A 2008 whale mass stranding in Madagascar linked to sonar mapping for the first time

An alien environment for a deep diving species. Photographer: Tim Collins

In 2008, approximately 100 melon-headed whales stranded in the Loza Lagoon system in Madagascar. The response effort was multi-faceted and included local people, government officials, conservation organisations and marine mammal experts. A significant amount of information was collected and, several years later, the International Whaling Commission facilitated a review of the circumstances of the stranding in conjunction with the US Marine Mammal Commission, the US National Oceanic and Atmospheric Administration, the US Bureau of Ocean Energy Management, ExxonMobil Exploration and Production (Northern Madagascar) Ltd, the International Fund for Animal Welfare, the Wildlife Conservation Society and the Government of Madagascar. An independent scientific review panel (ISRP) of five experts was invited to conduct a formal examination of the available facts.

Capturing a whale in a mangrove channel. Photographer: Yvette Razafindrakoto

The ISRP concluded that the mass stranding was primarily triggered by acoustic stimuli, more specifically, a multi-­beam echosounder system operated by a survey vessel contracted by ExxonMobil Exploration and Production (Northern Madagascar) Limited. According to the final report, this is the first known marine mammal mass stranding event of this nature to be closely associated with high‐frequency mapping sonar systems. Based on these findings, there is cause for concern over the impact of noise on marine mammals as these high‐frequency mapping sonar systems are used by various stakeholders including the hydrocarbon industry, military, and research vessels used by other industries.

Initial strandings at Antsohihy were the subjects of huge fascination, and were brought into town for inspection by the local government veterinarian. Photographer: Unknown local resident

Links to the report, which became available on 25th September 2013 and the associated material considered by them can be found at http://iwc.int/2008-mass-stranding-in-madagascar

Click Here for the full press release issued by WCS and IFAW.

First gray whale seen in the southern hemisphere

Written by Dr Simon Elwen, of the Namibian Dolphin Project

On the 4th of May 2013, marine tour operators working in Walvis Bay, Namibia, reported an ‘odd looking whale, possibly a gray whale’ to local researchers running the Namibian Dolphin Project (NDP). A few years ago, the presence of a North Pacific gray whale in the South Atlantic would have been dismissed out of hand, but the sightings in 2010 of a gray whale in the Mediterranean has changed ideas of what is possible. Analysis of photographs were conclusive, and confirmed that the animal was indeed a gray whale (Eschrichtius robustus). This is the first confirmed record of the species from the Southern Hemisphere that we know of and certainly the first in the South Atlantic.

Gray whale (Eschrichtius robustus) sighted in Walvis Bay, Namibia in 2013

A skin sample has been collected from the Namibian animal. We have no way of knowing the route followed by the whale to get to Namibia, but it seems most probable that it came via the North Atlantic, having arrived there via either the Northwest Passage across North America or the Northeast Passage across Eurasia. Climate change and specifically the reduction in ice coverage in the Arctic is making sightings such as this one less improbable.

Yangtze finless porpoise is listed as Critically Endangered

The Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis), the world’s only freshwater porpoise, has been upgraded to Critically Endangered on the IUCN Red List of Threatened Species. This follows the recent probable extinction of the other cetacean once found in China’s Yangtze River system, the Yangtze River dolphin or baiji (Lipotes vexillifer). The change in threat status (it was previously classified as EN) is based on analysis of data for 279 stranded porpoises collected from the middle and lower reaches of the Yangtze River from 1978 onwards, which reveal that the porpoise population is experiencing an accelerating decline, and predict a further population decline of >80% within three generations.

Recent survey results from late 2012 suggest that the porpoise population in the main Yangtze channel has almost halved since the previous survey in 2006, with initial estimates suggesting that there are now only around 500 individuals left in the mainstem compared to over 1,100 six years earlier. The primary drivers of this decline are still not clear because of the range of harmful anthropogenic factors operating in the Yangtze ecosystem, although ship collisions, by-catch in legal and illegal fishing gears, reduction of fish prey base, habitat degradation, and the effects of pollutants are all likely to play a role.

To read the full assessment on the Redlist, click here

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