Vaquita on the verge of extinction

CIRVA (Comité Internacional para la Recuperación de la Vaquita) met again in April 2017, just 5 months after the committee’s last meeting. The meeting report, which was officially released today at the IWC Scientific Committee meeting in Slovenia, points out that the vaquita is on the verge of extinction. Five dead vaquitas were recovered in March and April 2017. It was confirmed that at least three of these animals had been killed in gillnets (the other two were perinatal animals). CIRVA concluded that despite the enormous efforts by the government of Mexico, illegal fishing activity for totoaba has continued at a very high level. Thus far in the present fishing season, Sea Shepherd Conservation Society (SSCS), as part of a multi-institutional program with the government of Mexico to remove fishing gear, has retrieved over 150 active totoaba gillnets. SSCS also has observed a considerable amount of illegal fishing activity. CIRVA welcomed the Government of Mexico’s “Agreement Prohibiting the Use of Gillnets for Commercial Fishing in Waters of Federal Jurisdiction in the Northern Gulf of California.” However, the Committee reiterated its previous recommendation that the sale or possession of gillnets on land and at sea should be illegal in the area of the current gillnet ban and on adjacent lands.  

The full report can be read here

Posted in Critically Endangered, entanglements, Vaquita | Leave a comment

Lost Indus dolphins in the Beas River, India

Indus River dolphins (Platanista gangetica minor) inhabit the Indus River system of Pakistan and India.  Over the last 150 years, numerous irrigation barrages (gated dams) that divert river water into canals have been constructed in this system.  As a result, the range of Indus dolphins has declined by approximately 80% since the 1870s due to habitat fragmentation and reduced river flows.  Survey results suggest that the entire subspecies numbers well under 2000 individuals and it is listed as Endangered on the IUCN Red List.  Indus dolphins persist in 5 barrage-partitioned sections of the Indus mainstem in Pakistan, and a tiny isolated population persists in the Beas River in India, some 600km away from all the others.

The current distribution of Indus River dolphins. The Beas River is located on the far eastern side of this map (segment 17 of the system). Reproduced from Braulik GT, Arshad M, Noureen U, Northridge SP (2014) Habitat Fragmentation and Species Extirpation in Freshwater Ecosystems; Causes of Range Decline of the Indus River Dolphin (Platanista gangetica minor). PLOS ONE 9(7): e101657. https://doi.org/10.1371/journal.pone.0101657

As recently as last year, there were estimated to be between 18 and 35 Indus dolphins in the Beas River above Harike Barrage (Shahnawaz Khan 2016).  During periods of low flow, they have been observed to move downstream into the head pond above the barrage, which includes the Harike Wildlife Sanctuary.  On 27th March, 2017 the flow of the Beas River was virtually stopped in order to allow maintenance works to the barrage and canal gates.  River flow dropped from approximately 30,000 cubic feet per second (cusecs) to just 1,100 cusecs.  Many aquatic animals perished including freshwater turtles and fish.  An extensive search was made for the resident river dolphins, but only 4 have been located to date.  It is feared that the remaining dolphins became stranded and died in shallow pools, or slipped through the barrage into downstream areas near the India-Pakistan border where the river is almost always completely dry and where they will also eventually perish.  However no dead dolphins have yet been reported despite the extensive search.

This sad situation demonstrates the vulnerability of river dolphins that today live only in heavily managed rivers.  If the needs of wildlife are not considered in the management of rivers and barrages, more environmental catastrophes can be expected.

References

Khan, M. S. 2016. Abundance and distribution modelling for Indus river dolphin, Platanista gangetica minor, in Beas River, India. Current Science 111 (11) 1859-1864.

Posted in Dams, Endangered, Freshwater Dolphins, South Asian River dolphins, Unusual mortality | Leave a comment

Distribution and abundance of cetaceans in the European Atlantic – SCANS-III

A large-scale international survey for whales, dolphins and porpoises in European Atlantic waters has estimated a total of more than 1.5 million cetaceans in the study area in summer 2016. This survey is the third in a series that began in 1994 (SCANS) and continued in 2005 (SCANS-II) (SCANS stands for Small Cetaceans in the European Atlantic waters and North Sea). It was a collaboration among scientists in nine countries bordering the Atlantic and was coordinated by the Sea Mammal Research Unit, University of St Andrews, in Scotland, UK.

Observer Lea David looking through the bubble window of the SCANS-III survey aircraft. Photo credit Nino Pierantonio

Three ships and seven aircraft surveyed an area of 1.8 million km2 from the Strait of Gibraltar in the south to Vestfjorden, Norway in the north, over a 6–week period in summer 2016. The data were collected using line transect sampling methods designed to allow correction for animals missed on the transect line, without which estimates of abundance would be negatively biased. This was achieved using two semi-independent teams of observers on the ships and using the “circle-back” aerial survey method, in which the aircraft flies a loop to re-survey the same piece of transect.

White-beaked dolphins seen during SCANS-III aerial surveys. Photo credit: Hans Verdaat

Teams of observers searched along 60,000 km of transect line, recording thousands of groups of cetaceans from 19 different species. The most abundant species were harbour porpoises (467,000 animals), common dolphins (468,000) and striped dolphins (372,000), with a further estimated 158,000 either common or striped dolphins. Numbers of other species of dolphins estimated to be present were 28,000 bottlenose dolphins, 36,000 white-beaked dolphins and 16,000 white-sided dolphins. Deep-diving whales that feed primarily on squid in offshore waters were estimated to number 26,000 long-finned pilot whales, 14,000 sperm whales and 11,000 beaked whales of several different species. Of the filter-feeding baleen whales, 15,000 common minke whales and 18,000 fin whales were estimated to be present.

Observer Linn Lehnert entering data. Photo credit Steve Geelhoed

For harbour porpoises, white-beaked dolphins and minke whales in the North Sea, the series of abundance estimates shows no statistical support for a change, in other words, a stable trend in abundance over the 22 years covered by the surveys. For other species in the region, at least one more survey will be needed in the future before any trend can be assessed. Results indicate that the shift seen in harbour porpoise distribution in the North Sea from the northwest in 1994 to the south in 2005 was maintained in 2016, with highest densities found in the southwestern North Sea, and north and east of Denmark.

The new estimates of abundance will be integral to cetacean assessments undertaken for OSPAR ’s Quality Status Report (OSPAR is the mechanism by which 15 Governments & the EU cooperate to protect the marine environment of the North-East Atlantic.), and for the EU Marine Strategy Framework Directive assessments of Good Environmental Status. The results also make it possible to determine the impacts of bycatch and other anthropogenic pressures on cetacean populations, fulfilling a suite of needs under the EU Habitats Directive and the UNEP Agreement on the Conservation of Small Cetaceans in the Baltic, North-east Atlantic, Irish and North Seas (ASCOBANS).

The full report can be read here.

Posted in Uncategorized | Tagged | Leave a comment