The immense scale of the Pacific Ocean, at 165 million square kilometres, inspires awe and fascination, but for those who inhabit the 22 Pacific island countries and territories, it is the very source of life. Without it, livelihoods and economies would collapse, hunger and ill-health would become endemic and human survival would be threatened.

But as populations rapidly escalate, the sustainable future of this vast ecosystem hangs in the balance, while the pressing need for economic development in a region of Small Island Developing States competes with the urgency of combating climate change and stemming environmental loss.

In a message to the global community on Saturday, designated by the United Nations as World Ocean Day, U.N. Secretary-General Ban Ki-moon urged nation states to “reverse the degradation of the marine environment due to pollution, overexploitation and acidification.” Nowhere is this triple threat more evident than in the waters of the Pacific.

The largest ocean in the world, it covers one third of the earth’s surface and an area more expansive than the total of all its landmasses, while its natural processes determine the global climate.

The ocean’s health is crucial to the food security of the region’s population of 10 million, whose annual fish consumption is three to four times the world average. For the rural majority, 60 to 90 percent of sea harvests are used for sustenance, while 47 percent of households depend on fishing as a main source of income.

At the regional level, the commercial fisheries sector – dominated by the tuna industry – contributes to approximately 10 percent of gross domestic product (GDP) and 80 percent of all exports in one quarter of Pacific Island states.

However these coastal fisheries are now recognised as the most threatened by over-exploitation, pollution and climate change.

In Melanesian countries like the Solomon Islands – an archipelago nation of more than 900 forest-covered islands, lying just east of Papua New Guinea - population growth, which is 2.7 percent per year, is putting major pressure on resources. It is estimated that about 55 percent of Pacific Island nations have over-exploited coral reef fisheries.

Concerns about marine pollution have been exemplified by the ‘Great Pacific Garbage Patch’, also known as the world’s largest landfill, a massive swirling gyre of 3.5 million tonnes of waste in the North Pacific Ocean.

Joeli Veitayaki, head of the School of Marine Studies at the University of the South Pacific in Fiji, believes that “waste management is the biggest issue.”

“In some of the main population centres, there is no waste collection or treatment systems, while in others inappropriate methods are used. Communities and civil authorities are treating non-biodegradable and highly toxic waste as they have treated biodegradable waste,” he told IPS, adding, “Waste oil from some commercial operators is being disposed of in environmentally damaging ways that cause irreparable damage.”

The main sources of marine pollution are sewage, urban, agricultural and industrial run-off and plastic waste. In populated coastal island areas, plastic bags, containers and bottles are highly visible, suffocating marine habitats. Studies have revealed that fish in the North Pacific region are ingesting between 12,000 to 24,000 tonnes of plastic per year.

With UNICEF reporting that the average improved sanitation coverage in Oceanic countries is less than 50 percent, sewage remains a significant threat to the health of human and marine life. Up to 25 percent of rural communities practise open defecation and piped untreated sewerage from many urban centres is discharged directly into the sea.

Future challenges to the ocean will come from climate change as increasing sea temperatures and ocean acidity are expected to drive alterations in fish populations and lead to the breakdown of coral reef systems that are important harbours of marine biodiversity.

Marine life has already been impacted by factors ranging from destructive fishing to pollution. According to the International Union for the Conservation of Nature (IUCN)’s Red List of Threatened Species, Papua New Guinea has incurred the highest losses in the region, with a total of 196 endangered marine species, including 157 species of coral, 20 species of sharks and four species of turtles. This year the Secretariat of the Pacific Regional Environment Programme (SPREP) launched a regional marine species conservation programme to improve protection of dugongs, marine turtles, whales and dolphins.

Pacific Islanders who have maintained a close cultural, social and economic relationship with the sea for thousands of years acknowledge the imperative of preserving the ocean for future generations.

In 2010, recognising that “no single country in the Pacific can by itself protect its own slice of oceanic environment”, the Pacific Islands Forum launched the regional Pacific Oceanscape initiative, a strategic framework to improve ocean governance.

“So far no (Pacific Island) country has formulated a national ocean policy to guide the action and activities in its maritime zones,” Veitayaki pointed out.

But action at the national level has included the acclaimed development of Marine Managed Areas (MMAs) that incorporate customary traditions of resource access and governance. There are approximately 1,232 active MMAs in the Pacific region covering 17,000 square kilometres, with 10 percent being designated as ‘no-take zones.’

Significant Marine Protected Areas (MPAs) include the Phoenix Islands Protected Area established by the government of Kiribati – a low-lying nation in the Central Pacific Ocean comprising a coral reef and 32 atolls – and the one-million-square-kilometre Cook Islands Marine Park, currently the world’s largest.

The century ahead will witness increasing human stresses on the Pacific Ocean as islanders with limited land areas and resources turn to the sea in search of ways to boost economic development.

Burgeoning deep sea mineral exploration projects, such as the Solwara 1 project in the vicinity of Papua New Guinea, has galvanised regional debate about the potential economic windfalls versus long term environmental impacts, the dearth of knowledge about deep sea marine biodiversity and the present lack of national governance and legislative frameworks to regulate commercial activity on the seafloor.

The future success of ocean management is dependent on reliable marine scientific data and building national capacities that enable policy implementation.

“Lack of up to date data is a major hindrance as we are always reacting to problems, such as depleting fisheries, damaged coral reefs and high pollution levels,” Veitayaki explained. “If assessments were better, management could be more preventive.”

Capacity for implementation, which he acknowledges has always been a major challenge for developing nations in the region, whether in terms of financial, technical or human resources, will demand more innovative and collaborative approaches by the diverse Pacific Island peoples whose survival depends on a healthy ocean.