Sunday, May 6, 2012
Is sustainable seafood really sustainable?
A recently published paper in the journal Marine Policy by German scientists Rainer Froese and Alexander Proelss has attracted the attention of the Washington Post and other media.
The paper takes issue with sustainability certifications of marine fisheries by the Marine Stewardship Council and the Friends of the Sea.
They examined the most recent estimates of current biomass, (B) biomass at maximum sustainable yield (Bmsy), current fishing mortality (F) and fishing mortality at MSY (Fmsy) from national or international fisheries bodies and published papers for 71 MSC certified stocks for which they could find such information.
For 11% of these stocks the information was insufficient to make a judgement about stock status or exploitation levels. 31% of the stocks with sufficient information were overfished and were currently subject to overfishing.
They define “overfished” as those stocks where B is less than Bmsy and "overfishing" as taking place when F exceeds Fmsy
. They allow some latitude in
that if the ratio B/Bmsy is greater than 0.9 or F/Fmsy is less than1.1 it is not included in the
percentage total of overfished and overfishing.
National fisheries agencies and international fisheries organizations tend to be somewhat coy regarding their specific definition of sustainability with respect to marine fisheries.
The US, under the Magnuson–Stevens Act, is an exception in this regard although the criteria may vary somewhat on a stock by stock basis. Commonly the US definition of “overfishing” is the same as that adopted by Froese and Proelss (F>Fmsy) but the US tends to be more tolerant with regard to the definition of overfished, commonly requiring the stock to be above 50% of Bmsy or 50% of maximum spawner potential (spawner per recruit).
Under Principle 1 of their standard, MSC ideally requires that fisheries are managed so that they fluctuate around Bmsy or higher although stocks can still be certified under this criterion if they are above 50%Bmsy. Of course there are many MSC loopholes around this that allow fisheries to be certified even where there are no reliable estimates of where the stock is relative to these levels. Fmsy does not factor directly into the MSC certification standard, so that it is feasible that fisheries in which overfishing is taking place, such that the stock will be depleted over time, can still be certified as sustainable.
While Froese and Proelss may raise the bar a little too high, stocks that are consistently below Bmsy or are being fished consistently above Fmsy should not be given sustainable fishery labels. Also, data poor fisheries cannot be assumed to be sustainably managed based on vague and subjective notions. The fact that overfished stocks subject to overfishing, as well as data-poor stocks, are being certified as “sustainable” brings into question current standards.
National fishery agencies and international organizations would serve us well by developing clear globally accepted and simply applied standards for what constitutes a sustainable fishery. Fisheries that are shown to meet such standards through scientific peer review of assessment of stock status would not be in need of further sustainability accreditation.