Saba Bank

Bathygraphic map of the Saba Bank area with depth contours down to 1000 meters. the bank proper is bounded by the 200 meter depth contour (dark blue area is 200-500 meters).

The Saba Bank (17^o25’ N, 63^o30’ W) is an undersea elevation with a flattened top, located 3 – 5 km southwest of the island of Saba and 25 km west of St. Eustatius. It is raised about 1000 m above the general depths of the surrounding sea floor. With a length of 60 to 65 km and a width of 30 to 40 km, the total surface area is approximately 2200 km², as measured from 11-200 meter depth, 1600 km² of which is shallower than 50 m. The flattened top is somewhat tilted with the north-western part of the platform being deeper than the south-eastern part. On the eastern and south-eastern sides a prominent ridge system runs along the platform edge, with depths varying between 7 m to 15 m. 

About one third of the Saba Bank lies within the Saban territorial waters (12 mile zone), while the remaining two thirds fall within the limits of the Economic Fisheries Zone (EFZ) of the Netherlands Antilles.

In a 1996 study "Towards sustainable management of the Saba Bank", AIDEnvironment conducted a study financed by the KNAP fund in order to review the existing information on the Saba Bank and to update it.

CORAL REEFS

The Saba Bank has intrigued many scientists. Differences of opinion on the formation of banks such as this have caused heated debate in the past. Eventually, after a Dutch expedition led by Van der Land  thoroughly investigated the Bankin 1974, it was concluded that it is a submerged but living atoll. As an atoll the Saba Bank ranks among the largest in the world (i.e. the Suvadiva Atoll in the Maldives 2240 km2; the Kwajelein Atoll in the Marshalls, 1683 km2). The reefs on its eastern windward edges are actively growing in contrast to the leeward reefs that do not appear to be growing. 

View of the reef along the eastern edge of the bank, 80 ft (24 m) deep.The reef is well-developed. Sand channels cut through groove and spur-like formations on a relatively flat bottom. Coral cover is high as well as diversity. So far 38 hard coral species have been reported from the bank.

The total surface area of the Bank where reef structures are present is estimated at approximately 150 km². Of this area, 20-40 km² is conservatively estimated to consist of actively growing reef. Because of this large expanse of reef and the prevailing westerly ocean currents, the bank likely represents an important source of eggs and/or larvae of coral, fish, lobster, conch and other kinds of biodiversity for the many islands lying to the west and north-west of the bank, including the Virgin Islands and Puerto Rico.

From a brief reconnaissance of the reefs during the AIDEnvironment study, Meesters, senior author of the report, concluded that the reefs on the eastern edge are rich in terms of cover and diversity. He reports coral cover to be 60-90% and lists 28 scleractinian coral species.

In 1999 a brief reconnaissance by the Environmental Section added 10 species to the list of hard corals. A rapid survey as part of the Atlantic & Gulf Rapid Reef Assessment (AGRRA) Program was conducted on three sites in December 1999. An average live coral cover of only 24% was found, with individual sites showing a cover of 11, 25 and 40%.The surveyed sites were all in less than 70 ft depth however, with the deepest site having the highest coral cover. The deeper reef may have a higher coral cover than the shallower, more exposed reef, as it would seem from cursory impressions from some of the survey participants. Another explanation might be that the reefs, like elsewhere in the Caribbean, have deteriorated badly due to diseases and/or bleaching. The average percentage of 27.5% dead coral recorded by the survey would support this.

The shallowest parts of the bank consist of a hard rock bottom covered by a carpet of wave resistent brown algae, alternating with thin patches of sand and sparse patches of coral, which give cover to lobsters and fish, such as this school of White Margates (Haemulon album).

FISHERY

When the Coastguard of the Netherlands Antilles and Aruba started actively patrolling the area recently, many boats from the surrounding islands were found to be illegally fishing on the bank. They were  mostly fishing for red snappers, grouper and conch. No exact catch figures are known, but it is suspected that the Bank was severely overfished. At present, fishing on the bank is only allowed for Antillean boats in posession of a fishing permit. Issue of permits is limited. Fishery is now an important resource for the economy of Saba.

Catch Assessment Project

In May 1999 the Environmental Section embarked on a catch survey program in order to assess the state of the fisheries. All catches brought in by fishing vessels operating out of Saba are being identified, counted and measured. The program will continue at least until June 2000, and hopefully beyond that.

Measuring a lobster's carapax for the catch assessment project.

The objective of the study is to determine maximum sustainable yield and optimum sustainable fishing effort for each target species, in order to devise a sustainable management plan for the fisheries so as to prevent overfishing and allow depleted stocks to recover. The participation of all the fishermen in this project has been outstanding. They support the project and understand the need to regulate the fisheries. The fishermen are engaged in two types of fishery: Spiny Lobster (Panulirus argus) fishery, and snapper fishery, with two main target species: Silk Snapper (Lutjanus vivanus) and Blackfin Snapper (Lutjanus buccanella).

Snapper fishery is only practiced sporadically. Preliminary results from the study indicate that the average fish size is much smaller than elsewhere in the Caribbean, suggesting that the snapper stock is seriously depleted, probably due to overfishing in the past.

The main fishery activity on the Saba Bank now is the lobster fishery. Only a few fishermen occasionally go out to catch snappers. The lobsters are caught with lobster traps and the snappers mostly with hand lines or occasionally with bottom long lines. From the lobster traps a by-catch of demersal fish is landed, consisting mostly of Grunts, Queen Triggerfish, Red Hinds, Coneys and a small number of other Groupers (mostly Yellowfin Grouper) and small Nurse Sharks.

In 2000 the final report of the fishery assessment study was published. [download complete report (pdf 840Kb)]. The main findings are summarized here: The total lobster catch per year amounted to about 90 tons and the total red snapper catch came to 12 tons per year. During the study it became clear that a high percentage of lobsters landed were under the legal size limit and a substantial percentage of berried lobsters were landed. Furthermore a considerable number of traps were lost, due to ship traffic and hurricanes. None of these traps were fitted with a biodegradable panel, so the lost traps may be extremely damaging to the ecology and consequently the fish stock of the Saba Bank. Snapper catches were considered fairly good, although the targeted specimens were relatively small in size. About 50 fishermen were active in the fishery and the Saba Bank fishery sector generated a gross economical value of 2 million Guilders (1.1 million US$) over 1999.

A lobster trap or pot lying in place on the Saba Bank

Mainly as a result of the program the following regulations (stated in the fishery legislation, the National Fishery Ordinance [in Dutch] and the Nat. Fishery Decree [in Eng]) are now being strictly enforced by the Coastguard:

• Presence of a biodegradable panel in each trap;
• Legal mesh size of 1.5? or 3.8 mm;
• Legal size limit for lobsters;
• Prohibition to land berried lobsters;
• Prohibition to land lobsters in ecdysis;
• Prohibition to fish without a license in both the Saban territorial waters and the Economic Fishery Zone (EFZ) of the Netherlands Antilles.

OTHER USE

Ship traffic, related activities and risks
Ship traffic is heavy on and around the Saba Bank. Many freighters, tankers and cruise ships pass through the area. Statia Oil Terminals on neighbouring St. Eustatius is a busy oil transshipment facility with an estimated 100 visiting tankers per month, making it the busiest tanker port in the region. Many of these ships pass over the Saba Bank where they form a hazard to the small fishing boats as well as to the fish traps which are often destroyed or lost by the passing of a big ship. The tankers also frequently anchor on the shallow bank while waiting to unload at the terminal, this is of course highly destructive for the coral reef on the bank, as well as for other bottom types such as conch feeding grounds. In addition there are reports of tank rinsings, oil spills and the emptying of sewage tanks. The presence of the Coast Guard has probably caused these practices to diminish, but the bank should be declared an off limits to large ships and especially to anchoring. At present legislation to this end is lacking but is being worked on.

Dive tourism

At present there is no appreciable recreational diving being done on the bank. Reportedly there is one live-aboard dive boat that visits the bank now and then. In the future however, as information on the bank's spectacular reefs becomes more widely available, dive tourism on the bank will become a highly valuable resource, especially as reefs elsewhere deteriorate increasingly. 

Oil exploration 

In the past several attempts were made to explore the bank for gas or oil, however no commercially exploitable quantities were found.

INTEGRATED MANAGEMENT PLAN

In order to sustainably use the bank's resources and integrate different forms of usage, while at the same time protecting its biodiversity, an integrated management plan for the whole bank is necessary. MINA is presently preparing a project for a complete biodiversity survey of the bank. The results of such a study, in combination with the fishery assessment data, will form the basis for the formulation of an integrated management plan.