Developing New Approaches to Global Stock Status Assessment and Fishery Production Potential of the Seas

Lucy Towers
11 August 2014, at 1:00am

Stock status is a key parameter for evaluating the sustainability of fishery resources and developing corresponding management plans. However, the majority of stocks are not assessed, often as a result of insufficient data and a lack of resources needed to execute formal stock assessments. The working group involved in this FAO publication focused on two approaches to estimating fisheries status: one based on single-stock status, and the other based on ecosystem production.

Wild-capture fisheries provide a critical source of nutritional and economic benefits to people worldwide. In 2010, fisheries generated livelihoods and income for almost 38.5 million people (FAO, 2012) and currently fish provide approximately 3 billion people with almost 20 per cent of their intake of animal protein.

In the last half century, marine fisheries have been rapidly expanding and developing (Swartz et al., 2010). Fishing fleets have also been increasing, both in number and extent, since the 1970s (Anticamara et al., 2011; Watson et al., 2013), although this growth has stabilized in the last decade (FAO, 2010).

Concurrently, total landings increased from 16.8 million tonnes in 1950 to a peak of 86.4 million tonnes in 1996, but subsequently declined to 77.4 million tonnes in 2010 (FAO, 2012). With coastal populations projected to grow by 35 per cent in the next 20 years, the demand for fisheries resources is likely to continue to increase. 

The combined intensification in both pressures on and demand for fisheries resources necessitates a broad understanding of the state of global fisheries to support policy formulation and the development of effective marine management.

In spite of their importance, it remains a major challenge to determine the status and potential production of wild-capture fish stocks. Managers and policy-makers need information on individual fish stocks to evaluate their status so that effective management strategies can be developed. At the same time, it is also necessary to undertake ecosystem-scale assessments that account for the interactions between stocks, the impact of fishing on non-target fish, and other factors that cannot be determined by looking at each stock in isolation.

Costello et al. (2012) estimated that more than 80 per cent of the global catch comes from stocks that have not been formally assessed. Formal stock assessments require substantial data and resources to complete. Therefore, data-limited approaches are needed to assess the status of global fish stocks and to develop benchmarks for the fishery production potential of the oceans.

The working group addressed these challenges using two approaches to estimate fisheries status: one based on singlestock status, and the other based on ecosystem production. The single-species work stream focused on evaluating the operational performance of different methods for estimating stock status within a simulation framework to evaluate their performance robustly.

This simulation framework can also be used to examine the performance of other data-limited and data-rich approaches. The ecosystem production work stream was tasked with developing estimates of fishery production for each large marine ecosystem (LME) and FAO statistical area based on overall primary production in each area.

This information allows for the extracted production to be compared with the estimated total production in an LME or FAO area, which is useful for developing food security policies, for effective marine stewardship, and for understanding the potential gains in fishery production from enhanced ocean management. Results from both work streams can be used to compare current exploitation rates with estimated fishery production potential.

There is always a trade-off between risk and exploitation, and this study provides a suite of methods for evaluating fish stocks at greatest risk so that they can be prioritized for management and increased data collection. Estimating stock status and identifying regions that may be at risk for overexploitation are key components of moving towards ensuring sustainable exploitation. The work described in this report is an important step in investigating the performance of methods that can be used to estimate stock status. The results are not intended to provide direct advice to motivate management measures on specific fisheries, but to give an indication of the health of fish stocks and their production potential.

The approaches from the two work streams provide a more quantitative and consistent basis for evaluating global fish stock status than has previously been available. These estimates are vital for efforts to assess the health of marine ecosystems globally under data-limited situations.

Further Reading

You can view the full report by clicking here.

July 2014