A spatial multi-species operating model of the Antarctic Peninsula krill fishery and its impacts on land-breeding

An updated version of the Spatial Multi-species Operating Model (SMOM) of krill-predator-fishery dynamics is described. This has been developed in response to requests for scientific advice regarding the subdivision of the precautionary catch limit for krill among 15 small-scale management units (SSMUs) in the Scotia Sea, to reduce the potential impact of fishing on land-based predators. SMOM has been revised from the original version presented in Plagányi and Butterworth (2006a) in three main ways: 1) Accounting for seasonality; 2) Explicitly modelling fish and whales in addition to penguin and seal predators; and 3) Addition of an alternative movement model based on the results from the OCCAM model.
This modelling framework provides an example of a method for bounding some of the uncertainty associated with multi-species models used for management. Results are presented as probability envelopes rather than in point estimate form, giving a truer reflection of the uncertainty inherent in outcomes predicted on the basis of multi-species models as well as highlighting how such probability envelopes could be narrowed given improved data on key parameters such as survival. Results are useful for evaluating different spatial allocations of krill catches. An example is given of how such a framework can be used to develop a management scheme which includes feedback through management control rules.