Of the dominant coastal habitats, seagrass and coral reef habitats are among the most threatened in Cambodia. Key anthropogenic threats to seagrass habitats in Cambodia have been ranked from most to least significant as follows: destructive fishing such as the use of motorized push nets and trawls; overfishing; wastewater effluent; sedimentation from coastal development; coastal construction; and nutrients. Anthropogenic threats to coral reefs have been ranked in order of significance as: overfishing; destructive fishing; pollution (eutrophication); sedimentation; and coastal development. Charcoal production is considered the key contemporary anthropogenic threat to mangrove forest in Cambodia. Reclamation of mangrove forests for industrial uses and aquaculture are minor but persistent threat despite legislation banning all harvesting of mangroves in Cambodia. Natural threats have been identified as sea-level rise and episodic threats, including tsunamis and typhoons.

Key threats from fisheries have been categorized by the National Fisheries Committee in the Cambodia as:

• The twin problems of over-capacity and over-exploitation;

• Use of destructive and/or unsustainable fishing gear and practices;

• Pollution from coastal residents and small fishing vessels;

• Habitat destruction and pollution due to fish and shrimp farming; and

• Illegal fishing

Over-capacity in commercial and small-scale fisheries, combined with the problem of over-exploitation, are enduring issues facing regional fisheries. The impacts of over-capitalisation and over-exploitation are magnified by the use of subsidies and the dependence of coastal communities on fish resources for income, as well as food and nutritional security. As noted above, most areas of the South China Sea coast of Cambodia are characterized by a rapid increase in the number of fishing vessels and total engine capacity (hp), and although there has been a general corresponding increase in landings, catch per unit of effort (CPUE) has declined significantly. Recent interviews with fisherfolk suggest significant reductions in yields. A socio-economic survey conducted through Cambodia’s Coastal Zone Management project indicated that there was a significant reduction in abundance of some living marine resources. The survey found that a reduction in the abundance of shrimp had occurred, such that the capacity of a typical small fishing boat to catch shrimp had declined from 20 kg of shrimp per night to 5 kg per night. In O Krosa village, some species including smaung fish, white sparrow fish, mantis shrimp and other species of crustaceans have disappeared or become very rare. Similarly, the survey indicated that it is now very difficult to find mantis shrimp in waters adjacent to Angkaul village. Mantis shrimp and many species of crabs have disappeared from these areas. This, coupled with a lack of alternative livelihoods, is thought to be the key reason why both middle and small-scale fisherfolk are resorting to illegal and destructive fishing practices, including blast-fishing and the use of fish poisons (cyanide) in coastal areas of Cambodia. Effective management of over-capitalisation and over-exploitation of fisheries resources has been identified as an important element of achieving the desired outcomes for the management of fisheries refugia and will require effective linkage with broader efforts to curb high and increasing levels of fishing pressure in Cambodia

This issue is prevalent across a range of habitat types and regions of the Cambodia’s South China Sea coast. As noted above, the Kampot and Kong areas have been identified as hotspots for the use of destructive and/or unsustainable fishing gear and practice, representing a key threat to critical fisheries habitats. Examples include:

• Push netting and inshore trawl fishing cause habitat impacts and selectivity issues. Catches in these gear types from inshore waters are largely composed of juveniles, and at high fishing effort levels are thought to contribute to growth over-fishing in coastal areas. Such a situation hinders fisheries management efforts which largely focus on development of sustainable livelihoods, and is a key threat in Kampot where push nets are used extensively over seagrass beds to take juveniles of the economically important species. In Cambodia, the use of trawls is prohibited in waters less than 20 m deep, yet reports of fisherfolk trawling close to shore are common.

• Digging and gleaning of seagrass beds and mangrove forests is an area of concern at priority refugia site in Cambodia. Growing demand for seafood in local markets has resulted in a marked increase over recent years in the number of people digging for gastropods and crustaceans in the seagrass beds, leading to damage of seagrass plants, de-stabilisation of sediments (and subsequent erosion), and the over-exploitation of benthic organisms. Intensive digging and grazing in some mangrove areas of Koh Kong is also of concern.

• Blast fishing, poisons, and unselective fishing gears/practices is a well-known and documented threat to fisheries and habitats in East Asia, and such practices have become more prevalent in Cambodia in recent years. Such practices often result in mortalities of a wide range of size-classes of target and non-target species, which may contribute to both growth and recruitment over fishing. The effects of blasting on the physical structure of coral communities is of particular concern, and the occurrence of blast fishing “craters” on heavily blasted reefs is likely to have a major impact on coral reef associated fish assemblages. Non-selective fishing gears, such as gill nets (Mong Paehk) being used as trammel nets, are utilised in most fished coral reef areas in Cambodia. The growing need to minimise the impacts of such practices critical habitats necessitates the development of best practices in the management of these problems.

While this issue is well known at the community level, little action has been initiated to address this Cambodia. Seagrass and near shore coral reef habitats are particularly threatened by pollution from small fishing vessels and waste discharge from the coastal residents, particularly in the intensively used shallow water environment of Kampot. While volumes and contaminant loadings of wastewater discharges from local fish landing places and processing facilities are typically unknown, it is believed to be contributing to increased biological oxygen demand and nutrient concentrations in the coastal water areas of seagrass beds nearby Kampot. This issue is compounded by the discharge of solid wastes generated by fishing communities into areas of coral reef and seagrass. The discharge of oils, both hydrocarbons and fish oils, from small fishing vessels is also common and is potentially a problem across all priority fisheries refugia sites in Cambodia due to the widespread nature of the small-scale fishing sector, although it is recognized that the local significance of this problem will depend on oceanographic processes at the site-level.

Aquaculture has been identified as a key threat to seagrass and other soft-bottom fisheries habitats generally in the South China Sea, and with key contemporary threats being pollution from shrimp and fish farm effluent. Seagrass communities are used for small-scale shellfish production in many inshore areas, resulting in habitat degradation and the accumulation of deteriorating cage materials and shells in abandoned areas.

Particularly the use of illegal and destructive fishing gear is common at the selected site for the establishment and operation of fisheries refugia in Cambodia. The illegal encroachment of foreign fishing vessels into national waters, and the conduct of large commercial fishing operations in inshore areas set aside for small-scale fishing operations is common. In Cambodia, such activities have led to conflicts within fishing communities, some resulting in violence. There are also many reports of fisherfolk (both foreign and local) operating on an unlicensed basis. The Fisheries Administration has limited resources for enforcement and very little capacity to patrol offshore. However, the illegal fishing problem is complicated by poor definitions of “illegal” fishing gear and operations in fisheries law, low-level community awareness of the effects of unsustainable fisheries, and minimal resources for monitoring, control, and surveillance (MCS). While this issue is being addressed by broader regional programmes operated by FAO and SEAFDEC, local application of regional guidance on IUU management in the establishment and operation of refugia sites has been identified as a priority in Cambodia.