From strategic ambiguity to technical reference points in the Antarctic krill fishery: the worst journey in the world?

Abstract

SUMMARYThe goals of ecosystem based management (EBM) are strategically ambiguous, meaning that they require interpretation to identify objectives for ecosystem state. Ecosystem states that are useful for achieving such objectives are known as reference points. Soft reference points specify both a state and a probability of the ecosystem being in that state. They are used with simulation models to identify management measures for which the risk of the ecosystem entering an undesirable state is below a specified level. The Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) is responsible for the EBM of Antarctic krill fisheries. CCAMLR used soft reference points for the krill stock in the Scotia Sea and southern Drake Passage to set a regional catch limit. However, this catch limit needs spatial subdivision to protect predators from localized depletion. Modelbased evaluations of different options for subdividing the catch limit used illustrative reference points to assess the depletion risk to multiple predators. This study demonstrates that the apparent risk is sensitive to the choice of reference point and method for aggregating modelled predators. EBM practitioners and stakeholders need to be aware that these factors could therefore bias comparisons of management measures. Nonetheless, qualitative distinctions between different spatial subdivision options are relatively consistent except at high levels of aggregation and extreme reference points. This study also demonstrates a lack of generality in the relationship between current and future ecosystem state. Thus, the EBM goal of maintaining ecosystem resilience implies different reference points for the current state of different ecosystem components. Despite early progress in defining soft reference points for the krill stock, CCAMLR has not yet defined reference points for krill predators. Structured dialogue aimed at identifying collective objectives * Correspondence: Dr Simeon Hill e-mail: sih@bas.ac.uk The online version of this article is published within an Open Access environment subject to the conditions of the Creative Commons Attribution-NonCommercial-ShareAlike licence <http://creativecommons.org/licensesw/by-nc-sa/2.5/>. The written permission of Cambridge University Press must be obtained for commercial re-use. might be necessary to achieve further progress in CCAMLR and other EBM organizations.

Reference points for predators will progress ecosystem‐based management of fisheries

“…Environmental change can mean that goals, which are achievable under current conditions, are not achievable under future conditions. This has led to the development of relative reference points (Hill, ), which change over time to track environmental conditions. An example is the black‐legged kittiwake reference point (Table ) in which breeding success is assessed relative to that expected under current environmental conditions (Cook, Dadam, Mitchell, Ross‐Smith, & Robinson, ).…”

“…This lack of progress with adjustment methods is related to the lack of key input information, particularly about which predator state variables are important and what the objectives for them are (Hall & Mainprize, 2004;Punt et al, 2016). Reference points, which encapsulate these two pieces of information (Hall & Mainprize, 2004;Hill, 2013), are missing in most case-studies.…”

“…Ultimately, the lack of predator reference points indicates uncertainty about the specific objectives for predators. This uncertainty can exacerbate uncertainty about the nature of impacts and stall the development of appropriate management approaches (Hill, 2013;Regan, Colyvan, & Burgman, 2002).…”

“…Environmental change can mean that goals, which are achievable under current conditions, are not achievable under future conditions. This has led to the development of relative reference points (Hill, 2013), which change over time to track environmental conditions.…”

From Ice to Penguins: The Role of Mathematics in Antarctic Research

“…An assessment of risk based on the results of model projections with 34! intentionally high levels of uncertainty ,!Hill!2013a. The model 35!…”