IB-style question — IUCN criterion — why classified Endangered
The Irrawaddy river dolphin (Orcaella brevirostris) was reclassified from Vulnerable to Endangered on the IUCN Red List between 2000 and 2017. Identify one IUCN criterion that could explain this reclassification. [1]
How to answer it, step by step
- Step 1 — Choose a directional IUCN criterion
• The number of mature individuals decreased — the global population fell from an estimated 7 000 to fewer than 3 500 over three generations (a >50% decline).
• Alternatively: the extent of occurrence (geographic range) became further reduced and fragmented as river barriers (dams) divided sub-populations. - Step 2 — Link the criterion to the higher threat category
• A >50% population reduction over three generations meets the IUCN Criterion A threshold for Endangered.
• Small, isolated sub-populations each face higher local extinction probability, pushing the species across the VU→EN boundary.
Final answer
The mark scheme requires a comparative or directional word — 'decreased population size', NOT just 'population size'. Hunting, dams, and bycatch are threats (causes), not IUCN criteria — never state these as the criterion itself. Valid criteria: population size/decline, range size/decline, habitat loss/fragmentation, probability of extinction.
IB-style question — Data-deficient category — why status unknown
A large proportion of deep-sea fish species appear in the 'Data Deficient' category of the IUCN Red List. Explain one reason why a reliable conservation status cannot be assigned to these species. [1]
How to answer it, step by step
- Step 1 — Name and explain the sampling barrier
• Deep-sea environments are extremely difficult and expensive to survey — standard trawl or dive methods cannot reach depths below ~200 m.
• Without population-size or range data, none of the quantitative IUCN criteria (A–E) can be applied.
Final answer
One well-explained reason earns the mark — you do not need more than one. The explanation must link the practical difficulty directly to the lack of data (not just say 'we don't know about deep-sea fish'). Other valid reasons: highly cryptic species hard to identify/count; very long generations so trend data takes decades; vast ocean area makes complete surveys impossible.
Protecting species: the big picture
Big idea: Conservation status shows how likely a species is to become extinct and helps decide how urgently it needs protection.
What is conservation status?
Conservation status tells us whether a species is safe, under threat, or already extinct. It helps scientists and governments understand which species need the most help.
Conservation status = how close a species is to extinction.
Who decides conservation status?
Species are assessed globally by the International Union for Conservation of Nature (IUCN). The results are published in the IUCN Red List, which is used worldwide.
- Used by scientists and conservationists
- Used by governments and policymakers
- Helps set conservation priorities
How is conservation status decided?
The IUCN looks at several factors to judge how at risk a species is.
- Number of individuals left
- Whether the population is increasing or decreasing
- How easily the species can reproduce
- How wide its geographic range is
- Known threats such as hunting or habitat loss
In exams, mention population size, trend, range, and threats.
Understanding IUCN Red List categories
Species are placed into categories based on how serious the risk of extinction is.
- Least Concern (LC): widespread and common
- Near Threatened (NT): may become threatened soon
- Vulnerable (VU): high risk of extinction
- Endangered (EN): very high risk
- Critically Endangered (CR): extremely high risk
- Extinct in the Wild (EW): only survives in captivity
- Extinct (EX): no individuals remain alive
The higher the category, the greater the extinction risk.
Why conservation status is important
Giving a species a conservation status makes its situation public and encourages action to protect it.
- Raises awareness of threatened species
- Guides conservation funding
- Helps decide protection laws
- Supports long-term biodiversity protection
How governments help protect species
Governments play a major role in conservation by creating and enforcing rules.
- Passing laws to protect species and habitats
- Funding conservation and research
- Enforcing hunting and trade restrictions
- Working with other countries through agreements
How businesses affect conservation
Businesses can harm biodiversity, but they can also help protect it.
- Using sustainable materials
- Reducing pollution and waste
- Supporting conservation projects
- Developing technology to monitor wildlife
The role of NGOs
Non-governmental organisations (NGOs) support conservation by working directly with species, ecosystems, and communities.
- Funding conservation work
- Researching and monitoring species
- Raising public awareness
- Campaigning for better protection
What individuals can do
Individual actions may seem small, but together they make a big difference.
- Choosing sustainable products
- Reducing consumption
- Supporting conservation organisations
- Taking part in citizen science projects
Three real outcomes of conservation
- Some species go extinct when protection comes too late
- Some species remain critically endangered but survive with help
- Some species recover successfully with strong conservation action
Big exam takeaways
- Conservation status shows extinction risk
- The IUCN Red List is the global system
- Status is based on population, range, trends, and threats
- Governments, businesses, NGOs, and individuals all matter
- Early conservation action is most effective