The natural recovery of the sea cucumber in the Yucatecan coast would take up to five decades, due to the over-exploitation of the species, warned the specialist of the Merida Unit of the Center for Research and Advanced Studies (Cinvestav), Miguel Angel Olvera Novoa.
He pointed out that since 10 years ago the sea cucumber (Isostichopus badionotus) became an economically important fishing resource in the Yucatan Peninsula, due to its high value in the Asian market, and to a lesser extent, in the United States and Europe.
As a result of the high demand, there is an overexploitation of this species, which is why a permanent ban was established to prohibit its capture, distribution, and sale.
The ecological importance of the species lies in the fact that by feeding on the organic matter present in the sediment, they keep the seabed clean, he said.
According to the Cinvestav-Merida researcher, between 50 and 70 percent of the populations of these organisms in the world are overexploited and it may take up to five decades for them to recover naturally.
As the number of these animals decreases, the sea floor deteriorates and this affects other organisms, including some of commercial importance such as octopus and lobster, which has a negative impact on fishermen’s activities and the marine ecosystem.
Olvera Novoa participated together with researchers from the National Autonomous University of Mexico (UNAM) and the Autonomous University of Yucatan (UADY), in a study to evaluate two population restoration strategies for I. badionotus, which were focused on wild individuals transferred from other less affected areas and on juveniles of this species cultivated at Cinvestav’s Marine Station.
The data, published in Estuarine, Coastal and Shelf Science, indicate that both the individuals transferred and those cultured in the laboratory and then released in Sisal (north of the Yucatan Peninsula), in places close to natural and artificial refuges, survived in the new habitat, suggesting that I. badionotus populations have the potential to be restored.
According to the results, the survival of wild sea cucumbers was higher when they were planted at low densities, which could be due to less competition for space and food, he said.
The specialist attached to the Department of Marine Resources explained that in the case of cultured juveniles, this parameter increased significantly when they were released in areas with artificial shelters, which is attributed to protection against predation by other animals.
The increase in size and weight of the individuals included in the study was also estimated; the wild specimens planted at low densities showed no growth, while the opposite occurred with the juveniles cultivated and released in areas with artificial refuges.
He added that the differences in the growth of the organisms may be due to the fact that those transferred from less affected areas were adults or were close to being adults; on the other hand, the sea cucumbers cultivated and released were juveniles.
Overall, the information reported in the research indicates that if these sea cucumber population restoration strategies are chosen, the number of wild specimens to be transferred and the establishment of artificial refuges that guarantee greater survival of the cultured juveniles after their release should be taken into account.
“Although the results showed the survival and adaptation of the introduced organisms, for these strategies to work, information campaigns about the sea cucumber and its ecological importance are required. In addition to presenting coastal communities with productive options to reduce the capture of marine organisms in their natural environment, for example the cultivation of different species,” said the Cinvestav specialist.
The methodology of the study consisted of transferring 60 wild individuals of the species I. badionotus to the most affected areas in the Yucatan Peninsula, planted at high and low densities, and releasing the same number of cultured juveniles in places close to natural and artificial refuges.
The wild individuals were monitored in nine samplings during 133 days and the cultured individuals in eight samplings during 67 days, in order to analyze the survival and growth rate, key biological factors for the restoration programs of overexploited populations.
Finally, Olvera Novoa mentioned that it is necessary to continue research on sea cucumber biology (habits, food preferences, reproductive cycles, among other aspects) to optimize protection, restoration and culture strategies for this marine organism.
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