Page last updated at 16:05 GMT, Tuesday, 26 May 2009 17:05 UK

Ghosts of oceans past and future

Ian Poiner and Poul Holm
Ian Poiner and Poul Holm

Marine ecosystems are facing a litany of threats, ranging from overfishing to climate change - but the Census of Marine Life is key to mitigating them, say Ian Poiner and Poul Holm. In this week's Green Room, they argue that everything from long-ago tax accounts to eyewitness whale encounters are crucial in understanding the future of ocean life.

Queensland census researcher
Understanding the magnitude and drivers of change long ago is essential to accurately interpret today's trends

Joni Mitchell once famously sang that "you don't know what you've got 'til it's gone." But when it comes to marine life, in many cases we're only just starting to realize what the planet once had.

Imagine a nearshore off Cornwall, England, teeming with orcas, blue whales, shredder sharks, dolphins and harbour porpoises. Such were conditions in the 17th Century before humanity removed the top predators. It is now estimated that inshore regions of the seas historically held 10 times the volume of marine life seen today.

Establishing environmental history in mainstream marine science will be one of the great enduring legacies of the Census of Marine Life, which has united thousands of world researchers to assess and explain the diversity, distribution and abundance of marine life, past, present and future.

The historical research involves many disciplines, including palaeontology, archaeology, history, fisheries and ecology, and such diverse sources as old ships' logs, literary texts, tax accounts, newly translated legal documents and even mounted trophies.

Some 400 of these marine historians will gather from around the world this week at the University of British Columbia, Vancouver, Canada. And the images they are piecing together reveal fish of such sizes, abundance and distribution in ages past that they stagger modern imaginations.

They are also documenting the timelines over which those giant marine life populations declined. Sadly, due largely to fishing and habitat destruction by humans, the scale of decline is much larger than generally thought a few years ago.

'Cause for optimism'

The work has very practical value today, enlightening the management of fisheries worldwide, which typically use reference information spanning no more than 20 to 40 years. Consequently, policies, management strategies and conservation targets are set to a standard much below the oceans' potential productivity and can now be reviewed with a larger historical perspective.

Some of the research also provides cause for optimism, showing the ocean to be much more resilient to human pressures than the land. History shows that a moratorium on fisheries works. This is well illustrated by the rich harvests of fishermen after World War II and the rebuilding of North Sea herring after the decline of the 1970s.

In the last two or three decades citizens and politicians in rich and poor countries alike have come to recognise that our planet is small and vulnerable: a historic turn of the public mind. With the triumph of social engineering and science in the second half of the 20th Century, history was widely considered irrelevant to the practical concerns of modern society. Today, however, the need for historical insight is pressing.

While few marine species have gone extinct, there is concern that some marine ecosystems have been depleted beyond recovery and generally humans would benefit economically by fishing less and fishing smarter. Understanding historical patterns of resource exploitation is a key to identifying what has actually been lost in the habitat - essential to developing and implementing recovery plans.

On the rebound

Steller's sea cow (SPL)
Steller's sea cow was hunted to extinction in the 18th Century

In October of next year in London, the Census of Marine Life will present the results of its work: A Decade of Discovery. As part of that report, the census' History of Marine Animal Populations (HMAP) project will publish a general environmental history of marine animal populations, an image gallery, a series of maps of historical exploitations and impacts and papers that synthesise information on historical declines and recoveries.

Of particular note, the World Whaling HMAP project is in the process of creating colourful, large-format world maps showing the distribution of 19th century whaling ships and their prey, providing simple, high-impact visual representations of the times and places of whaling in that era. Based on records of 70,000 whale encounters over 450,000 days at sea, the maps invite comparisons of past and current whale distribution patterns, allowing resource managers to identify where populations have and have not recovered.

The insights and lessons emerging from this research of the past provide a new context for contemporary ocean management. Understanding the magnitude and drivers of change long ago is essential to accurately interpret today's trends and to make future projections.

If we stand back, if we fish less and reduce other stressors, the long term prediction, based on historical experience, is that the ocean will rebound, stocks will grow and we will have a much more plentiful sea and ultimately have plentiful sustainable fisheries.

The problem of course is that while this may be true in the long term, politicians are elected in the short term and for many poverty constrains options. But "short-termism" is what handed us a banking crisis, and it has already caused an ocean crisis. Perhaps now is a time when the longer-term view will have a chance.

Ian Poiner and Poul Holm chair the Scientific Steering Committee and History of Marine Animal Populations project, respectively.

The Green Room is a series of opinion articles on environmental topics running weekly on the BBC News website

Do you agree with Ian Poiner and Poul Holm? Do we need to be able to understand the past in order to effectively protect life beneath the waves? Are we changing marine ecosystems beyond the point of no return?

As dynamic - Yes; as resilient - No, not on the human time-scale - not anymore. The changes happening now, largely the result of fossil-fuel CO2 and global warming, may possibly stratify the oceans as they warm and change state. Recoveries of fish to date are already becoming historical curiosities, and are unlikely to recur under "business as usual" scenarios of the future. While there are no solid predictions as yet, palaeoclimatic and palaeontological evidence from the distant past has in it the records of many mass extinction events, many of which are increasingly being attributed to times of global warming. They are being called greenhouse extinctions, by such notables as Dr. Peter Ward of the University of Washington, an expert on mass extinctions of the past. The idea of creating an Industrial Revolution history of fish stocks is a sound one, and will tie in with the industrial human footprints elsewhere on Earth, for example, the CO2 emissions from 1751, the population explosion from the same date, etc... Perhaps this accumulation of real world evidence will help clarify the situation in the minds of the public?
Michael Desautels, Calgary, Alberta, Canada

They almost hit the nail on the head in pointing out that the problems need long term solutions and that politicians are in office based on short term cycles. Unfortunately the problem isn't just with poiticians it's with all we humans. In the main we focus on the short term. As a simple example consider pensions which are of fundamental importance to our well being just 40 or so years after most of us start work. The fact is that most people either have no provision or inadequate provision for their own futures so what hope is there for the flora and fauna of this world over a much longer time frame?

Paul Ingram

Great article. I wholeheartedly agree with the closing remarks. We need to re-focus a lot of policy on the long-term view. As a species we have made the "short-term" mistake many times; take Easter Island with a thriving civilization until the natural resources were plundered beyond replenishment. Maybe it's time we learned. We can have a thriving, enriching and sustainable civilisation if we start addressing these issues. We can enjoy the bounty of the sea, but we need to do it sustainably.

Chris, Bristol

I think that the ocean is in ok condition, but it should be ever on our minds to take care of it. As far as politicians go I don't think they have the first idea of whats going on, and further on we'll see it to be true, because most of them don't care for anything but their own well-being and fattening their purses, etc.
Lee Braun, St. Catharines, Ontario, Canada

The history report will be very useful. Yet, I am concerned about the resilience of the ocean because of greed, stupidity, extreme pollution which is making the ocean more acidic and climate change to name just a few of the problems. I would hope that the ocean is so dynamic that it can handle said problems yet I have some doubt about that.
Norman Fields, Castlegar, BC, Canada

I read a book recently about our present oceans holding about 10% of past times. It did use written logs and reports from many years ago. I see no problem with this as I work at sea and have recently returned to offshore Angola after 12 years and seen just a fraction of the marine life of a decade before. I saw my only whale shark here and many many hammerheads as well as huge tuna shoals. I'm told they sold the fishing rights to foreign fleets. Of course the oceans could recover but do you believe governments will allow it? I don't. I wish I did.
Max Hutchinson, Gunnislake, Cornwall

So glad they are doing this. We are in danger of a world with one dead sea if our population explosion can not find a sustainable way to live.
Namarow, Toronto

Unfortunately there is no mention of the effects of warming on our oceans or the alarming amount of acidification. Surely this should make us less optomistic? However setting up Marine Parks with bans on fishing does have beneficial effects as has been shown in New Zealand.
Annette O'Sullivan, Lower Hutt, New Zealand

I think history is going to be history if we don't get it together and stop global warming. The scale of the problems facing the oceans and seas are summed up in dead zones which are spreading and the changing circulation patterns which threaten to alter nutrient distribution and temperature variations fish populations depend on. It threatens the existence of coral formations which protect and feed coastal populations of people on islands and of mainland communities. Holding temperature rise within bounds is critical to both man and beast but only we can do something about it. Knowing what the productivity of the sea was before mankind started messing with it will set a baseline for comparison where it should be so if we ever do decide to get our act together we can start to build in margins of error so recovery is more likely. Compromise as a strategy ratchets up the likelihood the World will not be able to recover. It delays when action is needed.
Dale Lanan, Longmont, Colorado, USA

The key phrase in this article is the following: "If we stand back, if we fish less and reduce other stressors, the long term prediction, based on historical experience, is that the ocean will rebound, stocks will grow and we will have a much more plentiful sea and ultimately have plentiful sustainable fisheries." The ocean could be resilient but we have to fish less and more carefully. The idea that the ocean is resilient should not be misunderstood as: it will be okay, so just fish on regardless. Historically, the ocean has been seen too much as a place of "multitudes" that humans cannot have an effect on.
Mandy Swann, Sydney, Australia

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