Marine Mammals: Fisheries, Tourism and Management Issues: Fisheries, Tourism and Management Issues

By CSIRO PUBLISHING

Marine Mammals: Fisheries, Tourism and Management Issues brings together contributions from 68 leading scientists from 12 countries to provide a comprehensive, up-to-date review on the way we manage our interactions with whales, dolphins, seals and dugongs. The book examines how we have fared conserving the world’s marine mammal populations, with a focus on the key issues of fisheries and tourism.

From a unique southern hemisphere perspective, the authors consider how science informs the culling debate, how wild fisheries and aquaculture interact with marine mammal populations and how we might manage the effects of whale, dolphin and seal watching industries. The authors also address other issues such as the way in which ethics, genetics, acoustics, ecosystem models and pollution influence the management and conservation of marine mammals.

Marine Mammals is an invaluable and accessible resource for all those involved with marine mammals, including scientists, managers, policy makers, industry representatives and students.

Winner of a 2004 Whitley Award.

• Language: English
• Publisher: CSIRO PUBLISHING
• Release date: Oct 22, 2003
• ISBN: 9780643099265

Book preview

INTRODUCTION

Marine mammals are often considered as a group by the general public, biologists, natural resource managers and legislators. Nonetheless, they comprise members of three very different orders of animals with different evolutionary histories. The Carnivora includes 36 extant and recently extinct species of seals, sea lions and walruses (Rice 1998) as well as the polar bear and two species of marine otters. Systematists disagree about the exact number of species of the order Cetacea (whales, dolphins and porpoises). Rice (1998) lists 83 species in two sub-orders: the Mysticeti (baleen whales) and Odontoceti (toothed whales). There are four extant species of Sirenia (manatees and dugongs). The gigantic Steller’s sea cow (Hydrodamalis gigas) was hunted to extinction by sealers in the eighteenth century.

Despite their diverse taxonomic origins, it is sensible to consider marine mammals as a group in developing marine policy, as they are all dependent on aquatic ecosystems for survival (Reynolds et al. 1999). They have evolved similar anatomical, physiological and life history adaptations to aquatic and marine environments including large body size and a long lifespan. A primary reason that marine mammals are inherently vulnerable to overexploitation is that their intrinsic rates of increase are low, less than 10–20%. For some species this value may be as low as 1–3% (Wade and Angliss 1997). This is because they tend to mature late, have a single offspring at intervals of several years and have low natural mortality rates, some living for 100 years or more (Perrin 2002). They represent consummate K-selectors (Pianka 1970.)

Marine mammals are highly valued by humans for cultural and economic reasons, including food and other products (Twiss and Reeves 1999). The consumptive uses of marine mammals include killing them for their meat, oil and skins. Non-consumptive uses include ecotourism (e.g. whale watching), public display and research. Marine mammals are major public attractions as evidenced by the commercial success of oceanaria and whale watching (Reeves and Mead 1999). For example, a recent survey found that commercial whale watching businesses in 87 countries in 1998 attracted more than nine million participants and generated US$1 billion from fees for tours, and expenditures on food, travel, hotels and souvenirs (Hoyt 2000). Their large body size and value to humans makes marine mammals high-profile indicators of the degradation of coastal, marine and some riverine habitats.

Concern about the status of marine mammals has been heightened by the number of species listed as threatened (critically endangered, endangered or vulnerable) on the IUCN Red List of Threatened Species (Hilton-Taylor 2000). The status of 92 species of marine mammals is as follows: extinct (3 including one sub-species), critically endangered (3), endangered (12), vulnerable (18), data deficient (conservation status cannot be assessed) (40), low risk conservation dependent (15), and low risk not threatened (1). These assessments have been made at a global scale. Many species of marine mammals have huge ranges, and are locally extirpated in parts of their former range (Reynolds et al. 2002.)

The pressures on marine mammals have changed over time. In the past, the major pressures involved consumptive use for food, oil or skins. These pressures have been reduced, although not eliminated, as non-consumptive uses have increased. Many modern pressures stem from the increase in the world’s human population, particularly the proportion of the population living in the coastal zone. As human population increases in coastal areas, so does pressure on coastal ecosystems through habitat loss, fragmentation and change, increased pollution, and demand for coastal resources. Globally, 50% of people live within 60km of the coast. It is likely that this will increase to 75% by 2020 (Intergovernmental Panel on Climate Change in DeMaster et al. 2001). Especially in ‘developing’ countries, the situation has been exacerbated by the displacement and urbanisation of rural human populations, which has led to the loss of traditional values and taboos to resource exploitation. The provision of aid from ‘developed’ countries has increased the efficiency and level of exploitation of coastal resources, often without adequate legislation, enforcement and management (Cockroft, personal communication 2001). Marine mammals are adversely impacted by dams, effluents and all the other agents of habitat destruction (Perrin 2002). For example, the range of the dugong (Dugong dugon) includes at least 37 countries in the tropical Indo-West Pacific region. In a recent survey, coastal development was listed as a problem for the dugong in 31 of these countries and territories (Marsh et al. 2002). The situation is probably similar for many other coastal marine mammals, especially in the tropics. In contrast, very abundant populations of several pinniped species live in polar and sub-polar regions where coastal impacts are insignificant or non-existent.

The other major group of increasingly adverse effects derives from the growth of the world’s fishing industry. In the last 50 years marine fisheries production has increased more than fourfold. However, the rate of increase has dropped to zero in recent years and about three-quarters of individual stocks have been overfished or are being fished at or near the maximum long-term potential catch (for details see DeMaster et al. 2001). Many of the world’s marine mammal species are dependent on fish for food and are likely to have been adversely effected by this resource depletion. A major impact of the world’s fisheries on marine mammals results from their being caught as bycatch. The bycatch sometimes then becomes the target of a directed fishery, particularly in ‘developing’ countries (Perrin 2002.)

This chapter will assess trends in the management of marine mammals in the last ten years. Our objectives are to:

• Present the major trends and patterns, particularly in terms of policy changes;

• Identify major new developments and outstanding problems needing further attention;

• Provide concrete examples of successful or promising efforts by governmental, intergovernmental and non-governmental bodies; and

• Provide concrete recommendations to the international community for the next ten years.

Harwood (2001) provides a comprehensive review of the impact of climate change on marine mammals and concludes that, as highly mobile species, marine mammals should have the capacity to respond more rapidly to the effects of climate change than their terrestrial counterparts. However, central place foragers such as many otariid seals may be seriously affected (Harwood 2001). Concern has also been expressed about the impact of climate change on polar bears (IUCN Polar Bear Specialist Group, personal communication 2001). In this chapter, we review some of the other major anthropogenic pressures on marine mammal populations and discuss policy responses to those pressures. With the exception of the impacts of sound associated with boating activity, we have not reviewed the impact of underwater sounds on marine mammals but acknowledge that this is an area of burgeoning importance (Marine Mammal Commission 2002).

COMMERCIAL EXPLOITATION OF MARINE MAMMALS

Nature of the threats

Commercial whaling is the most controversial of the anthropogenic pressures on marine mammal populations. Whaling can be traced back to the Stone Age (Gambell 1999), and most whaling activities were probably sustainable until technological advances allowed the exploitation of whales to spread from coastal to offshore waters and from pole to pole, causing the successive depletion of species and stocks, culminating in the decline of the industry itself (Gambell 1999). The International Convention for the Regulation of Whaling was signed in 1946 with the aim of providing for the proper conservation of whale stocks and the orderly development of the whaling industry (IWC 1950). Membership of the International Whaling Commission (IWC) is open to any nation that formally adheres to the 1946 Convention. Membership increased from the original 15 whaling nations to 40 nations by 1980. The IWC became dominated by the anti-whaling nations and through the 1970s and 1980s, the number of whales and the areas in which they could be taken by the commercial industry gradually reduced until the Commission introduced a pause in commercial whaling in 1982 (Gambell 1999). The IWC set catch limits at zero for commercial whaling on all stocks effective with the 1986 coastal whaling season and the 1985–86 pelagic whaling season. Despite the Commission’s acceptance of the mathematical and scientific elements of the Revised Management Scheme for estimating sustainable catch limits for baleen whales, there are a number of outstanding matters that have not been resolved and the moratorium on commercial whaling has yet to be revoked.

Based on Article 8 of the International Convention of Regulation of Whaling of 1946 (ICRW), the Japanese government has authorised the Institute of Cetacean Research (ICR) to kill whales for research purposes since the 1987/88 Antarctic season. The ICRW requires maximum utilisation of the carcasses, offering a basis for the ICR to sell the whale products to finance research and other activities. The maximum number of whales that the ICR is currently permitted to take is 440 southern minke whales (Balaenoptera bonaerensis), 100 North Pacific minke whales (B. acutorostrata), 50 North Pacific Bryde’s whales (B. edeni), and 10 North Pacific sperm whales (Physeter macrocephalus). The Institute of Cetacean Research has produced numerous scientific publications from these operations. However, the value of this program has been questioned by some IWC members who have doubted whether: (1) the biological information obtained is critically important for management, (2) the objectives of the study really require lethal methods to be used, and (3) the proposed objectives of the study can be achieved by the program (IWC 2001a.)

From 1988 to 1995, Norwegian scientists conducted a research program that involved taking 289 North Atlantic minke whales (B. a. acutorostrata) for research, including studies of feeding ecology, age determination, and energetics. Since 1996, about 500 North Atlantic minke whales (e.g. 589 whales in 1999 and 487 in 2000) have been caught by Norwegian small-type whaling operations annually. This harvest has been legal under the Convention because the Norwegian government lodged an objection to the moratorium decision. Consequently the moratorium is not binding on the government of Norway. The IWC has adopted non-binding resolutions each year requesting the Norwegian government to reconsider its commercial harvest.

Small-type whaling has been defined by the IWC as ‘operations using powered vessels with mounted harpoon guns to take minke, bottlenose (Hyperodon sp.), pilot (Globicephala sp.) or killer whales (Orcinus orca)’ (Gambell 1999). The governments of both Norway and Japan have argued that the moratorium on small-type whaling is unjustified as they claim that it should be considered in the same category as Aboriginal subsistence whaling, which is allowed by the IWC. The majority of IWC members have disagreed with this opinion. However, in 1993 the Commission adopted a resolution recognising the socioeconomic and cultural needs of four coastal communities in Japan and the distress to these communities caused by the cessation of minke whaling. Despite this resolution, efforts by the Japanese government to allow an interim relief allocation of 50 minke whales have been unsuccessful.

The question of the legal competence of the IWC to make management decisions concerning small cetaceans is one over which Commission members have been divided. Concerns have been twofold: (1) whether the term ‘whale’ applies only to the baleen whales and sperm whale listed in an attachment to the convention, or the remaining toothed whales not so listed, and (2) national sovereignty over waters in an Exclusive Economic Zone. The government of Japan currently allows its nationals to fish eight species of toothed whales, which it and several other members consider to be outside of the competency of ICRW. The types of fisheries involved are: (1) small-type whaling, (2) the crossbow fishery (which shoots harpoons from a crossbow mounted on the bow), (3) the drive fishery which drives whole schools of cetaceans into bays from which they are prevented from escaping and then killed, and (4) the hand-harpoon fishery. The current total annual quota for these fisheries is 22 437 small-sized toothed whales including: 62 Baird’s beaked whales (Berardius bairdii), 550 short-finned pilot whales (G. macrorhynchus) from two stocks, 50 false killer whales (Pseudorca crassidens), 1300 Risso’s dolphins (Grampus griseus), 1100 bottlenose dolphins (Tursiops sp.), 725 striped dolphins (Stenella coeruleoalba), 950 spotted dolphins (S. attenuata), and 17 700 Dall’s porpoises (Phocoenoides dalli; at least three stocks are involved.)

The Scientific Committee of the IWC (SC/IWC) has repeatedly expressed concern that these harvests of Dall’s porpoises may be unsustainable, especially as these stocks are also impacted by an unknown level of mortalities in net fisheries (IWC 1992; IWC 1999). In addition, the striped dolphin catches are taken from already depleted stocks (e.g. IWC 1994; Perrin 1999). The sustainability of large catches of other species is also unproven. Exploitation occurs only in near shore waters, but the reported sizes of the targeted populations are often inflated by including population estimates from offshore waters (except for Baird’s beaked whales). There are problems in stock identification and the extent of the movement of whales between near shore and offshore waters is unknown.

In contrast to the controversy surrounding Antarctic whaling, there has been no commercial sealing in the waters surrounding Antarctica since the Convention for the Conservation of Antarctic Seals was concluded in 1972 (Kimball 1999). This Convention was developed in response to the threat of possible resurgence of Antarctic sealing in the 1960s.

Recent initiatives

The Japanese Government Fisheries Research Agency used to present catch statistics, abundance estimates and results of biological studies of its harvested odontocetes to the SC/IWC. The government of Japan refused to present the statistics and biological information concerning the fishery to SC/IWC in 2001. Since 1997, some fishing groups have allowed only Fisheries Research Agency scientists to collect data and specimens from their catch. The cause of this change in attitude is unknown, but these actions are likely to exacerbate the international polarisation associated with the commercial whaling debate.

The IWC has the power to designate open and closed areas for whaling. The Indian Ocean sanctuary was established by the IWC in 1979, initially for 10 years in an area extending south to 55° latitude. Commercial whaling is still prohibited in this area. Member nations adopted the Southern Ocean Sanctuary in 1994, designating it an area in which commercial whaling is prohibited.. The sanctuary is reviewed by the Commission at 10-year intervals. The government of Japan lodged an objection to the sanctuary to the extent that it applies to minke whale stocks, which are currently being subject to catches under scientific permit (Gambell 1999.)

Concluding remarks

The 1946 Convention for the Regulation of Whaling was developed as an agreement to control an industry that had a long history of overexploitation of the target species. The Convention is now interpreted as an instrument of protection that reflects the environmental ethics of anti-whaling nations (Gambell 1999). This ethic is not accepted by some of the countries and communities most affected by the current moratorium. Unfortunately, the polarisation of IWC members is preventing a comprehensive evaluation of the relative importance of anthropogenic impacts on cetaceans, as well as of an assessment of the sustainability of current commercial whaling practices. Thus, the overall outcome of this polarised situation is not in the best interests of the whales nor in those interested in their sustainable utilisation. If support for the IWC process fails and membership of the IWC fall to marginal levels, it is extremely likely that the membership of organisation(s) that replace that IWC will be less conservative in managing commercial whaling than the IWC has been. It is difficult to see how the situation can be satisfactorily resolved with opinions so entrenched.

INDIGENOUS HARVEST OF MARINE MAMMALS

Nature of the threats

Marine mammals continue to be hunted by many indigenous peoples to meet their dietary, social, economic, ceremonial, spiritual and identity needs (e.g. Takekawa 1996; Freeman et al. 1998; Marsh et al. 2002). Animals hunted include several species of seal, whale, dolphin, and porpoise, as well as sea otters, dugongs, polar bears and the walrus. In general, indigenous fisheries or hunts do not pose significant conservation threats to these species. In the case of seals, walrus, toothed whales, dolphins and porpoises, the species hunted are mostly abundant and widely distributed, harvests are usually small relative to population size, and demand for the resource (in quantitative terms) is often less now than in earlier times.

Despite the absence of significant threats at the species level, some local populations of marine mammals may be at risk, for example some populations of the dugong (Marsh et al. 2002). This is partially a cultural problem, reflecting the differences in the beliefs of animal protectionists at one extreme and local hunters on the other. Protectionists and some biologists believe that wildlife populations should be maintained at, or restored to, historic levels of abundance. Local peoples often have a different understanding, believing that all changes in population size can be ascribed to natural fluctuations over time and space. The lack of long-term records of population numbers exacerbates such disagreements.

However, marine mammals may be subjected to a number of environmental stresses, such as fisheries bycatch, so that even when hunting itself does not constitute a threat, in combination with other stresses hunting removals may contribute to a local conservation problem.

Recent initiatives

During the 1990s there was increasing recognition and use of users’ knowledge in management (Gadgil et al. 1993; Williams and Baines 1993). An associated increase in co-management arrangements, wherein indigenous resource stewardship practices may be combined with management based on western science (Berkes and Folke 1998) has also occurred. The effectiveness of such co-management initiatives varies greatly, for the cultures of science-based western environmental management and of indigenous peoples are often difficult to reconcile, and resources to sustain such innovative regimes may be scarce.

Many indigenous groups recognise that wildlife cannot be directly ‘managed’, because nature cannot be directed by human action (Freeman 1999). However, biologists/managers and indigenous user groups know that the human–non-human relationship can be regulated, and it is this relationship that is critical for achieving sustainable use practices.

Examples of successful or promising efforts

Several indigenous peoples have recently re-established their customary relationships with marine mammals through hunting, including Chukchi, Inuit, and Makah whalers in Russia, Canada and the United States. While debate has remained polarised on this issue, many conservationists recognise that reconnecting people with wildlife-based traditional values and practices can result in important conservation benefits (Berkes 1999), such as protecting habitat from potentially damaging industrial activities (Freese and Ewins 1998).

The World Council of Whalers provides a forum for whaling/ whale-consuming peoples, government agencies, and conservation organisations from over 20 countries to hold management-relevant discussions. The High North Alliance, representing North Atlantic whalers’ and sealers’ interests, promotes similar objectives. The challenge for these issue-based, advocacy organisations, and those that hold opposing views, is to separate the issues of ecology, conservation and sustainability from those of commerce and politics.A regional (rather than global) approach to marine mammal conservation has also gained favour; regional regimes include ASCOBANS (Agreement on the Conservation of Small Cetaceans of the Baltic and North Seas), NAMMCO (North Atlantic Marine Mammal Commission), and ECCO (Eastern Caribbean Cetacean Commission). The eight-nation Arctic Council and NAMMCO are both seeking to incorporate indigenous whalers’ knowledge into conservation and management programmes. Promotion of this aspect was a major aim of a recent workshop sponsored by the US Marine Mammal Commission to discuss the effects of sea ice change in the Arctic with Inuit and other Arctic indigenous peoples.

Outstanding problems

The growth of animal protection organisations opposing animal use (even if sustainable) is an on-going challenge for marine mammal conservation. Seal pups, dolphins and whales are emotionally appealing animals, whose welfare (real or imagined) allows animal protection organisations to conduct aggressive fund-raising and political campaigns. Such campaigns may even claim that the poster animal is in danger of extinction (when in fact it is not). This tactic helps raise funds but may mislead the public, media and politicians (Kalland 1993; Aron et al. 2000.)

This misinformation has resulted in governments disrupting or banning trade upon which indigenous and non-indigenous smallholders’ cultural and economic existence depends. These disruptions have had serious social consequences (Wenzel 1991) and continue to cause problems for those hunting mediagenic or charismatic species (Freeman and Kreuter 1994.)

Today, conservation is widely understood to mean safeguarding animals and plants for sustainable use, in contrast to protectionism, which saves animals and plants from use (Edwards 1995). Governments need to be aware that these differences have important policy and fiscal consequences. Setting conservation priorities, and identifying where conservation programmes are needed, will better ensure urgent conservation issues are adequately funded (Gerber et al. 2000).

Governments also need to be more aware that sustainable and equitable resource use (which may include selling the surplus product) can provide important conservation benefits (Edwards 1995; Freese and Ewins 1998). Adoption of this approach would necessitate changing the law in some countries.

Recommendations

Co-management has the potential to improve the conservation of marine mammals. However, co-management is not a panacea. It is very challenging to implement, requiring time, sustained funding and capacity building before showing results. Co-management should be established under legislation, rather than through purely administrative arrangements that can easily be changed.

In countries where marine mammals are not used for food, politicians, educators, and the media, need to become aware that very few of the species hunted for food today by indigenous peoples are threatened with extinction (Clark 1989; Aron et al. 2000). Those species considered to be at highest risk (for example, the northern right whale Balaena glacialis, several river dolphins) are not subject to hunting and require location-specific protective measures to be instituted. Similar local measures are required for those geographic stocks (of dugongs or whales) that are known to be at risk (e.g. Marsh et al. 2002). All species require management at stock level; some species such as the vaquita (Phocoena sinus) or the baiji (Lipotes vexillifer), which have very restricted distributions and low numbers, are critically endangered at the species level and require management at that scale.

Governments should understand how animal protectionists mobilise concerned, yet uninformed, citizens to clamour for an end to any animal use (Kalland 1993; Aron et al. 2000), and be more attentive to decision making based on the best scientific advice and the rule of international law (Jacobson 2001.)

FISHERIES INTERACTIONS

Nature of the threat

Interactions with fisheries are some of the most pressing threats to the diversity of marine mammals, especially at the stock level. Interactions between marine mammals and fisheries may be operational, in which marine mammals interact with fishing gear to the detriment of animals, gear, or both and ecological, in which animals and fisheries interact through trophic pathways (Beverton 1985; DeMaster et al. 2001). The two types of interactions require different conservation approaches (Northridge and Hofman 1999.)

The primary threat to marine mammals from operational interactions comes from the entanglement and mortality of animals in fishing gear. For example, large-scale high seas drift net fishing was responsible for killing large numbers of marine mammals and many other non-target organisms especially in the 1980s. Concern about this impact led to the United Nations moratorium on large-scale gillnet fishing in 1992 (see Northbridge and Hoffman 1999 for a more detailed discussion). The causes of entanglement are diverse and, in general, poorly understood. In some cases, animals may not perceive the presence of fishing gear and become entangled purely by accident. In other situations, animals are aware of the gear but become entangled because they are feeding around nets or on captured fish. In the eastern tropical Pacific, fishers set purse seines around schools of pelagic dolphins to capture yellowfin tuna (Thunnus albacares) that associate with the dolphins, resulting in capture and mortality of the dolphins (Joseph 1994). Fisheries bycatches threaten the existence of several species of marine mammals, including the critically endangered vaquita and the endangered North Atlantic right whale.

Ecological interactions between fisheries and marine mammals can also have adverse effects on the latter if important prey species are depleted by fishing activities. For example, there has been considerable concern about the potential impact of harvesting krill in the Southern Ocean on species whose diet is largely krill, such as many of the great whales. This concern led to the Ecosystem Modeling Program conducted under the aegis of the Convention on the Conservation of Antarctic Living Marine Resources (CCAMLR), possibly the most important attempt yet made to manage fisheries from an ecosystem perspective (Chapter 3, this volume).

The predatory behaviour of marine mammals on fish is another cause for concern and controversy because of real or perceived cost to fishers. For example, the very large populations of harp (Pagophilus groenlandicus), hooded (Cystophora cristata) and gray (Halichoerus grypus) seals in the North Atlantic are seen as a threat to fish stocks and fishing gear (see Northbridge and Hoffman 1999, and Chapter 2, this volume for further details). In most of these cases, our understanding of the true nature of the interactions is limited by the complexity of trophic dynamics (DeMaster et al. 2001). Perhaps the one case in which we do understand these ecological interactions is the competitive interaction between sea otters and shellfish fisheries in California (Estes and Van Blaricom 1985). In many other areas, predation of commercially valuable species or damage to gear caused by marine mammals has lead to calls for culls or reductions in the populations of marine mammals; in such cases the interactions may be either operational or ecological.

Trends and patterns

Conflicts between marine mammal populations and commercial fisheries have increased in frequency and intensity and this trend is likely to continue (DeMaster et al. 2001). In part, this is because of continued human population growth, particularly in coastal regions, and the increasing demand for protein from the sea. Global fisheries landings have stabilised over the past few decades and current removals of approximately 100 million tons/year may be close to the maximum that the world’s oceans can sustain (DeMaster et al. 2001). However, the increasing demand for protein results in a cycle of excessive harvests, depletion of fish stocks, increasing fishing effort, development of new fisheries and more frequent interactions with marine mammals. This problem is exacerbated in areas where marine mammal populations are recovering from previous directed harvests.

New developments and outstanding problems

Over the past decade there have been promising developments at both the national and regional levels. A few countries have developed comprehensive scientific and management programs to evaluate the scope of interactions between marine mammals and fisheries (e.g. Read and Wade 2000). This approach is costly and beyond the means of many developing nations. When fisheries exploit common pool resources and cause adverse effects on marine mammals, however, it may be appropriate to require fisheries to underwrite the costs of such programs. In New Zealand for example, the costs of programs directed at understanding and mitigating conflicts between marine mammals and fisheries have been funded by conservation levies on fisheries.

A promising, but as yet unfulfilled, development is the establishment of two regional agreements under the Bonn Convention: the Agreement on the Conservation of Small Cetaceans of the Baltic and North Seas (ASCOBANS) and the Agreement on the Conservation of Cetaceans in the Black and Mediterranean Sea (ACCOBAMS). A similar approach is being discussed for marine mammals in South-east Asian waters (Perrin, personal communication 2002). These agreements provide a framework for addressing conflicts between marine mammals and fisheries, but to date there has been little effective action taken by member nations.

There are three categories of outstanding problems. First, our understanding of the global extent and impact of interactions between marine mammal stocks and fisheries remains woefully inadequate, especially in ‘developing’ countries. Most countries and inter-governmental fisheries organisations (including the FAO) have not yet addressed the problem adequately. Second, even in countries where the scope of interactions is well understood, there is a lack of cooperation and common purpose between the agencies responsible for the management of fisheries and those with a mandate to manage marine mammals. Remarkably, even when the same agency is responsible for both tasks, there is little coordination of management; most fisheries agencies are still directed to maximise or optimise yield, with little or no concern for impacts on other ecosystem components. Thus, when new fisheries are developed, little or no thought is given to potentially adverse effects on marine mammals and the burden of proof still falls on individuals or organisations to demonstrate that such an effect exists. Finally, ecological interactions are particularly complex and it is still very difficult to determine the effects of fisheries harvests on the population biology of marine mammals (and vice-versa) (See Chapter 17, this volume).

Examples of successful governmental, intergovernmental and non-governmental efforts

One of the most successful and concerted efforts to deal with operational interactions has been the implementation of the 1994 amendments to the US Marine Mammal Protection Act 1972 (Read and Wade 2000). In the US there is now a systematic research program directed at estimating the mortality of marine mammals in all commercial fisheries and to reduce this mortality, where necessary, by negotiating changes to fishing practices with all stakeholders (fishers, managers, and representatives of environmental organisations).

Several techniques have been developed and implemented to reduce the bycatch of marine mammals in commercial fisheries. These include acoustic alarms (Kraus et al. 1997), which are now used in European and North American fisheries and spatial restrictions on fishing effort, such as reserves and temporary time-area closures, which have been implemented in Australia, New Zealand, Europe and North America. These successful initiatives follow the development of several effective methods used to reduce the bycatch of pelagic dolphins in the eastern tropical Pacific purse seine fishery for yellowfin tuna (Joseph 1994).

Recommendations

First, a global review of the extent and impact and cost of interactions between marine mammal populations and fisheries should be conducted, supported by international agencies such as the FAO, IUCN and IWC. Second, a small number of concerted, well-funded research efforts should be focused on representative interactions between marine mammal populations and fisheries to determine which mitigation methods work and are cost-effective. Finally, a dialogue must be encouraged between fisheries managers and those responsible for marine mammals at the national, regional and international levels.

BOATING AND SHIPPING IMPACTS

Nature of the threats

Boating and shipping can affect marine mammals in several ways: mortality, injury, disturbance, and habitat destruction. Collisions between watercraft and various species of marine mammals are well documented (e.g. Ackerman et al. 1995; Wells and Scott 1997; Laist et al. 2001; Marsh et al. 2002). For at least two endangered populations (West Indian manatees (Trichechus manatus manatus) in Florida and North Atlantic right whales) boat or ship strikes represent a major impediment to recovery, or even to the survival of the population. The water-craft-related mortality of West Indian manatees in Florida has been especially well documented (O’Shea et al. 1985; O’Shea 1995; Ackerman et al. 1995; Wright et al. 1995; Reynolds 1999). Over half of the deaths are caused by the impact of the collision, rather than slicing by the propeller (Rommel, personal communication 2001). This may be the case for collisions between vessels and other marine mammal species as well, making both diagnoses and mitigation more difficult than would be the case if propeller cuts alone were the issue.

Not all collisions with watercraft result in the immediate death of a marine mammal; a variety of species are struck and injured, but do not die (e.g. Beck and Reid 1995; Wells and Scott 1997; Goldstein et al. 1999). Although it is often relatively easy for qualified scientists to diagnose that the death of a marine mammal is due to collision with a watercraft, it remains quite unclear what the effects of immediately sub-lethal injuries may be (e.g. O’Shea 1995; Reynolds 1999; O’Shea et al. 2001). Analysis of scar patterns on a manatee recovered dead in 2001 indicated that it had been struck on at least 50 separate occasions (O’Shea et al. 2001). The effects of such multiple, serious strikes cannot be predicted, especially since it is unclear what the effects of a single serious strike may be.

However, the multiple, and sometimes subtle sequela to sub-lethal injuries are not as subtle as some consequences of disturbance by heavy boating activity. Scientists have documented that a range of marine mammals react to approaching vessels by behaviours such as the following: moving rapidly away from the disturbance, altering swimming tracks, changing habitat use patterns, or modifying surfacing, respiration, or diving cycles. These behavioural changes could be accompanied by significant stress, which is difficult to assess in free-ranging marine mammals, and are likely to impact or interrupt ‘normal’ resting, feeding, and nurturing behaviours. Altogether, boat-related disturbance could affect energy budgets and general health and well being of individuals and groups (see O’Shea 1995). Such impacts occur due to deliberate approaches (e.g. whale watching, see below) and to routine boat traffic. Among the species for which specific behavioural changes associated with boat disturbance have been documented are West Indian manatees (Buckingham et al. 1999); bottlenose dolphins (Evans et al. 1992; Wells 1993; Janik and Thompson 1996; Allen and Read 2000; Nowacek et al. 2001); harbor porpoises, P. phocoena (Polacheck and Thorpe 1990); bowhead whales, B. mysticetus (Richardson et al. 1985; Richardson 1995); killer whales (Kruse 1991); Hector’s dolphins, Cephalorhynchus hectori (Bedjer and Dawson 1999) and various Stenella spp. (Au and Perryman 1982). The population level effects of such disturbance are generally not known.

On the other hand, marine mammals may be attracted to the sounds of certain types of watercraft. Bottlenose dolphins can be attracted to working shrimp trawlers to feed (e.g. Corkeron et al. 1991; Chilvers and Corkeron 2001). The apparent attraction of other marine mammals (e.g. killer whales and some species of pinnipeds) to boats deploying fishing gear can lead to entanglement and death of the marine mammals, destruction of gear, and consumption of netted or hooked fish. For certain pinniped populations (e.g. California sea lions Zalophus californianus and harbor seals Phoca vitulina along the west coast of the United States), such interactions represent an issue about which feelings are especially intense.

In addition to noise pollution, boat activity may erode habitat quality and local/regional productivity, making locations favoured by marine mammals less suitable. For example, boating activity in shallow areas can lead to extensive seagrass scarring, an increase in suspended sediments, which impairs seagrass productivity (Zieman 1982), and bottom-shear stress that erodes seagrass beds. These impacts affect the herbivorous marine sirenians directly and indirectly affect coastal carnivorous marine mammals whose prey depends on seagrass beds for shelter or energy.

Boats and boating are proliferating worldwide. In the state of Florida (US), for example, there are nearly 900 000 registered boats, representing an approximate 100% increase in 25 years. Those boats go faster than previously, and as a result of changes in hull design, can easily enter shallow areas while maintaining high speeds. The coastal species of marine mammals, thus, have more and faster boats to contend with and fewer areas of safety than was the case just a few years ago. Offshore, a similar situation exists. Laist et al. (2001) noted that the number of oceangoing ships experienced dramatic increases, at least through 1980, when the rate of increase slowed, and that the maximum speed of many types of vessels increased as well. In both inshore and offshore areas, such increases are correlated with increases in collisions with certain marine mammals.

Recent initiatives

Among the possible solutions that are more commonly endorsed by scientists and conservationists are: reducing speeds of boats and ships; better enforcement of boat speed and access regulations; careful monitoring of special events (e.g. power boat races); adjusting hull designs to eliminate the effects of strikes by external propellers, drive shafts and gear cases, and to deflect some energy during a collision and minimise injury; creating restricted zones where boats may not enter or vessel lanes which boaters are encouraged or required to use; creating better ways for boaters to detect marine mammals in sufficient time to minimise the likelihood of a collision; and reducing noise produced by boats to reduce noise pollution.

Example of a successful or promising effort

Mortality and serious injury due to ship strikes is a major threat to the North Atlantic right whale, a species for which fewer than 300 individuals remain. The Southeastern US Implementation Team (part of the right whale recovery effort) developed and coordinated an Early Warning System to notify operators of large vessels of the presence of right whales in an area. In addition, the US Coast Guard and the US National Marine Fisheries Service with concurrence from the International Maritime Organization, established mandatory ship reporting systems in key right whale habitat. In addition, outreach efforts contribute to educating operators of risks to right whales and appropriate precautions. This sort of multi-faceted approach by a group of responsible agencies and organisations should help provide better protection for right whales and other species.

Outstanding problems

Implementation of optimal solutions is impaired by uncertainties about what the different species of marine mammals can hear or otherwise detect and how animals behave once they do detect an oncoming boat. Additional insights into the effects of large amounts and multiple sources of noise on marine mammals and other organisms are also needed. Sensory physiologists, behavioural ecologists, and other scientists will have an important role to play in creating solutions that reduce impacts to marine mammals and other aquatic/marine organisms, while not unduly restricting human activities.

For manatees, one hypothesis is that manatees do not adequately hear boats (Gerstein et al. 1999). Consequently, some individuals have suggested that it would make sense to produce an alarm to make oncoming boats more detectable by the manatees so that avoidance is enhanced. It is uncertain whether this would work for manatees since some scientists believe that manatee hear boats without alarms. In addition, there is no reason to assume that, even if a manatee is better able to detect a boat equipped with an alarm, it will associate the alarm sound with a threat and avoid it. However, even if this ‘solution’ works for manatees, it may be unwise since it would increase levels of inshore noise pollution.

We consider the burden of proof to create workable solution should be on the users of boats and ships, rather on the interest groups most concerned with the welfare of marine mammals. Because the range of marine mammal responses is limited by their biology, solutions are more likely to arise from efforts to adjust human institutions, activities, and values (Reynolds 1999).

Recommendations

The approaches listed above provide a useful place to start in terms of local, regional, or international initiatives intended to mitigate the threat of boats and ships to marine mammals. These initiatives are difficult to implement because: (a) they require establishment and coordination of partnerships among governmental and non-governmental entities, (b) they may involve significant costs for people, in terms of both time and money, and (c) they may have implications for military functions. Nonetheless they can be implemented where the will to do so exists. Development of partnerships and shared goals takes time, however some efforts should start as soon as possible.

In addition, studies should be initiated to establish clearer understanding of the effects of boats and large ships on the behaviour, physiology, and health status of marine mammals exposed to moderate-to-heavy traffic. Scientists need also to develop a clearer understanding of the sensory capabilities of marine mammals.

TOURISM IMPACTS: MARINE MAMMAL WATCHING AND SWIM WITH PROGRAMS

Nature of the threats

Marine mammal watching, particularly whale watching, is a growth industry. Hoyt (2000) listed 66 independent countries and 21 overseas territories or dependencies where commercial whale watching occurs, an increase from only 33 countries in 1991. He estimated that nine million people participated in whale watching cruises in 2000, compared with four million in 1991. Revenue in 2000 directly associated with whale watching tours was estimated at US$299.5 million. Except in the United States, United Kingdom, Australia and Japan, most whale watchers are international visitors. Thus marine mammal watching can be a significant source of foreign income. Marine mammal watching has been put forward by various non-government organisations (NGOs) (e.g. Greenpeace, International Fund for Animal Welfare (IFAW), Whale and Dolphin Conservation Society) as a viable alternative to commercial whaling, a point disputed by the whaling industry (Komatsu and Misaki 2001; Moyle and Evans 2001).

Marine mammal watching cannot be considered totally benign. Potential threats include risk of physical injury from boat strikes (Laist et al. 2001) and disturbance of the animals leading to effects such as habitat displacement (IFAW 1995); interference with key activities such as feeding, socialising, mating and calving; and noise trauma. The last is of particular concern given the anatomical and experimental evidence that sound is important in cetacean orientation and behaviour (Wartzok and Ketten 1999). With the growth in marine mammal watching, concern has been raised about cumulative effects, both locally and along the migration routes of more widely ranging species.

Special activities such as feeding programs and commercial swims with wild cetaceans have also been the focus of concern (see Chapter 14 and 15, this volume). For the former, concerns have been raised about effects on natural foraging behaviour and ‘strong indications’ of a link between human provisioning of dolphins and increased juvenile mortality (IFAW 1995). As for swim programs, there is concern that the close approaches necessary for underwater observation may cross the boundary from benign observation to interference (IWC 2001b). Additional concerns regarding possible inter-specific transmission of diseases and human safety have also been raised in relation to swim programs. One additional factor that complicates the issue in some countries (e.g. the US) is that swimming with dolphins is commonly and legally done in public display facilities. However, the agency responsible for human interactions with free-ranging dolphins (i.e. National Marine Fisheries Service) has adopted the view that swimming with wild cetaceans is at least ill advised, if not a violation of provisions of the US Marine Mammal Protection Act 1992. Given the disparate messages that swimming with captives is fine, but swimming with wild marine mammals is not, the public is confused. The confusion has been exacerbated because the US Fish and Wildlife Service has been rather tolerant of people swimming with free-ranging manatees. The inconsistent messages need to be clarified and addressed if progress is to be made in educating the public about appropriate behaviour with marine mammals.

Recent initiatives

Carlson (2000) reviewed the whale watching guidelines and regulations that were current or proposed in 27 independent countries or overseas dependencies. Most guidelines were voluntary, drawn up by individual operators or local tourism organisations, however increasingly these are supported by state or national legislation (e.g. US Marine Mammal Protection Act 1972; Australian Environment Protection and Biodiversity Conservation Act 1999). National legislation can address management of species that have a restricted distribution (e.g. the majority of coastal dolphins) but international efforts may be necessary for more wide ranging species, e.g. most baleen whales. Since 1993, a working group of the Scientific Committee of the International Whaling Commission (IWC) has addressed whale watching management issues. Generalised principles applicable to whale watching and endorsed by the IWC were published in IWC (1997).

About 70% of whale watching is from vessels (Hoyt 2000). Accordingly, most guidelines focus on the regulation of ‘no approach’ distances and manoeuvering procedures for vessels, identification of disturbance indicators that should lead to ceasing a whale watching encounter, as well as suggestions on vessel design (e.g. to minimise engine and propeller noise), and maintenance of vessels (to avoid pollution). The Scientific Committee of the IWC expressed serious concerns about continued feeding of wild cetaceans and recommended that such activities be prohibited (IWC 2001a). A common legislative approach to swim with dolphin programs has been to ban the activity outright (e.g. Argentina, Brazil, South Africa) or to limit the activity to certain species of dolphins (e.g. New Zealand, Azores).

Research on the effects of marine mammal watching has concentrated on documenting short-term effects. For example, Bejder and Dawson (1999) documented the reactions of Hector’s dolphins to boats and swimmers in New Zealand. Although the animals were not displaced by either boats or swimmers, the dolphins showed short-term reactions to the whale-watch boat. A major issue is the general inability to establish the biological significance of such short-term effects on the target species or to link any negative effects (short term or long term) to the activity of marine mammal watching (e.g. IFAW 1995). Bejder and Dawson (1999) concluded that most of the effects they observed would be cumulative rather than catastrophic. They were concerned about the potential for increased disturbance on the dolphins. The increase in marine mammal watching worldwide documented above suggests that this concern should be widespread.

Recommendations

Given the iconic status of cetaceans, it is not surprising that considerable attention has already been given to developing guidelines and regulations for whale watching. What needs to be established is the extent to which various types of marine mammal watching activities comply with the general principles proposed by the IWC or to stricter proposals and whether marine mammal watching has a neutral effect on the species being observed (i.e. elicit neither avoidance nor approach responses). This must be assessed on a case-by-case basis, considering unique features of the marine mammal watching operations and the species observed. In the case of swim programs, most of the information is based on interactions with dolphins, which cannot be generalised to cover programs with other species, such as the swims with humpback whales (Megaptera novae-angliae) in Tonga or dwarf minke whales in Australia.

The study of cumulative effects is particularly important, especially in situations where heavy boat traffic affects resident or semi-resident populations of marine mammals (e.g. killer whales in western North America). In countries with a significant proportion of private boat owners, recreational marine mammal watching is also an increasing activity that must be considered in assessing cumulative impacts.

It has been recommended (IWC 2001a) that, rather than concentrating on linking short-term to long-term (e.g. population level) effects (IFAW 1995), effort should be concentrated on identifying biologically significant effects (such as noise generated by vessel activity) and establishing critical threshold values. This approach should be pursued. Long-term studies are essential to track operational changes in the industry and to assess cumulative impacts, both of which may lead to apparent changes in behaviour such as documented by Constantine (2001).

There is a greater need for using data on visitor experiences (e.g. Orams 2000) in refining the management of marine mammal watching. Such studies have identified the importance of knowing what visitors expect and, through appropriate information such as pre-trip briefings, of ensuring that passengers have realistic expectations about the whale watching encounters, e.g. limits on approach distances. The importance of education of both passengers and operators is crucial given that management of marine mammal watching is an exercise in managing people, not marine mammals. Involvement of industry representatives in developing management options is crucial to maximise compliance, especially where resources for monitoring and enforcing the regulations are limited.

ENVIRONMENTAL CONTAMINANTS

Nature of the threat

Agriculture, urban settlement and industrial activities around the world have contributed to the widespread contamination of global marine ecosystems with pesticide residues, organochlorine compounds and heavy metals (Fowler 1990; Tatsukawa et al. 1990). These pollutants are persistent, highly toxic and many are now permanent additions to the environment that have the potential to have adverse impacts on marine mammals. However, the nature of these impacts is often hard to establish (see Chapter 21, this volume).

Organochlorine pesticides and heavy metals

Chlorinated organic compounds (or organochlorines) are carbon-based chemicals that contain bound chlorine. These compounds are mostly artificial and enter the environment mainly through industrial and agricultural applications. Many of them are now banned from production because of their adverse environmental effects. Organochlorine compounds are hydrophobic and once in the water column, tend to adsorb to fine particulates or be bioaccumulated into lipids in aquatic biota (Olsen et al. 1982). Organochlorine pesticides and poly-chlorinated biphenyls (PCBs) have been implicated in reproductive and immunological abnormalities observed in marine mammal populations (Boon et al. 1992). Examples include adrenocortical hyperplasia and disruption of steroid metabolism in seals attributed to DDE metabolites (methylsulphones) produced in the liver (Lund 1994), and reduced testosterone concentrations in Dall’s porpoise associated with organochlorine contamination (Subramanian et al. 1987).

Dioxins and modern pesticides

Dioxins are a group of 210 chlorinated compounds consisting of chlorinated dibenzo-para-dioxins (PCDDs) and chlorinated dibenzofurans (PCDFs). They are formed during various chemical and industrial manufacturing processes, by combustion of organic material (Kjeller et al. 1991), and also via lesser known natural processes (Hashimoto et al. 1995; Alcock et al. 1998). They display a diverse and complex array of toxicological properties and have been detected in a variety of marine mammals (Norstrom et al. 1990; Oehme et al. 1995; Jarman et al. 1996; Muir et al. 1996; Tarasova et al. 1997). The impact on marine mammals of several new generation insecticides and herbicides now used by the agricultural industry is also of concern. For example, chronic herbicide exposure from agricultural run-off has the potential to negatively impact on seagrasses, the main food resource for dugongs (Vandermeulen et al. 1972; Haynes et al. 2000a, b).

Heavy metals

Heavy metals are natural constituents of rocks and soils and enter the environment as a consequence of weathering and erosion (Förstner 1989). Many metals are biologically essential, but all have the potential to be toxic to biota above certain threshold concentrations. Following industrialisation, unnatural quantities of metals such as arsenic, cadmium, copper, mercury, lead, nickel and zinc have been released, and continue to be released into the aquatic environment through mining, agricultural, urban stormwater and wastewater discharges. Another metallic compound, organotin, is generally introduced into the marine environment, principally as a constituent of antifouling paints. Although particulate metals in suspension and in bottom sediments are not generally directly available to marine mammals, they can be accumulated in the acidic digestive juices of sediment-feeders, which are eaten by marine mammals (Waldichuk 1985). Once dissolved in the water column, metals may also be accumulated by marine invertebrates from solution via passive uptake across permeable surfaces such as gills and the digestive tract (Rainbow 1990). Such invertebrates can also be eaten by marine mammals which bio-accumulate the toxic heavy metals (see Chapter 21, this volume).

Cellular metal toxicity is primarily due to the chemical inactivation of cellular enzymes responsible for normal organism survival and function (Förstner 1989). Organism growth, reproduction and behaviour are also potentially affected by elevated environmental metal concentrations (Langston 1990). The consequences of elevated heavy metals over time in marine mammals are not well known. Indeed, some marine mammals, such as the dugong, can accumulate extraordinarily high concentrations of a number of metals without apparent impact (Denton et al. 1980; Langston 1990; O’Shea 1999).

Example of a successful or promising effort

Considerable effort has now been directed at the assessment of body burdens in marine mammals (see O’Shea 1999). An example of one such program is that initiated for the Great Barrier Reef and southern Queensland (Australia) coastal region. This program includes monitoring of pollutant concentrations in near shore marine sediments, a toxicological assessment of the potential impact of the dominant pollutant (the herbicide diuron), and monitoring and modelling of contaminant body burdens in marine mammals (Haynes et al. 1999; Vetter et al. 2000; McLachlan et al. 2001). This monitoring program has contributed to the preparation of water quality targets for all catchments draining into the Great Barrier Reef World Heritage Area in an attempt to achieve better land management practices which will ultimately protect the Great Barrier Reef and its associated biota including several species of marine mammal (Brodie et al. 2001).

Outstanding problems

Reliable estimates of historical and current emission rates and sources of persistent organochlorine pollutants are unavailable. This information is fundamental to establishing an inventory for source reduction measures for these pollutants (Jones and de Voogt 1999). There is also a lack of basic knowledge concerning the natural formation mechanisms of some compounds such as dioxins (Gaus et al. 2001). Most importantly, the role pollutants play (if any) in disease expression in marine mammals needs to be resolved (O’Shea 1999).

MARINE DEBRIS

Nature of the threats

Marine debris has been defined as any manufactured item that may be lost or discarded in the marine environment. Marine debris includes objects such as plastic bags, wrappers, bottles and cups, synthetic rope and line, glass bottles, metal cans, lumber, cigarette butts, raw plastic pellets and balloons and may be made of paper, cloth, wood, concrete, glass, rubber, leather or plastic (Laist et al. 1999). Because plastics resist corrosion in the marine environment, they are popular with mariners. When lost, however, many plastics float and degrade slowly, and can be carried by winds and currents thousands of kilometres from their point of entry into the sea. Individual items of debris may circulate in the world’s oceans for years or rest on the bottom for decades. As a result, no area, no matter how remote or protected, is immune from marine debris pollution.

Marine mammals can be injured or killed by marine debris by entangling in it or by ingesting objects (Laist 1987). Entangled animals may become exhausted and drown, lose their capacity to feed or avoid predators, incur wounds and infections, or be forced to behave in a manner that leaves them vulnerable to predation. Ingesting debris may leave marine mammals with their digestive tract blocked, irritated or punctured, affecting their food intake or rate of nutrient absorption. There are records of ingestion or entanglement for 60% of baleen whale species, 34% of toothed whale species, 79% of fur seal and sea lion species, 42% of true seal species, 25% of sirenian species and the sea otter Enhydra lutris (Laist 1996a). For most species of marine mammal, entanglement is more likely to injure or kill than ingestion. Most entanglements involve debris from commercial and recreational fisheries, especially fishing nets, mono-filament fishing line, rope, and strapping bands used to close bait boxes. The impacts of derelict fishing gear also take the form of ghost fishing (i.e. the unrecovered catch of derelict gear), which can cause substantial long-term impacts to stocks of commercially valuable fish and shellfish and reductions in available catch opportunities (Laist 1996b). For the most part, however, the significance of marine debris problems at population levels is unknown because there is no easy way to determine deaths at sea, which are necessary to estimate total debris-related mortality. Nonetheless, several species of marine mammal known to be killed by marine debris are designated as endangered (e.g. Hawaiian monk seals (Monachus schauinslandi) and Florida manatees (Trichechus manatus latirostris)) and can ill-afford any additional mortality.

Recent initiatives

The recognition of marine debris as a pollutant capable of significant effects on marine life and aesthetic quality prompted widespread research and management efforts by international and national governmental organisations, as well as NGOs in the late 1980s. These initiatives included international conventions, national and international research programs, community-based beach clean ups, and a series of international conferences to review information and progress on marine debris issues (Laist et al. 1999). A number of these efforts have been carried forward over the last 10 years. In general, efforts have been more successful in cleaning up marine debris than in preventing it.

In many areas, the principal actions being taken to address marine debris pollution now involve the development of long-term clean-up programs by NGOs and national and local government bodies with support from businesses and industries. For example, the Ocean Conservancy has played a lead role in securing and organising cooperative efforts by federal and state agencies, local industry groups in Hawaii, and others to initiate a multi-year program to remove derelict nets and fishing line from near-shore reefs in the remote North-western Hawaiian Islands. Such debris has posed a significant entanglement problem for the area’s wildlife including the endangered Hawaiian monk seal. The clean up of marine debris is a positive example of increasing public awareness by offering the public constructive opportunities to help solve a problem.

Other efforts to address marine debris pollution include the international regulations governing the discharge of garbage from ships (i.e. Annex V to the 1973 International Convention for the Prevention of Pollution from Ships – the MARPOL Convention) have been strengthened by various amendments and been adopted by additional nations and by CCALMR. Between January 1987, when Annex V of MARPOL entered into force, and 1992, the number of signatory nations increased from 31 to 59. Since 1992, 44 additional nations have signed, bringing the total number of parties to 103 as of this writing. In other respects, however, the past decade has seen a marked decline in governmental efforts to address marine debris pollution, even as NGOs have increased their efforts to support voluntary clean-ups. For example, international funding was abruptly ended in 1998 for a solid waste management project aimed in part at establishing ‘special area’ status for the Wider Caribbean Region under MARPOL Annex V. With loss of that project, special area status and attention to marine debris in this area has stalled. Similarly, funding for the only national level US program designed to address the full range of marine debris research and management issues (i.e. the US Marine Entanglement Research Program in the National Oceanic and Atmospheric Administration) was eliminated in 1996. With the elimination of this program, most of the research in the United States directed at assessing and monitoring the impact of marine debris on marine life ceased.

Outstanding problems

Despite efforts since the 1980s, many problems related to marine debris pollution remain. Since adoption of Annex V, there is little evidence that the impacts or amounts of marine debris have actually declined but the data required to make this evaluation are lacking. Among the few examples where impacts may have declined are the entanglement rates for northern fur seals on the Pribilof Islands and Antarctic fur seals at South Georgia Island. In other cases, however, there appear to be no apparent changes. Routine efforts since the early 1980s to disentangle Hawaiian monk seals and to remove derelict fishing gear from their pupping beaches in the North-western Hawaiian Islands have found no apparent decline in either the number of entanglements or the amounts of such material removed (Henderson in review.) Unfortunately, government support for studies to assess and monitor impacts on marine life have declined in recent years, preventing progress toward resolving key questions concerning marine debris impacts at population levels and the proportion of animals that die at sea compared to those seen on land.

Although the number of parties to MARPOL Annex V has increased steadily, implementation and enforcement of its provisions have been problematic in most areas. Flag-state enforcement of violations reported by other parties has been poor and several special areas identified in the Annex have yet to become effective because requirements for garbage reception facilities in ports have not been met. Developing effective, sustainable programs to encourage participants in fishing industries to properly dispose of fishing gear has been a particular problem.

Recommendations

Further actions to address marine debris pollution can be divided into three categories: clean-up, prevention, and research. With regard to clean-up work, NGOs have been effective in organising local programs and enlisting the help of millions of volunteers and industry to periodically clean up beaches and other coastal areas. Government agencies at all levels should continue to encourage and assist these efforts wherever possible. In recent years, underwater clean-ups, such as the multi-year program organised by the Ocean Conservancy and the National Marine Fisheries Service to remove net debris from reefs in the North-western Hawaiian Islands, also have proved possible and helpful. To expand such efforts, government agencies should provide funding and other support, to develop and test new underwater clean-up techniques, such as grappling trawls, to remove lost and discarded gillnets and fishing traps from fishing grounds or other areas where such materials may accumulate. Because entanglement risks appear to be greatest for