The management of marine species and ecosystems to prevent their decline and extinction. As in terrestrial conservation, the goal of marine conservation is to preserve and protect biodiversity and ecosystem function through the preservation of species, populations, and habitats. The importance of conserving marine species and ecosystems is growing as a consequence of human activities. Negative impacts on marine biological systems are caused by such actions as overfishing; overutilization, degradation, and loss of coastal and marine habitats; introduction of nonnative species; and intensification of global climate change, which alters oceanic circulation and disrupts existing trophic relationships. Marine conservation biologists seek to reduce the negative effects of all these actions by conducting directed research and helping to develop management strategies for particular species, communities, habitats, or ecosystems.
A variety of approaches and tools are used in marine conservation. These include population assessment; mitigation, recovery, and restoration efforts; establishment of marine protected areas; and monitoring programs. Many of these approaches overlap with those in terrestrial conservation. However, fundamental differences between terrestrial and marine environments in spatial dimension, habitat type, and organismal life history require that basic conservation techniques be modified for application to the marine environment. See also Biodiversity; Ecosystem; Marine ecology; Oceanography.
Effective management requires knowledge of the size and status of populations. Trends in abundance can be detected through stock assessment methods first developed for marine fisheries and subsequently modified for application to other marine organisms. These methods use estimates of population size, reproduction, survivorship, and immigration to determine whether populations are increasing, decreasing, or stable. Population viability analysis is a specialized statistical assessment in which demographic and environmental information is used to determine the probability that a population will persist in a particular environment for a specified period of time. This method can be used to guide management decisions, and has been used in efforts to manage marine mammals, turtles, seabirds, and other species. See also Ecological communities; Population ecology.
Depleted, threatened, or endangered populations are often subject to mitigation or recovery efforts. The purpose of these efforts is to reduce the immediate threat of extinction or extirpation. This is typically achieved by direct human intervention to increase the size of a population or to prevent further decline in population size. Methods used to achieve recovery for fish and marine invertebrates include reducing fishing quotas, restricting the use of certain types of fishing gear, restricting the seasonal or annualdistribution of a fishery, or closing fisheries altogether.
Recovery efforts can be most successful if they are based on multispecies orecosystem-level management strategies. These strategies take into accountpositive and negative interactions between species, such as facilitation,competition, and predation. They further take into account interactions betweenspecies and their environment. Key to the success of assessment and recoveryprograms is identification of the appropriate biological unit for conservation(for example, population, subspecies, stock, or evolutionarily significantunit). Maintaining genetic diversity is an important goal of conservationbiology, because genetic diversity confers evolutionary potential. Thus,conservation efforts often are aimed at populations that are geneticallydistinct from other populations of the same species.
Restoration efforts are aimed at returning habitats to an ecologicallyfunctional condition, usually consistent with some previous, more pristinecondition. See also Endangered species; Fisheries ecology; Marine fisheries.
Marine protected areas are set aside for the protection or recovery ofspecies, habitats, or ecosystems. They include marine parks, marine reserves,marine sancturaries, harvest refugia, and voluntary or legislated no-takeareas. Some marine protected areas allow for consumptive use (such as fishing)or extraction of resources (for example, oil drilling), while others are closedto most human activities.
Monitoring programs are necessary to determine the outcome of specificconservation actions and to guide future conservation decisions. Monitoringprograms vary according to the objectives of specific conservation projects buttypically include such activities as long-term surveys of population size andstatus, and the development of mathematical models to help predict specificoutcomes.
