Indus Estuary and Creeks IMMA

Criterion A – Species or Population Vulnerability

The Indian Ocean humpback dolphin (Sousa plumbea) is endangered (EN) and the Indo-Pacific finless porpoise (Neophocaena phocaenoides) is vulnerable (VU). The Indian Ocean humpback dolphin and the Indo-Pacific finless porpoise are obligate nearshore inhabitants and ecologically constrained to a narrow coastal strip, and therefore these species are facing severe threats to their conservation in the Indus estuary, creeks to Mandvi harbour, due to negative impacts from accelerated coastal development and associated human pressure. Known and suspected threats include accidental entanglements in fishing gear, habitat degradation, pollution, probable competition for food due to widespread use of non-selective fishing gears (such as gillnets) and increasing vessel traffic with associated noise pollution and risk of boat strikes (Iqbal, 2014; Kiani, 2014). Coastal areas in close proximity to industries, port installations (e.g. Port Qasim, Mandvi harbour) and major human settlements are of highest concern. Both these species, however, are legally protected in both India and Pakistan. Along the entire Indus estuary, creeks to Mandvi harbour, entanglement in fishing nets appears to be the principal threat to the two species of cetaceans. The impact is most severe during peak fishing season, i.e., the northeast monsoon (from November to February). Fisheries in the area are generally open access, which resulted in overcapacity of the fishing fleet. Use of gillnets of different types is very common in coastal as well as offshore waters, with high risk for cetacean entanglements. Industrial and domestic sewage pollution in coastal waters and tidal creeks is a major concern specifically around the populous and rapidly expanding industrial city of Karachi, on the northwestern most part of the delta, as well as industrial activities in Jahku and Mandvi Harbour area. In the south-eastern part, major pollution sources include pesticides like organochlorines and domestic water flushed into the Indus River from inland areas and from other population centres in the area (Kiani and Waerebeek, 2015). Loss of habitat (mangrove forest) due to land reclamation for development projects, deforestation and camel grazing are considered to be important threats to the population of two cetacean species. Mangrove deforestation results in the destruction of vital nursery grounds of small fish and perhaps other neritic species that are prey to both cetaceans occurring in the area (Kiani, 2014).

Criterion B: Distribution and Abundance

Sub-criterion B1: Small and Resident Populations 

The Indus estuarine area and associated creeks extending to Mandvi harbour are known for populations of humpback dolphins and finless porpoises regularly occurring in the area; these, if subjected to a single large scale event, could significantly alter the long term survival of the species. In the Indus River Delta, group sizes varied considerably from 1 to 35 animals (Kiani, 2014) whereas 27.6% typically consisted of large solitary animals, probably mostly adult males. Overall, groups of 1–10 animals made up 91% of total sightings. Generally in the bigger groups, some subgroups stayed close to each other and merged occasionally while chasing prey and feeding. Group composition of Indo-Pacific finless porpoise in the Indus estuary, creek was highly variable, i.e., only adults, only juveniles, mixed adults and juveniles, mother and calf pairs and undetermined.