Search for nursery areas
Malpelo Foundation – Search for nursery areas
In November 2019, the Malpelo Foundation published a report on hammerhead shark nursery areas in the Colombian Pacific Ocean.
While gatherings of adult hammerhead sharks are known, especially in what is referred to as the Golden Triangle of Sharks (Malpelo Island, Cocos Islands and Galapagos), nursery areas must be located in order to establish conservation measures in coastal areas where juveniles are found and thus preserve shark populations.
In 2017, the Malpelo Marine Protected Area was extended to 27,096 km². This is a major step in the preservation of marine species. Nevertheless, as hammerhead sharks are a migratory species, what happens to them when they leave this area? Despite categorization by IUCN and Cites, hammerhead sharks continue to be affected by fishing throughout all stages of their lives.
Search for nursery areas
Some studies have already shown the link between adult sharks from Malpelo and new-borns off the Colombian coast. As such, the females leave their feeding area in the open sea from mid-May to June to give birth on the north coast of Choco, some 505 km from Malpelo.
Five pregnant female hammerhead sharks (Sphyrna lewini) tagged with satellite tags in March 2018 confirmed these studies by migrating to the Choco coast in May-June.
The study conducted by the Malpelo Foundation aims to locate female hammerhead sharks as they leave Malpelo island and evaluate possible nursery areas using acoustic telemetry together with information from local communities.
Establish the nursery areas
A nursery area satisfies 3 criteria: sharks are more likely to be seen there than in another area, individuals tend to stay there or come back for weeks or months, and the habitat is repeatedly used over the years.
The Gulf of Tribugá (photo 1) satisfies all three conditions and is likely to be one of the most important nursery areas for the species due to the high concentration of new-borns.
Three receivers were installed along the Gulf; 13 sharks were tagged in 2018 (4 males and 9 females) and a further 17 sharks were tagged in 2019 (9 males and 8 females). Out of these 13 sharks, six were spotted by the Jurubirá receiver between June and September, and one was also spotted by the Guachalito receiver in October.
The information collected suggests that the Jurubirá sector is a breeding ground for hammerhead sharks between June and September.
Local fishermen have also confirmed that there are hundreds of sharks in this area between June and September.
Protect this coastal area
Protecting this area by adopting conservation measures is essential to the survival of hammerhead sharks and this measure must be taken in conjunction with small-scale fishermen who, according to the Malpelo Foundation, catch more than 5,000 sharks each year. A port project in the region could also threaten the survival of the species that come here to breed.
The Foundation will continue to accurately pinpoint the nursery area and develop conservation processes with the community, for example, by testing tools to limit by-catch.
Nausicaá on a field mission with the Malpelo Foundation
In May 2019, Ludwig and Renaud, two Nausicaá carers, joined the members of the Malpelo Foundation in Colombia. During this mission, they collected data accumulated from the acoustic receivers in 2018 and 2019; the receivers were then replaced to capture the data again when the tagged sharks passed through the area.
Photos: Renaud Herbert, Alexis Rosenfeld – Divergences