Masked, diluted and drowned out: how global seafood trade weakens signals from marine ecosystems

By Jake Jerome, RJD Graduate Student

It has been shown that global seafood trade inherently drives seafood production, negatively impacting marine ecosystems worldwide. While it is well known that these ecosystems are deteriorating, most research has been focused on global stock assessments, catch trends, or fisheries dynamics, with little attention given to researching the ways in which global trends are linked to consumers through trade. Fish prices can potentially be used as a feedback signal to consumers about the state of fisheries and marine ecosystems, but this method faces several issues. Crona et al 2015 dive deeper into the usefulness of using fish prices as a feedback signal, but develop a set of mechanisms that combine to weaken this signal from global trade to consumers.

The first mechanism that weakens price signals is masking. Masking occurs within individual fisheries and consists of two parts. First, negative impacts that arise from fishing are often separated from the operating cost of the fishery. For example, fisheries may cause habitat destruction or result in bycatch of endangered animals, but neither of these have a large impact on the yield or cost. Second, short-term catch trends may not provide accurate representation of target stock declines due to factors such as increased effort, technological advances, and fishing deeper or farther from shore.


Shrimp trawl net with bycatch (Elliott Norse, Marine Conservation Institute/Marine Photobank)

The second mechanism discussed is dilution. Dilution occurs when the amount of supply that an individual fishery has declines but is hidden from consumers by using the supply from another resource area. For example, the UK imports Atlantic cod from Iceland and Faeroes to make up for the decline of North Sea cod. Through dilution, changes in any one ecosystem are concealed from consumers because substitutable products are made available from different ecosystems.

A third mechanism examined is the ‘drowning out’ of price signals. This is usually due to other market factors that affect fish prices. Things like changes in consumer spending patterns or price/availability of alternative protein sources can combine to alter fish prices that do not necessarily connect with ecosystem or species decline.

Chilean Seabass for sale at Whole Foods (Gerick Bergsma 2011/Marine Photobank)

Chilean Seabass for sale at Whole Foods (Gerick Bergsma 2011/Marine Photobank)

In conclusion, the authors suggest that the feedback from individual fisheries to consumers worldwide is highly asymmetric and that price signals reflecting changes in the source ecosystem typically are masked, diluted, or drowned out unless large proportions of seafood stocks collapse. Despite this, opportunities do exist that possibly could help provide a positive feedback signal to consumers, resulting in promoting sustainable seafood practices.

Source: Crona, B. I., Daw, T. M., Swartz, W., Norström, A. V., Nyström, M., Thyresson, M., Folke, C., Hentati-Sundberg, J., Österblom, H., Deutsch, L. and Troell, M. (2015), Masked, diluted and drowned out: how global seafood trade weakens signals from marine ecosystems. Fish and Fisheries. doi: 10.1111/faf.12109