The standard reaction to a quantitative reduction in the take of any commercial fish is resistance—despite all available evidence that show the current level of capture to be non-sustainable. Although one can argue indefinitely about the validity of the data, there is no such thing as definitive, scientific evidence—but in timing there is too soon or too late. That said, data about a species’ declining biophysical sustainability requires that we heed the precautionary principle (do no harm), which means opting for the risk of too soon. On the other hand, economic/political interests inevitably argue for too late—as evidenced in the following story, which has the major components of an unvarnished, chronicle of historic overfishing due to maximum exploitation by arguing for too late. This argument always takes place without regard to the biophysical requirements of all generations or the overall biophysical sustainability of the ecosystem as a whole.
To wit, decades of overfishing have brought the potential collapse of the Gulf of Maine cod fishery—but not as the independent variable the fishermen and politicians deem it to be.
Fishermen and federal officials grappled Friday with the increasingly bleak prospect of finding some way for the historic industry to avoid collapse amid troubles with the health of Gulf of Maine cod.
Their meeting came in the week after regional regulators bought fisherman a yearlong reprieve from what would have been devastating cuts in 2012. But projections discussed Friday showed fishermen still face disastrous cuts in 2013 that most won’t survive.
. . .
The cod in the Gulf of Maine has been crucial to New England fishermen from Cape Cod to Maine for hundreds of years, and four years ago, after a major assessment, it was thought to be one of the region’s strongest species. It brought in $15.8 million in 2010, second highest amount behind Georges Bank haddock among the region’s 20 regulated bottom-dwelling groundfish.
But data released last year indicated the fish was so severely overfished that even if all fishing on it ended immediately, it wouldn’t rebound by 2014 to levels required under federal law.
As a result, fishermen were looking at an 82 percent cut in what they were allowed to catch in 2011, a catastrophic reduction that would have wiped out fishermen around the region—not just those who rely on cod. That’s because major restrictions on cod severely limit fishing on the other key groundfish species, such as flounder and haddock, in order to protect the cod they swim among [emphasis mine].
. . .
From the first indications of cod trouble, fishermen and their advocates have questioned the science behind the new data and Friday was no exception.
“We don’t trust your data,” New Hampshire charter boat fisherman Bill Wagner told regulators. “We don’t believe there’s a shortage of codfish. We don’t believe there’s a crisis in codfish.”
Massachusetts Rep. Ann-Margaret Ferrante, who represents the port of Gloucester, criticized what she characterized as the constant, massive swings in scientific assessments on the size of fish populations.
“We’re always in the same dilemma and I don’t understand why,” she said.
Gloucester fisherman Al Cottone said the new assessment has put the fishing industry “on death row.”
“The anxiety the industry feels is unprecedented,” he said.
The above sequence of events is illustrative of the impetus underpinning the concept of marine protected areas, where fishing is excluded as an effective means of repairing complex reef communities, as well as others, while protecting populations of species vulnerable to overfishing. The argument rests on predictions of increases in abundance and size of fishes after the elimination of anthropogenic mortality; in turn, these increases lead to greater production of eggs per area of reef and greater pelagic dispersal to fishing grounds.2
These concepts proved valid in the responses of fish populations to areas closed to fishing in a small Caribbean protected area surrounding the island of Saba in the Netherlands Antilles and in the 44-square-mile Cabo Pulmo National Marine Park, which sits close to where the Gulf opens into the Pacific.3
Cabo Pulmo National Park (created in 1995) is the only well-enforced, no-take marine protected area in the Gulf of California, Mexico, primarily because of widespread support from the local community. Within 14 years of Cabo Pulmo closing its borders to fishing, the total biomass of its denizens more than quintupled. Over the same period, the share of top predators, sentinels of a healthy ecosystem, soared also—trends counter to those for fish in unprotected regions of the Gulf. Moreover, the biomass of fish did not change significantly in other protected areas or areas of open access over the same time period.
Nevertheless, the absolute increase in fish biomass at Cabo Pulmo within a decade is the largest measured in a protected area worldwide, and is probably due to a combination of social (strong community leadership, social cohesion, effective enforcement) and ecological factors. The recovery of fish inside Cabo Pulmo has resulted in significant economic benefits, demonstrating that community-managed marine protected areas are a viable solution to non-sustainable coastal development and chronic overfishing.4
This strategy is likely to work as intended, however, only if networks of stepping-stone-protected-areas are established within a relatively short distance of one another. Within these protected areas, ocean currents form the corridors between and among larger areas of protected habitat throughout the fish community’s areas of reproduction, larval transport and settlement, and feeding grounds for adults. That said, planning new protected areas will require serious forethought because the jet stream drives the ocean currents. A shift in the jet stream caused by global warming will affect the location of the various currents and will thus have a potential impact on existing and future networks of protected areas. Before delving too deeply into the idea of protected areas, however, a basic understanding of habitat is necessary.
A FUNCTIONAL UNDERSTANDING OF “HABITAT”
As with all terrestrial species, marine species are variously adapted and adaptable to existing and changing configurations of their habitat. Whereas some species are narrowly adapted to a specific set of conditions and thus restricted in both area and flexibility with respect to change, others are broadly adapted and thus more adaptable to pending climate-induced shifts within their oceanic habitats, such as the bluefin tuna that mingle in and traverse the Atlantic and parts of the Pacific in total disregard to international boundaries.5
Most people are at least somewhat familiar with the components of habitat because they, like all terrestrial animals, require: food, water, shelter, space, privacy, and connectivity among them. The same is true in the marine realm, with the exception of fresh water.
Every habitat is based on composition, structure, and function. We perceive objects by means of their obvious structures or functions. Structure is based on the configuration of elements, parts—composition of constituents, say a picture frame or a chair—be it simple or complex. The structure can be thought of as the organization, arrangement, or make up of a thing. Function, on the other hand, is what a particular structure either can do or allows to be done to it or with it. For example, the structure of a chair is designed for a sitting person, whereas a picture frame is designed for a totally different purpose—enclosing a picture.
To maintain biophysical functions means that we humans must maintain the characteristics of an ecosystem in such a way that its processes are sustainable. The characteristics we must be concerned with are: (1) composition, (2) structure, (3) function, and (4) Nature’s disturbance regimes, which periodically alter an ecosystem’s composition, structure, and function.
We can, for instance, change the composition of an ecosystem, such as the kinds and arrangement of plants in a forest, grassland, or agricultural corp. This alteration means that composition is malleable to human desire and thus negotiable within the context of cause and effect. In this case, composition is the determiner of the structure and function in that composition is the cause, rather than the effect, of the structure and function.
Composition determines the structure, and structure determines the function. Thus, by negotiating the composition, such as sinking ships in some of the world’s oceans during World Wars I and II, we simultaneously negotiate both the structure and function of those particular marine ecosystems. On the other hand, once the composition is in place, the structure and function are set—unless, of course, the composition is altered (the salvage and removal of a sunken ship), at which time both the ecosystem’s structure and function are altered accordingly.
In this sense, the composition or kinds of corals and their age classes within a coral reef create a certain structure that is characteristic of the reef at any given age. It is the structure of the reef that creates and maintains certain functions. In turn, it is the composition, structure, and function of a coral reef that determines what kinds animals can live there, how many, and for how long.
Thus, if swimmers wear suntan lotion, which kills part of a coral reef, they change its structure, hence its function, and thus affect the animals. The animals living in and around the reef are not just a reflection of its composition at any given point in time. They are ultimately constrained by it.6
Thus, once the composition is ensconced, the structure and its attendant functions operate as an interactive unit in terms of the habitat required for the animal(s). In other words, the connectivity—accessibility—of habitat components is particularly important for the resident population, regardless of species, because each habitat has a biological carrying capacity, meaning a finite number of individuals that can live in a particular area without altering it to their detriment.
Nevertheless, people are continually altering the structure and function of this ecosystem or that ecosystem by manipulating its composition—either consciously or unconsciously, as in overfishing. Each manipulation has the capacity to change the diversity of species dependent on the structure and function of the resultant habitat. By altering the composition of an ecosystem, people and Nature alter its structure and, in turn, affect how it functions, which in turn determines not only its potential ecosystem services but also what uses humans can derive from those services.
HABITAT FRAGMENTATION VERSUS HABITAT CONNECTIVITY
One of the most basic—but neglected—components of a given habitat is its “connectivity,” both within a given area and among areas. Human-introduced disturbances, especially fragmentation of habitat, impose stresses with which an ecosystem is ill adapted to cope. Not surprisingly, the connectivity of habitats with a seascape is of prime importance to the persistence of plants and animals in viable numbers, which is a matter of biodiversity. In this sense, the seascape must be considered a mosaic of interconnected patches of habitats—stepping stones, if you will—that act as corridors or routes of travel between patches of suitable habitats, such as coral reefs or beds of seagrass.
Seagrasses, which are any one of four submerged, marine, flowering plants, are sometimes termed ecosystem engineers because they create their own habitat by slowing ocean currents. In doing so, they increase sedimentation, which not only gives seagrasses a more nutrient-rich substrate in which to grow but also augments their roots and rhizomes in stabilizing the seabed. Their importance to associated species is due mainly to their three-dimensional structure in the water column, which provides both shelter and vegetated corridors between and among different patches of habitat, such as coral reefs and mangrove islands. Like land plants, seagrasses require sunlight for photosynthesis and thus are limited in their distribution by the clarity of the water in which they grow. In addition, they produce oxygen.7
Seagrass serves as habitat for the settlement of larval lobsters and is thus likely associated with the increased abundance of lobsters found in isolated habitats connected by corridors of seagrass. In one study, immigration and emigration of juvenile lobsters were three to four times higher on islands connected by seagrass than on islands surrounded by bare rubble or sand. Rubble fields functioned as barriers to the sea-floor dispersal of all but adult lobsters. Hence, the effects of insularity on a population of lobsters could be lessened by surrounding islands with “stepping-stone habitats” in the form of seagrass corridors because they have important functional roles as areas of larval settlement, foraging grounds, or passageways of relative safety through otherwise hostile territory.
Conversely, vegetated corridors can facilitate the access of such predators as the blue crabs to beds of oysters, on which they prey. Accordingly, the spatial proximity of one habitat to another can strongly influence both the population and community dynamics of both. Understanding the trade-off effects of seascape characteristics in estuarine habitats could be useful in predicting the consequences of habitat fragmentation in marine ecosystems, especially where the conservation or repair (or both) of a system is required for the sake of biodiversity and its associated services.8
Whether populations of plants and animals survive in a particular seascape depends on the rate of local extinctions from a patch of habitat and the rate with which an organism can move among existing patches of habitat. Those species living in habitats isolated as a result of fragmentation—from such things as bottom dredging—are therefore less likely to persist. Fragmentation of habitat, the most serious threat to biological diversity, is the primary cause of the present global crisis in the rate of biological extinctions. In the world’s oceans, much, if not most, of the fragmentation of the habitat is a so-called “side effect” of techniques employed in overfishing that increasingly stresses the short-term take of commercial fishes at the long-term expense of the environment. “Side effect” is an economic euphemism. There is no such thing as a side effect—only a direct, but an unintentional effect!
Modifying the existing connectivity among patches of habitat strongly influences the abundance of species and their patterns of movement. The size, shape, and diversity of patches also influence the patterns of species abundance, and the shape of a patch may determine which species can use it as habitat. The interaction between the processes of a species’ dispersal and the pattern of a seascape determines the temporal dynamics of the species’ populations. Populations of wide-ranging organisms may not be as strongly affected by the spatial arrangement of habitat patches as more sedentary species are, which brings me to “marine protected areas.”
MARINE PROTECTED AREAS
Marine protected areas are spatially defined marine units in which one or more human activities—particularly fishing—are restricted or prohibited. They represent an ecosystem-based approach to using the oceans for our human benefit based on the precautionary principle: “Do no harm.” As such, marine protected areas are best seen as tools that complement other approaches aimed at the sustainability of marine resource. Unlike terrestrial parks and nature reserves, marine protected areas can disrupt livelihoods, especially if a protected area provides few tangible benefits to local people who have traditionally depended on it. On the other hand, they attract scientists, tourists, as well as others interests, thereby creating a complex system for protection. Fortunately, however, more effort is being devoted to enhancing habitat connectivity by creating networks of marine protected areas. Nevertheless, one widespread threat to the sustainability of these areas is climate change, which may require further increases in their size—or significant shifts in where they are located.9
There will undoubtedly be resistance to the establishment of a network of marine protected areas as the central component of a sustainable, ecosystem-based fishery. Such resistance will manifest in large measure because of the newness, novelty, and inherent constraints of the approach, whereas species-specific fisheries management has a long, economically defined history. Moreover, decisions about the size of protected areas, their site selection, and the disturbance levels within them may be difficult due to the relative variability and complexity of marine ecosystems.10
Our responsibility now is to make our best biophysically decisions about patterns across the seascape, while considering the consequences of those decisions on the ocean’s potential productive capacity for generations to come. Although the decisions are up to us, one thing is crystal clear. The current trend toward overfishing and the subsequent fragmentation of various areas of the seascape may help maximize short-term monetary profits and current lifestyles, but it devastates the long-term biophysical sustainability and adaptability of the oceans and thus plays a role in devastating the their potential capacity for long-term productivity.
To counter some of this degradation, representatives of Western Pacific island nations put the finishing touches on a series of bold, new measures during the last week of May 2009, decisions aimed at saving the world’s last great stocks of tuna. They decided to bar fishing in two huge pockets of international waters, creating the largest ever no-fishing zone. The result is four no-take areas totaling 745,645 square miles stretching from French Polynesia to Palau—a distance of 4,350 miles. When combined, the no-take zones are more than three times the size of California and dwarf the 223,695 square-mile protected area in the Northwestern Hawaiian Islands, whose waters contain far fewer fish. Fishing in the rest of the Western Pacific is regulated by the Western and Central Pacific Fisheries Commission, a treaty-based organization that includes 15 island nations and 10 countries that pay for the right to fish in their so-called Exclusive Economic Zones, which stretch 200 nautical miles from land.11
However, it is not the relationship of numbers that confers sustainability on ecosystems. Sustainability flows from the patterns of relationship that have evolved among the various species. A relatively stable, culturally oriented seascape, even a very diverse one, which fails to support these ecologically co-evolved relationships, has little chance of being sustainable.
To create viable, culturally oriented seascapes, we must begin now to work toward the connectivity of habitats because biophysical sustainability—thus adaptability—depends on such connectivity. We must therefore ground our culturally designed protected areas within Nature’s evolved patterns and take advantage of them if we are to have a chance of creating a good-quality marine environment that is ecologically adaptable.
If we are to have adaptable seascapes with sustainable productive capacities to pass to our heirs, we must focus on four primary things: (1) caring for and protecting/creating the sustainable connectivity and biological richness among the different components of the seascape, (2) specifically locating protected areas in the most heavily fished locations,12 (3) protecting existing biodiversity—including habitats—at any price for the long-term sustainability of the biophysical wholeness and the species richness of the patterns we create across global seascapes, and (4) the personal willingness to change our thinking from the narrow confines of our old, institutionalized, self-centered point of view with its endless attempts at symptomatic, quick fixes to embrace a systemic view for the social-environmental sustainability and long-term productivity of the world’s oceans for all generations.
BEYOND THE PROTECTED AREAS
Yet, despite the best planning, there are some marine creatures that protected areas may not be able to help survive. Maintaining a particular biophysical service may necessitate returning a threatened population of an ecologically pivotal species to near its former abundance. However, it is often difficult—and in some cases nearly impossible—to estimate the historic size of a species’ population once it has been heavily exploited.
To illustrate, the gray whales in the Eastern Pacific, which play a fundamental role in their Arctic feeding grounds, are widely thought to have once again achieved their pre-whaling abundance. At previous levels, gray whales may have seasonally re-suspended 24,720,266,705 billion cubic feet of sediment while feeding, as much as twelve Yukon Rivers, and thus provided food to a million sea birds.
Although recent spikes in their mortality might signal that the population has reached a long-term carrying capacity, an alternative explanation for this decline is due to shifting climatic conditions in their Arctic feeding grounds. Using a genetic approach to estimate the pre-whaling abundance of gray whales, researchers determined that a population of 76,000–118,000 individuals was the norm, approximately three to five times more numerous than today’s reputed average population of 22,000 individuals. Amalgamating data suggest that an average of 96,000 individuals was probably distributed between the Eastern and currently endangered Western Pacific populations, which means that the Eastern population is at most at 28 to 56 percent of its historical abundance—and thus should be deemed depleted. Therefore, human-caused mortality in this population necessitates a reduction from 417 to 208 individuals killed per year.13
A potentially significant loss of ecosystem services may have resulted from a decline of 96,000 gray whales to the current population about 22,000 individuals. Therefore, it must be noted, that the loss of a single species—be it a plant, animal, or otherwise (marine or terrestrial)—would impoverish, rather than enrich, the world for all time.
Oceans in Crisis:
1. Jay Lindsay. Fishermen Meet Amid Bleak Cod Prospects. http://abcnews.go.com/US/wireStory/fishermen-meet-amid-bleak-cod-prospects-15559779#.TzW-ehw0gpd (February 11, 2012).
2. (1)Jane Lubcheco, Steven Gaines, Kirsten Grorud-Colvert, and others, “The Science of Marine Reserves,” Partnership for Interdisciplinary Studies of Coastal Oceans, (2007):1–21; and Peter H. Taylor, “Coastal Connections,” Partnership for Interdisciplinary Studies of Coastal Oceans, 6 (2007):1–17.
3. (1) Callum M. Roberts, “Rapid Build-Up of Fish Biomass in a Caribbean Marine Reserve,” Conservation Biology, 9 (1995): 815–826, (2) Octavio Aburto-Oropeza, Brad Erisman, Grantly R. Galland, and others. Large Recovery of Fish Biomass in a No-Take Marine Reserve. PloS One, August 12, 2011.
4. (1) Octavio Aburto-Oropeza, Brad Erisman, Grantly R. Galland, and others. Large Recovery of Fish Biomass in a No-Take Marine Reserve. PloS One, August 12, 2011 and (2) Janet Raloff. Big Fish Return To Mexican Marine Park. Science News, 180 (Number 7, 2011:14).
5. (1) Rachel Ehrenberg. Bluefins Mingle Across the Ocean. Science News, (number 9, 2008):15; (2) Jay R. Rooker, David H. Secor, Gregorio De Metrio, and others. Natal Homing and Connectivity in Atlantic Bluefin Tuna Populations. Science, 322 (2008):742–744; and (3) Giulia Riccioni, Monica Landi, Giorgia Ferrara, and others. Spatio-Temporal Population Structuring and Genetic Diversity Retention in Depleted Atlantic Bluefin Tuna of the Mediterranean Sea. Proceedings of the National Academy of Sciences, USA, 107 (2010):2102–2107.
6. Ker Than. Swimmers’ Sunscreen Killing Off Coral. http://news.nationalgeographic.com/news/2008/01/080129-sunscreen-coral.html
7. (1) Charles A. Acosta, “Benthic Dispersal of Caribbean Spiny Lobsters among Insular Habitats: Implications for the Conservation of Exploited Marine Species,” Conservation Biology, 13 (1999):603–612; (2) “Seagrass,” en.wikipedia.org/wiki/Seagrass; and (3) Department of Environmental Protection, Florida Marine Research Institute, “Seagrasses,” http://www.dep.state.fl.us/coastal/habitats/seagrass/
8. The previous two paragraphs are based on: Fiorenza Micheli and Charles H. Peterson, “Estuarine Vegetated Habitats as Corridors for Predator Movements,” Conservation Biology, 13 (1999): 869–881.
9. Bonnie J. McCay and Peter J. S. Jones. Marine Protected Areas and the Governance of Marine Ecosystems and Fisheries. Conservation Biology, 25 (2011):1130–1133.
10. (1) Peter J. S. Jones. Marine Protected Area Strategies: Issues, Divergences and The Search for Middle Ground. Reviews in Fish Biology, and Fisheries, (2001):11:197–216 and (2) Peter J. S. Jones. Point Of View—Arguments for Conventional Fisheries Management and Against No-Take Marine Protected Areas: Only Half of the Story? Reviews in Fish Biology and Fisheries, 17 (2007):31–43.
11. Christopher Pala. Protecting the Last Great Tuna Stocks. Science, 324 (2009):1133.
12. Benjamin S. Halpern, Sarah E. Lester, and Karen L. McLeod. Placing Marine Protected Areas onto the Ecosystem-Based Management Seascape. Proceedings of the National Academy of Sciences, USA, 107 (2010):18312–1831.
13. The preceding discussion of gray whales is based on: S. Elizabeth Alter, Eric Rynes, and Stephen R. Palumbi. DNA Evidence for Historic Population Size and Past Ecosystem Impacts of Gray Whales. Proceedings of the National Academy of Sciences, USA, 104 (2007):15162–15167.
Text © by Chris Maser 2012. All rights reserved.