Marine Statistics
You learn to swim, rather than fly,
flopping from the cliffs with a splash in the sea,
emulate turtles, long turned into soup-we don't miss them,
or the wetland coast.
Oceanic populations are passˇ,
and abalone shells decorate swimming pool walls.
At a tender age, I learned to be suspicious of statistics. There are a variety of procedures that can be and have been used to intentionally lead an unwary reader to a conclusion other than the one actually supported by the data. Statistics can be skewed to support information, which may be aimed at convincing its audience to buy a product, vote for a candidate, or enter into a war with a foreign country.
When I was first exposed to statistics regarding the effects we human beings are having on the Earth and its inhabitants, I was flabbergasted. Are 99% of the commercially important fish in the oceans really gone? Is one-third of the 6-12 billion tons of CO2 going into the atmosphere every year actually being produced by U.S. citizens? Are about 30% of the world's natural resources being used solely by Americans, who make up only 5% of the world population? Are nearly 50,000 species really going extinct every year due almost exclusively to human activities? These statistics are most distressing, but they come from what seem to be reliable sources.
In checking some of these statistics, I learned, for example, that estimates of species extinction due to our activities vary from about 10,000 to 100,000, and that estimates of the fraction of the world's resource and fossil fuel consumption due to the U.S. population alone varies from 25% to 50%. In each such case, the truth probably lies somewhere in between the extremes, but even accepting the lowest estimates, the statistics are terribly disturbing. It is clear that one species, Homo sapiens, is wreaking havoc on our planet, rendering it unsuitable for millions of other living species, and that the U.S. is leading the pack as the number one offender.
I learned about the depletion of our oceans from Paul Dayton, a professor at the Scripps Institution of Oceanography in La Jolla. To verify his claims, I decided to give him a call and arrange to meet with him. In response, Paul invited me to attend a presentation at which he showed slides and data bearing on his conclusions, followed by personal discussions. I learned that his primary research efforts deal with the preservation of oceanic populations here in San Diego, in Antarctica and elsewhere around the world. He has first-hand access to the available research data; I was getting the information from the horse's mouth.
Paul began his talk by noting that 12,000 years ago, a very short period of time when put on an evolutionary scale, there was an animal ecosystem in North America that was completely different from the one we find today. Pigs as large as horses, about four feet across at the shoulders, roamed the continent, and multiple species of elephants were prevalent. Exceptionally fast bears were among the most ferocious of predators. Cats of tremendous variety and many other large wild animals were also present. Almost all of these species are now extinct.
The existence of these now extinct animals some 12,000 years ago is well documented by the fossil record. What is not certain is what fraction of the extinction of these animals can be attributed to human activities. Paul pointed out that it is possible, even plausible, that Native Americans played a key role in eliminating many of these creatures. They probably killed many of the herbivores for food, and predators may have been destroyed to insure safety. Even when the numbers of humans were much smaller than those found today, man may have already been upsetting the balance of nature.
Obviously, no one living today was around to observe these now extinct creatures. Most of us are completely unaware of their earlier existence, and therefore we don't miss them. We barely notice changes in our biosphere that occur over a period equal to the life span of a single human being, and we certainly don't notice those that occur over a longer time interval.
The same considerations apply to the effect of development on our coastal wetlands. Before the white man came to California there were extensive wetlands spaced minimally every 5 miles along the Southern California coast, and Mission Bay in Northern San Diego extended to the Mexican border. San Diego was planned and then built at the directives of Mr. Horton, a shrewd businessman and developer, who made a fortune draining and then building upon the wetlands where downtown San Diego now stands. Over 90% of the Southern California wetlands have been wiped out, and almost all of the large animal and plant life that they harbored have disappeared with them. Why? Because people like to live near the coast! They build asphalt roads with drains and sewers, and the watershed is gone. We don't need to resort to the fossil record for these facts. We can find the relevant information in the written accounts of San Diego history.
As San Diego developed, industrious workers took advantage of the city's vast natural resources. Fishing industries boomed, and in the city's early days, the supply was plentiful. In the 1920s, San Diego housed a prosperous industry that canned turtle soup. The slow growing green turtles were huge and numerous both in San Diego Bay and in the coastal waters. But most of the largest and oldest varieties of turtles have been virtually eliminated from the entire Pacific Ocean. Worldwide, only a small fraction of them have survived. The green turtle population has disappeared into cans of turtle soup, to the profit of local fisheries. These amazing creatures are now virtually extinct.
Similarly, Leatherback turtles have all but disappeared. A single Leatherback could circle the globe in its long lifetime. Its navigational skills were phenomenal! These were truly fascinating creatures from which we could have learned a lot; they would have provided us with a wonderful source of information if we could have come to understand them. Among the oldest types of turtles found in nature, Leatherback turtles have been on Earth for well over 100 million years. They could have seen living dinosaurs! The largest would grow to over 800 pounds and reach lengths of 10 feet. They were creatures of great majesty, sometimes hundreds of years old. Just two hundred years ago, as many as 20,000 such creatures would go ashore and lay their eggs on a single beach in Michoacan, Mexico every year. By 1990, though, the number sighted was down to 200; in 1998, only 11 were seen, and in 2000, only four were detected.
Sea Turtles are not the only species to suffer from human industry's greed. Large California lobsters were plentiful into the 1950s, but very few can be found nowadays. Those that do occasionally appear are only a quarter the size of the largest specimens that roamed the beaches and tide pools of the early 20th century. The San Diego Historical Society has photographic documentation of huge fields of lobster skeletons, 3 feet deep, in the San Diego area. Lobster tails were commercially canned, but the rest of the animal was discarded. Nowadays a lobster is caught on the average of eight times before it is large enough to legally keep. It's no wonder that they don't grow beyond the legal size limit!
Abalone populations have also been decimated. They were so numerous in the early 1950s that anyone could go out and catch a meal without effort. At the turn of the century, a competent commercial diver could gather two tons of abalone in a single dive! The bottom of the ocean was covered with them. The San Diego coast boasted several species, all present in the millions. Among them was the white, red, pink, green and black abalone. Today only the red abalone is left, and it is down to less than 5% of its original population. No one has seen a white abalone in the area in years; it is close to extinction. The black and green abalone are also in serious trouble. Only the pink abalone might be making a slow comeback. In fact, most of the previously prevalent sea life is gone. Even the kelp beds have been sorely depleted. Our continental shelves are an underwater "ghost forest" in which only a few of the previously identified species remain.
Another important sea species that is suffering because of human intervention is the king crab. As late as 1960, crabs the size of dogs could be found in the Gulf of Alaska and off Kodiak Island, but just 20 years later, they were completely gone. Even though major fisheries were forced out of business by the lack of commercially important crab, the king crabs have not returned. Statistics are available for "relative catch rates", that is, the number of a species of crab caught per unit effort. For every species, this rate is far below what it was 50 years ago.
What does Professor Dayton feel is the major problem? Why have so many documented species disappeared? One major problem is that the state and federal governments don't regulate fisheries until after the fish become severely depleted. Another problem is the practice of trawling the ocean bottoms, in which divers rake the ocean surface in order to efficiently collect desirable species of fish. This not only depletes the stocks of the profitable fish, but it destroys the habitat for all species in the trawled area. Most upsettingly, this practice is not unique to the San Diego area; it has devastated virtually all coastal areas worldwide. Trawling has destroyed all but the deep-sea habitats almost everywhere, and over-fishing has depleted the worldwide sources of most commercially important fish species to negligible values.
The problem of trawling illustrates that the fishing industry has been responsible not only for the depletion of fish stocks, but also for the destruction of the marine eco systems that allow the fish to breed. Deep-sea coral reefs provide the primary breeding grounds for thousands of fish species such as the Orange Roughy, which spawns almost exclusively above sea mounds. Some of these coral reefs have been growing for over 20,000 years, and before man's intervention, many reached over 200 feet high! More than 700 species of these deep coral are known, and many cohabitate in a single location. However humans disregarded the importance of these unique coral forests and have ravished most of them. Trawling destroys the smaller species, and the larger varieties, some of which are over six inches in diameter, have been systematically and intentionally destroyed by fishermen who considered them a nuisance because the coral got in the way of their boats and nets. To destroy them, the ends of huge metal chains are attached to two boats. These chains are dragged through the waters so the coral stems break off; the fishermen then gain easier access to the desired fish and squid.
There is at least one place left in the world where coral reefs grow unhindered. In Norway, the importance of coral was recognized relatively early by the fishermen themselves. The destructive tactics of earlier fishermen were broadcast over national TV, and since then, the remaining coral reefs off the coast of Norway have been protected. However, Norway is one of the few countries that seem to recognize what's at stake. Most sea mound communities worldwide were destroyed before anyone even considered them worthy of study.
The few reefs that have not been destroyed by the fishing industry are unfortunately also suffering from human impact. Coral diseases are a rampant problem. Recent studies by marine biologists have revealed that about two-thirds of the world's remaining reefs are infected with pathogenic microbes. Given this deplorable state, you would think that scientists would have accumulated the knowledge necessary to combat these diseases. Unfortunately, such studies are only now beginning, and in most cases the disease-causing microbes have not even been identified. It's eminently clear, however, that pollution, systematic physical destruction, and global warming are the indirect causes of these diseases.
Just as fishermen destroyed coral reefs because they interrupted fishing practices, sharks were considered a nuisance and persecuted violently. Initially, sharks were killed by the tens of thousands by the fishermen, who had no reason other than just the desire to get rid of them. The carcasses of the dead sharks were of no use to the fishermen and were left to rot. However, then shark fins became a delicacy, therefore profitable to the industry. Once they realized the potential profit to be made off of these creatures, fishermen would catch them, cut off their fins, and leave them to die, bleeding to death at the bottom of the sea. Most estimates suggest that overall shark densities have been reduced by over 90%.
Although present-day societies seem to view the ocean as an open goodie basket, with marine life free for the taking, some human cultures have recognized the need for protective measures. Many years ago the Polynesians recognized the importance of fish spawning grounds and created laws to protect them so the spawning fish could continue to provide them with a source of livelihood. However, the European settlers were not as intelligent. Only now that it's too late have Europeans and their American descendants begun to express concern and pass legislation to protect our dwindling heritage. The Marine Life Protection Act of California was passed but is now in grave danger because sports fishermen are trying to have it repealed. They've teamed up with the National Rifle Association, notorious for their selfish motives. Because these shortsighted men are wealthy, they have far more impact than their numbers should warrant, and unless strong countermeasures are taken, it looks like they may win!
What's to be done? Professor Dayton noted that we should all express our concerns and take political action so as to prevent extermination of the remaining life in our oceans. However, few take the time and expend the effort to make a difference. He believes that everyone knowledgeable about our wildlife reserves should contact their representatives and become politically active, expressing their disdain for the policies of the past that have so devastated our oceans. We should elect and support officials who will vote for bills like the Marine Life Protection Act.
Why are people not more concerned? Professor Dayton attributes it to what is known as the "boiling frog" principle. A frog that jumps into boiling water will quickly jump out if it can. But if the frog is put in cool water and then the water is slowly warmed, it will remain until it is cooked, not recognizing the pending danger. Similarly, because the marine life has disappeared over a period of decades, few people have noticed the dramatic effects our careless human population is having. To most people, oceans with sparse marine life just seem normal. These people have no knowledge or memory of the profusion of sea life that existed just a few hundred years ago.
Finally, back to statistics. Have the statistics presented in this article been manipulated to alter the major conclusions? Is it really true that we have forced thousands of species into extinction and have reduced the global sea life to around 1% of its previous level? Precise statistics are not available to allow us to pinpoint a number. Even within the last few decades, few attempts have been made to estimate the sizes of the impacted fish populations in the oceans, and before 1950, almost no such attempts had been made. Estimates of fish life in earlier centuries are best taken from historical accounts and fossil records. It is therefore impossible to say with precision whether for each species we are down to the 10%, 1% or 0.1% level. Further, some species, like the salmon and halibut, have survived the human onslaught better than others and are still harvested in a potentially sustainable manner. For many other species, it is not too late to provide the protective measures that will allow them to return. However, many are already extinct, unnoticed, and some that are reduced to very low numbers are virtually extinct because their low numbers don't allow them to find mates with which to reproduce.
The fact is that the precise numbers are of no consequence. We don't have to know exactly what fraction of the fish populations we have decimated to accept the severity of the problem. It is an unequivocal fact that we have dramatically altered the oceanic biosphere in a way that is detrimental not only to millions of marine species but also to the one terrestrial species that has caused the damage. No manipulation of the statistics can alter these facts, and no matter how you look at the data, the conclusions are the same.
Facts About Marine Destruction
A. Pollution: A recent National Academy of Sciences study estimated that the oil running off our streets and driveways and ultimately flowing into the oceans is equal to an Exxon Valdez oil spill - 10.9 million gallons, every eight months. More than 13,000 U.S. beaches were closed or under pollution advisories in 2001, an increase of 20 percent from the previous year.
C. Habitat Alteration: Fishing gear that drags along the seafloor destroys habitats needed by marine wildlife including commercially fished species. Typical trawl fisheries in the U.S. trawl the same section of sea bottom more than once per year on average, Bottom-dwelling invertebrates take over five years to recover from one pass of a dredge.
D. Bycatch: Worldwide, scientists estimate that fishermen discard about 25% of what they catch, about 60 billion pounds each year. Bycatch of albatross, petrels and shearwaters in longline fisheries is one of the greatest threats to seabirds and sea turtles.
E. Invasive Species: Introduced species crowd out native species, alter habitats, and impose economic burdens on coastal communities. Over the past decade, nearly one million non-native Atlantic salmon have escaped from fish farms and established themselves in streams in the Pacific Northwest.
F. Coastal Development: Sprawl development is consuming land at a rate of five times the rate of population growth, thereby destroying wildlife habitats. Coastal marshes, which trap floodwaters, filter out pollutants, and serve as "nurseries" for wildlife, are disappearing at a rate of 20,000 acres per year.
Sala, E, Aburto-Oropeza, O., Paredes, G., Parra, I., Barrera, J.C., and Dayton, P.K. (2002). A general model for designing networks of marine reserves. Science 298: 1991-1993.
Dayton, Paul K., Tegner, Mia J., Edwards, Peter B., Riser, Kristin L.; Sliding Baselines, Ghosts, and Reduced Expectations in Kelp Forest Communities, Ecological Applications, by the Ecological Society of America, c.1998
Dayton, Paul K., Thrush, Simon, Coleman, Felicia C.; Ecological Effects of Fishing in Marine Ecosystems of the United States, PEW Oceans Commission, c.2002.