Overexploitation, habitat loss, degradation and fragmentation leading to loss of aquatic, terrestrial and avian migratory species
Millions of iconic migratory animal species are in peril because of anthropogenic pressures, said a report released at the start of the 14th Conference of Parties (COP14) to the Convention on the Conservation of Migratory Species (CMS) of Wild Animals in Samarkand, Uzbekistan on February 12, 2024.
The State of the World’s Migratory Species has revealed that aquatic ecosystems are the worst-hit — 97 per cent of migratory fish listed under CMS face the risk of extinction. These fish species have seen a steep decline in relative abundance in the past 50 years on average.
Twenty-eight of the total fish species facing threats are categorised as ‘Critically Endangered’ under the International Union for Conservation of Nature (IUCN)’s Red List.
The CMS is a global treaty among countries that addresses conservation and effective management of migratory species, whose range is spread across human-created political boundaries.
The evidence presented by researchers show that a significant proportion — 44 per cent (520 species) — of CMS-listed species are undergoing population declines. One in five CMS species face risks of extinction.
As far as CMS appendices go, 82 per cent (142 out of 180 listed species) of Appendix I species face threat of extinction, while 76 per cent (137 species) show declining population trends.
Eighteen per cent of Appendix II species face extinction threats and almost 42 per cent (477 species) showing declining population trends.
The two appendices of CMS cover diverse species of terrestrial and aquatic mammals, reptiles, fish, birds and insects.
The authors of the report drew extinction risks and abundance trends based on data sourced from the IUCN Red List assessment and Living Planet Index (managed by the Zoological Society of London, in collaboration with World Wildlife Fund for Nature).
According to the report:
There are 4,508 species that are considered to be migratory, have had a global IUCN Red List assessment and occur in multiple Range States (non-endemic species). Of these, 3,339 (74 per cent) are not currently listed in the CMS appendices.
Of the 3,339 non-CMS species, 277 (eight per cent) are considered to be ‘Globally Threatened’ and another 122 species (four per cent) have been categorised as ‘Near Threatened’. The report recommends considering 399 Globally and Near Threatened species to meet the CMS criteria listed in the appendices.
Eighty nine per cent of Appendix I species are impacted by overexploitation, while 86 per cent are impacted by habitat loss, degradation and fragmentation. The figures for Appendix II species are 68 per cent and 74 per cent respectively.
Three of four CMS-listed species are impacted by habitat loss, degradation and fragmentation while seven of 10 such species are victims of overexploitation.
The report lists bycatch as one of the overexploitation factors and as the most concerning threat to seabirds, particularly albatrosses and petrels which are estimated to be killed in the hundreds of thousands due to getting caught in longline and gillnet fisheries.
The report estimated that illegal killing claims about 11 and 36 million birds in the Mediterranean region alone, while 1.7 to 4.6 million birds are estimated to be killed in the Arabian Peninsula, Iran and Iraq.
Overfishing was also identified as significant threat to slow-growing sharks, rays and chimaeras. The report estimated that migratory shark zones were exploited by global industrial fishers. Global populations of oceanic shark and ray species experienced a 71 per cent decline from 1970, an 18-fold spike in fishing pressure.
Agriculture, aquaculture, noise and light pollution, climate change, use of pesticides, natural system modification, non-timber crop production, invasive species, mining, and others have also been included under the threat category.
The report noted:
The Serengeti-Mara ecosystem in the United Republic of Tanzania and Kenya is experiencing significant pressure from the expansion of agriculture, settlements, roads and fences. This affects the quality and availability of habitat for some of the world’s largest free-ranging populations of migratory ungulates, including Blue Wildebeest (Connochaetes taurinus) and Plains Zebra (Equus quagga), which support populations of CMS-listed apex predators including Cheetah (Acinonyx jubatus), Lion (Panthera leo) and African Wild Dog (Lycaon pictus).
Infrastructure development barriers like dams and river infrastructure prevent migratory fish from reaching their spawning grounds, alter water flow regimes and prevent juvenile fish from dispersing, the report states. The phenomenon was observed highest in North America, South America, East-Asia, Europe and Indian subcontinent.
On land, long-range movements of Mongolian gazelles (Procapra gutturosa) have reduced due to increased road traffic. While disturbance from industrial energy development has prevented mule deer (Odocoileus hemionus) from synchronising their migration with the emergence of spring vegetation.
In terms of climate change, the report noted that the phenomenon’s effects are experienced by many migratory species; but not all will be able to adapt to climate change. For instance, increasing sea surface temperatures, with sea ice shrinking, is expected to reduce the habitat range of the narwhal (Monodon monoceros), a species found in Mideast and Southeast Greenland that tends to avoid sea water temperatures above 2 degrees Celsius (ºC) and depends on sea ice for foraging.
Sharp rise in summer temperatures up to 6.3ºC have been observed that is a high deviation from species’ preferred thermal range.
The report noted that light, noise, plastic and chemical pollution such as oil spills and contamination such as lead, mercury, agricultural pesticides also resulted in increased number of birds dying of collisions, affect their breeding and non-breeding places and foraging locations.
Noise pollution underwater from shipping vessels results in less feeding among species such as harbour porpoises (Phocoena phocoena) and killer whales (Orcinus orca). Foraging bats, which using echolocation, are also facing impacts of noise pollution as anthropogenic noise pollution is affecting their hunting efficiency.
The report stated that 58 per cent of the monitored sites recognised as being important for CMS-listed species are experiencing unsustainable levels of human-caused pressure. The CMS has identified 16,335 Key Biodiversity Areas, which are listed according to the breeding, non-breeding, feeding or stopover sites used by the species across landscapes and seascapes.
As many as 9,469 sites crucial for CMS-listed species are noted to experience unfavourable to very unfavourable levels of pressures, namely hunting and collecting terrestrial animals, recreational activities, livestock farming and ranching, and non-timber crop production.
The authors urged reducing overexploitation and addressing incidental catch of non-target species, mitigating unsustainable killing, hunting and trading of migratory birds by coordination between countries and use of tracking technologies.
“Net illumination has emerged as a promising mitigation tool in gillnet fisheries to reduce the incidental catch of small cetaceans, birds and turtles without affecting target catch or value,” the report said.
The report called for urgent steps for protection and conservation of key habitats for migratory species, in addition to avoiding, minimising and restoring the migratory routes and habitats.
The authors noted that though 70 CMS species showed deterioration in their conservation status, 14 species had shown improvement in conservation status over the past five decades.
For instance, fragmented habitat restored by removing fences in the Okavango Delta in Botswana enabled the movement of Burchell’s zebra (Equus burchelli), historically known for migration. The species’ traditional movement was restored after 30 years.
In another case, the report noted that the Altyn Dala Conservation Initiative in Kazakhstan of Central Asia played a crucial role by creating a refuge for the Saiga antelope (Saiga tatarica). The move of reviving steppes and wetland habitats enabled the increase from 50,000 individuals in 2006 to over 1.3 million individuals in 2022, thereby bring the migratory species back from the verge of extinction.
Inger Andersen, United Nations (UN) under-secretary-general and executive director, UN Environment Programme, said in her foreword to the report, “Given the precarious situation of many of these animals, and their critical role for healthy and well-functioning ecosystems, we must not miss this chance to act — starting now by urgently implementing the recommendations set out in this report.”
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