Which nursery is best for Peru’s baby smooth hammerhead sharks?
Eduardo’s project will be running stable isotope analyses to understand what baby hammerhead sharks are eating and how they are using different habitats. He is focusing on three nursery areas that were identified in southern Peru, testing whether there are differences between the hammerhead populations in each nursery, and which baby hammerheads are in the best condition. This information will be used to inform conservation and management plans for each nursery area or baby hammerhead population.
Eduardo Segura
I have been interested in the interaction and connection between humans and marine ecosystems since I was a child. I was amazed by fishers’ stories about the big sharks or the sea lions they saw. Contact with fishers also helped me to understand the essential role of the ocean in coastal communities’ efforts to earn a livelihood. When I graduated as a marine biologist, I started working with rays and was very surprised that so little is known about their ecology, given that rays are such an important component of the Peruvian fishery. So I started working as a researcher...
Which nursery area contributes the most benefits to the Smooth Hammerhead populations in Peruvian waters?
The project aims to assess the trophic niche (where and what they eat) and nutritional state (how fit they are) of juvenile smooth hammerhead sharks in three shark nursery areas along the coast of northern Peru in order to guide where conservation efforts should be directed to benefit rapidly declining smooth hammerhead populations.
Globally, the abundance of smooth hammerhead sharks has declined drastically over the past decade due to overfishing. The relative importance of the three nursery areas for smooth hammerhead recruitment is not yet known. As it is impossible to protect all three areas, we will evaluate the importance of each one to help decide which should be prioritised for conservation.
The Northern Humboldt Current Ecosystem is a zone of high abundance for smooth hammerhead sharks from the coastline to approximately 150 kilometres (93 miles) offshore. This zone is characterised by coastal upwelling and high fish productivity and accommodates an important artisanal fishery. The smooth hammerhead populations could be fully exploited in Peru, but historically neonates and juveniles dominated fishery landings in summer. This fact led to the closure of the smooth hammerhead fishery between January and March. Despite this, the smooth hammerhead catches have been decreasing and no biomass recovery has been observed. Shark nursery areas are coastal zones of abundant food resources that accommodate juvenile sharks, facilitating their growth and recruitment to adult populations. Three potential smooth hammerhead nursery areas have been identified in this zone, based on the frequency of neonate and juvenile captures. One is located in the Tropical East Pacific Marine Province and the other two in the Warm Temperate South-eastern Pacific Marine Province. The IUCN has recommended ‘the protection of known adult aggregation sites and nursery areas’ for this species due to its essential ecological role as a top predator. Nevertheless, there is no scientific evidence to assess the quality and contribution of these nursery areas to overall population recruitment. Studies to obtain such evidence are essential so that appropriate marine protected areas for effective conservation may be designated. In Peru, only three marine protected areas exist to date, but none focuses on the conservation of recruitment areas of open-water marine species. One more marine protected area, which included a smooth hammerhead nursery area as well as open-water habitats, was proposed in the north of Peru, but its proclamation foundered due to the lack of scientific evidence of benefits for target species.
The aims and objectives of this project are:
- To assess the diet and habitat use of juvenile smooth hammerhead sharks in three nursery areas by analysing stable isotopes of carbon, nitrogen and sulphur and fatty acids in muscle and liver tissues in order to identify their fishery stock structure and feeding grounds;
- To determine and compare the nutritional status of the smooth hammerhead juveniles from the three nursery areas in order to identify which nursery area provides superior conditions for juveniles’ survival and growth;
- To generate a map that delineates areas in relation to the nutritional status of juvenile smooth hammerhead populations and propose the most important nursery area that should be prioritised as a marine protected area to protect populations of this species in Peruvian waters.