The Impact of Ghost Fishing on Hong Kong's Artificial Reef Communities  

Project No. 32/99

Project Title: The impact of ghost fishing on Hong Kong's artificial reef communities

Applicant: The University of Hong Kong (Prof. Brian Morton, J.P.)

Total Approved Grant: $994,729.71

Duration: March 2001 to June 2003

Project Status/Remarks: Completed


'Ghost fishing' can be defined as the capacity of a fishing gear to continue to fish after it has either been lost or the fishermen have lost control of it. The impact of such discarded and lost fishing gear on the environment has aroused considerable concern in recent years (Laist, 1995). Public attention has focussed on the danger posed by ghost nets to rare and endangered marine mammals, seabirds and turtles. It has been estimated that millions of seabirds and thousands of turtles and marine mammals may die each year when entangled and trapped in lost gear (Colema and Wehle, 1983). In contrast, little is known about catches of less high-profile organisms such as crustaceans and fish. Clearly, however, incidental mortality of marine organisms due to gear that fishermen have lost control may be highly significant.

In addition to being a source of mortality, lost fishing gear has the potential to interfere with normal fishing and diving operations and may even be a cause of further fishing gear loss. Lost fishing gear may also have negative impacts on the environment, particularly in terms of habitat degradation, i.e., smothering of sensitive marine animals. Both these types of detrimental impacts have been observed in other locations, e.g., Southern Portugal (Erzini et al., 1997). Here, artificial reefs became so heavily fouled with fishing gear that reef fishes had reduced access.

While the possibility of either partial or total gear loss exists in all fishing activities, certain types of fear, in particular active gears such as trawls and purse seines are not a major source of concern as their catching ability is negligible once lost. Concomitantly, static gears such as gill nets, trammel nets and traps may continue to fish, once lost, efficiently for unknown periods of time. For example, Breen (1987) estimated that ghost-fishing traps caught an amount equivalent to 7% in weight of the reported commercial catch of Dungeness crab from the Fraser River Estuary, British Columbia. It is a sad feature of such 'ghost fishing' gear that following the death of the initial catch, scavengers are attracted to feed on the dead and decomposing bodies. Such scavengers in turn become trapped and, therefore, become the prey of other ill-fated conspecifics and scavengers, which again may become trapped, further increasing the attraction.

Over the last two decades Hong Kong's fisheries resources and much of its marine habitat have come under increasing pressure from stock exploitation, coastal development and pollution. A recent study (ERM for AFCD) concluded that Hong Kong's fisheries are overexploited and have moved from one dominated by slow growing high commercial value species to one composed of faster growing, small, short-lived predominantly pelagic and low value species. These changes have largely been the result of uncontrolled fishing activities. As a result of growing awareness, attention is being focussed on the maintenance and preservation of remaining resources. Recent initiatives include proposals for fisheries management, designation of marine parks and reserves and the establishment of a system of artificial reefs. Under the proposed plans both trapping and gill netting would be allowed within most of these protected areas and is indeed allowed within marine parks currently. Given recent and planned future efforts to restore Hong Kong's fisheries, it would be a shame for management to be ineffective due to unconsidered factors such as the impact of lost fishing gear.

Discarded and lost fishing gear are unfortunately a common feature of Hong Kong's subtidal environment and can be found smothering corals (see attached photos), entangled on rocks and submerged reefs and even on sandy and muddy bottoms. The amount and types of fishing gear lost and the longevity and effectiveness of the ghost fishing once a net is lost is unknown for the coastal waters of Hong Kong. In the Hoi Ha and Yan Chan tong marine parks, however, 7 tonnes of discarded nets were collected during a 1998 beach clean up. In 1999, 12 tonnes of nets and rubbish were collected from all the marine parks ( Fishing is regulated within these areas and, therefore, the situation for the remaining coastal waters is likely to more serious. Limited evidence from studies in other Atlantic areas suggest that discarded gear may continue to fish for considerable periods of time and catch the equivalent of up to 30% of annual landing levels (Laist, 1995). For example, at a rocky inshore location in South Wales, gill and trammel nets continued to trap commercial species of crustaceans, nine months after the initial loss (Kaiser et al., 1996). In Kuwait, lost fish traps were estimated to catch an equivalent of 3-13.5% of total landings (Matthews et al., 1987). Furthermore, the decline of the St. Lawrence Queen Crab fishery has partially been attributed to mortality associated with lost crab traps (Blois, 1992). It is considered of great importance to know how much fishing gear continues to ghost fish, for how long it does so and what species of marine organisms are most affected. Such basic information in unknown for the coastal waters of Hong Kong and indeed much of the tropical Indo-Pacific.

Summary of the Findings/Outcomes:

The main question raised by all of this is ?§Who owns the fish in Hong Kong waters??¨ Many answers are possible and each sets an interesting precedent. One certain fact is that the local fishing industry is not self-policing. It needs to be managed. Now that blast fishing is almost non-existent in local waters, it is time that other wasteful, irresponsible and non-sustainable fishing practices are also addressed. The AFCD has been aware of the ghost net problem for many years and has slowly been implementing measures which will eventually counter this and other current problems. The word ?§slowly?¨ was used in the last sentence, because some communities in Hong Kong are very much against any change, including those which today sustain their survival. Unfortunately, the fishing community is one of these. This along with the fact that the fishing community has a significant lobby has meant that any changes implemented have had to be slow.

This report would not be complete without some recommendations. The problem of ghost nets in Hong Kong is alarming and contradictory to government efforts to restore commercially viable fish species and stocks. These recommendations involve action from several government departments like the Marine Department (MD), Environmental Protection Department (EPD) and the Agriculture, Fisheries and Conservation Department (AFCD). A combined and co-ordinated effort is required. The amounts of ghost nets in local waters preclude the possibility of an SAR-wide cleanup. The cost involved, the logistics and the damage that would be done to the sessile benthos as the nets are ripped up are all too great to consider. Any effective solution to this problem lies in reducing the number of ghost nets introduced to local waters. It must, however, be a priority to reduce the total amount of net fishing occurring in local waters. There are several measures that could be considered.

(a). To increase the current efforts of fisher education. There has to be a greater drive towards sustainable fishing practices and a reduction in the wastage of fishery resources. The WWFHK Hoi Ha Wan Education Centre could possibly become involved in this process.

(b). A public campaign to educate fishers to properly dispose of useless and damaged nets on land should be implemented. This includes the establishment of specific collection points at existing litter stockades, particularly in fishing villages around Hong Kong. The final disposal of all nets and associated materials needs special consideration since weights contain lead. Recycling old nets is an option, but the end result of this may only be cheaper nets available to fishers. This in turn may compound the ghost net problem.

(c). The existing proposals for the setting up of areas where netting is prohibited should be accelerated. More areas should be protected from the devastation caused by inshore trawling. Large areas of water have already been proposed by the AFCD where all bottom net fishing should be banned. These include all marine parks, Tolo Harbour, Long Harbour, Outer Port Shelter as Fisheries Protection Areas, in which trawling would be banned.

(d). In-shore trawling needs to be banned. Trawlers are responsible for dynamic ghost nets and for trawling up static nets. These trawled static nets are usually discarded over the vessel??s side to become reactivated ghost nets.

(e). Smaller scale net fishing needs to be controlled, perhaps through licensing in some form or another. Part of the ghost net problem lies in the cheap price of nets. One comment used by a fisher in Tap Mun was ?§Well, if I catch one large grouper (~> 50cm) my net is already paid for. Then I really don??t care if I loose it?¨. There is no understanding of the much larger cost to the environment which ghost nets cause. Net licences can be introduced to exclude all but serious fishers. Nets should also be tagged so that the origin of a ghost net can be traced. This hopefully will lead to some responsibility for the proper recovery of ghost nets by the fishers themselves.

(f). The use of the local ?§tangle net?¨ should be banned throughout Hong Kong??s waters especially in the marine parks, permitting only true gill and trammel nets to be used. China is already proceeding with legislation to achieve this. Net mesh sizes and net lengths should be strictly controlled. Netting seasons could be introduced to avoid the breeding periods of important commercial species of fish in Hong Kong, as is the current practice in Mainland China.

(g). The P4 boat fishing community needs to have other sources of income available to them other than just net fishing. The licensing of the vessel should allow for legal paid rental for recreational fishing and diving activities on vessels that are banned from carrying any form of fish trap or nets. This solution would mean that two licenses would be available for the owners of P4 vessels to choose from. One license allowing netting but no paid passengers, and another allowing rental and paid passengers. The current practice is to ?§turn a blind eye?¨ and allow netting P4 vessels to carry no more than three paying passengers at any one time. It is interesting to note that during interviews carried out with fishermen around Hoi Ha, Tap Mun and Kau Lau Wan, the suggestion was welcomed, but everyone claimed that the government would never consider this option.

(h). More net removal exercises need to be carried out in strategic areas of Hong Kong. The existing programme of cleanups needs to be expanded to include more frequent activities in all marine parks and known major coral areas. The cleanup methodology detailed in this report (Appendix F) should become a standard procedure to ensure the safety of participants.

(i). Local recreation fishing and the surrounding mariculture industry needs to be expanded to help supply the demand for seafood in Hong Kong. More success with line fishing and the expansion of the cost effective mariculture industry in China would help to reduce the need to net fish local marine life, reducing the level of ghost nets in Hong Kong.

(j). Technology may be able to assist with biodegradable floats on the fishing nets as has been carried out with other fishing devices (Matthews et al. 1987; Blois 1992). The vertical profile of a ghost net has a direct impact upon the amount of marine life caught in it. If the net floats could also sink over time, then the fishing profile could be reduced accordingly.

(k). Currently Annex V of the International Convention for the Prevention of Pollution from Ships (effected 1989), is designed to ban the disposal of ship-generated plastics at sea. Nets are plastics. However, plastics may be thrown back into the sea if they are caught incidentally in retrieved fishing gear (Laist 1995). Accidental gear loss is also excluded from this convention. It may be possible to modify this international agreement to ensure the proper disposal of any recovered ghost nets. Discarding a fishing net can be construed as littering, carrying a fine of HK$1,500. An unmarked, unattended net could also be treated as littering. This would help cleanup exercises.

The problems involved with ghost nets in Hong Kong??s waters may be complex. From the results of this study, it is obvious that something needs to be done to reduce the amount of marine life wasted due to ghost net fishing, and the solution lies with education. Perhaps when the fishers realise that it is not just the few hundred dollars cost of the net that they have lost when a net becomes a ghost net. It is also the cost of all of the marine life that the net will continue to catch over the next year or so as well.