Spiny lobsters are an important fishery in the MesoAmerican reef system, and efforts are being made to promote the sustainability of their populations. In Quintana Roo, Mexico, I am working with the National Parks office on a new project to attract and provide habitat for juvenile lobsters in the protected area of the coast of Isla Mujeres (a critical breeding area).
The area we chose named “Sac Bajo” is shallow, with an ‘artificial reef.’ Around the world there are many types of artificial reefs, including sunken ships, which serve to provide additional habitat options for organisms whichhave lost much of their natural habitat. These structures also provide protection to the coast, and in the case of Sac Bajo in particular, an alternative destination for tourists to limit destruction of the natural reef. The artificial reef at Sac Bajo is constructed through the use of reef balls, which are molded concrete hollow mounds about 1m in diameter. Corals are planted on them, and the complex structure attracts a variety of fish and other organisms. At Sac Bajo there are two different styles of reef ball, one with large round holes scattered all over the sides, and one with horizontal tiered holes, aptly named “layer cakes.” These layer cakes are more attractive habitat to lobsters, which aggregate in the spaces with their antennae pointed out.
Spiny lobsters, and other crustaceans such as shrimp and crabs, have a life cycle in which their eggs hatch larvae, and the larvae move away from the shore, develop through a number of stages, then move back in to shallow water to ‘settle.’ Once settled they are considered juveniles, and look like miniature versions of the adults. In the case of these lobsters, the juveniles nestle into a part of the coral reef, and grow to adults.
When the larvae are seeking a place to settle, they prefer a complex, algae-type habitat. Then, when they transform into juveniles, they prefer a coral reef/rocky type habitat. In Sac Bajo, the layer cake reef balls provide the rocky habitat for the juveniles, but not the algae-type habitat for the larvae. So, we decided to place larval collectors of the type used in studies monitoring the influx of larvae, because they are known to provide habitat suitable for the larvae. These collectors float at the surface, and are anchored to the sea floor. In this case, we could anchor them to the layer cakes, and the rope would provide a ladder of sorts for the lobsters to move down into the new habitat.
There are various types of collectors, we chose to use the economical and functional GuSI type collector, which is rather like a bucket wearing a hula skirt. The ‘skirt’ is actually bunches of filastica which is strips of plastic, which serve as a durable algae-like material for the lobsters to hide in.
The construction, deployment and monitoring of the collectors is made possible by the collaboration of the national park guards (guardaparques) who go out every day to patrol the protected areas. Their experience on the water and in the deployment of buoys provides invaluable assistance in carrying out this research.
Sac Bajo has a unique set of challenges for this research, as not only do we have to design collectors to appeal to lobster larvae, we must protect them from possible storms and also deal with boats, tourists and illegal fishing. In addition, lack of resources limits accessibility to the field site and number of collectors that can be deployed. However, these are obstacles that can be overcome and we are excited about the potential applications for this research, not just in enhancing the lobster population in the area but also in assisting a new effort to start lobster aquaculture on Isla Mujeres.
Underwater view up at collector, anchored to layer cake