Marine spatial population dynamics are often addressed with a focus on larval dispersal, without taking into account movement behavior of individuals in later life stages. Processes occurring during demersal life stages may also drive spatial population dynamics if habitat quality is perceived differently by animals belonging to different life stages. In this study, we used a dual approach to understand how stage-structured habitat use and dispersal ability of adults shape the population of a marine fish species. Our study area and focal species provided us with the unique opportunity to study a closed island population. A spatial simulation model was used to estimate dispersal distances along a coral reef that surrounds the island, while contributions of different nursery bays were determined based on otolith stable isotope signatures of adult reef fish. The model showed that adult dispersal away from reef areas near nursery bays is limited. The results further show that different bays contributed unequally to the adult population on the coral reef, with productivity of juveniles in bay nursery habitat determining the degree of mixing among local populations on the reef and with one highly productive area contributing most to the island’s reef fish population. The contribution of the coral reef as a nursery habitat was minimal, even though it had a much larger surface area. These findings indicate that the geographic distribution of nursery areas and their productivity are important drivers for the spatial distribution patterns of adults on coral reefs. We suggest that limited dispersal of adults on reefs can lead to a source–sink structure in the adult stage, where reefs close to nurseries replenish more isolated reef areas. Understanding these spatial population dynamics of the demersal phase of marine animals is of major importance for the design and placement of marine reserves, as nursery areas contribute differently to maintain adult populations.
A management plan was prepared in close consultation with a considerable number of stakeholders and stakeholder group representatives.
The plan specifies management goals and strategies for the Saba Bank Management Organization (SBMO) related to the organization mission. It also identifies the major existing and potential threats and issues facing the Bank from ecological, social and cultural perspectives and includes substantial input from stakeholders. It is designed to be an adaptive management tool.
Below is a very brief overview of the management plan
Part I: Saba Bank Background Information
- Location and situation
- Geology and geomorphology
- Marine habitats, flora and fauna and natural resources
- Human uses
- Critical threats to the Saba Bank:
- Overexploitation of fishery resources
- Impacts from tanker anchorage on benthic communities
- Impacts of tanker traffic on fishermen and traps
- Global climate change
PART II: Management Environment
- Vision: To secure a natural protected area that represents a unique and spectacular ecosystem; Mission: To contribute to the preservation of Saba’s natural heritage and promote the sustainable use of the natural resources; and Goals.
- Human resources
- Physical resources
Summary of Issues (see below)
Management Recommendations (PART III: Management Environment)
Key issue: Create a clearly defined conch reserve on the Saba Bank.
Actions: Create and implement the queen conch reserve with no commercial take of conch. Research into queen conch stocks.
Key issue: Monitor the landings of commercial fish catches (there is currently very little data available on the yearly landings from the commercial fishermen of Saba).
Actions: Collect records of fishing activity on the Saba Bank. Develop a system to report landing from commercial fishermen. This dataset will lay the foundation for establishing a long-term commercial fisherman reporting system, which in turn will enable the SBMO to assess the state of the Saba Bank’s fish stocks.
Key issue: Enforcement of fisheries regulations (there is currently minimal enforcement of the fisheries regulations)
Actions: Collaboration; work with the Government, Harbour Office and Police to establish clear enforcement procedures and publicize the outcome. Encourage local fishermen to work with the police in the enforcement of the regulations. The SCF is in the process of having one of their rangers trained as a special agent.
Key issue: Monitor red hind spawning aggregation; assist in the development of a spawning aggregation closed season.
Actions: Gather initial information: determine where the majority of the fishermen are from and gauge trends in fish densities during the aggregations. Consult with stakeholders, including both the public and fishermen. Provide assistance in draft legislation for closing the spawning aggregation.
Key issue: Monitor tanker anchorage damage on the Saba Bank.
Actions: Monitor the impacts of anchoring. Prevent anchorage within the 12 miles of territorial waters. Provide whatever support is required for the Central Governments proposal to have the Bank recognized as a Particularly Sensitive Sea Area (PSSA).
Key issue: Evaluate the potential for artificial reef development on the Saba Bank.
Actions: Create and monitor an experimental artificial reef.
Key issue: Monitor and evaluate coral health.
Actions: Continue to monitor bleaching. Continue to monitor the state of the coral at existing sites established in 2007 on a regular basis. Adapt methods where appropriate. Co-ordinate with other islands. Communicate methods and results with St. Eustatius, St Maarten, and other DCNA islands, as well as the regional Global Coral Reef Monitoring Networkm (GCRMN) nodes.
Key issue: Facilitate and promote research from visiting scientists
Actions: Promote scientific research on the Bank (conferences, local, national media, and presentations). Provide assistance to researchers (providing logistic support and access to equipment)
Key issue: Work with the commercial fishermen in the management of the fisheries resource.
Actions: Promote the creation of a fisheries association among the fishermen as key stakeholders.
Key issue: Establish sustainable financing mechanisms
Actions: Raise money from fishing permits. Seek structural funding from the Dutch government under the new constitutional relationships.
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.
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.
The St. Eustatius National Marine Park conducted an Economic Valuation of St. Eustatius’ coral reef ecosystems in the fall of 2009. This attempted to put a monetary estimate on the coral reefs surrounding Statia. Coral Reefs are one of the island’s most valuable resources; they provide a livelihood through dive tourism and fishery and provide protection from large, damaging waves caused by hurricanes. In order to properly manage the coral reef ecosystem, an economic valuation is a useful tool to determine what exactly the monetary value of a coral reef is. With an attached value, better management decisions can be made to adequately protect this most precious of resources.
In order to complete the study four questionnaires were distributed. Two dealt specifically with fisheries, one with hotel accommodations, and one with dive tourism. Data was also provided by the Statia Tourism Office. Coral reefs have direct and indirect influences on a wide range of economic factors, and the generation of data was crucial to the successful completion of this study. Data was inputted into a computer program created by the World Resource Institute and which was adjusted by STENAPA to reflect Statia’s unique ecological and economic situation.
The findings of this study have outlined that Statia’s coral reef resources provide important goods and services to the economy of the island. The revenue that the resource is able to generate through coral reef associated tourism and fishery is approximately USD $11,200,454. Although this number is high, and highlights the importance of coral reefs to the island, it also suggests that there is an increased need for conservation, so that the value does not diminish. It is therefore in the best interest of Statia to incoroporate environmental economic data to: (1) Enforce land-use and development regulations in the coastal zone, (2) Enforce strict usage of anchorage areas, (3) Incorporate economic valuation into EIAs, (4) Include economic impacts in assessing fines for damages to reefs from activities such as anchoring in the reserves, oil spills etc, (5) Weigh revenues from a growing tourism industry against long-term economic losses from environmental impacts, (6) Evaluate distributional effects (“winners” and “losers”) of proposed coastal development projects, (7) Invest in Scientific Research, (8) Increase support from the private and public sector in the Marine Park Management Authority, STENAPA.
The Lesser Antilles include high volcanic islands with a limited marine shelf, and low coralline islands with a more extensive shelf. Withinthe group, reefs are affected to a greater or lesser degree by widely differing conditions of rainfall and runoff, hurricane damage, recreational use and fishing pressure. While degradation is reported in many areas, there are few long-term studies that quantify trends in reef status. In recent years there has been an increase in the number of management initiatives, and in the number of reef areas under active and effective management.
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.
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.
- 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.
New observations indicating undesirable trends on Bonairean reefs
Unusual high abundances of the colonial tunicate Trididemnum on Bonaire’s Northwestern reefs
Population explosions of coral and gorgonian eating snails
Overgrowth of deeper reefs by the brown alga Lobophora variegata
Increased abundance of coral‐destroying territorial damselfish
Unprecedented predation on native fish by the invasive red lionfish
Historic factors negatively affecting the “health” of Bonaire’s reefs
Unknown stressors for Bonaire’s reefs
In comparison to other CARICOMP sites, the tiny island of Saba, in the Windward Islands arc of the Lesser Antilles, can be described as atypical in terms of its topography, geology, and marine environment. Saba has a small human population and anthropogenic impacts on the nearshore marine environment are limited. Sedimentation, dive tourism, and fishing are the three main impacts in coastal waters. Saba is devoid of mangrove stands; Thalassia seagrass beds and coral communities are restricted to a narrow shelf and offshore seamounts. CARICOMP sampling occurs only at one reef area on the leeward west coast. Physical oceanographic data are available for this site, and meteorological data are available for the island. Benthic composition is described based on CARICOMP surveys carried out to date and on a baseline monitoring program that was executed in 1993 as part of a study for the Saba Marine Park