Jul 10, 2008

What is a Red List?

Earlier, I posted the happy story of the return of a Bailer snail.
From Ng, P. K. L. & Y. C. Wee, 1994. The Singapore Red Data Book: Threatened Plants and Animals of Singapore. The Bailer snail (Melo melo) is "thought to have been exterminated from our waters, but a recent isolated sighting confirms their continued presence".

An anonymous comment was left on this post:

"I doubt they are threatened as the book says, but probably common in deeper waters. Drift nets snag them very frequently. Likewise, noble volutes are very common. It's about time someone revises the 'book' that we are so fond of drawing reference from."
Before we make comments about the hard work put into writing a book and drawing up a list, let's find out more about these issues shall we?

What is a Red List?

from About the IUCN Red List

The IUCN Red List is the world's most comprehensive inventory of the global conservation status of plant and animal species. It uses a set of criteria to evaluate the extinction risk of thousands of species and subspecies. These criteria are relevant to all species and all regions of the world. With its strong scientific base, the IUCN Red List is recognized as the most authoritative guide to the status of biological diversity.

The overall aim of the Red List is to convey the urgency and scale of conservation problems to the public and policy makers, and to motivate the global community to try to reduce species extinctions.
On a local scale, the Red List of Singapore serves the same purposes but may have different animals with different status from the global Red List.

How is the Red List drawn up?

from About the IUCN Red List

The IUCN Red List Categories evolved over a four-year period through extensive consultation and testing with more than 800 SSC members, and the wider scientific community. The more precise and quantitative Red List Categories and Criteria were adopted by IUCN in 1994.
Is a Red List of any use?

from About the IUCN Red List
A Red List can answer questions such as:
  • How threatened is a particular species?
  • What are the threats to a species?
  • How many threatened species occur in a given country?
  • How many known extinctions have there been?
Uses of a Red List include:
  • Draws attention to the magnitude and importance of threatened biodiversity
  • Identifies and documents those species most in need of conservation action
  • Provides a global index of the decline of biodiversity
  • Establishes a baseline from which to monitor the future status of species
  • Provides information to help establish conservation priorities at the local level and guide conservation action
  • Helps influence national and international policy, and provides information to international agreements such as the Convention on Biological Diversity (CBD) and the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).
Is everything on the Red List extinct?


from About the IUCN Red List
There are nine categories in the IUCN Red List system:
  • Extinct
  • Extinct in the Wild
  • Critically Endangered
  • Endangered
  • Vulnerable
  • Near Threatened
  • Least Concern
  • Data Deficient
  • Not Evaluated.
Classification into the categories for species threatened with extinction (Vulnerable, Endangered, and Critically Endangered) is through a set of five quantitative criteria that form the heart of the system.

These criteria are based on biological factors related to extinction risk and include: rate of decline, population size, area of geographic distribution, and degree of population and distribution fragmentation.

What are the details of each category on the Red List?

from About the IUCN Red List

A taxon is Extinct when there is no reasonable doubt that the last individual has died. A taxon is presumed Extinct when exhaustive surveys in known and/or expected habitat, at appropriate times (diurnal, seasonal, annual), throughout its historic range have failed to record an individual. Surveys should be over a time frame appropriate to the taxon's life cycle and life form.

A taxon is Extinct in the Wild when it is known only to survive in cultivation, in captivity or as a naturalized population (or populations) well outside the past range. A taxon is presumed Extinct in the Wild when exhaustive surveys in known and/or expected habitat, at appropriate times (diurnal, seasonal, annual), throughout its historic range have failed to record an individual. Surveys should be over a time frame appropriate to the taxon's life cycle and life form.

A taxon is Critically Endangered when the best available evidence indicates that it meets any of the criteria A to E for Critically Endangered (see Red List Categories and Criteria booklet for details) and it is therefore considered to be facing an extremely high risk of extinction in the wild.

A taxon is Endangered when the best available evidence indicates that it meets any of the criteria A to E for Endangered (see Red List Categories and Criteria booklet for details), and it is therefore considered to be facing a very high risk of extinction in the wild.

A taxon is Vulnerable when the best available evidence indicates that it meets any of the criteria A to E for Vulnerable (see Red List Categories and Criteria booklet for details), and it is therefore considered to be facing a high risk of extinction in the wild.

A taxon is Near Threatened when it has been evaluated against the criteria but does not qualify for Critically Endangered, Endangered or Vulnerable now, but is close to qualifying for, or is likely to qualify for, a threatened category in the near future.

A taxon is Least Concern when it has been evaluated against the criteria and does not qualify for Critically Endangered, Endangered, Vulnerable or Near Threatened. Widespread and abundant taxa are included in this category.

A taxon is Data Deficient when there is inadequate information to make a direct, or indirect, assessment of its risk of extinction based on its distribution and/or population status. A taxon in this category may be well studied, and its biology well known, but appropriate data on abundance and/or distribution are lacking. Data Deficient is therefore not a category of threat. Listing of taxa in this category indicates that more information is required and acknowledges the possibility that future research will show that threatened classification is appropriate. It is important to make positive use of whatever data are available. In many cases great care should be exercised in choosing between DD and a threatened status. If the range of a taxon is suspected to be relatively circumscribed, and a considerable period of time has elapsed since the last record of the taxon, threatened status may well be justified.

A taxon is Not Evaluated when it is has not yet been evaluated against the criteria.


Anonymous said...

Great effort and detail in spelling out the background of the Red List. I posted the comment and must apologize that it did sound critical of the book. Perhaps I should phrase it in such a manner 'Which category does the Melo melo fall into?' Often times when we quote its listing in the book, many ppl tend to think it is threatened or near extinction, which might not be true...

Ria Tan said...

Yes, it is good to be mindful of the huge amount of work that goes towards building a Red List. It takes years and the efforts of many many individuals to come up with a Red List.

Everyone does their imperfect best and those of us who love our shores can help by contributing field sightings and other field notes about the animals on the Red List.

You are right in that things do change, and if for the better, that would be ideal. We await the updated Red List and hope for good news.

The Melo melo is listed as endangered in the quoted book.

The book defines endangered as "In immediate danger of extinction and whose survival is unlikely if the factors causing the decline of the species is not reduced or eliminated. The species included here are those whose populations have been reduced to a critical level or whose habitats have been so disrupted or destroyed that their chances of survival are poor."

While Melo melo might still be common in suitable habitats, we must ask ourselves questions about these habitats.

How extensive are these habitats? Say, compared to before reclamation on the East Coast?

And if they are indeed still common on Changi, how does the Changi habitat now compare to the past?

Have we lost Melo melo habitats on the Northern shores recently? Tekong?

What are the pressures on the remaining Melo melo habitats? Dredging, coastal developments, threats of chemical spills come to mind. During the flooding incident in 2007, many volutes died on Chek Jawa.

Uncontrolled collection is an additional pressure.

How much collection can be tolerated before the populations of Melo melo are so reduced that they no longer reproduce effectively?

The Red List suggests that we should take a preacautionary approach to this magnificent animal.

Anonymous said...

Chek Jawa no enough? Want to hype more places?

Red list huge amount of work? Don't be a laughing stock! Just look through the "specialist" list and you will surely know they cannot be good at every single living organism found on this island.

Anonymous said...

Why don't you greeny and greedy people visit the Jurong or Senoko fish ports early in the morning instead of having huge footprints on the shorelines? That baler or volute are traded for ages! Thousands and thousands of gong gongs are collected for food. Red list? What red list? On this tiny space call Singapore? You are a joke!

Ivan said...

The outright animosity and caustic remarks expressed by the previous two commenters bewilders me. Plus the fact that the incoherence and irrelevance of their statements leaves me scratching my head wondering just what they are trying to say.

The Singapore Red Data Book may be outdated and obsolete, but it is after all the best that we have. I'm sure that the people who contributed to the book tried their best to ensure that the information was as accurate as possible, to the best of their ability. Given the limitations involved in accurately surveying marine life in Singapore, such as poor underwater visibility, in ability to dive in many parts due to heavy shipping traffic or pollution, plus the fact that these are snails which spend part of their time buried in the seabed, I can only say that instead of freely dispensing such thinly-veiled insults, perhaps we should look at ways in which we can improve and refine the research such that distribution, population status, and abundance can be more accurately surveyed for future editions.

Singapore is certainly not as well-studied as other countries, and various environmental factors constrain the ability to accurately assess abundance and distribution, Not to mention that there is a dearth of well-trained biologists with adequate funding to spend their time studying the population dynamics of marine gastropods. So even though the book is likely to have been an imperfect, even obsolete, assessment, it represents the best attempt we've had so far in trying to catalogue and gauge the status of our imperiled wildlife.

Unless the people who babble here are willing to volunteer their apparently vast knowledge and contribute as "specialists", as they seem to assert the superiority of their knowledge, I don't see any reason why we should disregard the book so readily.

It's not as if we have hordes of malacologists ready to survey our waters to accurately assess the abundance of bailer snails or noble volutes.

Anonymous said...

There's alot of truth in what's said Ivan, but I think you have to consider why many 'specialists' have not been able to contribute their knowledge. One of them is that collectors are often discriminated against by conservationists. This is not so overseas where collectors are seen as useful tools to further increase what we know. I'm sure there are many good collectors out there who might be willing to help, but after being lumped into the same categories as 'poachers' and ppl who do not care about our environment, its difficult. The truth of the matter is, many collectors collect sensibly and care very much about our environment. Without our habitats, we can forget of doing what we enjoy most.

Anonymous said...

I am from the States and I am working in the university that deals with natural history. There ain't any discrimination between the various parties here and we are happily a group regardless of our backgrounds. It is sad to hear that from Singapore a place known for its efficiency over here.

Anonymous said...

Well written! Sorry for my animosity.

Anonymous said...

Overall, I think you are moving in a positive direction.

Imposing collecting restrictions can't hurt but I suspect it will do little good if pollution is the primary cause.

Much is already known about volutes, writing an expert would help. Simply understanding a particular species life cycle and its means of reproduction will go a long way.

From the little I know about volutes, most (if not all?) progress through their veliger stage within their egg case. (For most mollusks, they are planktonic.) So they emerge as a young snail within the same local population as their parents. How large and widespread the population would likely depend on the habitat and conditions they require.

As a collector myself, I too dislike any association with poachers and people who do harm to the environment. We would rather be associated with educators and researchers, fostering knowledge and understanding.

Anonymous said...

Throwing the book at the public is rude and crude! We don't do that here in Portugal!