Baly Bay National Park is divided into four parcels with 10 core zones. The core zones cover 47,966 ha, with the remainder of the park being a buffer zone. Six of the core zones are located in the western part of the site. The three largest are Beheta (19,769 ha) and Cape Sada (1,192 ha) in the east, and a large part of the Amparafaka peninsula in the west. The terrain is gently undulating, with low hills and cliffs rising to c.80 m. There are many seasonal streams, two main permanent rivers, the Andranomavo and Kapiloza, and several permanent lakes, of which Lake Sariaka (c.300 ha) is the largest. The southern part of Baly Bay consists of mangrove, dominated by Avicennia and Rhizophora. The main lake vegetation is water-lilies Nymphaea and other floating plants. In flooded valleys and nearby a significant number of Raphia palms are present. Dry deciduous forest, dominated by Dalbergia, Commiphora and Erythrophleum couminga (a very restricted-range tree species), is found mainly in the Tsiombikibo and Ambinda region, with remaining areas covered mainly in secondary vegetation of savanna with Bismarckia palms, or Hyphaene palms in humid valleys, or, on the hills, a rather characteristic formation composed of clumps of bamboo, mainly Perrierbambos madagascariensis. The tortoise Geochelone yniphora lives in these clumps, mainly at Cape Sada and Antsokotsoko, with a small surviving population in Beheta and Betainalika.
See Box and Tables 2 and 3 for key species. A total of 118 species are known from the area, of which 35 are endemic to Madagascar. Lake Sariaka holds a few pairs of Haliaeetus vociferoides and a colony of breeding waterbirds that includes Platalea alba, Mycteria ibis, Ardea cinerea, Ardea humbloti and Threskiornis (aethiopicus) bernieri. The mudflats, lagoons, bay and west coast of the Ampasindava peninsula hold species such as Haliaeetus vociferoides, Threskiornis (aethiopicus) bernieri and Charadrius thoracicus. During the summer, there is a gathering of 10,000 terns near Cape Amparafaka, mainly composed of Sterna bengalensis and Sterna hirundo.
Non-bird biodiversity: Lemurs: Microcebus ?myoxinus (VU), Hapalemur griseus occidentalis (VU), Propithecus verreauxi deckeni (VU), Daubentonia madagascariensis (EN). Carnivores: Cryptoprocta ferox (VU), Eupleres goudotii (EN). Cetacean: Sousa chinensis (DD). Sirenian: Dugong dugon (VU). Reptiles: Chelonia mydas (EN), Lepidochelys olivacea (EN), Geochelone yniphora (EN; the world population is confined to the national park).
Pressure/threats to key biodiversity
The Soalala region is the distribution area of an endemic tortoise, the angonoka Geochelone yniphora, which has been a flagship species for the Durrell Wildlife Conservation Trust (DWCT) since 1983. The approach adopted by DWCT has resulted in much progress being made in the sustainable development of natural resources. Lake Sariaka is protected by several taboos, in particular taboos against the use of boats and nets. Threats include conversion of wetlands to rice-fields, duck-hunting and the taking of waterbird eggs (except at Lake Sariaka). Recently, the development of commercial fishing, especially for shrimps, has reduced the catches of traditional fishermen, and exploitation of sea-cucumbers and shark-fins has become almost excessive. There is also a proposal for shrimp-farming in the area. The forests of the park have been significantly degraded by logging (for local and commercial purposes) and by the burning of savanna, which have apparently contributed to the complete destruction of Antsakoamileka Forest. Fishermen from the Kajemby clan hunt the Dugong dugon and marine turtles. In a few areas, Eulemur fulvus rufus is hunted.