Milan Boers, 2009
“[L]ife on land is utterly dependent on the life… in the ocean.”
Alanna Mitchell, Sea Sick
Some friends dine in a high-end restaurant, never dreaming that the poached wild salmon they are enjoying with gusto may soon be a rare delicacy. The salmon, caught on the Pacific coast and shipped inland, is smaller than those caught fifty years ago, although this fact is unknown and irrelevant to the diners. The fisherman who caught the salmon is worried; he is finding it increasingly difficult to catch enough fish to make the payments on his fishing rig. And the adolescent salmon, caught in the open ocean, didn’t travel upstream to the spawning beds with its fellows; its particular genetic code is lost forever to the species.
Commercial fishing feeds millions of people each year; many nations depend on seafood as a major source of protein. Over the past fifty years, technologies and techniques have improved, and the fishing industry now feeds an expanding human population more efficiently than ever before. The fish we eat are the product of a long and intricate web of marine life, a convoluted food chain beginning with microscopic sea creatures and ending with humans – one of the top predators feasting at the apex of this marvelous chain.
And, like any other chain, when you break the links, it falls apart. Climate change, among other things, threatens those links.
Steve Canipe, 2009
Biodiversity is an essential part of the marine food chain, knitting it into mesh, the way chainmail interlocks to make a stronger whole. There are three kinds of biodiversity joining marine systems together: genetic diversity, where a species has a high variation of genes within its populations; species diversity, which refers to variety in species interacting within an ecosystem; and ecosystem diversity, describing the wide range of habitats and environments available for species to populate (RSC, 2). Climate change, and especially the warmer temperatures it brings, has far-reaching impacts on all three types of diversity in the ocean. Projected effects of climate change include warmer waters, ocean acidification from excess carbon entering the system, and altered sea levels (RSC, 3). These factors are changing the composition of the ocean itself, wreaking havoc on cycles and systems that have been in place for millions of years. This alteration of the physical characteristics of the ocean (such as temperature, acidity and salinity) directly threatens its habitats in ways we are still determining (Worm, 787).
Ecosystem diversity underpins both species and genetic variation. Just as terrestrial animals inhabit particular areas, ocean plants and animals are firmly connected to their habitats, despite the huge geographical scope and complexity of the ocean. Plankton, for example, thrives in cold waters at higher latitudes, and warming temperatures can lead to disconnects between plankton and consumers. Earlier or later plankton blooms, or blooms in deeper, cooler water, may mean that juvenile fish larvae or hatchlings can’t access the food they need (RSC, 3), because they are out of synch with food sources at critical stages. Loss of juveniles weakens diversity of the parent species, as well as other creatures that feed on them.
At times, system changes that are adverse for some organisms can prove enormously beneficial to others. A species with typically small population levels in an ecosystem can explode if changes to habitat or predators prove favourable for them, and such invasions edge out more vulnerable populations in the region. Baskin, in “Elbowing out the Natives”, refers to such species as “transformers”, because they can physically alter ecosystems, essentially “rewriting the rules” for other creatures in the community (85). Competition from invaders for food and space forces the natives out, sometimes driving them to extinction (Baskin, 89).
Species biodiversity also directly influences the function and makeup of the ecosystems themselves. Death of a keystone species, such as corals, can cause declines in entire regions. Healthy corals are essential for a reef habitat; without them the foundation of the system disappears, and so does biodiversity. And there is no going back on a reef, at least not quickly: dead coral structures create a litter of bleached skeletons that turn to “limestone rubble and slime” (Mitchell, 27), conditions hardly conducive to new growth. Corals grow slowly even under optimal conditions, taking years to form a reef. To make matters worse, as Mitchell points out, nearly one-fourth of all marine species that humans use commercially rely on reef ecosystems for some part of their lifecycle (29). So far, 20% of the world’s reefs have vanished, and half of the remaining reefs are showing signs of distress (Mitchell, 101).
NOAA’s National Ocean Service, 2011
Similar chinks in the armor of diversity are appearing in all of the world’s oceans. A recent report from the Royal Society of Canada on biodiversity in Canadian waters warns that “[a]t some point, cumulative loss of biodiversity will lead to catastrophic ecosystem change. We don’t know when that tipping point is for marine biodiversity” (RSC 2).
Marine ecosystems are essential for life support services on earth. By various means, marine systems provide planetary carbon storage and oxygen production, and clean water and food supplies for millions of people. Ocean species also benefit from these services, and biodiversity is crucial in maintaining them. Adding yet more links to the chain, biodiversity provides valuable “healthcare” services to ecosystems themselves. In their paper titled “Impacts of Biodiversity Loss on Ocean Ecosystem Services”, Worm et al find that biodiversity increases the productivity of ecosystems on a log-linear scale (787). In other words, the more species there are, the healthier the system becomes. The study outlines several important effects of increased diversity, including:
- provision of a mixed diet from diverse sources – organisms at all trophic levels that consumed a mixed diet showed increased growth, survival rates and fecundity, and all life processes were optimized
- increased ecosystem stability – habitats were more resistant to disturbance, and recovered more quickly from disruptive events
- enhanced efficiency of resource use – species shared resources more effectively
- increased resistance to species invasion – highly diverse systems were able to control or repel invaders
(Worm et al, 787-788)
Worm et al. also studied systems with reduced diversity in coastal systems. They found that substantial loss of diversity was associated with regional losses of ecosystem services like nursery habitats, water filtration and detoxification, and viable food fishery populations. They conclude that loss of these services poses significant risks for coastal inhabitants (788).
This study concludes that all global fish stocks are in danger of complete collapse by 2048 from loss of marine biodiversity on a global scale (Worm, et al, 788). This prediction has grave implications both for global food security and for the Canadians who depend on commercial fishing for food and employment.
Here in Canada we already know how the story goes. In 1992, the northern cod fishery collapsed. Between thirty and forty thousand people in Atlantic Canada lost their jobs. Estimates on social and financial aid costs put the totals between two and three billion dollars (RSC, 12). Nineteen years later, the cod fishery still has not recovered (Mitchell, 123; RSC, 12), and yet we pulled $14.3 million worth of this collapsed species out of the Atlantic in 2011, according to Fisheries and Oceans Canada (Table: 2011 Atlantic and Pacific Coasts Commercial Landings by Province). This charts a market driven race to extinction; as stocks decline, scarcity drives prices higher, making the species more attractive to commercial fishing. Better technology is soon brought to bear, often in deeper waters, and more time and money are spent catching scarce and elusive targets. As Mitchell puts it, “[i]t’s a recipe for trying to catch the very last fish” (135).
Canada isn’t the only country badly mismanaging its fisheries; in 2003 Myers and Worm published a study in Nature estimating that more than 90% of the populations of every single large predatory fish species around the globe has vanished in the fifty years since the onset of commercial fishing (282). Changes in Canadian species have been among the greatest recorded worldwide, showing the same 90% decline since the 1960s (RSC, 4).
Looking at the economic implications, Fisheries and Oceans Canada (DFO) reports that the commercial fishing industry nets about $2 billion per year of Canada’s gross domestic product (2). Over 2% of the Canadian population is employed by the industry, most living in rural and coastal communities in the Atlantic provinces (DFO, 2, 5). A further $3.9 billion in 2010 came from exports – Canada is the eighth largest seafood exporter in the world, and it’s our biggest exported food commodity (DFO, 2).
All told, if our commercial fisheries collapse by 2048, as predicted by Worm et al, the Canadian economy will lose nearly $6 billion dollars per year, 2% of the population will face unemployment, and countless jobs will disappear in value-add industries and export businesses. The amount of financial and social aid that may be required to assist those communities hardest hit by the collapse is unknown. The global ecological cost to marine ecosystems is incalculable.
Worm et al. conclude that “marine biodiversity loss is increasingly impairing the ocean’s capacity to provide food, maintain water quality, and recover from perturbations” (787). But they also say it might not be too late: “available data suggest that at this point, these trends are still reversible” (787).
If it is possible to reverse these trends, we must control our relentless appetite for the fruits of the sea with better fishery management practices, ecosystem conservation and species protection. Fish stocks must be given time to recover from human harvesting to increase biodiversity and give all marine ecosystems resiliency and strength to deal with climate change.
Our position at the top of the food chain won’t matter much if there’s nothing left to eat. If we don’t take action now, kettles of fish, fine or otherwise, may soon be a thing of the past.
Baskin, Y. “Elbowing Out the Natives”. A Plague of Rats and Rubbervines: The Growing Threat of Species Invasions. Washington, DC: Island Press, 2002: 71-97. Print.
Canada. Fisheries and Oceans Canada. Department of Fish and Oceans (DFO). Canadian Fishing Industry Overview. Economic Analysis and Statistics. March 2011. Web. 4 Nov. 2012. http://www.apcfnc.ca/en/fisheries/resources/Aboriginal%20Fisheries%20in%20Canada%20-%20Overview%20-Canadian%20Market%20Trends%20-%20David%20Millette.pdf
– Fisheries and Oceans Canada. Department of Fish and Oceans (DFO). Statistics. Table “2011 Atlantic and Pacific Coasts Commercial Landings by Province”. 2011. Web. 4 Nov. 2012. http://www.dfo-mpo.gc.ca/stats/commercial/land-debarq/sea-maritimes/s2011pv-eng.htm
Izakson, Orna. “The California Coast: Marine Migrations and the Collapsing Food Chain.” Feeling the Heat: Dispatches from the Frontlines of Climate Change. 2004. Ed. Motavalli, J. New York: Routledge, 2004. Print.
Mitchell, Alanna. Sea Sick: The Global Ocean in Crisis. Toronto: McClelland & Stewart Ltd., 2009. Print.
Myers RA, Worm B. “Rapid worldwide depletion of predatory fish communities”. Nature 423: 280-283. 2003. Web. 6 Nov 2012. http://wormlab.biology.dal.ca/ramweb/papers-total/nature01610_r.pdf
Royal Society of Canada (RSC). Royal Society of Canada Expert Panel. Hutchings, et al. Sustaining Canada’s Marine Biodiversity: Responding to the Challenges Posed by Climate Change, Fisheries, and Aquaculture. February 2012. Web. 02 Nov 2012. http://rsc-src.ca/sites/default/files/pdf/RSC_MBD_1_3_25_Twenty-Five_EN_FORMAT.pdf
Worm, Boris, et al., “Impacts of Biodiversity Loss on Ocean Ecosystem Services.” Science 314 2006: 787-790. Web. DOI: 10.1126/science.1132294. 5 Nov 2012. http://www.sciencemag.org/content/314/5800/787