Ecosystem Considerations Research Articles

Ecosystem consideration in conservation planning: energy demand of foraging bottlenose whales ( Hyperoodon ampullatus) in a marine protected area

The Gully, a submarine canyon off eastern Canada, was nominated as a pilot Marine Protected Area (MPA) in 1998, largely to safeguard the vulnerable population of northern bottlenose whales ( Hyperoodon ampullatus) found there. The boundaries and ultimate management regime for the MPA for this area remain under review. We have estimated the energy consumption of bottlenose whales in the Gully based on the number of whales present at any time, their trophic level, the food requirements of each whale, and the rates of energy transfer between trophic levels. These calculations suggest that there must be a substantial spatial subsidy in the underlying foodweb of the submarine canyon to support the bottlenose whales using the Gully. A substantial area beyond the distribution of bottlenose whales in the area will therefore require protection. Conservation priorities to protect such subsidies will primarily involve additional protection at the level of the sea floor. Spatial subsidies are probably common in the marine environment, urging careful ecological analysis in the establishment of marine reserves and suggesting that conservation priorities need to take into account key ecological linkages and processes that are vital for sustaining species and habitats of concern.

A new role for MSY in single‐species and ecosystem approaches to fisheries stock assessment and management

In 1977, Peter Larkin published his now‐famous paper, ‘An epitaph for the concept of maximum sustained yield’. Larkin criticized the concept of single‐species maximum sustained yield (MSY) for many reasons, including the possibility that it may not guard against recruitment failure, and the impossibility of maximising sustainable yields for all species simultaneously. However, in recent years, there has been a fundamental change in the perception of the fishing mortality associated with MSY (FMSY) as a limit to be avoided rather than a target that can routinely be exceeded. The concept of FMSY as a limit is embodied in several United Nations Food and Agriculture Organization (FAO) agreements and guidelines, and has now been incorporated into the US Magnuson–Stevens Fishery Conservation and Management Act. As a result, the United States now requires the development of overfishing definitions based on biological reference points that treat the FMSY as a limit reference point and must also define a lower limit on biomass below which rebuilding plans with strict time horizons must be developed. This represents a major paradigm shift from the previously mandated (but often unachieved) objective to simply maintain fishing mortalities at levels below those associated with recruitment overfishing. In many cases, it requires substantial reductions in current fishing mortality levels. Therefore, the necessity of the new paradigm is continually questioned. This paper draws on examples from several fisheries, but specifically focuses on the recent US experience illustrating the practical difficulties of reducing fishing mortality to levels below those corresponding to MSY. However, several studies suggest that even more substantial reductions in fishing mortality may be necessary if ecosystem considerations, such as multispecies interactions, maintenance of biodiversity and genetic diversity, and reduction of bycatch and waste, are taken into account. The pros and cons of moving beyond single‐species assessment and management are discussed. A US plan for improving stock assessments indicates that even a ‘basic’ objective such as ‘adequate baseline monitoring of all managed species’ may be extremely costly. Thus, the suggestion of Larkin (1983, 1997) that the costs of research and management should not exceed 10–20% of the landed value of the catch may preclude comprehensive ecosystem management. More importantly, neither single‐species nor ecosystem‐based fisheries management is likely to improve appreciably unless levels of fishing capacity are aligned with resource productivity, as is currently being promoted by FAO and several individual nations.

Acoustics in fisheries in the 21st century

The history, current state, and future potential of acoustics in fisheries research and management will be addressed. Fisheries management worldwide is undergoing a fundamental paradigm change in response to population pressures and overharvesting of marine and freshwater stocks. Future fisheries management will be more conservation based and responsive to ecosystem considerations. These trends will demand more comprehensive knowledge of the components of fisheries’ ecosystems and their dynamics, and more realistic estimates of the precision of ocean measurements. Acoustics is poised to take a new and leading role in these developments. Acoustics is nondestructive of marine life, can be near-synoptic, and can measure most of the water column. However, acoustic methods are still hampered by problems with detectability, especially near boundaries, uncertainties about target strengths of the myriad of species and life stages whose scattering properties are complex and behaviorally mediated, and taxonomic identification. These problems will be discussed, and a general experimental plan will be laid out to solve them. The 21st century of fisheries belongs to acoustics and allied technologies.

Symposium overview: incorporating ecosystem objectives within fisheries management

Following an introduction to the broader context of the Symposium, the scope of the oral presentations is summarized under three themes: a global synthesis of fisheries impacts in different ecosystems; an overview of the methods available for quantifying ecosystem impacts; and the integration of fisheries and environmental management. The presentations generated substantial evidence that marine ecosystems have been impacted by fishing. Also there appeared to be a broad consensus that the present approach to achieving conservation objectives of fisheries management does not sufficiently take into account ecosystem considerations. There was not, however, a consensus on what additional restrictions are required, or on what features of ecosystems need to be protected. A way forward is to add ecosystem objectives to the conservation component of fisheries management plans, as well as to the management plans for other ocean-use sectors. The aggregate ocean-use activities would need to be evaluated in a nested manner, at a range of geographic scales, in relation to the more broadly defined conservation objectives. It is suggested that the geographic scales for evaluation of ecosystem considerations could be defined in a pragmatic manner based on the somewhat artificial boundaries of political and administrative systems already in place. The six conservation objectives proposed are maintenance of (1) ecosystem diversity, (2) species diversity, (3) genetic variability within species, (4) directly impacted species, (5) ecologically dependent species, and (6) trophic level balance. Indicators for each objective are discussed, as well as reference points that would trigger management actions. Such a broadening of conservation objectives for fisheries mangement would require both enhanced monitoring and a greater workload added to the process of provision of scientific advice through peer review. Of equal importance would be the challenges of establishing a governance framework to address multiple uses of marine resources. The spirit of the Symposium was that these coupled scientific and governance challenges will be very stimulating.

Definitions of overfishing from an ecosystem perspective

Ecosystem considerations may be incorporated into fisheries management by modifying existing overfishing paradigms or by developing new approaches to account for ecosystem structure and function in relation to harvesting. Although existing concepts of overfishing have a strong theoretical basis for evaluating policy choices and much practical use, they do not provide direct guidance on issues such as biodiversity, serial depletion, habitat degradation, and changes in the food web caused by fishing. There is, however, little basis for defining optimum fishing by using related metrics such as diversity indices, slopes of size or diversity spectra, or average trophic level of the catch, and these may produce ambiguous results. If ecosystem-based overfishing concepts are to assume a greater role in management, unambiguous, quantifiable, and predictive measures of ecosystem state and flux must be developed to index: (1) biomass and production by the ecosystem and relationships among its parts, (2) diversity at different levels of organization, (3) patterns of resource variability, and (4) social and economic benefits. Ecosystem considerations do not need to substitute for existing overfishing concepts. Instead, they should be used to evaluate and modify primary management guidance for important fisheries and species. In practice, they emphasize the need to manage fishing capacity, supported by broader use of technical measures such as marine protected areas and gear restrictions.

An ecosystem-based approach for Alaska groundfish fisheries

Witherell, D., Pautzke, C., and Fluharty, D. 2000. An ecosystem-based approach for Alaska groundfish fisheries. – ICES Journal of Marine Science, 57: 771–777. An ecosystem-based approach is being developed for the management of groundfish fisheries in the North Pacific Ocean off Alaska, USA. The approach involves public participation, reliance on scientific research and advice, conservative catch quotas, comprehensive monitoring and enforcement, by-catch controls, gear restrictions, temporal and spatial distribution of fisheries, habitat conservation areas, and other biological and socioeconomic considerations. The basic ecosystem consideration employed is a precautionary approach to extraction of fish resources. Off Alaska, all groundfish stocks are considered healthy, while providing sustained yields of about 2 million tonnes annually. Management measures are also taken to minimize potential impacts of fishing on seafloor habitat and other ecosystem components such as marine mammals and seabirds. 2000 International Council for the Exploration of the Sea

The Martian and extraterrestrial UV radiation environment—1. Biological and closed-loop ecosystem considerations

The Martian surface is exposed to both UVC radiation (<280 nm) and higher doses of UVB (280–315 nm) compared to the surface of the Earth. Terrestrial organisms have not evolved to cope with such high levels of UVC and UVB and thus any attempts to introduce organisms to Mars, particularly in closed-loop life support systems that use ambient sunlight, must address this problem. Here we examine the UV radiation environment of Mars with respect to biological systems. Action spectra and UV surface fluxes are used to estimate the UV stress that both DNA and chloroplasts would experience. From this vantage point it is possible to consider appropriate measures to address the problem of the Martian UV environment for future long term human exploration and settlement strategies. Some prospects for improving the UV tolerance of organisms are also discussed. Existing artificial ecosystems such as Biosphere 2 can provide some insights into design strategies pertient to high UV environments. Some prospects for improving the UV tolerance of organisms are also discussed. The data also have implications for the establishment of closed-loop ecosystems using natural sunlight on the lunar surface and elsewhere in the Solar System.

The Future of the International Law of Capture Fisheries

The future of the international law of capture fisheries must have as its continued foundation the 1982 United Nations Convention on the Law of the Sea. However, a new environmental awareness and a more specific articulation of legal responsibilities in international fisheries conservation and management are reflected by the recent adoption of the UN Agreement on Straddling Fish Stocks and Highly Migratory Fish Stocks and the Agreement to Promote Compliance with International Conservation and Management Measures by Fishing Vessels on the High Seas. These Agreements, plus the Code of Conduct for Responsible Fisheries, contain a number of provisions that reflect environmental goals that are both broader and more specific. These goals include the need for consideration of aquatic ecosystems, the need for an ecosystem approach to management, and the need to minimize by-catch, pollution, waste and discards. As such, they illustrate what is essentially a in international fisheries, which flows from the increasing nexus between international fisheries law and international environmental law. This paradigm shift involves growing recognition of the requirement for ecosystem concerns and steps to protect fisheries habitat for the sustainable conservation and management of capture fisheries. In response to this paradigm shift, regional fisheries organizations like NAFO must incorporate an ecosystem perspective in their work if they are to remain relevant in the next century.

Biological Diversity and Biological Integrity: Current Concerns for Lakes and Streams

Abstract In discussing various concepts of biological diversity and biological integrity, we trace development of the terms from a focus on species to a consideration of ecosystems. We urge the public to extend its concern with species extinction and tropical rain forests to include temperate aquatic assemblages. Examples of losses in biological diversity and biological integrity are given for the genetic, species, assemblage, fauna, ecosystem, and landscape levels of biological organization. After discussing the recent recognition of biological diversity concepts by the U.S. Environmental Protection Agency in its surface water assessment and regulation programs, we conclude that a broadening of environmental ethics is needed to protect ecosystems and species before they become endangered.

The commons revisited: Thoughts on marine mammal management

Abstract This article explores the United States approach to marine mammal management. Questions are raised about the implications of current actions which are primarily protective. Impacts of such protection, both in terms of ecosystem considerations and the resulting social, economic, and international political consequences are examined. The key issue raised by the paper is whether mammals are managed to achieve a goal built around nonconsumptive values which may be primarily moral or ethical, or if they are managed for purposes of extractive conservation.

Ecosystem considerations of the KwaZulu-Natal sardine run

The annual winter sardine run along the South African east coast impacts the KwaZulu-Natal (KZN) coastal system in a variety of ways. These include ecological impacts, such as enrichment of a largely oligotrophic environment, competition between migrant sardine Sardinops sagax, other migrant and resident small pelagic fish species, and interactions with predators, as well as the socio-economic impacts of the sardine run on the local people. Enrichment of KZN coastal waters with organic nitrogen contained within the sardine is compared with alternative sources of nitrogen such as upwelling, river, sewage and stormwater runoff, and groundwater discharge. The sardine run appears to contribute most nitrogen to this system—96 000 t compared to 500–3 300 t for each of the other significant sources at trophic level 2, although upwelling estimates are extremely wide. Nonetheless, the majority of surviving sardine, their young and predators return southwards, suggesting that the nett export of nitrogen to KZN waters during the run is likely to be of a similar order of magnitude as that from other sources. Further, whereas the sardine supply of nitrogen is exclusively during winter, the bulk of the riverine input is in summer, thus ensuring that nitrogen supply in the region is maintained at fairly constant levels throughout the year. Competition for food between small pelagic fish is minimised by resource partitioning, but further dietary data are needed for resident species. Although interactions between sardine and top predators must exist, further studies are needed to confirm links between top predator life cycles and the sardine run. The estimated value of sardine as a tourist spectacle is compared to that from a seasonal beach-seine or boat-based purse-seine fishery for this species. Whereas the estimated value of the sardine as a tourist attraction appears substantially higher than could be derived from catching them, the small-scale beach-seine fishery itself draws tourists and also provides limited, seasonal employment opportunities.