Marine Threats

Perceived marine and other threats in Niue

This is a summary of a UN report studying causes and concerns in relation to inshore fisheries from consultations with village members at Alofi North and Makefu (PSA report, Niue IWP National Programme). Causal agents have been hypothesised to be the dominant agent or agents in terms of coastal ecology effects by the author. A number of causal agents are left as unknown or unlikely to be addressed because of the uncertain connection between the concern and the likely cause(s).

Overuse by visitors degrading area (such as Matapa Chasm and Talava Arches) or tourist activities invading area (M)

Over use of tracks (walking and cars) may increase erosion along tracks when it rains; and walking on reef flat may trample sensitive organisms. Cause – Effect data unavailable; Personal observations confirm water – erosion on tracks but no little evidence of trampling.

Unknown impacts of introduced species by yachts and ballast water from cargo ships (eg starfish) (AN, M)

Introduced species transported in ballast water. Volume of cargo is relatively small per visit so amount of discharge is low. Data unavailable; no recorded introduction that has caused a problem.

Over harvesting and impacts from traditional fishing methods such as Tuha (Kava Niukini), or Kieto toxic plant root for poisoning fish. The impact of this plant root is lethal to all marine life including coral and seaweeds and takes a very long time for marine life to recover (AN, M)

Broad-spectrum poisons are used in confined areas like pools to target a few species only. A wide range of non-target species and all sizes of target species are usually affected. No cause-effect data but logically this will be a significant factor in over harvesting resources. Data required on frequency of poison use and where is used.

Coral damage from the use of non- traditional fishing methods, for example uses of hammers, axes, and crowbars when reef gleaning (AN, M)

Metal implements can be defined as non-traditional tools for gleaning. Efficient tools also encourage over harvesting of resources as rates higher than traditional harvest levels. Substrate damage is deep and neighbouring organisms can be damaged as well. No quantitative data available to show cause and effect. Most small organisms collected with modern tools result in minimal disruption to substrate probably minimal. Larger organisms like octopus may be harvested with resultant high substrate damage.

Over harvesting (in specific reef areas (AN, M))

Areas with easy access tend to be used more frequently, allowing mobility for more people and greater harvest time per tide cycle. No before-after data available on harvest pressure to confirm effect. Well-constructed and maintained tracks to shoreline are present (pre-Heta) which did channel activities to those areas.

Over harvesting due to nets -Tautau ika – catches large numbers of small size fish. It also occurs everyday, resulting in overfishing (AN)

Set gill nets can ‘catch’ for as long as they are deployed, and depending on mesh size, nets catches most fish to the size of the net mesh. No data available but could be collected (esp. for mesh size, and frequency of use).

Destruction of breeding holes (Feke) (From use of axes and hammers when harvesting?) (AN, M)

Animals that hide can be extracted by breaking away the surrounding substrate. Strong modern tools are very useful for this purpose. No data available but relevant catch effort data would indirectly indicate the degree of damage.

Overly concentrated use of some reef resources due to lack of easy access to sea tracks (AN, M)

Areas with easy access tend to be used more frequently than low access areas, allowing mobility for more people and greater harvest time per tide cycle. No before-after data available on harvest pressure to confirm the claims. Well-constructed and maintained tracks to shoreline are present (pre-Heta) which did channel activities to those areas (pers.obs.).

Over harvesting because of introduction of modern fishing gear (M)

Increase in catch per unit effort can be a result of improvements in the tools used in catching and harvesting resources. No data available for Niue, but in theory and from experiences in other countries it is a valid argument. Fishing effort may be quite low due to the low resident numbers but gear efficiencies can still maintain high fishing effort.

Displacement of seasonal fish such as kaloama, atule, ulihega, big eye scad, skipjack tuna and flying fish from reef edge, drawn away by FAD’s. These fish used to be caught by canoes but no longer. (AN, M)

There may be a correlation between decreases in nearshore catches and the introduction of offshore FAD’s. Inter-annual variability in fish abundance may also correlate with the introduction of FAD’s. FAD’s are proven to attract fish especially when they are in low densities, making them more vulnerable to fishing. No data available to indicate a shift in distribution patterns of fish that is related to the deployment of FAD’s.

Residents concerned the reduction in fish catch results in more reef gleaning. (AN, M)

Displacement of fishing effort from one habitat to another often is a consequence of stock depletion in certain areas. No data available for Niue but is a well-accepted consequence of localised depletions of certain stocks.

Lack of traditional practices of feeding and caring of fish and fishponds – ava ika. This practice undermined but is important to protect important fish stocks (AN, M)

Traditional management and farming methods may have enhanced the harvest of more fish at a frequency that follows consumption rates. Reef flat deep pools were sealed to retain fish and they were fed and then harvested as required. No data available but in theory may be a mechanism to increase local harvest levels, though it would require a source of fish food and careful management to succeed.

Traditional practice of keeping all fish. Some people keep to old ideas that you need to keep all fish caught) as was practiced in the past. This was done due to uncertainty of sea conditions and the need to maintain food security (M)

The taking of all available target species if caught, does not allow protection for any size or life stage to grow into breeding adults. There is a belief that all caught animals need to be kept because it enhances the production of more individuals. No data available, but believed by locals to be widely practised. Taking more to produce more is not logical at the harvest levels that can be attained in the present day.

People from other areas using reef resources without permission. (AN, M)

Over harvesting in some previously lower-use areas can in the short-term result in an unsustainable level of fishing effort by shifting the fishing effort. Lack of village-based management also can be an outcome due to the lack of communication to people outside a village. No data for Niue to show a sustained high harvest effort correlating with stock depletions for certain locations. Gleaners from different villages were harvesting outside their village areas when I was there in December 2003.

People from other areas not respecting local rules (eg tabu areas, seasonal closures use of proper baits, or harvesting methods) (AN, M)

Spearfishing – Residents concerned it is scaring fish away from protected fishing holes or impacting on fish reef stocks (AN, M)

Fish that are pursued by spearfishers learn to avoid contact or the proximity to people, therefore catch rates are reduced. Spearfishing (esp. at night) is very efficient and can lead to localised depletions. No data available for Niue but information from other examples indicate that spearfishing can be unsustainable.

Night diving, which is bad because (? Not completed in PSA report). (AN, M)

Night reef fishing with torches – residents say with past use of handmade traditional torches people did not harvest as much; now they can see better and catch more (AN, M)

Example of the introduction of modern tools that greatly enhances fishing efficiencies for the reasons outlined on the left. No data available for Niue, but locals know they can catch more by having more reliable, brighter, and long lasting light sources.

Diving on fishing grounds (AN, M)

People avoidance by fish may be due to spearing but the general presence of diver-associated noise may cause some fish to stay away from the well-used dive areas. No data to show this cause and effect. There is relatively low diving activity in Niue so it is not likely to be a significant effect.

Netting of fish by foreign boats out at sea (M)

Purse seine nets can be very exploitative with low natural stock sizes. Licensed tuna boats mainly use long lines and not purse seine nets. Poor available data for catch effort for the foreign fleet, but indications are that the boats visit seasonally and not all year round.

Crabs like uga and kalahimu being harvested during spawning season (AN, M)

The taking of animals when carrying eggs or young offspring severely reduces the ability of these species to sustain future generations. No data are available on the prevalence of this behaviour but there appears to be no common practise that addresses this concern.

Traffic is running over crabs (AN, M)

Land crabs and coconut crabs move between the shoreline and the inland forest area, requiring them to cross the main road ringing the island. Daily road mortality of land crabs from cars was evident and is high during lunar migrations, but there are no data to validate cause and effect, particularly in relation to general depletion of marine resources, or depletion in land crab numbers.

People are not using enough resources

There is a belief in the certain sections of the community that if resources are not used, they do not sustain their presence in the longer term. There is no information to support this belief, though ecological theory states that communities left undisturbed for long periods (either by man or natural disturbances), will show a succession of species relative abundance that results in a fewer number of larger dominant species.

Aao taking over alili (AN)

Some people believe that hermit crabs (aao) are more abundant now than previously and that this is because the crabs are eating the turbo shell animal (alili) and taking over the shells. No data are available to show an increase in hermit crab numbers, and there is no biological evidence to suggest the crabs are overtaking live turbo shells. More vacant turbo shells may be a result of greater mortality of turbo species but there is no evidence to show this.

Segame being eaten by ugauga (AN)

Belief that algae (?segame) are eaten by crabs marine crabs (ugauga). No data to show increase in crabs or decrease in algae, to extent that crabs are affecting algal abundance.

Eggs of uga eaten by feke (M)

Belief that coconut crabs eggs are eaten by octopus (feke). Not likely to be true as uga eggs are too small to be caught by octopus, and eggs float away from reef areas are being released, i.e. away from octopus hunting grounds.

Increased numbers of dogs and wild pigs eating resources (like uga) (AN, M)

Uga (coconut crabs are susceptible to predation from carnivores like pigs and dogs. No data to support increase in feral animals.

Increased predation by birds – Motuku (Heron) (M)

Local belief that heron birds are becoming more abundant to extent they are reducing near shore fish abundances. No data to show increase in heron numbers.

Change of fish habits – they do not appear to be where they are supposed to be in protected fishing holes (AN, M)

Fish behaviour may be changing to the extent that protected areas may not be used by fish  in the same way as in the past. No data to show lack of positive response by fish to protected areas or in change in fish behaviour.

Damage to the reef flats from siltation –  residents concerned about makatea (silt) running into reef flat zone from the storm water drains and development of sea tracks, car parks, and picnic areas. Siltation also said to affect caves and pools on reef flat (AN, M)

Sedimentation observed to be more prevalent and seen in certain areas. Sediment smothering and interfering with feeding and growth of benthic organisms. Nutrient enrichment via increased runoff of land material. No data available to demonstrate mortality due to sedimentation nor to increased sedimentation/ erosion of near shore areas. Sediment runoff observed in developed areas. Theoretically probable if sediment runoff in sufficient quantity to affect Niue habitats adapted to low sediment loads.

Development of sea tracks using dynamite and other harmful chemicals (AN, M)

Development disturbances perceived to correlate with stock depletions. No data to demonstrate cause and effect though is theoretically possible that increased erosion occurred from development (see above saltation issue). Also have possibility of explosive material based on nitrates and phosphates to add some elements to the marine habitats but more likely that the effect is through erosion mechanisms.

Wharf construction project has blasted around this area and damages coral (AN)

Disturbances from development may include physical damage and nutrient release from the reef substrate. No before –after data available to validate or refute claim. Physical local damage to habitat would have occurred.

Development of small pools? (M)

Not clear as to cause, but may relate to growth and infilling of pools over time due to coral and algal growth. No data to address claim, though relatively fast growth of living edges of pools is sometimes evident, especially in cases where there is regular water exchange with the open ocean, (providing good growing conditions for corals and coralline algae).

Dying coral from overexposure to heat and sun, sea to calm, this may be related to global warming and climate change (AN, M)

Unusual exposures to air and sunlight can kill organism not adapted to such exposures. No data to support the cause and effect though local stories have confirmed some periods of unusually low tides on Niue.

Growth of corals narrowing swimming holes (M)

Swimming holes and pools in the reef flat will naturally fill in over time from growth of coral and coralline algae. This may restrict access for purposes of harvesting of fish etc from these holes. It will also gradually reduce the favourable conditions in this habitat as a living place for certain species. Pools with connections to the open ocean have strong water flushing which is beneficial to rapid growth of corals and coralline algae. Growth is fastest in the upper pool rim, leading to its eventual sealing off. Many pools do show varying degrees of edge growth. This natural process could not be seen as having a significant contribution to the widespread decline in fisheries yield.

Traditional treatment of ‘Fou’ sticks used for skirts from the bark were placed in these swimming holes. (M)

Branches from the beach hibiscus (fou tree) are soaked in seawater prior to being stripped of the bark that is used in producing skirts. The holes were good locations where soaking could be carried out without them being washed away. The soaking process draws out many compounds in the bark, which may be toxic to some organisms. The bark may contain saponins and other compounds that can be toxic or ‘unpleasant’ to fish and other organisms. No such activities were observed during the first visit, though hibiscus trees were observed growing in the vicinity of the shoreline. The high flushing rates of many swimming holes mean that very high quantities of fou bark would . .

Lack of protection (village regulations) of sea shrubs (AN, M)

Not certain of the intent of this issue though it possibly may refer to the disturbance of coastal shrubs leading to increased erosion and flow of sediment into the sea. Some evidence of small scale and large scale clearing of understory vegetation was evident, but there were no strong indications of high erosion occurring, except associated with sea track development.

Wastes and sewage discharge from septic tank leakage or toilets without septic systems (such as some water seal/ flush toilets and long drops) polluting sea area (AN, M)

Soakage of toilet waste into the ground is necessary in the absence of a full reticulated sewage system with accompanying treatment. Toilet wastewater contains high nutrients with nitrogen and phosphorus compounds, which can cause adverse effects on many calcifying reef organisms. All occupied households have septic systems of varying proficiencies, and it is theoretically feasible that the porous nature of the soils will lead to rapid transmission of waste fluids possibly without sufficient time for total absorption of the compounds of concern before they enter the coastal environment. Indicators such as high macro algae abundance in intertidal areas were not present.

Waste and sewage draining into caves and crevasses and that leads into sea area. (AN, M)

Same as above.

Lack of proper drainage system and contamination by pollutants from storm water flowing into coastal areas and reefs (AN, M)

Stormwater management currently consists of re-direction of major road runoff towards the shoreline (some drains flow directly onto the reef flat, others through caves or the substrate surface). Stormwater does flow off the roads and rapidly onto the coastal areas. There was no definitive evidence that . .

Wastes and sewage discharge from pig styes draining into sea area.*(AN, M)

Nutrient enrichment of water flowing from piggeries can be attributed to the crowded conditions of the pens with the resultant concentration of waste. Eight piggeries are located along a major fault line inland from Alofi North village houses. One piggery in Makefu is located on the seaward side of the main road. No data are available to validate the flow of waste from the piggeries.

Sewage draining from resort and hotels going into reef area (pollution source and smells) (M)

Soakage of toilet waste into the ground is necessary in the absence of a full reticulated sewage system with accompanying treatment. Toilet wastewater contains high nutrients with nitrogen and phosphorus compounds, which can cause adverse effects on many calcifying reef organisms. All resorts and hotels have septic systems but may be inadequate to cope with high use periods. It is theoretically feasible that the porous nature of the soils will lead to rapid transmission of waste fluids possibly without sufficient time for total absorption of the compounds of concern before they enter the coastal environment. Indicators such as high macro algae abundance in intertidal areas were not present.

Lack of facilities such as toilet facilities (such as around Utuko swimming area). (M)

Some heavy use tourist sites may require toilet facilities for the same reasons as explained above. Some sea tracks and swimming locations have toilet facilities. Some low use sites do not have these facilities. There was no definite proof of such a cause (with or without facilities), either within the bounds of the sea tracks, or in the immediate reef flat areas.

Dumping of wastes and sewage from yachts and ships into sea. (AN, M)

Ships and yachts usually have containment facilities on board boats so if they are discharging into the near shore areas whilst at anchor, it could be a localised problem for the harbour area. No data are available to validate this possible cause. There is a clear season for visiting yachts, and more regular visits by large supply ships but not observations were offered as to this being a regular occurrence.

Oil pollution run off into the coastal area (Sites mentioned – Amanau area toxic wastes)(AN, M)

Unmanaged oil spillage will eventually contaminate surface and sub surface water. Oils contain toxic hydrocarbons and potential nutrients through chemical breakdown. Considerable areas of oil spillage were observed on the ground that was associated with activities using oil and petrol in the Amanau industrial area. No clear evidence was found to validate that run off from this area was affecting the coastal habitats.

Unsafe storage of petrol and fuel tanks (bulk fuel depot) Residents concerned storage tanks are too close and petrol and diesel runs off into the sea (AN, M)

Transferring fuel to and from the storage tanks can result in some spillage. Fuel contains toxic compounds as well as nutrient when compounds are broken down. Containment walls were present to prevent serious spill accidents, but a stormwater drainage system was present to drain away rain water, so there is the potential to . .

Leaks during transfer from tanker (AN, M)

Fuel has to be transferred from tankers anchored offshore to shore facilities because of the small harbour. No information to validate the cause but is highly likely that spillages will occur some times. Fuel will float on the seas surface and unless winds blow it onshore, it will be dispersed away from the shoreline and will evaporate rapidly.

Oil from ships (AN, M)

Automatic bilge discharges from ships adjust internal bilge levels. There is usually a lot of oil mixed with bilge fluids. No information available but it is a common issue associated with all ship activities.

Batteries being dumped into the sea (M)

Convenience of getting rid of used batteries. No evidence during pilot surveys of two villages. No other information to validate extent and frequency.

Pollution from ballast water (M)

Same as “Oil from ships” above.

Ocean littering, for example plastics, empty cans and people treating the sea as dumping place (AN, M)

Some toxic effects may be associated with rubbish, depending on the contents. There are also some physical effects of rubbish accumulations. Generally rubbish is an eyesore but a symptom of general disregard for coastal areas by some individuals. Some evidence of rubbish in the coastal environment.

Rubbish and littering (around Alofi wharf area, sea tracks, and roadsides) (AN, M)

Same as above.

Dumping of household rubbish in coastal area, or caves and crevasses (M)

Same as above.

Waste fishing lines and plastics dumped by fishermen and by boats, yachts and cargo boats into the sea and reef (M)

Same as above.

Concerned about rubbish (for example mooring ropes) at tourist and swimming sites (Utuko) (M)

same as above.

Rubbish from boats and ships swept into sea and drifting into shore (M)

Same as above

Steel and pipes rusting in the sea and the possible bad effects on fish feeding on these (AN, M)

Metal objects slowly degrade in the sea, and there is the likelihood of a chronic heavy metal release into the environment. Extensive metal present in harbour sub tidal habitat.

Dumping of dead animals (at dump, along roadside, into caves, into sea) (AN, M)

Convenience of disposal. No evidence during my visit.

Cemeteries close to coastal areas and if graves not sealed properly can pollute water (AN, M)

Common activity accepted by the community. Large numbers of gravesites present along the coastline, though there are cemetery locations in Alofi North and Makefu.

Using of explosives at wharf area. Residents concerned that this contributes to the poison fish (AN)

Expansion of wharf facilities required the use of explosives. The breakage of rock and the explosive material contributes to the introduction of nutrients into the sea. Difficult to validate and to correlate ciguatera with a single prior event with no persistent effect.

Vai pamu pupu (paraquats/grammoxone) impacts of these leaking into deep water lens contaminating drinking water (M)

Herbicides and pesticides used extensively in agricultural production. Surplus and persistent chemicals will be transferred to groundwater and potentially flow out to coastal habitats. No data available. No regular monitoring of groundwater monitoring bores (piezometers).

Wastes and sewage discharge from septic tank leakage or toilets without septic systems (such as some water seal/ flush toilets and long drops) (M)

Same as relevant sections above.

Waste from pig styes down into water lens (M)

Same as relevant sections above.

Waste oil (M)

Same as relevant sections above

  • Habitat degradation
  • Harvesting
  • Animal behaviour
  • Degradation of coastal habitat
  • Coastal pollution – from sewage and household wastes
  • Coastal pollution – from toxic wastes
  • Coastal pollution – from solid wastes
  • Sickness from Ciguatera poisoning
  • Contamination of groundwater