Population tendencies: a key tool to study marine fauna

Studying marine fauna is critical to detect threats and implementing effective conservation measures. Fundación Malpelo is one of the leading organizations in Colombia in charge of the monitoring and scientific program at Malpelo Sanctuary, a Marine Protected Area in the Tropical Pacific.

Felipe Ladino de la Fundación Malpelo, haciendo un censo de tiburones en la zona conocida como el Acuario en Malpelo, mientras un tiburón martillo nada a su lado. A partir de estos censos que se hacen desde el 2002 se ha podido evidenciar la disminución poblacional de los tiburones martillo, por lo que se están desarrollando proyectos de conservación con la especie. Foto © Olivier Borde

We use different techniques to study marine fauna, for example since 2002, we have been carrying out underwater censuses, and from these, have been possible to demonstrate decreases in the population tendencies of multiple shark species, such as the scalloped hammerhead shark, silky shark, and whale shark. For example, big aggregations of silky sharks have not been seen since 2015, and hammerhead shark populations have decreased by 73% in the last ten years.

Grupo de tiburones Silky, Malpelo era reconocido por tener grandes agregaciones de tiburones Silky, con grupos de más de mil animales, sin embargo, a partir de 2015, sus números no han sobrepasado los 80 individuos. Al ser una especie migratoria es muy vulnerable a pesca, razón por la cual es una de las especies más capturadas en la región. Foto © Fundación Malpelo

Interesting to mention that these censuses have also demonstrated that resident species, such as spotted eagle ray and whitetip reef shark, have shown positive population tendencies. Therefore, these results demonstrate that the conservation measures taken at the MPA, such as prohibiting fishing, broadening the area, and strengthening control and surveillance, have greatly contributed to the conservation of these species.

Un grupo de rayas aguila en Malpelo, esta especie residente del santuario es la raya más comun y sus poblaciones se encuentran en buen estado e incluso en los últimos años ha aumentado ligeramente. Foto © Sandra Bessudo

Overall, these results indicated that just the designation of MPA is not enough regarding highly mobile species, and developing stronger conservation projects at the national and international levels is critical to ensure their conservation.