‘Where Have All the Cod Gone?’ and the Sustainability Imperative

by Brian Rothschild

In “Where Have All the Cod Gone” (New York Times, Jan. 2) history professor W. Jeffrey Bolster claims that the “… recent ban on cod fishing in the Gulf of Maine (GOM) was an important step toward restoration.” He thinks that the present low levels of cod in the Gulf of Maine are the “tragic consequence of decision makers’ unwillingness to steer a precautionary course in the face of environmental uncertainties” and that “decisions could have been made to exploit fish stocks more sustainably” over the last 150 years. He states “overfishing has been the norm for a very long time.”

But Bolster’s analysis is an oversimplification and a misunderstanding of this important conservation issue. And in a broader sense, it is symptomatic of how we misunderstand and oversimplify our conservation and sustainability issues, and how this limits our ability to develop efficient and cost-effective solutions.

There is a lot at stake! We need to understand that practical solutions require a reasonably accurate understanding of what we know and what we do not know. Faulty assumptions can easily engender unrecoverable societal costs. If decision makers do not use balanced and reasonably correct information in the development of conservation policy, we cannot hope to emerge intact from our current sustainability crises.

The state of the Gulf of Maine cod makes an excellent case study concerning the sustainability of our fish resources. So let’s ask three critical questions: 1) how reflective is the GOM cod of fisheries management in general; 2) is there a GOM cod stock; and 3) has the decline of the GOM cod really been caused by “massive nets dragged along the bottom that snared every fish in their path”(as stated by Bolster — a point in fact, the efficiency of trawl nets is closer to 30 percent than 100 percent)?

The answer to the first question is that fisheries management in the GOM/Georges Bank is very complex. There are 19 stocks of groundfish. They interact ecologically and in the fishery. For example, it is virtually impossible to catch 2 pounds of species X, without catching 3 pounds of species Y. While we can bemoan the state of GOM cod, how do we respond to the fact that of the 100 thousand tons of fish that could be caught from GOM/Georges Bank, only 30 thousand ton are actually caught. In other words, underfishing wastes 70 thousand tons. It is clear that complaints about overfished GOM cod cannot be casually transferred to the other stocks.

The answer to our second question is that the term “GOM cod” represents an artifice. The boundaries for cod stocks in the northwest Atlantic were established by international treaty organizations in a more or less ad hoc fashion for statistical reporting purposes. They do not represent boundaries between separate cod populations. Cod tagged in the GOM quasi-statistical area are recovered in the Georges Bank quasi-statistical area and cod tagged in the latter are recovered on Browns Bank in Canadian waters. This means that the cod that happen to be swimming in the GOM at any particular time are not unique to the GOM. What is important here is not that the GOM cod might be somewhere else. The point is that the calculations of cod abundance and mortality rates that are used to set catch limits in the GOM, or on Georges Bank, are bound to be in error, since they are made on the assumption that cod are confined to these statistical areas when in fact, they are not.

The answer to our third question is that nets that are too massive or boats that are too efficient have not caused the decline in GOM cod. The effects of fishing on fish stocks depend on how many fish are captured, not on the size of the boat, with or without GPS, or the efficiency of the gear.

So now we can ask the bigger question: Have too many cod been taken in the GOM? Is the decline in cod in the GOM the result of overfishing?

Let’s begin with looking at an instructive history of Canada’s northern cod, which inhabits the shores of Newfoundland, and was at one point, one of the biggest cod stocks (about 3 million tons) in the world. In 1985, the northern cod began to disappear. Its subsequent precipitous collapse was attributed to overfishing and as a result, the Canadian government placed a moratorium on cod fishing that created tremendous personal hardships and dislocation in the Newfoundland fishing industry.

However, there were many signs that the collapse of the northern cod over the period 1985-1990 had nothing to do with overfishing. During this period the growth rate of individual fish declined by about 50 percent. The geographic range of the cod contracted substantially. The mortality rate of the population quadrupled. The fish became noticeably skinnier, a possible sign of malnutrition. There were some records of changes in their food. And in the early 1980s, oceanographic conditions were unusual, with huge slugs of cold fresh water overlaying otherwise oceanic productive areas.

So let’s return to the so-called GOM cod. Could the stock have declined for reasons other than overfishing? We really do not know. But we can trace similarities with the northern cod. The geographic distribution of cod in the GOM has contracted. The growth rate of individual fish has been declining for the last 10 years. The natural mortality rate of the population appears to have at least doubled.

We also know that the cod on Georges Bank (most likely mixed with GOM migrants) has been declining for the past 10 years. There is evidence that individual cod there are also becoming skinnier. Estimates of mortality have increased substantially, but these estimates are so high that further study is needed to determine why: Are they correct or statistical artifices?

So what was the fate of the northern cod? If overfishing was the cause of their decline, we could expect the cessation of fishing would allow the northern cod to return to their former abundance. They have not, now 25 years hence. While there have been some increases in abundance, it is fair to say that the stock has not recovered, even under substantially reduced fishing. It might be argued that if the Canadian government had not issued the moratorium, the jobs and livelihoods lost as a consequence would have been saved, for a time, allowing families and communities more time to adjust.

So, one thing becomes clear. Overly simplistic conclusions on environmental issues can mislead decision makers who are trying to engage in sustainable policies. The press needs to better inform the public on the dividing line between what we know and what we do not know in response to our current sustainability imperatives. In the case of our fish stocks and the families and communities that depend of them, the type of assertions made by Bolster give the public and decision makers a distorted view of the interactions between fishing and fish populations. If we are to develop efficient public policy for sustainable resource use, then we need to understand the boundary between what we know and what we do not know.

Brian Rothschild is the president of the Center for Sustainable Fisheries and founding dean and Montgomery professor emeritus at the school for Marine Science and Technology, University of Massachusetts Dartmouth.