Thursday, April 2, 2015

New paper provides evidence that critically endangered Taiwanese white dolphin is distinct, endemic subspecies

It was already clear that the pink-coloured dolphins living off Taiwan’s west coast were different from other nearby populations of the same species (Sousa chinensis, also known as the Indo-Pacific humpback dolphin). But a new paper has now revealed that the Taiwanese population also meets the criteria for being recognised as a subspecies.

The authors, John Wang, Shih Chu Yang and Samuel Hung*, who have been researching the critically endangered Taiwanese dolphins since 2002, propose a new scientific name for them - Sousa chinensis taiwanensis, to recognise their special local status.

The findings are the result of a study that compared pigmentation patterns in the Taiwanese population with those of neighbouring populations in the Jiulong River Estuary and the Pearl River Estuary, in the coastal waters of China. Dolphins in all three populations are born grey and gradually become pink or white with age, with the grey pigmentation becoming spots, and sometimes fading away altogether. However, examination of the spotting on individuals shows that the patterns on dolphins from the Taiwanese population are distinct from those in the other two regions.
In such situations, if at least 75% of the population is distinct from more than 99% of other provisional populations, it is commonly accepted as a subspecies. The study found that 94% of the Taiwanese population could be seen to be different from more than 99% of the other two populations, easily meeting this criterion. Further evidence of their uniqueness includes behavioural differences between the Taiwanese dolphins and other populations, and the fact that they are geographically isolated by the deep waters in the middle of the Taiwan Strait; Sousa chinensis are usually only found in shallow, coastal waters.

Recognition as a subspecies would make protective action for the Taiwanese dolphins even more urgent than previously thought, because their extinction would mean not only that Taiwan would lose this charismatic and ecologically important creature from its waters, but also that the world would lose a kind of dolphin that exists nowhere else. This subspecies may even be on a path to becoming a distinct species if the separation is sufficiently long to allow greater differentiation.
Local non-governmental organisations continue to call for official government recognition of the dolphins’ habitat, and for long-delayed action to reduce the five key threats to their survival – bycatch in fishing equipment, air and water pollution, noise and disturbance, loss of freshwater flow into their habitat, and land reclamation. Little has been done to address these threats over the thirteen years that researchers and concerned local groups have been drawing attention to them, and they continue on a trajectory towards extinction.

The full scientific paper about the subspecies recognition can be accessed freely (without subscription) at the website of the journal Zoological Studies at http://www.zoologicalstudies.com/content/54/1/36.

*While Hung has contributed to research on the Taiwanese population, he has also spent many years researching the Pearl River Estuary population from his base in Hong Kong.

Thursday, August 7, 2014

100 dolphin vision vs 100 year extinction: Taiwan’s choice for white dolphins

Following a workshop in Taiwan in May, where experts proposed a recovery target of 100 for the critically endangered population of Taiwanese white dolphins, new research has painted a clearer picture of the alternative: their path towards extinction.

In a paper published recently in the journal Endangered Species Research, Claryana Araújo and colleagues describe what is likely to happen to the dolphins, currently numbering no more than 74, in a range of scenarios that could occur over the next 100 years.

Using a simulation programme, they first show what is likely to happen to the population if there is no change to the current serious threat of injury and entanglement in fishing gear – the subject of the May workshop. According to the results, in this baseline scenario the population declined and, in 66% of the simulations, became extinct in 100 years or less.

Unsurprisingly, when the researchers then looked at other future scenarios in which the impact from fishing gear increased and the size and quality of the dolphins’ coastal habitat declined, the likelihood of the their extinction within 100 years also increased, with up to 92% of the simulations giving this result.

Araújo said, “The results of this study confirm the very delicate situation of the Taiwanese white dolphins, and that the population is declining.”

Indeed, the fact that the dolphins are critically endangered is already no longer a matter of debate. However, the results of the study confirm that simply stopping the situation from becoming worse will not be enough to save them: the existing threats need to be reduced and, where possible, removed.

This message will be important as the government sets about responding to the situation. Thanks to campaigning by Taiwanese NGOs, the dolphins are already considered in Environmental Impact Assessments for major new projects. Now, with the proposed designation of part of their habitat as ‘Major Wildlife Habitat’ under the Wildlife Conservation Act in May, there could soon be an even stronger mandate both at the national and local government levels to address their plight.

A rapid, coordinated effort will be needed to address the existing threats, which, in addition to fishing gear, also include water and air pollution, underwater noise, land reclamation, and the loss of freshwater flowing into the dolphins’ habitat, due to the damming and diversion of rivers along western Taiwan.

Compared to the threat from fishing gear, less information is available on these other factors, which, the researchers point out, means that they probably underestimated their impact in the study. This suggests that the danger to the dolphins may be even greater than the results show, and their extinction more imminent if action is not taken.

“Based on the data available,” said Araújo, “the mortality due to fisheries interactions is the most serious, immediate threat for this population. And even with uncertainties regarding the level of the other threats and the exact mortality rate, the population shows a decline. This tells us that urgent conservation actions are needed.”

Reducing the number of dolphin deaths from fisheries interactions will not be as straightforward as simply monitoring fishing boat activities and enforcing penalties for catching dolphins.

According to the researchers, thousands of fishers, many of them small scale artisanal fishers, operate along Taiwan’s west coast, making it impossible to effectively observe all their activities and prevent dolphin deaths.

The only feasible solution would be to implement a total ban on gill nets and trawlers within the dolphins’ habitat, they say, echoing the findings of the May workshop.

The workshop also explored ways to work with fishers and fishing authorities to achieve adequate protection for the dolphins while also addressing the issue of overexploitation of fish, and working towards more sustainable long-term fisheries.

Saturday, May 24, 2014

Interview with Dr Louella Dolar on protected areas, fisheries and fishing communities in the Philippines


Dr Louella Dolar, of Silliman University in the Philippines, talks about the establishment of protected areas with restrictions on fishing activities, and how this has helped marine ecosystems recover and brought benefits to fishers in the Philippines.

This interview took place at the workshop on Sustainable Fisheries and the Conservation of the Taiwanese White Dolphin, from 28 April to 2 May, 2014, in Taiwan.

Saturday, May 3, 2014

Dr Peter Ross: three recommendations on Taiwanese white dolphin fisheries impacts


Dr Peter Ross* on the three recommendations of the international expert group after a week-long workshop on fisheries impacts on the critically endangered Taiwanese white dolphin population.

*Chair of the Eastern Taiwan Strait Sousa Technical Advisory Working Group and Program Director at the Vancouver Aquarium in Canada.

Taiwan’s White Dolphins and fisheries can benefit from dolphin-friendly fishing, says international expert group

Scientists propose target of 100 dolphins by 2030

Taiwan’s critically endangered and biologically distinct White Dolphins (Sousa chinensis) and its fishers could both benefit from a switch to dolphin-friendly fishing gear, concluded scientists at an international workshop yesterday in Taipei.

The workshop participants, from Brazil, Canada, Hong Kong, Mexico, New Zealand, the Philippines, Taiwan, the United Kingdom and the United States, were invited by the Biodiversity Research Centre at Academic Sinica, the Marine Biology and Cetacean Research Center of National Cheng-Kung University, and Matsu's Fish Conservation Union. The workshop was held under the auspices of the Eastern Taiwan Strait Sousa Technical Advisory Working Group, an international group of scientists established in 2007 to provide conservation-based scientific advice to recover the Taiwanese white dolphins.

The Taiwanese white dolphins, which inhabit the nearshore waters of Taiwan’s west coast, number approximately 74 individuals. They face numerous threats, including entanglement in fishing nets, particularly gillnets. Dolphins can drown if they are unable to break free from a net, and such an impact may jeopardize the survival or recovery of the population.

More than 30% of the dolphins bear the scars of previous entanglements, and some dolphins still have nets wrapped around their bodies. This causes terrible suffering and impairs their ability to feed and reproduce.

Workshop participants suggested that Taiwan could set a target to increase the number of dolphins to 100 individuals by 2030.  This would improve the population from the IUCN ‘Critically Endangered’ listing to the ‘Endangered’ listing.

“The Taiwanese white dolphins are suffering from terrible injuries associated with fishing nets. The best hope to reduce this threat, and recover this critically endangered population, would come from banning gill nets in their habitat, and encouraging fishers to switch to more selective fishing gear,” said Dr. Peter Ross, Chair of the Eastern Taiwan Strait Sousa Technical Advisory Working Group and Program Director at the Vancouver Aquarium in Canada.

Switching to alternative, more selective fishing methods can also bring significant benefits to fishers, with recovering fish stocks leading to increased income for fishers.

The international expert group welcomed the recent announcement by the Forestry Bureau that it will soon designate Major Wildlife Habitat for the dolphins.

The expert group encouraged the Forestry Bureau to consider increasing the Major Wildlife Habitat area from Longfeng Harbour (Miaoli County) in the north to Jiangiyun Harbour (Tainan City) in the south, and increasing the offshore boundary to 3 nautical miles from the shore.

The designation of Major Wildlife Habitat represents a management tool, but it will only be meaningful if accompanied by actions to reduce the threat from pollution, freshwater diversions, noise, habitat destruction and fisheries impacts.

Friday, April 18, 2014

Fisheries bycatch must stop to avoid extinction of Taiwan’s humpback dolphins

Fishing activities pose the most serious, immediate and obvious threat to Taiwan’s critically endangered humpback dolphins (Sousa chinensis), but can be addressed most easily, according to researchers.

In a study published in the journal Endangered Species Research, Dr. Elizabeth Slooten and colleagues say that the impact of fishing gear on the small population of dolphins, also known as the Eastern Taiwan Strait (ETS) humpback dolphins, must be reduced in order to avert their extinction.

Taking action to switch to more dolphin-friendly fishing equipment would require short-term investment, but the benefits both for the dolphins and for the fishing industry could be significant and lasting.

There are estimated to be fewer than 75 dolphins in the population, and more than 30% show signs of having been caught in or injured by fishing gear. Some can be seen swimming with lines still attached to their fins and around their bodies, while others bear deep, lasting scars from previous entanglement.

Surveys of fishing activities within their habitat reveal widespread use of the kinds of fishing gear most likely to cause humpback dolphin ‘bycatch’ - death from fisheries interactions. Of most concern are the thousands of gillnets along the west coast of the island, which are designed to catch fish by their gills but are also known to kill humpback dolphins, as well as most other kinds of cetaceans.

One kind of gillnet, called a trammel net, consists of multiple (usually three) layers of netting, some more slack than others, which makes it particularly easy for marine wildlife to become entangled. This is the most prevalent kind of gillnet in the dolphins’ range.

Trawling, another kind of fishing that can cause Sousa bycatch, has been banned in much of the dolphins’ near-shore habitat, but continues illegally nevertheless, often in plain sight.

The study shows that, in order for the population to survive and recover, levels of bycatch must be reduced to less than one dolphin every seven years. It is not known how many dolphins are killed or have a reduced lifespan due to fisheries injuries, but photographic evidence and bycatch reports suggest that the mortality rate is higher than this.

To prevent the extinction of this unique population, the researchers recommend halting the use of gillnets and trawling within the humpback dolphins’ habitat. This would include strict enforcement of the existing trawling ban, and adopting alternative fishing methods which are more selective, and less damaging to cetaceans and other marine life and their habitat.

Converting to these methods will cost money in the short term. But in addition to giving the dolphins a good chance of recovery, the benefits for the fisheries themselves could be significant as populations of higher value fish species recover and grow, the entire ecosystem improves, and the fishing industry becomes more sustainable.
 
The study notes that bycatch is only one of five major threats to the dolphins: habitat loss from land reclamation, pollution, loss of freshwater flow from rivers, and noise and other disturbance, are also contributing to their decline, and all need to be addressed. But in the short term, argue the researchers, because of the immediacy and seriousness of fishing impacts, stopping the use of certain fishing practices would be the ‘single most effective conservation measure for ETS Sousa.’

Wednesday, January 9, 2013

New Taiwan Pink Dolphin paper published

A new paper on mark-recapture analysis of the ETS Sousa (aka Taiwan Pink Dolphin) by John Y Wang et al has been published in the Bulletin of Marine Science (Volume 88 Number 4). The abstract is given below. To access the full paper see the Bulletin of Marine Science website or here.


MARK-RECAPTURE ANALYSIS OF THE CRITICALLY ENDANGERED EASTERN TAIWAN STRAIT POPULATION OF INDO-PACIFIC HUMPBACK DOLPHINS (SOUSA CHINENSIS): IMPLICATIONS FOR CONSERVATION. BULLETIN OF MARINE SCIENCE. 88(4):885–902.
 

John Y Wang, Shih Chu Yang, Pedro F Fruet, Fabio G Daura-Jorge, and Eduardo R Secchi.
 
Abstract
 
Accurate and precise estimates of abundance and survival rates are important for assessing the conservation status of cetacean populations. Mark-recapture analysis of photo-identification data of the critically endangered eastern Taiwan Strait (ETS) population of Indo-Pacific humpback dolphin, Sousa chinensis (Osbeck, 1765), was conducted on data collected between 2007 and 2010 to refine a preliminary, and the only available, abundance estimate for this isolated population (n = 99; CV = 51.6%), as well as to provide survival rates. About 14,000 good quality photographs (about 2100–6300 yr−1) were used to estimate both parameters for marked animals under Pollock’s Robust Design model. The total population size (NT) was determined by correcting for the proportion of the population possessing long-lasting marks (i V ). The annual point estimates were lower, varying from 54 to 74, and had much better precision (CV varied from 4% to 13%) than previous estimates, suggesting that mark-recapture is a suitable method for estimating abundance of this population. These estimates also further supported the precarious state of the ETS population under another criterion of the IUCN Red List of Threatened Species. As expected for long-lived mammals, annual apparent survival rate was high at 0.985 (95% CI = 0.832–0.998). Continuing to monitor the ETS population of humpback dolphins with such high precision and accuracy will allow examination of the population’s trends over time and to better understand its future persistence.