Critically Endangered Species of the Week: The Gharial!

    Our critically endangered species this week is the Gharial (Indian Gharial; True Gharial; Gavial) - I have specifically chosen this species because it is one of the lesser known species of an otherwise well-known group, and its evolutionary relationships are the subject of my dissertation! If this species were to go extinct no further research could be undertaken, likely limiting this extremely contentious area of research.

About:
     The Gharial, Gavialis gangeticus, is a crocodilian with a characteristic elongate, narrow snout adapted for its fish-based diet [1,4]. Males of the species can also be classified by their bulbous growth on the tip of the snout called a Ghara (after the Indian word for 'pot') [2,]. Gharials are also much more agile in the water (related to their piscivorous diet) than on land, and cannot move in a 'high-walk' gait, like many other crocodilian species [2].
     The species is one of the largest crocodile species alive, behind the salt-water crocodile; males can grow to be around 6m long [3; 2].


The Gharial, Gavialis gangeticus, displaying the extremely slender
snout and bulb at the snout-end. Photo from [4].

The extremely elongated, thin snout of the Gharial. Photo from Saravana Kumar at [3].

Number left in existence:
     Recent surveys indicate there may be less than 200 surviving individuals in the wild [3;1], with the highest total number across all populations found to be around 436 in the peak year of 1997 [1]. 182 made up the estimated number of individuals from 2006; indicating a currently declining population [1].

Geographical Range in the wild:

Geographical range of the Gharial; along 3 rivers in
India, and one in Nepal - these are clearly widely separated.
From [1].

     The Gharial can be found in both India and Nepal. However it is likely that only three actually breeding subpopulations survive in India (Chambal River, Girwa River and Son River), and one in Nepal (Rapti/Narayani River) [1; 2; 3]. Furthermore, these are all widely separated, giving no chance of recovery without human intervention if one subpopulation fails.

    The remaining populations of the Gharial are remnants of mostly unsuccessful reintroductory programmes [1]. The species historically lived in Pakistan, other parts of India, Bangladesh, Myanmar and Butan, but are now extinct in these areas [1; 3].



Why they are endangered:

• Mainly anthropogenic alteration of habitat, through: damming, (throughout all the present range of the Gharial), divertion for irrigation (Gharials cannot move between dried rivers) and sand-mining [1; 2; 3].
• Increased intensity of fishing; decreasing food stocks, as well as causing the death of many adults through gill-netting [1; 2; 3].
• Crop planting and animal farming during the dry months interrupts the breeding season and uses the sandbanks where this takes place [1].
• Hunting and use of the Gharial and traditional medicines, mainly in Nepal [1; 2; 3].
• Gharial eggs are sought out as food; leading to almost all of the nests being raided between 2001 and 2005! [1; 2].

What can we do to help?
     Conservation programmes have already been undertaken in India and Nepal, establishing the present frail populations by captive breeding and restocking [1;]. Around 5,000 young adults were released to these river systems, however recruitment or retention of these reintroduced individuals (survival rate and breeding) has been very low, at 3-10% [1; 2; 3].
     If the species is to survive, more effective methods need to be put in place for their protection, as the reintroduction attempts have been less than effective so far (and mostly a waste of resources!). Conservation now needs to turn to habitat assessment and protection, fisheries enhancement and local education if the species is going to have any hope [1; 2; 3]. Perhaps after education of residents and increased knowledge on why previous reintroduction attempts have failed, individuals could be released into their historical ranges.


References:
1. http://www.iucnredlist.org/details/8966/0
2. http://nationalzoo.si.edu/animals/reptilesamphibians/facts/factsheets/gharial.cfm
3. http://www.gharialconservation.org/
4. http://www.bbc.co.uk/nature/life/Gharial