Maximising net economic returns from a multispecies fishery
CSIRO Oceans and Atmosphere Hobart
An objective of the Fisheries Management Act 1991 is ‘maximising the net economic returns to the Australian community from the management of fisheries’, which has been interpreted as achieving the biomass that, on average, produces maximum economic yield (BMEY) in the Commonwealth Fisheries Harvest Strategy 2007 and the more recent Borthwick (2012) and DAFF (2013) Reviews cited earlier. To date, only two Australian fisheries (the Northern Prawn Fishery (Punt et al 2011) and the Great Australian Bight trawl fishery (Kompas et al 2013) have models suitable for assessing MEY. These are data rich fishery, both in terms of economic and biological information. Methods for estimating proxy target reference points in single and multispecies fisheries have recently been developed (FRDC 2011/200 and FRDC 2010/044) but not yet applied in any fishery. Other approaches have also been developed elsewhere (e.g. FRDC 2008/08). These methods have not accounted for environmental externalities, particularly in terms of bycatch and discards, which may affect the optimal outcome. A range of other complications were also identified during a technical review of economic issues (FRDC 2012/225) and the review of the Commonwealth Policy on fisheries bycatch. Developing harvest strategies that maximise net economic returns is a different problem to that of identifying targets. The latter is an endpoint while the former is the process to achieve the end point. The purpose and aim of this project is to establish a practical and cost effective method for managing a multispecies fishery towards maximising net economic returns as a whole, taking into account non-target catches.
1. Development of a methodology for maximising net economic return to a multispecies fishery as a whole, and with regard to by-catch and discard species
2. Development of a framework to operationalise the methodology into fisheries management objectives
The Australian Commonwealth Harvest Strategy and Policy identifies maximising net economic returns as the primary objective of fisheries management. This has largely been interpreted as maximising the net economic yield (MEY) in fisheries. For multispecies fisheries, this has been based on maximising the net present value of total profit in the fishery over all stocks. The estimation of MEY has largely focused on the benefits to the fishing industry. This may potentially have adverse effects on consumers if achieving MEY results in lower catches and higher prices. At the same time, not all costs are considered when estimating profits to the industry. Costs such as the non‐market value of species caught as bycatch are generally ignored. In this report, we examine how including benefits to consumers and the non‐market costs associated with bycatch affect the definition of MEY (and how it relates to net economic returns).
Identifying MEY is just one part of the challenge facing fisheries managers. How to achieve MEY in multispecies fisheries is another. A major part of the study was how we might implement MEY in a multispecies fishery. Using a model based on the Southern and Eastern Scalefish and Shark Fishery (SESSF), we examine the effectiveness of different harvest strategies in achieving fishery wide MEY, and also how different approaches to estimating MEY affect the outcomes.