Saba Bank

Findings

The main conclusion from this study is that no new fishing permits should be issued until a long-term fishery monitoring program is in place. The study emphasizes the need for effective enforcement of existing regulations.

Findings from the study include:

• 14 fishing vessels use the Saba Bank.
• Saba Bank fishermen engage in two types of fisheries: a spiny lobster fishery (most frequent), and a snapper fishery (least frequent).
• The total lobster catch amounts to about 90 tons per year and the total red snapper catch amounts to about 12 tons per year.
• A considerable number of traps are lost due to ship traffic and hurricanes. None of these traps are fitted with a biodegradable panel, so the lost traps pose a huge threat to the fish stock of the Saba Bank.
• In 1999, the Saba Bank fishery sector generated a gross economical value of 1.1 million US$.
• An important issue that came out of this study is that a substantial part of the landings of lobsters consist of illegal lobster catch. High percentages of under-sized lobsters and berried lobsters in the catch are a serious concern. A high percentage of lobsters landed are under the legal size limit and a substantial percentage of berried lobsters are landed. The mean CL (carapace length) of lobsters from the Saba Bank (10.7 cm) was set at this level so that future harvesting is not endangered as long as the legal size regulation is strictly enforced. 

Management Recommendations:

Fishery regulations must be strictly enforced for a successful management of the Saba Bank fishery:

(As a direct result of this catch assessment survey the Coast Guard of the Netherlands Antilles has commenced to strictly enforce the fishery regulations.) The following regulations are currently being enforced:

• Legal mesh size
• Use of the biodegradable panel
• Legal size limits for lobsters
• No landing of berried lobsters
• No landing of soft-shell lobsters (lobsters in ecdysis)
• Requirement of Fishing License for both Saban Territorial Waters and Economic Fishery Zone (EFZ) of the Netherlands Antilles.

The implementation of the fishery regulations by the Coast Guard of the Netherlands Antilles has resulted in a substantial decline in illegal fishery activities:

• The number of under-sized lobsters has decreased, and practically no berried lobsters and lobsters in ecdysis were brought in.
• Illegal (non-licensed) fishing activities from both foreign and domestic vessels have practically stopped.

Restrictions should be made on landing berried lobsters and lobsters in ecdysis, and on catch and effort through size limits (lobsters).

The total fishing effort for snappers should not be increased until more data is available (average length of the main snapper species of the Saba Bank is relatively small).

Further research and accurate catch and effort and length-frequency data are required to formulate sound regulations.

A communication network should be developed which involves fishermen, Central and Island Governments, the Coast Guard and the research community.

Both the Saba island Government and the Central Government need to strictly enforce the regulations concerning the legal mesh size and the biodegradable hatch for traps to reduce the amount of ghost traps on the Saba Bank.

The lobster fishery should not be expanded; there are already concerns that the fishing effort might have reached sustainable levels of exploitation.

Continued monitoring of the fishery is needed to show clear trends on the lobster fishery exploitation level.

The Central and/or Saba Island Government should ensure that data continues to be collected and interpreted.

Fishermen should be encouraged to exploit the resources of the Bank in a sustainable manner.

Both the Central Government and the Saba island Government should conform to the inspection procedures and standards required by the EC, so that fish products can once again be legally exported to the French islands.

It is recommended that both the Central Government and the Saba island Government specify the nature of the fishing licenses per target species. The resource users should pay a fee for these licenses according to regional standards. The income generated from the fishing licenses fee can be used for management and monitoring of the fishery, whereby the resource users contribute to the management and monitoring of the stock.

Abstract:

This paper provides a context for the results of recent biodiversity surveys of Saba Bank.

Recent biological surveys of corals, fishes, and algae emphasized habitat diversity and the relative richness of the marine flora and fauna. These assessments formed the basis for a management plan to protect Saba Bank’s biodiversity and a draft proposal seeking Particularly Sensitive Sea Area (PSSA) status for the Bank. The intention of the PSSA proposal is to protect the benthic habitat on Saba Bank from anchor damage. It is hoped that this collection will serve as a knowledge baseline and provoke further research in the area.

Findings:

Meesters et al, 1996: review of existing knowledge and quick field survey of Saba Bank.

• This study confirmed that Saba Bank is of great interest, both geologically and biologically.
• This study confirmed that the area is a regionally unique ecosystem, relatively pristine and remote from human influences, with high biological diversity and productivity.
• The study highlighted threats from overfishing and anchoring by large tankers.
• Meesters recommended further study of Saba Bank, improved legislative instruments, including international instruments, and enforcement to control current and future activities as well as capacity and awareness building.

This study formed the basis for the N.A government’s policy for Saba Bank. Lack of resources and capacity delayed implementation of this policy.

Dilrosun, 2000: first in-depth fisheries catch assessment that provided solid data about the state of the Saba Bank’s fisheries.

• This study concluded that no new fishing permits should be issued until a long-term fishery monitoring program was in place.
• The study emphasized the need for effective enforcement of existing regulations.

This study had immediate effects on Saba Bank policy; the island government of Saba declared a moratorium on fishing permits and a capacity building effort to strengthen the Coast Guard’s enforcement of existing regulations began.

Several studies were requested so as to demonstrate that the Saba Bank satisfies all the criteria that the International Maritime Organization requires for the area to become a Particularly Sensitive Sea Area (PSSA)

2006 Rapid Assessment Program (RAP) of Saba Bank: the aim was to produce appropriate and realistic conservation recommendations.

• This survey really demonstrated the richness of the Saba Bank’s biodiversity.
• Many new species were reported, and Saba Bank was found to have a uniquely diverse marine macro-algal flora.
• The expedition brought worldwide publicity for Saba Bank and helped to earmark Dutch development funding for further study of the Bank.

2007 high-resolution bathymetric GIS map of Saba Bank

• The map was produced using the Navy’s sonar data within a Geographic Information System (GIS) framework.
• The map formed the basis for further study of Saba Bank.

2007 Second Fisheries Assessment: the goal was to assess the crustacean and gorgonian fauna of Saba Bank.

• Two undescribed octocoral species were discovered
• Two different shallow water gorgonian habitats were distinguished

The number of anchoring tankers and the damage caused by them was documented through a vessel monitoring system and the report of a few cases.

Saba Bank Management Plan Draft

• In-depth description of Saba Bank’s biodiversity.
• More data on the use being made of the Bank.
• Better idea of the habitats present on the Bank.

A PSSA status proposal has been drafted and is currently being finalized.

New legislation to regulate international shipping in the waters of the Netherlands Antilles, needed in order to submit a PSSA proposal to the IMO, was passed. This legislation also makes it possible to declare the area an EEZ (another requirement for the PSSA proposal). The process is underway and is expected to be finalized in 2010. The anchoring prohibition will also be extended to the whole of the Bank in 2010.

Management Recommendations:

• Further study and monitoring of the Bank’s biodiversity and use will be required to guide the Bank’s management in a feedback loop.
• Interaction of biodiversity research and policy development is essential to developing effective management of biodiversity and public support.
• Carry out further research into the various habitats of the Bank, about which far too little is as yet known. To date, only a very small part of the huge area has been adequately sampled.
• Another priority is a study of marine mammals on Saba Bank to determine their presence and use of the bank. Anecdotal evidence suggests that humpback whales may use the Bank for calving, and sperm whales may find prey around the steep edges of the Saba Bank platform. Other areas of research that would contribute to more effective management include further studies of conch (Lobatus gigas) and lobster (Panulirus argus) populations, and sea turtles’ use of the Bank. Socio-economic studies would also be welcome. 

Background:

Located in the Dutch Windward Islands, Saba Bank is a flat-topped seamount (20–45 m deep in the shallower regions). The primary goals of the survey were to improve knowledge of biodiversity for one of the world’s most significant, but little-known, seamounts and to increase basic data and analyses to promote the development of an improved management plan.

Methodology/Principal Findings:

Our team of three divers used scuba to collect algal samples to depths of 50 m at 17 dive sites. Over 360 macrophyte specimens (12 putative new species) were collected, more than 1,000 photographs were taken in truly exceptional habitats, and three astonishing new seaweed community types were discovered. These included: (1) ‘‘Field of Greens’’ (N 17u30.6209, W 63u27.7079) dominated by green seaweeds as well as some filamentous reds, (2) ‘‘Brown Town’’ (N 17u28.0279, W 63u14.9449) dominated by large brown algae, and (3) ‘‘Seaweed City’’ (N 17u26.4859, W 63u16.8509) with a diversity of spectacular fleshy red algae.

Conclusions/Significance:

Dives to 30 m in the more two-dimensional interior habitats revealed particularly robust specimens of algae typical of shallower seagrass beds, but here in the total absence of any seagrasses (seagrasses generally do not grow below 20 m). Our preliminary estimate of the number of total seaweed species on Saba Bank ranges from a minimum of 150 to 200. Few filamentous and thin sheet forms indicative of stressed or physically disturbed environments were observed. A more precise number still awaits further microscopic and molecular examinations in the laboratory. The expedition, while intensive, has only scratched the surface of this unique submerged seamount/atoll. 

Findings:

Combining the findings of this study with that of other studies, the authors conclude that the coral assemblage on the Saba Bank is diverse and healthy; it is representative and typical of those found elsewhere in the Caribbean.

Coral Richness

• A total of 43 species were documented.
• There were no significant differences in coral composition amongst bottom types or depth classes.
• There was a significant difference between sites near and far from the platform edge. The number of coral species observed ranged from 0 and 1 in algal dominated habitats to 23 at a reef habitat on the Bank’s southern edge.
• Coral species richness was higher on reef dominated areas as opposed to algal dominated ones.

Coral Condition

• Bleaching was evident at 82% of the sites assessed with 43 colonies bleached.
• Only three coral colonies were observed to have disease.
• Five reef sites had stands of Staghorn Coral (Acropora cervicornis), a critically endangered species on the IUCN Red List.
• No physical damage consistent with anchor usage or sand scour from shipping activity was noted at any of the sites assessed.

Management Recommendations

1. Immediate action is necessary to protect the diverse coral reef habitats documented.
2. The five healthy stands of staghorn coral (A. cervicornis) and their surrounding should be given highest priority for full protection in the zoning use plan under development (in consultation with all stakeholders).
3. More information is needed on the Saba Bank to create a comprehensive zone use plan. For example, more sites need to be studied so as to get a more comprehensive coverage of the bank’s coral composition.

Abstract:

Biodiversity surveys were conducted on Saba Bank, Netherlands Antilles, to assess ichthyofaunal richness and to compare with published surveys of other Caribbean localities. The primary objective was to estimate the total species richness of the Saba Bank ichthyofauna. A variety of sampling techniques was utilized to survey the fish species of both the visually accessible megafauna and the camouflaged and small-sized species comprising the cryptic ichthyofauna. Based on results presented herein, the number of species known on Saba Bank is increased from 42 previously known species to 270 species. Expected species-accumulation curves demonstrate that the current estimate of species richness of fishes for Saba Bank under represents the actual richness, and our knowledge of the ichthyofauna has not plateaued. The total expected fish species richness may be somewhere between 320 and 411 species. The Saba Bank ichthyofaunal assemblage is compared to fish assemblages found elsewhere in the Caribbean. Despite the absence of shallow or emergent shore habitats like mangroves, Saba Bank ranks as having the eighth highest ichthyofaunal richness of surveyed localities in the Greater Caribbean. Some degree of habitat heterogeneity was evident. Fore-reef, patch-reef, and lagoonal habitats were sampled. Fish assemblages were significantly different between habitats. Species richness was highest on the fore reef, but 11 species were found only at lagoonal sites. A comprehensive, annotated list of the fishes currently known to occur on Saba Bank, Netherland Antilles, is provided and color photographs of freshly collected specimens are presented for 165 of the listed species of Saba Bank fishes to facilitate identification and taxonomic comparison with similar taxa at other localities. Coloration of some species is shown for the first time. Preliminary analysis indicates that at least six undescribed new species were collected during the survey and these are indicated in the annotated list. 

Findings:

The main conclusion from this study is that the health of the reefs of the Saba Bank has deteriorated since the first observations in 1972, 1996, and 2002. The general impression is that the Bank is still recovering from the 2005 bleaching disaster, but there is not enough data to exclude other reasons (e.g. overfishing, anchor damage, hurricanes).

• In 1996, Meesters et al. estimated coral cover at 7 locations to lie between 60 and 90%. These percentages were nowhere observed this time. The best site visited had an estimated coral cover of around 50%.
• There is now a high cover of algae (mainly Dictyota spp. and Lobophora spp.) on the reefs of the Bank.
• The present absence of important grazers such as the black sea urchin are likely to slow down recovery.
• Fish numbers appeared to be lower than previously observed, though sharks were observed on almost every dive, indicating a still intact food chain. The low numbers of fish may be a seasonal effect, a result of the presence of predators, or a result of changes that followed from the 2005 bleaching event.

However, corals appear healthy and the reefs of the Saba Bank are probably slowly recovering to their previous grandeur.

• Very few coral colonies with diseases were observed.
• Some colonies were bleached as result of the seasonal high water temperatures, but there appeared to be almost no mortality among these bleached colonies. 

Management Recommendations:

Begin to regularly monitor the health of the Bank’s coral reefs and the impact of human activities such as fishing as soon as possible (permanent video transects are planned to be installed in 2011 at a number of sites on the Bank).

Botanical and zoological collections may serve as archives for historical ecologi- cal research on the effects of global change and human impact on coral reef biota. Museum collections may harbour old specimens of reef-dwelling species that have become locally extinct. Such collections also help to determine whether early records of invasive species can be obtained from times when they were not yet recognized as such. A case study (2006) involving Saba Bank, Caribbean Netherlands (former Netherlands Antilles), suggests that the coral reef fauna here may have become impoverished when compared with data obtained during an earlier expedition in 1972. However, the 1972 sampling may have been incomplete, as it was performed by professional divers who were not trained taxonomists, whereas the collecting in 2006 was done by expe- rienced marine biologists who knew the taxa they were sampling. As Saba Bank has been under stress due to the anchoring of large vessels, and invasive species have been a potential threat as well, future studies are needed to obtain more insights into the changing reef biota of Saba Bank. Using this Saba Bank exam- ple, we want to address the importance of natural history collections as reser- voirs of valuable data relevant to coral reef biodiversity studies in a time of global change. As such, these collections are still underexplored and underexploited. 

Saba Bank is a 2,200 km2 submerged carbonate platform in the northeastern Caribbean Sea off Saba Island, Netherlands Antilles. The presence of reef-like geomorphic features and significant shelf edge coral development on Saba Bank have led to the conclusion that it is an actively growing, though wholly submerged, coral reef atoll. However, little information exists on the composition of benthic communities or associated reef fish assemblages of Saba Bank. We selected a 40 km2 area of the bank for an exploratory study. Habitat and reef fish assemblages were investigated in five shallow-water benthic habitat types that form a gradient from Saba Bank shelf edge to lagoon. Significant coral cover was restricted to fore reef habitat (average cover 11.5%) and outer reef flat habitat (2.4%) and declined to near zero in habitats of the central lagoon zone. Macroalgae dominated benthic cover in all habitats (average cover: 32.5 – 48.1%) but dominant algal genera differed among habitats. A total of 97 fish species were recorded. The composition of Saba Bank fish assemblages differed among habitat types. Highest fish density and diversity occurred in the outer reef flat, fore reef and inner reef flat habitats. Biomass estimates for commercially valued species in the reef zone (fore reef and reef flat habitats) ranged between 52 and 83 g/m2 . The composition of Saba Bank fish assemblages reflects the absence of important nursery habitats, as well as the effects of past fishing. The relatively high abundance of large predatory fish (i.e. groupers and sharks), which is generally considered an indicator of good ecosystem health for tropical reef systems, shows that an intact trophic network is still present on Saba Bank

Findings

Abundant coral growth within the Saba Bank is restricted mainly to the two large windward reefs. These two reefs carry a very rich reef fauna.

The rest of the Bank only has a very small growth of corals due to several factors:

• Most of the food supply is probably filtered away by the large windward reefs.
• These reefs are located at a least favorable leeward position.
• These reefs are located at a considerably greater depth.

As in most other atoll lagoons, coral growth in the lagoon area is restricted to small patch reefs; the number of species is not significantly lower than on the reef, but the colonies are smaller in size and number.

The Saba Bank undoubtedly has a volcanic base but no information on this has been collected. This study did uncover some black sand, presumably of volcanic origin, on the southwestern part of the Bank. Geologists believe that a composite volcanic island is buried under the more recent formations.

Only the eastern and largest part of the Saba Bank can be called a living atoll with an open lagoon, while the western part is a bank with drowned fringing reefs.  Whether the western part is included or not, the Saba Bank ranks among the largest atolls in the world.

Findings

The main conclusion from this study is that the Saba Bank has little modern material/ sediment deposited in relation to present sea level. This contradicts with previous beliefs such as Spencer’s claim that the bank surface “has been leveled by coral growth and sands derived from them”.

The study found the following:

• Minimal reef development.
  • Limited data from the survey revealed a sparse coral cover but   abundant crustose coralline algae and sponges.
  • The Saba community showed no sign of forming an interlocking reef framework.
• Sediments rich in residual material derived from late Cenozoic limestone bedrock.
• Most samples from this area had relatively large quantities of calcite, which suggests erosion of bedrock on Saba Bank.
• The internal structure of Saba Bank remains unknown; the surveys lacked sufficient sub-bottom penetration to disclose information about internal structure.