**1. Introduction**

Freshwater ecosystems are fragile environment, are rich in biodiversity and are believed to be at risk than other freshwater animals. To understand the mechanism, driving losses in aquatic biodiversity, is important to the conservation and restoration of freshwater environments worldwide [1].

how the changes of the said species can be related to the health of Indicator species in the river. This would help to implement various programes for restoration of the river system. This was the first survey of its kind in recent times, where an attempt was made to objectively assess the status of important bio resources of the Girwa River in Katerniaghat

Status of the Important Bioresources of Girwa River with Special Reference to Ganges River…

http://dx.doi.org/10.5772/intechopen.72661

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The Karnali River arises in Nepal and bifurcates into two rivers, the Girwa and the Kauriala which reunites again in India to form Ghagra (WWF-India unpublished, 2001). The Girwa River, in the Katerniaghat Wildlife Sanctuary ca.18 km in length is bounded upstream by the Nepalese border and downstream by the Girijapuri barrage in India (**Figure 1**). The river is home to large aquatic animals such as endangered Ganges river dolphin (*Platanista gangetica gangetica)* (**Figure 2A**)*,* critically endangered gharial (*Gavialis gangeticus)* (**Figure 2B**)., mugger (*Crocodilus palustris)* (**Figure 2C**).*,* Smooth coated otter *(Lutragale perspicillate),* several freshwa-

**Figure 1.** Study area showing dolphin sightings in different locations of Girwa River. (*Map Source: WWF-India*).

Wildlife Sanctuary.

**2. Study area**

ter turtle species and aquatic birds (**Figure 2D**).

The Ganges River dolphin is distributed in the Ganges, Brahmaputra, Karnaphuli-Sangu, and Meghna river systems and their tributaries, from the foothills of the Himalaya to the limits of the tidal zone in India, Bangladesh and Nepal [2, 3]. It has already become extinct from most of its earlier distribution ranges and even in its present day distribution range the population is purported to be declining [4]. Extensive population fragmentation has resulted from the widespread construction of dams and barrages [5]. The Ganges River Dolphin however, is a true River Dolphin; it occurs only in fresh water, and is considered endangered [6]. The Government of India declared it as the "National Aquatic Animal" [7] and it has received protection in nine protected areas (PAs); of these the Vikramshila Ganges River Dolphin Sanctuary near Bhagalpur is specifically known for the conservation of the Ganges River Dolphin. They have also received some protection in the Girwa and Chambal River, specially created for the protection of the gharial [8]. In recent years several workers estimated the population of Ganga river dolphin in different segments of Ganga River and its tributaries e.g. In Ganges River ca.1200 km (Bijnor to Varanasi), with an encounter rate of 0.21 dolphin/km. In Yamuna River ca. 400 km (Pachnada-Allahabad), with an encounter rate of 0.07 dolphin/ km [8]. In River Girwa, ca. 18 km, with an encounter rate of 1.56 dolphins/ km. In Ghaghara river with an encounter rate of 0.45 dolphins/km. In Saryu River, ca. 30 km with an encounter rate of 0.51 dolphin/km. In Rapti River ca. 30 km with an encounter rate of 0.26 dolphin/km. However, no dolphin was recorded in Ken river ca. 30 km and Betwa River ca. 29 km [8]. In Chambal river ca. 425 km (Pali-Pachnada), the encounter rate of dolphin was 0.19 dolphin/km [9].

The north Indian State of Uttar Pradesh includes a large extent of the present day distribution of crocodile species, which occurs in the several large rivers flowing through the State viz. the Ganga [10], the Yamuna [11], the Chambal [11], the Ghagra, the Gandak [12] and the Sone River [13]. Early records reveal that these aquatic reptiles were, at one time, very abundant throughout their distribution range [14]. However, due to commercial exploitation and habitat destruction, populations of Crocodile species have been reduced to near extinction. In many habitats, Crocodile populations have been totally wiped out [15]. Considering their vulnerability, the gharial is now listed as Critically Endangered and the Mugger is listed as endangered on the International Union of Conservation of Nature (IUCN) Red List [16].

In Girwa River dolphin prefers to stay in deep water in and around the confluence of rivers, shares its habitat with few indicator species such as crocodiles, freshwater turtles and aquatic birds many of which are fish eaters and potential competitors with dolphins [17]. Studying indicator species could create the basis for a sustained research program to see how the changes of the said species can be related to the health of Indicator species in the river. This would help to implement various programes for restoration of the river system. This was the first survey of its kind in recent times, where an attempt was made to objectively assess the status of important bio resources of the Girwa River in Katerniaghat Wildlife Sanctuary.
