Thursday, May 24, 2012

What is a sustainable fishery?

It seems that nobody has the answer.  At least not an answer that is widely supported by environmentalists, fisheries managers, fisheries scientists, third party certifiers and the fishing industry.

A clear, succinct and widely adopted definition of a sustainable fishery would provide a benchmark against which individual fisheries could be compared.  It would cut down on the wiggle room jargon of “conditionally sustainable”, “on the road to being sustainable” and “more sustainable than it was”.  Simply put, a fishery would be deemed currently either “sustainable” or “not sustainable” based on a few carefully chosen and measurable conditions.

Currently MSC requires 23 criteria to be addressed under three principles in order to determine whether or not a fishery is sustainable.  Each of these criteria has one or more sub-criteria, each with an associated performance indicator that has to be scored and added together to determine a pass or fail.   It is a complex system which allows depleted fisheries, data poor fisheries and fisheries with collateral environmental damage to be certified conditionally sustainable provided a plan is proposed to ameliorate these flaws.  This leaves the public confused and environmental groups shaking their heads.  

Unfortunately scientific experts do not agree on a definition of a sustainable fishery. 

In the “Comments” section of the Washing Post related to the article “Some question whether sustainable seafood delivers on its promise” (by Juliet Eilperin, Published: April 22 2012),  Ray Hilborn of the University of Washington draws the distinction between sustainability as a state of a stock, and sustainability as a process. He believes that “sustainability is clearly the result of a process, stocks can be overfished, by anyone's definition, and still be sustainable if the management system responds to changes in abundance and reduces fishing pressure allowing stocks to rebuild”.

The notion, that a fishery on a stock in a depleted state can be considered “sustainable” provided there is a management process in place to reduce fishing pressure and allow the stock to rebuild in the future, is highly controversial.

In contrast, many would argue that a sustainable fishery is one in which overfishing is not taking place and the stock is not overfished at the present time.  In other words the “process” should have already led to the stock being rebuilt before the fishery on that stock can be termed “sustainable”.

Translated into fisheries science jargon, a sustainable fishery is one in which fishing mortality is on average below Fmsy (no overfishing) and spawning biomass is on average above Bmsy (not overfished) at the present time. 

Here Fmsy is the fishing mortality that gives maximum sustainable yield on average and Bmsy is the average spawning stock biomass that results from fishing at Fmsy.  
Secondary but important considerations include a societally acceptable low level of collateral  damage through ecosystem alteration, bycatch impacts and habitat destruction.  

1 comment:

  1. Yes, the holy grail: a "clear, succinct and widely adopted definition." Unfortunately, I feel like we're about as capable as the Monty Python movie of that name in our search for a definition. Probably if everyone were sincere we could reach a definition. The power struggle over the definition is anything but sincere, since there's a lot at stake.

    Thanks for your thoughts.