Ancient Overfishing?

The cover story in the July 28 issue of the journal Science is titled “Historical Overfishing and the Recent Collapse of Coastal Ecosystems.” Written by a group of 19 researchers from several disciplines, in a heavily referenced 8 pages they attempt to place the blame for most of the major ills currently afflicting coastal waters around the world on examples of what they consider to be overfishing. They have done this, they claim, through an analysis of paleoecological, archaeological, historical and ecological records extending from 125,000 years ago (the rise of modern Homo sapiens) to the present. They then use this analysis to support a “top-down” rather than “bottom-up” approach to marine resource management, focusing on organisms at the top of the food chain rather than those at the bottom.

Much of the article focuses on the authors’ attempts to fix the blame for the current deterioration of four salt water ecosystems. They claim they’ve determined through an examination of nontraditional (to ecologists) records that serious problems confronting coral reef, kelp forest, sea grass and oyster reef areas today can all be traced back to some form of “overfishing” at some point in the past.
 
 

Before they even get into the “meat” of their article, the authors set their stage by stating “There are dozens of places in the Caribbean named after large sea turtles whose adult populations now number in the tens of thousands rather than the tens of millions .... Place names for oysters, pearls and conches conjure up other ecological ghosts of marine invertebrates that were once so abundant....” While the nostalgic appeal makes this a compelling introduction to the assault on past and present fishermen that follows, we were a little skeptical about the idea of the existence of solid relationships between place names and the local occurrence of the species that those places were named after. Deciding to do a bit of our own digging, we searched the web for Drives, Lanes, Streets and Roads named for various birds and beasts using Google, a web search engine (http://www.google.com). We got over 1600 hits for “Osprey” and only 250 for “Buzzard;” over 15,000 for “Fox,” less than 400 for “Possum” or “Opossum” and less than 100 for “Skunk;” well over 10,000 for “Lion” (mostly in the US and the UK); over 5,000 for dolphin (this after having the search engine exclude all 48,000 instances of “green dolphin”), under 100 for “Mako” and none for “Sculpin;” slightly over 500 for “Oyster” and only 27 for “Clam.” It seems that, at least in the modern, internet accessed world, one can’t make anything approaching valid judgments on local populations based on place names. (By the way, Google located over 200 addresses containing “Unicorn.”) Were Caribbean islanders in the past  that different or, like us, did they name places according to some idealized or imagined rather than actual view of their world? More importantly, did the authors - or the editors at Science - give this question any consideration at all or were they more interested in making their point regardless of the answer?

In an article with as many authors as this one has and tackling a topic as complex and far-ranging as this one does, there are bound to be disagreements with some of its content, and while it’s not our intent to do a paragraph by paragraph critique of it here, there are segments which appear to be critical to some of the “bottom-down” conclusions which did raise questions. Among them are:
 

• The reliance in instances on what appear to be scant data - Regarding the demise of kelp forests in the Gulf of Maine, the authors fix the blame on overfishing of codfish stocks, which they claim has reduced the average size of Gulf of Maine cod from a mean body length of 1 meter to 0.3 meters. Their “proof” of this size reduction, or at least that portion of the reduction that occurred in the 5,250 years preceding 1950, is based on the measurement of codfish vertebrae found in the excavation of a single shell midden in Maine. It’s certainly interesting to read that a regression analysis of the diameter of vertebra thrown out with the garbage at a single location during four distinct time periods spread out over 5,000 years indicates that the size of the fish they were taken from decreased. Can the decreasing size of those few vertebrae be realistically projected to a corresponding trend in the size of all of the codfish throughout the 28,000 square miles of the Gulf of Maine?
• The seeming indifference to other factors which could be as or more important than the authors’ bottom-down considerations - In the discussion of impacted seagrass beds, we find “all the factors that have been linked with recent die-off of turtle grass beds in Florida Bay, except for changes in temperature and salinity (emphasis added), can be attributed to the ecological extinction of green turtles.”  Excepting changes in temperature and salinity might make the downfall of Florida Bay’s turtle grass beds via the agency of “overfishing” of green turtles a logical conclusion, but is it logical to accept that changes in temperature and salinity should be excepted? And what of the changes in weather patterns/climate, whose profound influences on the distribution and occurrence of living marine resources we are just starting to understand?
• Apparent inconsistencies among the authors’ own conclusions - The authors liken the situation with reef fish in Jamaican waters to American lobsters off New England. While subjected to heavy fishing pressure which prevented “local” reef fish from reaching sexual maturity, recruitment from neighboring reefs which weren’t so heavily fished had kept the Jamaican fishery alive until recently, when the distant reefs became overfished as well and the Jamaican fishery collapsed. They write “A similar scenario has been proposed for the American lobster with regard to loss of larvae from deep-water offshore stocks.” Yet in their previous discussion of the Gulf of Maine kelp forests we read “Formerly dominant predatory fish are now ecologically extinct.... Lobsters, crabs and sea urchins rose in abundance accordingly.” It kind of leaves the reader grasping in the dark for the actual condition of the lobster stocks, doesn’t it? (Lobster landings in New England have been at record levels for the past several years.)
• Apparent inconsistencies with “conventional wisdom” - For at least a generation it’s been accepted that the anthropogenic disturbance and/or destruction of submerged aquatic vegetation (by boat and personal watercraft passage, commercial fishing operations or dredging activities) can have detrimental environmental effects. Yet the authors conclude that the deterioration of seagrass beds  can be attributed to the uncontrolled growth of  the submerged vegetation in the absence of continuous, intensive cropping and “the cessation of systematic plowing of the bay floor” by once abundant but now “overfished” dugongs and sea turtles. What is the difference between the anthropogenic and natural disturbances? (It can’t be a matter of scale. They also write that the physical disturbance of seagrass beds by dugongs, which can reportedly remove “up to 96% of the above-ground biomass and 71% of below-ground biomass of seagrasses,” is a “major factor” in preventing a “dramatic decline in water quality due to eutrophication and runoff of sediment.”)

However, from our perspective these are relatively minor points when compared to the primary thesis of the article, which is nothing but the latest chapter in the “blame it on overfishing” litany. 

Our concern, both with the article and with it’s publication in a  journal like Science, is the total reliance of its central premise - that coastal ecosystem degradation today has been caused by “overfishing” in the past - on a definition of “fishing” that is seriously out of step with any usage that we’re familiar with. “Fishing” is the taking of fish and shellfish for commercial or recreational purposes. That’s the way it’s used in conversation, that’s what dictionaries say it means, and that’s the way it’s defined (with the addition of “all other forms of marine animal and plant life other than marine mammals and birds”) in the Magnuson Fisheries Conservation and Management Act, legislation that has governed federal fisheries management in the US since 1976.

When it comes to taking mammals, whether on land or in the water, “hunting” is the word of choice. And yet this doesn’t quite fill the bill for the  authors. They provide their own definition of “fishing,” which includes “hunting and gathering all kinds of organisms in the oceans.” This is a convenient definition if you’re goal is to gain a seat near the front on the “blame it all on overfishing” bandwagon by having an important article published in a prestigious journal. Other than that, there seems to be no reason to refer to activities as “fishing” that go far beyond common usage to include what are clearly (and even by the authors own “definition”) entirely different activities. According to everyone except these authors and their editors, hunting definitely isn’t fishing. 
 
 

In the 9/10/01 issue of US News, T. Hayden writes “Now, a survey of fisheries data, archaeological excavations, and historical records, published in the journal Science, reveals a surprising thread uniting virtually every instance of marine ecosystem collapse. The cause, says lead author Jeremy Jackson of  in San Diego, is ‘fishing, fishing, and fishing.”’ Were Jackson to use a definition of fishing more in-line with the rest of the English speaking world, he’d probably be more prone to blame the collapses on “hunting, hunting, and fishing.”

The authors provide a table (Table 1) of deterioration “baselines” for particular parameters of their selected coastal ecosystems (coral reefs, seagrass beds, etc.) that they determined from examining various records. They “inferred” that each of the listed parameters was due to one or more of three causal factors: fishing, mechanical habitat destruction by fishing, or other inputs. Of the total of forty-six “causes” that the authors listed in their table, twenty-six were attributed to either fishing or mechanical habitat destruction by fishing. While twenty-six out of forty-six is hardly an overwhelming majority, it is just barely over half and could just barely justify the claim that “fishing” is the predominant cause for the deterioration of the listed ecosystems. But, rather than the author’s definition, what if we use the one that the rest of the world has settled on? What if we don’t include as “fishing” the hunting of manatees, sea otters, dugongs, seals, etc.? We then have twenty out of forty-six causal factors that are, in the authors’ judgment, fishing-related and twenty-six that are not.* Nothing approaching a majority, in no way justifying titling the article “Historical overfishing...,” but not guaranteed to get the authors front row seats anywhere. From this perspective it seems pretty obvious why the authors felt compelled to provide their own definition of “fishing.” It was either that or come up with another title and miss the ride.
 
 

*If we disregard the Magnuson Act definition and the taking of sea turtles is not counted as fishing, then the count becomes sixteen for fishing and thirty not.

But why the bandwagon and why the ride? We’ve written previously about the number of “charitable” foundation dollars that have been and are being spent on vilifying commercial fishermen (see the Previous FishNet at ). From the outside, part of the reason for that  seems to be a drive to declare huge areas of the sea floor off-limits to fishing through the formation of what have become known as Marine Protected Areas (MPAs). This drive for MPAs is inextricably tied into the so-called “marine conservation” program of the Pew Trusts, which are becoming notorious for using their Big Oil generated endowment - they were established by descendants of Joseph N. Pew, the founder of the Sun Oil Company - to mold public policy (see “Charity Is New Force in Environmental Fight” by D. Jehl in the NY Times, 06/28/01). And true to the Pew program, the 19 authors - 8 of whom, incidentally, were either “Pew Scholars,” signers of a self-styled “Scientific Consensus Letter” advocating MPAs resulting from an effort heavily subsidized by Pew, or both - end their article with an argument that the only way our coastal ecosystems may be saved from this history of abuse caused by “fishing” is through the adoption of more and bigger MPAs.

The negative fallout that this semantic manipulation has had on the image of today’s fishermen, and today’s fisheries management system, in the broadcast and print media has been significant. The impact it’s going to have in shifting the public focus away from real and ongoing coastal development and water quality problems is going to be equally dramatic. The idea that the impact we have had and are having on our coastal waters due to overdevelopment and pollution is negligible compared to the effects of “overfishing” dating back hundreds or thousands of years seems like an environmentalist’s nightmare - and a polluter’s dream. Yet, as the following quotations from the popular media demonstrate, thanks to this article - and its successful “selling” - that’s where we are.
 

• “The paper, by 19 of the world’s leading marine biologists, is written in sober academic language but it paints a shocking picture of the destruction wrought by many centuries of global overfishing.” (C. Cookson, Financial Times, 07/28/01)
• “Overfishing that took place hundreds if not thousands of years ago is a key culprit in the collapse of coastal marine ecosystems today, an international group of researchers reports. Up until now, scientists have tied the current collapse of the world’s coastal ecosystems almost entirely to recent human impacts—pollution, increased nutrient runoff, and climate change.” (H. Mayall, National Geographic News, 07/07/01)
• “Fishing, not pollution, has decimated the seas” (E. Check, Newsweek, 08/06/01)
• “The depleted state of many coastal ecosystems has its roots not so much in pollution or other current destructive practices but in over harvesting of marine resources dating back hundreds, and sometimes thousands, of years, a new scientific study has found.” (NY Times, 07/29/01)

Fortunately, at least some of the reporting on the article went beyond the information and the conclusions it contained. 

“While the Science piece is a welcome boost for mounting an even larger oyster restoration, (Ed) Houde (a fisheries ecologist with the University of Maryland.) and nine fellow bay scientists caution in a letter sent to the magazine that some of its conclusions are simplistic and overreaching. The Science authors, for example, scarcely acknowledge that polluting nutrients from sewage, air and land have taken a tremendous upswing since the 1950s — long after the oysters, and their filtration capacity, crashed. Unless pollutants are reduced, “restoration of oysters even to pre-Colonial abundances is unlikely to eliminate algal blooms, and [loss of oxygen] and recover sea grasses,” the bay scientists write. In another simplification, the Science authors imply that the overfishing of oysters led to the bay’s current oyster diseases. But MSX, the most virulent disease, has been identified as coming from the unauthorized introduction of Pacific Coast oysters into mid-Atlantic waters in the 1950s.” (T. Horton, Baltimore Sun, 08/10/01)