vs. ecosystem processes. (B) If harvest rate is the main driver of stock productivity, control of harvest rate remains the main tool. (C) If (also) ecosystem processes significantly impact stock productivity, identify the relevant ecosystem drivers through analyses of variance reduction and focused process studies. (D) Modify monitoring programmes and stock assessment models to incorporate relevant processes and drivers. (E) Provide advice and (F) reassess the management strategy on a regular basis.
Fish stock productivity, and thereby sensitivity to harvesting, depends on physical (e.g., ocean climate) and biological (e.g., prey availability, competition and predation) processes in the ecosystem. It could therefore be argued that management systems should adapt to changing ecosystems to enhance responsiveness and precision relative to changes in stock production (King and McFarlane 2006, Brown et al. 2012). While traditional fisheries management focuses on harvest rates and stock biomass, incorporating the impacts of such ecosystem processes is one of the main pillars of the ecosystem approach to fisheries management (EAFM). The EAFM management framework has been formally adopted by many governments and international organizations and agreements since the 1990s. Despite this little has been known about to what extent ecosystem drivers of fish stock productivity are actually implemented in fisheries management.
To examine this we recently conducted an over-arching evaluation of the extent to which ecosystem information has been included in tactical fisheries management practice (Skern-Mauritzen et al. 2015). Based on worldwide review of more than 1200 marine fish stocks, we found that such ecosystem drivers were implemented in the tactical management of only 24 stocks (not an accurate number, but in the ballpark). This may be rather surprising, both from an ecological point of view and based on that the ecosystem approach to fisheries management (EAFM) framework has been formally adopted by many governments and international organizations and agreements since the 1990s. However, also Pitcher et al. (2009) found that few countries are actually moving towards EAFM. Further, Vert-pre et al. (2013) state that fisheries management is still predominantly based on a ‘single-species equilibrium’ paradigm. This assumes that fluctuations in vital rates (growth, mortality and recruitment) and the resulting stock productivity are centred on a stationary mean at a given harvest rate, and that stock production is predominantly linked to stock abundance per se, which may be controlled through regulating the harvest rate. Thus, if management targets, such as maximum sustainable yield, are based on a high-productivity regime, a shift to a low-productivity regime will result in increased risk of overfishing. Conversely, management targets based on a low-productivity regime will result in overly cautious harvest during high productivity regimes (Vert-pre et al. 2013).
Most of the 24 cases we identified were in the North Atlantic and North-east Pacific, where the scientific support is strong. However, the diversity of ecosystem drivers implemented, and in the approaches taken, suggests that implementation is largely a bottom-up process driven by a few dedicated experts. Our results demonstrate that tactical fisheries management is still predominantly single-species oriented, taking little account of ecosystem processes, and hence implicitly ignoring that fish stock production is dependent on the physical and biological conditions of the ecosystem. Thus, while the ecosystem approach is highlighted in policy, key aspects of it tend yet not to be implemented in actual fisheries management.
Skern-Mauritzen et al. (2015) advice that when a stock is known or expected to respond to changes in the ecosystem, alternative management strategies should be contrasted in formal Management Strategy Evaluations (MSE, Butterworth and Punt 1999). In MSE, simulations of each step in the management cycle are run, including the responses of fish stocks to ecosystem change scenarios, to test the robustness and precision of different management frameworks. A roadmap for such an MSE process is outlined in Figure 1.
The article by Skern-Mauritzen et al. (2015) is open access and can be downloaded from http://onlinelibrary.wiley.com/doi/10.1111/faf.12111/epdf
Skern-Mauritzen, M., Ottersen, G., Handegard, N., Huse, G., Dingsør, G., Stenseth, N.C., & Kjesbu, O. (2015). Ecosystem processes are rarely included in tactical fisheries management Fish and Fisheries DOI: 10.1111/faf.12111
Brown, C., Fulton, E., Possingham, H., & Richardson, A. (2012). How long can fisheries management delay action in response to ecosystem and climate change? Ecological Applications, 22 (1), 298-310 DOI: 10.1890/11-0419.1
Butterworth, D. & Punt, A.E. (1999). Experiences in the evaluation and implementation of management procedures ICES Journal of Marine Science, 56 (6), 985-998 DOI: 10.1006/jmsc.1999.0532
King, J., & McFarlane, G. (2006). A framework for incorporating climate regime shifts into the management of marine resources Fisheries Management and Ecology, 13 (2), 93-102 DOI: 10.1111/j.1365-2400.2006.00480.x
Pitcher, T., Kalikoski, D., Short, K., Varkey, D., & Pramod, G. (2009). An evaluation of progress in implementing ecosystem-based management of fisheries in 33 countries Marine Policy, 33 (2), 223-232 DOI: 10.1016/j.marpol.2008.06.002
Vert-pre, K., Amoroso, R., Jensen, O., & Hilborn, R. (2013). Frequency and intensity of productivity regime shifts in marine fish stocks Proceedings of the National Academy of Sciences, 110 (5), 1779-1784 DOI: 10.1073/pnas.1214879110