The European Union's fish stocks will not recover before 2015.Matthew Dixon/iStockphoto.comEurope's fish stocks are so heavily depleted by over-exploitation that even if all fishing were suspended now, nearly a quarter of species would not recover in time to meet international targets set for 2015.
Although the continent's waters are notoriously overfished, a new analysis by researchers based in Kiel, Germany, suggests that Europe may soon be in breach of its legal obligations. Under the United Nations Convention on the Law of the Sea (UNCLOS), the European Union (EU) should "maintain or restore populations of harvested species at levels which can produce the maximum sustainable yield"1.
Fisheries biologist Rainer Froese and Alexander Proelß, an expert on public law, analysed data on all major northeast Atlantic fish stocks and found that, at current levels of fishing, 91% would not meet that target by 2015.
"Even if fishing were halted in 2010, 22% of the stocks are so depleted that they cannot be rebuilt by 2015," they warn in the journal Fish and Fisheries2. "If current trends continue, Europe will miss the 2015 deadline by more than 30 years."
Froese, of the Leibniz Institute of Marine Sciences, and Proelß, based at the Walther Schücking Institute of International Law, looked at data on 54 fish stocks. To determine the current status, they used the ratio of actual stock biomass to the biomass capable of producing maximum sustainable yield. The vast majority of stocks had ratios less than one, indicating that they were below the level demanded by UNCLOS.
The authors also determined the degree to which the stocks were being sustainably managed by calculating the ratio of actual fishing mortality for a given stock to the fishing mortality that would allow the stock to stabilize around a biomass giving maximum sustainable yield. A ratio of one would indicate that stocks were being sustainably fished but the authors found that only 6 of the 54 stocks met this criterion.
"The extent of it was certainly a surprise when we got down and added the numbers up," says Froese.
Disappointingly, Froese says, the analysis of fish stocks over time shows little change in trend since the UN Convention was signed in the late 1990s or the 2002 conference in Johannesburg at which the 2015 deadline was set.
"It had very little influence. It had a bit, but close to nothing," says Froese.
No punishments
Although the 2015 target is a legal obligation, the sanctions for missing this target are "sadly, very little beyond temporary embarrassment", says Andrew Serdy, a UK specialist in international fisheries law at the University of Southampton's Institute of Maritime Law.
He adds: "This is partly because the EU is merely the worst of a mostly bad bunch and partly because of the unsatisfactory way in which the 2015 deadline came about."
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The UNCLOS convention itself does not set a date for achieving populations that can sustain maximum yield. The 2015 date comes from the 2002 meeting at which, Serdy explains, "those in the know will tell you that it was negotiated by environment ministries with very little input from fisheries ministries and they essentially just plucked a date out of the air with no regard for whether it was biologically, economically or politically achievable".
In a statement to Nature, the European Commission said it agrees that there is "a serious problem and that a fundamental change is needed", with "serious overfishing relative to maximum sustainable yield" occurring "in many European fisheries". In 2008, the commission admitted that 88% of fish stocks were being overfished.
This fact is cited by the commission as one of the main reasons that it launched a "root and branch" reform of the Common Fisheries Policy last year. Fisheries mortalities — fish killed by fishing — are being reduced, it says, although not quickly enough.
"There is a strong political commitment to rebuilding stocks to MSY [maximum sustainable yield] and the Commission will do everything in its powers to respect and implement that commitment," the Commission statement added.
It is always difficult to achieve a goal, especially if you do not know where it is! Reading the article of Rainer Froese and Alexander Proelß it is surprising that there still remains confusion about the Beverton-Holt model. Beverton-Holt capture a simple biological principle: “We must harvest fish at harvest time, but the speed with which we do that is immaterial.� Consider page 318 of B-H (On the Dynamics of Exploited Fish Populations, 1957) or if one prefers the internet: http://demonstrations.wolfram.com/BevertonAndHoltsYieldPerRecruitModel/. There we see isopleths suggesting precisely this. In contrast to the view of the authors, one obtains the maximum yield per recruit by increasing fishing mortality to infinity (not by limiting mortality). If we should calculate yield by multiplying the yield per recruit by average recruitment, the position of the maximum remains unchanged. We clearly see that we get the maximum yield at an infinitely high fishing mortality. Therewith the overcapacity of the fishing fleet disappears as an often-cited reason for overfishing. De facto the selection of the harvest age of fish (choosing an appropriate mesh size) is important and not the control of fishing mortality. However, this changes the way the fisheries management has to go in future. Instead of reducing the existing fishing fleet we have to build large amounts of new fishing vessels. But do we really want to pursue with an armada of fishing vessels (and trawls with an optimized and therefore a much larger mesh size) the last harvestable fish, regardless of income and resulting costs. Nothing else means management of resources according to the principles of the MSY. Has the desire to reach a pre-specified position and the avoidance of a loss to explain distorted the insight of the B-H model while writing the article?
Response to Comment by Bethke
Colleague Bethke suggests that Froese and Proelß (2010) have
misunderstood or misapplied the Beverton & Holt Yield per Recruit model. That is not the case. The B & H model has indeed a trajectory where, at optimum minimum size in the catch, the maximum yield per recruit is reached asymptotically with infinite fishing effort. Since infinite effort comes with infinite cost, this property of the B & H model is of little practical consequence. In reality, and in Europe, minimum size in the catch is far below the optimum size, and in these cases the B & H model indicates a level of fishing mortality Fmax beyond which the yield per recruit decreases. This Fmax and its corresponding
yield-per-recruit is given by ICES and has been used by Froese and Proelß (2010). We hope this clarifies the issue.
With best wishes
Rainer Froese and Alexander Proelß.
Response to Comment by Froese and Proelss:
First, let us notice that the authors suggest aiming not for the maximum sustainable yield (MSY), which is nonsensical from an economic perspective, but for the maximum sustainable yield for a fixed mesh size (MSYFM). To achieve this yield, fishing effort must be limited in a way that the fishing-mortality-reference-point (Fmax) is not exceeded. However, from the yield model of Beverton and Holt (http://demonstrations.wolfram.com/BevertonAndHoltsYieldPerRecruitModel/) it is clear that at a slightly larger age at first capture (larger mesh size), and with a slightly higher fishing mortality (fishing effort), maximum yield is even greater. As we see, the reference point (Fmax) is only valid for a certain age-at-first-capture (AAFC) and for the corresponding mesh size. To be precise here, we must speak about Fmax as a conditional reference function of AAFC and not an unspecified reference point. Unfortunately, this is often overlooked—even in textbooks.
How is it possible to aim for a smaller maximum sustainable yield at the present AAFC while a larger MSYFM could be achieved with a bit more fishing effort? Recall that for stock protection it is irrelevant if we: (1) reduce fishing mortality; or (2) increase AAFC. In both cases we achieve a larger spawning biomass which in turn produces more offspring. Why the difference? Limiting fishing effort at a small mesh size leads—over time—to larger fish remaining in the stock. Such fish eat more and yet add little to their own biomass. With higher fishing pressure, and with a larger mesh size, we maintain more fast-growing (and smaller) fish in the stock.
This of course has an impact on the business aspects of fishing. The authors propose to limit fishing mortality to a value of Fmax = 0.27 per year for the cod stock in the western Baltic. This would result in fishing mortality approximately equal to natural mortality. In other words, only one-half of the stock is being captured by industry—the other half remains and soon die. Surely this is curious fishery policy. It seems far wiser, socially and economically, to increase mesh size and adjust fishing effort accordingly (Council Regulation (EC) No: 1226/2009). Stock protection is not diminished, and aggregate annual production is increased. This means more jobs, higher incomes, and more reasonable prices for the market.
With best wishes, Eckhard Bethke