Potential new breeding area revealed for critically endangered Baltic Sea harbour porpoises

The critically endangered vaquita (see news item below) is not the only cetacean seriously threatened by gillnet entanglement. The small subpopulation of harbour porpoises (Phocoena phocoena) in the Baltic Sea has been drastically reduced, initially by large historical commercial catches in the Danish Straits and more recently by incidental mortality in fishing nets, primarily set and drifting gillnets. Other threats probably exist but are not well understood. Baltic Sea harbour porpoises are red-listed as Critically Endangered (click to see assessment).

The need for improved methods of collecting data on Baltic Sea porpoise numbers and range, and how these change over time, led to initiation of the Static Acoustic Monitoring of the Baltic Sea Harbour Porpoise (SAMBAH) project. which involved all EU countries bordering the Baltic Sea.  The overall objectives of the project were to develop and implement a best practice methodology and provide data for reliably assessing porpoise distribution and habitat.

Porpoise echolocation signals were recorded by acoustic data loggers called C-PODs deployed at 304 locations in waters 5-80 m deep throughout the Baltic Sea, making it one of the largest projects of its kind in the world – a huge collaborative effort. The project is now complete and the results have been released.

The number of harbour porpoises in the Baltic Sea was estimated as 447 (95% confidence interval 90–997). Seasonal distribution maps (see below) show a clear spatial separation of populations in the Baltic Proper and in the Western Baltic during May-December when the porpoises mate, give birth and nurse their calves. Spatial modelling of the acoustic data revealed a major breeding area of the Baltic Proper population around the Midsjö banks southeast of Öland, where the presence of porpoises had been virtually unknown previously.

Image Caption: Dots indicate positions of acoustic data loggers (C-PODs) that recorded harbour porpoise echolocation signals in January-April, and May–December 2011 and 2012, combined. The line indicates the likely seasonal division between the population in the Baltic Proper and porpoises in waters to the west.

The combination of the new (albeit very imprecise) population estimate and the new information on porpoise distribution in space and time within the Baltic is expected to enable dedicated conservation action in areas where it is most needed. Also, the methodologies developed by the project offer new possibilities for assessing porpoise densities elsewhere using passive acoustics.

 


New evidence that Mexican authorities are not adequately enforcing fishing regulations to protect vaquitas

Mexico’s endemic Gulf of California porpoise, the vaquita (Phocoena sinus), is the most endangered marine mammal species in the world.

A vaquita that died in a gillnet – note the markings left by the net on the animals face.

In that context, the CSG chairman has just received a set of photographs taken on 5 December 2014 over the Vaquita Refuge (see polygonal area in map below). In total, 90 pangas (gillnet fishing boats) were photographed inside the Refuge. Seventeen individual gillnetting “activities” are visible on the aerial imagery. Of these, three are pangas deploying nets, ten are pangas recovering nets, and four are nets “soaking,” unattached to a vessel. Although some pangas appeared to be respecting the Refuge and were observed to the south and east of the boundary, 90 were counted within the vaquita habitat that is supposed to be protected. This imagery and associated observations show that even within the Vaquita Refuge, gillnet fishing continues and the vaquita will continue to decline unless decisive action is taken immediately by Mexican authorities.

Google Earth image showing the location of fishing vessels and gear inside the Vaquita Refuge on December 5th, 2014. Red circles and white lines denote the reserve boundary.

To download the google earth image files shown above in .kmz format, click here.

Below is a selection of aerial photographs of individual fishing vessels and their gear (photos are from location 4, 25, 29, and 11 in the google earth image above)

To read more about the background and history of vaquita conservation click here
For recent vaquita news items showing the progression of conservation efforts see below:


Bangladesh Declares a New Marine Protected Area For Dolphins, Whales, Sharks, and Sea Turtles

On 27 October, 2014, the Government of Bangladesh signed into law the country’s first Marine Protected Area, the ‘Swatch of No Ground’ (SoNG), designed to safeguard whales, dolphins, sea turtles, sharks, and other oceanic species.  The SoNG MPA spans 1,738 km2 including waters at the head of the submarine canyon from which it gets its name as well as coastal waters offshore of the world’s largest mangrove forest: the Sundarbans.

The Bangladesh Cetacean Diversity Project has worked with the Government of Bangladesh since 2004 to ensure the long-term protection of cetaceans through collaboration with local communities. During the course of this work, large numbers of Irrawaddy dolphins, finless porpoises, Pacific humpback dolphins, Indo-Pacific bottlenose dolphins, pan-tropical spotted dolphins, and spinner dolphins were observed, as well as what may prove to be a resident population of Bryde’s whales.

It is hoped that the creation of the SoNG MPA—which borders the territorial waters of India—will promote discussions on a trans-boundary protected area, as neighbouring waters likely contain similar species richness and the cetaceans on both sides of the border face the same threats such as entanglement in fishing gear and climate change.


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