II. FISHERY RESOURCES DEVELOPMENT IN SAMOA

[ II-A | II-B | II-C ]

B. Inshore and marine pollution issues

Samoilys and Carlos (1990) conducted preliminary surveys of stocks of selected reef fish species and habitats at specific reef sites around Upolu. Their results revealed that all upper reef slopes and lagoons surveyed were dominated by hard substrate consisting of dead coral and rock with less coverage of live hard and soft corals. They observed a general trend of increasing fish abundance and biomass with higher cover of hard substrate in all survey areas although this relationship was more variable on the outer reef slopes.

They concluded:

• biomasses were lowest and mean sizes of individuals smallest in the heavily fished inshore lagoons.

• biomasses were higher and mean sizes of selected species larger in deeper outer reef slopes.

• highest biomass and sizes were found on reef slopes at the least fished site.

The team found two types of over-fishing:

1. Growth over-fishing; deduced by the very small size of reef species offered for sale at the market, including a wide variety of fish species, crabs, lobsters and clams;
2. Stock over-fishing. Some species of fish and invertebrates were so heavily fished that they became locally endangered. These included:

• Giant clams (Tridacna squamosa, T. maxima) now extremely rare in most locations.

• Edible snails Tectis pyramis, Turbo chrysostomus were uncommon in all areas surveyed.

• The gastropod Dollabella and the edible sipunculid worm Siponosoma have disappeared from north western Upolu.

• The palolo worm, Eunice viridis, a national delicacy, has also vanished from north western Upolu.

• Stocks of the edible jellyfish Cassiopea have decreased.

3. Declines in inshore fish catches were dramatic between 1986 and 1992. The study found:

• a ten-fold decrease in landings of scads, mullets and rock cods.

• a 20-fold decrease in landings of trevally.

• 80 per cent of all reef fishers interviewed considered catches of all kinds had declined over the past 10 years (sample size 1000).

Shortly after publication of their survey, Cyclone Ofa did extensive damage to the coastal and lagoon reefs.

In 1995, the Department of Marine and Wildlife Resources, American Samoa reported that the coral systems they studied on Upolu were in good condition on outer reef slopes in depths of 5-10m. They agreed with Samoilys and Carlos that these areas may be a refuge for fishes from the heavily fished reef tops and lagoons. The researchers recommended controls over future exploitation of this zone (Green 1996).

The team also recommended a long term monitoring programme for the coral reef resources starting with a repeat of the 1990 survey by Samoilys and Carlos which provided the only quantitative data available for the island prior to Cyclone Ofa. The Fisheries Division requested funding from SPREP to initiate such a programme in February 1997.

In 1990, Cyclone Ofa, stripped the upper portions of outer reefs of living coral and covering the lagoons and reef flats with fragmented coral debris. The storm-driven coral fragments covered and smashed the lagoon corals and completely eliminated the lagoon fauna on exposed reefs. Cyclone banks from 30 to 50 m wide and 2 to 3m high extending for hundreds of metres are still common.

Although tropical depressions and small cyclones are reasonably common in the area, Cyclone Ofa was the most destructive one in recorded history, with twice the radius of normal cyclones. The eye passed about 60 nautical miles south of the group, bringing the most destructive quadrant of the cyclone over the Samoa islands. Sustained winds of 140 knots generated high storm waves that hit the normally protected northern reefs. The most serious reef damage was along the western and northern shores.

The following year, Cyclone Val hit the same areas and although the 1991 Cyclone was smaller, it was intense and compounded the damage done by Ofa.

Healthy reefs recover quickly from Cyclone damage, but reefs under stress recover more slowly with the result that by 1997 coral recovery was still negligible.

The Crown of Thorns starfish (Acanthaster planci) is an efficient coral predator. Population explosions of this starfish have caused considerable damage to the living corals of Samoa over the past 20 years.

The first recorded major outbreak of the starfish in Samoa was along the south coast of Upolu in 1969. Between 1978 and 1985 a larger series of outbreaks developed on the coral reefs of Upolu. Savaii had outbreaks between 1980 and 1987. Despite government and village efforts at control, coral damage was severe. Recovery in the southern and eastern reefs was rapid but the northern and western reefs - those reefs subjected to the greatest stress from fishing and pollution - have been slow in recovering and numbers of starfish remain high in many areas.

In almost all shallow water lagoons, the corals were degraded through physical breakage during fishing and reef gleaning activities. In some cases, corals were accidentally damaged by people walking on them, in other cases, the corals were broken deliberately to remove fish or invertebrates from within the protective branches or blocks of coral. Fishermen sometimes broke coral to frighten fish into nets. In areas damaged by Cyclone Ofa, reef gleaning activities hindered regrowth of corals (FAO 1993).

In deeper lagoons and outer reef slopes, boat anchors caused severe damage to corals, especially in frequently fished sites.

Corals have also been damaged by the illegal use of chemicals or explosives for catching fish (Johannes 1982). The extent of damage by agricultural chemicals is not known. Testing for agricultural toxins is expensive and often targets a limited range of chemicals. Tests in 1982 by GKW Consultants showed DDT in marine organisms sampled near Samoan river outfalls, but all organochlorine poisons have now been banned. No tests were conducted on the effect of pesticides or herbicides on the coral reef environment of Samoa, but researchers in the Virgin Islands found pesticides suppressed photosynthetic activity of reef corals (McCloskey and Chesher 1971). Agricultural pesticides have also been considered a contributing factor in population outbreaks of the crown-of-thorns starfish.

Soil erosion from construction activities, roads and trails, farming and logging increased sediment loading of Samoa's abundant streams. The watersheds are steep and the rivers and streams wash the silt directly onto adjacent reefs. For example, in the vicinity of Apia (FAO 1993),

Dredging, sand mining and land reclamation also damaged reefs near Apia.

According to the Pesticide Registration Officer, Samoan farmers are reducing the use of Paraquat and turning to Glycophosphate herbicides. Phosphates are an extremely important limiting factor in tropical waters and may increase alga populations on reefs at the expense of the stony corals. Nevertheless this effect is not as great as the nutrients introduced from soaps, domestic garbage, sewage and agricultural processing wastes.

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