Plight of the Pink Dolphin - Sailors for the Sea

Plight of the Pink Dolphin

By: Kerry Whittaker, PhD a Knauss Marine Policy Fellow Alumni, marine science faculty at Coastal Studies for Girls & adjunct professor at Bowdoin College. | March 3, 2015

Marine Conservation of Small Populations

On this planet there exist pink dolphins. Not just “pinkish,” but bubblegum pink.  And not just a single mutant or ‘pink’ individual among the masses, but an entire species of pink dolphin: Sousa chinensis. Well, to be accurate, only the oldest and wisest of the Sousa chinensis clan exhibit full-fledged pinkness. Younger individuals start out grey, and acquire pink splotches throughout their lives, like badges of honor as they age. Sousa chinensis makes its living along narrow strips of coastline throughout the Indo-Pacific and Asia, traditionally feasting off small fish produced in the nutrient rich ecosystems at river mouths. Some call this species the Indo-pacific Humpback Dolphin, or the Chinese White Dolphin. But trust me: they’re pink and sadly in trouble. One of the challenges of making your living off the productive interface of freshwater and ocean is that humans like to do that too.

The meeting of the river and sea is an estuary.

Across the world, estuaries experience some of the highest levels of human traffic and impact. This is particularly true in Asia and the Indo-Pacific, land of the pink dolphin. Out of the rivers flow nutrients to fuel coastal marine life. Along with those nutrients, all orders of pollution from land-based industry, agriculture, and residences. Estuaries, as access nodes for marine transportation, become hubs of fishing and commercialization. In pink dolphin territory, the goal of expanding cities often takes the form of large-scale shoreline development projects, which wipe out rich coastal ecosystems to make way for man-made peninsulas on which to build new factories. Nutrients from rivers fuel plankton growth, and plankton growth means more fish.  Fish productivity means food for the pink dolphin, but also heavy fishing pressure by humans. In pink dolphin territory, the coasts are packed to the gills with nets and fish farms. All of this human traffic makes it difficult to get around if you’re a dolphin, highly dependent on access to an estuary. As a result, pink dolphin populations are declining: dangerous shipping interactions, pollution, loss of habitat, and entanglement in fishing gear among some of its greatest threats.

I follow rivers

Sousa chinensis’ dependence on rivers plays an interesting role in structuring their populations. They’re found in very patchy distributions all the way from India to the Indo-Pacific, China, and Taiwan; isolated populations huddled around productive estuaries experiencing ever-increasing human impact. Based on behavioral studies, it is thought that the long-distance deep-water travel needed for pink dolphin individuals to migrate between isolated populations is rare. If groups of individuals within a species don’t have the opportunity to interbreed, one might expect that genetic divergence between them will occur. Because of this, researchers believe that pink dolphins are likely comprised of more than one species, but lines between those potential species remain confused due to lack of data.    

Conservation?

What mechanisms are out there to conserve the pink dolphin? For foreign species, the first place to look is usually CITES, or the Convention for the International Trade of Endangered Species. CITES regulates trade of endangered animals through a large international agreement between governments. Some sharks and whales are CITES listed.  So is Sousa chinensis. Unfortunately, CITES regulations only take effect when species are involved in international trade and commerce. For many populations within Sousa chinensis, fishing entanglement, habitat loss, and pollution pose far greater threats than trade.  In January, 2008 an international group of scientists convened to form an Eastern Taiwan Strait Technical Advisory Working Group to provide expert advice and guidance on the conservation of the Taiwanese pink dolphin population.  While this group contains many concerned and knowledgeable parties, it does not have the regulatory authority to enforce a formal conservation management plan for the population. 

For a species facing high levels of threat leading to population declines, one might look to an Endangered Species Act (ESA) listing for protection. The ESA is one of the most powerful environmental laws on the books. However, Sousa chinensis lives in the Indo-Pacific, making an ESA listing limited in regulatory scope. While the U.S. Endangered Species Act consists of some foreign species, the only regulatory foothold for the law in foreign territory is the regulation of U.S. activity. For example, if the U.S. Navy made plans to enter the waters in another nation where a protected species lives and run underwater tests that might affect the species, the Navy would have to conduct a formal consultation, and only be allowed to proceed if their actions were determined to avoid any harm to the species. However no other country is controlled by the ESA listing and would not be required to consider any impact on a protected species. The biggest benefit of putting a foreign species on the U.S. Endangered Species list is to bring international awareness to the species status.

Protection requested

This past year, the U.S. government received a petition to list a small isolated population of the pink dolphin: perhaps one of the more threatened populations within the species persisting off the coast of Taiwan. This Taiwanese population experiences some of the highest levels of threat from pollution, fishing, gear entanglement, and habitat loss. It’s also one of the smaller populations within the species, estimated at less than 100 individuals and falling. In a federal register notice, a response to the petition stated reasons why the Taiwanese population of the pink dolphin was not warranted for listing under the Endangered Species Act. Most of this reasoning has to do with criteria for listing a single population within an act targeted at single species. 

What is a distinct population segment?

Like any good law, the Endangered Species Act leaves room for interpretation. The Act says that species or ‘distinct population segments’ may be listed if determined threatened or endangered. So, single populations (like the Taiwanese pink dolphins) can be listed!  But what is a distinct population segment or ‘DPS’? This question represents an ongoing debate. In general, the role of ‘distinct population segments’ in ESA law stirs up plenty of concerns. For instance: From a conservation management standpoint, is it better to list a whole species? Or, would it be easier to manage conservation if that species were broken up into smaller populations? What if many overlapping populations are listed separately? How would managers tell them apart to meet their unique conservation needs? While many questions on interpretation and practice abound, the current guidelines define a ‘distinct segment population’ under the ESA as a population determined to be ‘discrete’ and ‘significant’ to the species as a whole. Now, these words ‘discrete’ and ‘significant’ can also be debated and interpreted in a variety of ways. However, case law sets the tone for legalese in action. In the case of the Taiwanese population of pink dolphin, its restriction to coastal waters and high isolation from other populations placed it solidly in the ‘discreteness’ category. But, in regards to the ‘significance’ criterion, the population was determined too small and too peripheral to be significant to the species as a whole. Thus, ESA listing was not warranted. 

From a conservation standpoint, the population structure of Sousa chinensis poses some conservation challenges. Each population of the species may be genetically unique, and each population is faced with different challenges specific to the estuary and narrow strip of coastline it calls home. If one population is conserved, the benefits aren’t likely to spill over into other isolated populations. Populations of pink dolphins in the bay of Hong Kong face similar challenges to those off the coast of Taiwan, but helping to conserve one will likely not help the other.  This is one reason that the Taiwanese population of the pink dolphin didn’t pass the “DPS” test, despite the fact that it faces some of the highest threats of any population across the species’ range.

How do you protect the unprotected?

So what to do with small isolated populations, falling through the cracks of large international treaties, environmental species law, and facing challenges unique to local environments? While some large mammals, and highly migratory species like sharks and whales may receive international legal protection, the peripheral populations of naturally small species like the pink dolphin often get overlooked. But it’s these small isolated populations that contribute to the rich tapestry of biodiversity on our planet. Loss of one small dolphin population off the coast of Taiwan may not immediately lead to declines in other populations of the same species. However, loss of that population means yet another dip in the scale of global marine biodiversity needed to support a healthy rich ocean ecosystems. Perhaps there isn’t an international mechanism or set of regulations in place to capture the many small populations rapidly declining and disappearing.  But loss of these small populations en masse means a vast loss of biodiversity, and a loss of ecosystem resilience.  

Healthier fish, healthier humans, healthier dolphins.

Improved mechanisms for ecosystem management may be one way to protect these small populations of species that create the vast majority of biodiversity on our planet. If local governments and communities work towards healthy coastal ecosystems, the plight of the pink dolphin could be avoided. For example, pollution management would provide benefit to both dolphin and human. ‘Land reclamation’ is another threat to the pink dolphin; this is the act of destroying wetlands by filling them with concrete, therefore reducing coastal resiliency and ecosystem services provided by estuaries. Preventing ‘land reclamation’ means estuaries continue to provide the resources necessary for young fish. By maintaining healthy coastal estuaries, fish nurseries will see improved productivity, meaning more fish for fishermen and dolphins! These are just some examples of why, for the pink dolphin, singles-species management may not work, but ecosystem management may. 

The plight of the pink dolphin is the plight of many species: small, patchily distributed, and comprised of multiple populations facing different threats across international boarders. Perhaps now is the time to consider the role of ecosystem management in protecting these small populations.

Think of it as a home for the many misfits having a tough time squeezing into the legal criteria of single-species law. 

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