From November 12th to 22nd, a team of eight scientists and conservation practitioners from Holland, Martinique, Bonaire and Saba came together on Saba for a mapping expedition to the Saba Bank. The expedition forms part of a joint project called CARIBSAT, between Martinique, Saba and Bonaire, to test a way to use satellite images to map the life on the bottom of the ocean.
Both Bonaire and the Saba Bank need a good map of bottom life, showing different types of coral reefs, seaweed fields and sand bottom. In Martinique a detailed map was made a few years back, which was then compared to satellite images showing various colors reflected back from the bottom, which can be translated into corals, seaweeds, rocks and sand. Once this translation was made for Martinique, it could in theory also be applied to satellite images from other areas such as the Saba Bank, providing a map of the bottom. To ensure that this map resulting from satellite imagery would in fact be correct, the expedition went out to the Saba Bank to get video imagery of as many parts of the Bank as possible and measure the exact spectrum of light reflected back from the bottom. A total of 200 camera “drops” were made, lowering a camera from the boat to film a few tens of meters of the bottom, while measuring the light both at the bottom and at the surface. A number of dives were also made to film longer video transects, in order to carefully describe everything growing on the bottom. The dives were also used to count lobsters, conch and fish species.
This same exercise will also be undertaken on Bonaire, which has much shallower coral reefs and a different bottom structure. Once al the work has been analyzed it will result in a map for the Saba Bank and for Bonaire that will show various types of marine habitats.
The scientists expressed concern for the amount of dead coral reef they found at many places, presumably killed as a result of the 2005 Caribbean wide coral-bleaching event, attributed to global climate change. They also noted a paucity of fishes. Paul Hoetjes, who participated in previous dive expeditions on Saba Bank said: “It was worrying to see so few Red Hinds. The last time I was here in 2007, Red Hinds were numerous on every dive, one of the most common fish on the Bank, even during the spawning season when most Red Hinds migrate to their aggregation area on the Bank. This time we only saw a few of them. I am very concerned that this may be a result of irresponsible fishing of the red hind spawning aggregation area, which started in 2007.
There is no more effective way of eradicating a fish species than fishing them in the few months per year when they aggregate in huge numbers in a very small area to spawn, and that is exactly what is happening I have been told.” Erik Meesters who was one of the first scientists to dive on the Bank back in 1996 when he made the first report on the Saba Bank for the Netherlands Antilles government, confirmed this, “When I was diving on the Bank in 1996, the first thing that struck me was the large number of fishes everywhere. I don’t see those anymore.” The group concluded that it is imperative to start active management of the fisheries on the Saba Bank as soon as possible, in close cooperation with the fishermen, who in general do recognize the need to fish responsibly. While that is not yet in place, the group makes an urgent plea to all fishermen to stop fishing in the red hind spawning aggregation area in the upcoming season, which is starting next month.
The CARIBSAT project is funded mainly by the European Union with some matching funding from various partners such as the RCN (Rijksdienst Caribisch Nederland), which made it possible to bring this team of various specialists to Saba. The team consisted of three marine biologists from the Observatoire du Milieu Marine de Martinique (OMMM) who will be doing the technical analysis of the collected data, marine scientist Erik Meesters from the Dutch IMARES institute for marine research who will be involved in future research and monitoring of the Saba Bank, manager of Bonaire’s Marine Park, Ramon de Leon, Kai Wulf and Gregoor van Laake of the Saba Conservation Foundation, and Paul Hoetjes of the RCN.
Written by Kai Wulf, Parks Manager
Saba Conservation Foundation