Magazine article Oceanus

Marine Reserves: They Enhance Fisheries, Reduce Conflicts, and Protect Resources

Magazine article Oceanus

Marine Reserves: They Enhance Fisheries, Reduce Conflicts, and Protect Resources

Article excerpt

In wildness is the preservation of the world.

Henry David Thoreau, 1862

It has taken almost a century for Thoreau's words to be applied to the oceans. In that time, the world population has quadrupled, and more people are migrating to the coast with the hope of utilizing the marine environment as a source of food and employment, and also for recreation, tourism, education, and research. Unfortunately, increased use brings user conflicts, and many fisheries have been depleted or have collapsed. To most people the ocean seems boundless, its resources inexhaustible, and its ability to tolerate human activities unlimited. We now know that these perceptions are false: Ocean resources are finite, and human activities can be devastating.

For the first time in human history, we have the ability to catch fish faster than they are produced. Our catch ability must be tempered with new ways of preventing overfishing and resource depletion. Marine fishery reserves, areas protected from all fishing and other harvesting activities, provide one approach. Since the first modern reserves were established in the mid-1970s, they have been increasingly used for fisheries management and resource protection.

Species Protection is a Fundamental Goal

The primary purpose of marine reserves is to ensure that fisheries continue by protecting a portion of the spawning stock from exploitation. In a refuge, abundance, average size, and total egg production can be increased over what it would be if the area were fished. Eggs and larvae produced in reserves are then spread by oceanic currents to both exploited and protected areas.

The concept of marine reserves is simple: If protected from human interference, nature will take care of itself. A large body of scientific literature attests that harvested stocks will recover if fishing stops. The reserve concept is not really new. Until recently, most reef fisheries were probably partly maintained by natural refuges: areas too deep, too remote, or too difficult to locate easily. With improved fishing methods and more people fishing, the effectiveness of natural refuges diminishes. Marine reserves are best suited to protecting species with the restricted geographical movements typical of most reef organisms. Reefs are common in coastal areas, and include some of the world's most taxonomically diverse, biologically complex, and productive ecosystems. "Reefs" include not only coral reefs, but also rock outcrops, artificial reefs, and other hard-bottom areas. Reef habitats are geographically well defined, long-lasting, and restricted to relatively small areas of ocean bottom. Their importance, however, far exceeds the percentage of bottom covered because of their high biological productivity. Tropical reefs support economically important species such as snapper, grouper, spiny lobster, coral, and conch; those found at temperate reefs include rockfish, kelp, lobster, and abalone.

Life History on a Reef

The ecology and life history of reef organisms make them vulnerable to fishing. Most species have a two-stage life cycle: a pelagic (open water) egg or larval stage, and a demersal (bottom) juvenile and adult stage. Eggs and larvae are passively transported and dispersed as plankton by ocean currents. Depending on the species and location, eggs and larvae can drift from about a week to several months before larvae settle (recruit) to bottom habitats. Once settled, juveniles and adults live a comparatively sedentary demersal existence. Most settled individuals are considered "sedentary" because they tend to associate with a particular reef or a specific area for most of their adult lives.

Planktonic survival is generally very poor. Abundance at settlement can vary by orders of magnitude from year to year due to uncertainties in currents, weather, food availability, and predation. This annual variability results in good or poor recruitment years, reflected by the abundances of various year classes for individual species. …

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