Understanding key population parameters of threatened species helps to inform their conservation. Saratha is using long-term mark-recapture data for juvenile blacktip reef (Carcharhinus melanopterus) and sicklefin lemon sharks (Negaprion acutidens) to investigate trends in body condition by means of various condition indices.
As a born citizen of the Republic of Seychelles, I can say that I have been fortunate enough to experience paradise at its finest. A place on the map that lies between latitudes 4° and 11°S and between longitudes 46° and 56°E, Seychelles is home to the most enchanting diversity of flora and fauna. As a child I was fascinated by wildlife and nature in general, but growing up I became even more intrigued and captivated by the life that exists below water. So much is known about what exists on land, yet more than 80% of the ocean is...
To investigate trends in the body condition of juvenile sharks using a remote nursery site in the Amirantes, Seychelles.
Both study species are classified as threatened on the IUCN Red List due to declining populations globally. Estimates of population decline rely on accurate information about the structure of the population, so information that helps us to understand how these sharks use key habitats will help to inform future conservation status assessments.
Condition indices are used to assess the health of animals and to evaluate how life-history strategies, ecological interactions and environmental threats affect them. Some of the most commonly used indices, such as condition factor, are calculated from an animal’s morphological measurements and have been used extensively to assess condition in marine fish. However, far fewer studies have investigated condition in sharks.
St Joseph Atoll is home to juvenile populations of blacktip reef and sicklefin lemon sharks. Previous research has investigated how these species share this space and how they grow and survive. An understanding of body condition and how this varies across temporal and spatial scales is critical to our understanding of the fitness and survival of these sharks in the early years of life. Baseline information about the condition and health of shark populations will be important for gauging the impacts of future environmental disturbances and threats.
The aim of this study is to use condition indices to assess variations in the condition of two juvenile carcharhinid populations using a nursery site and to weigh up the findings in the context of conserving and managing these threatened species.
To do this, the study will address several specific objectives:
– collect morphometric data from juvenile blacktip reef and sicklefin lemon sharks to calculate condition factor and investigate trends in condition for the populations of the two species;
– assess differences in condition factor across year, season, sex and size class;
– assess any variation in condition between various sub-habitat zones to investigate potential differences in habitat suitability.
Nico is using acoustic telemetry and BRUVs around Seychelles to explore how reef sharks are using their reef homes. What are they eating? What prey is available? His project aims to explore what factors influence ideal habitats for sharks and will combine information from both pristine and degraded reefs to create a model to test this suitability. The point? To build on work by the Marine Futures Lab across the Indian Ocean and the Indo-Pacific and to help identify priority shark conservation areas.
Jeremy wants to understand when blue whales and other whales and dolphins visit Seychelles, and how many visit when they do. He investigates which factors, such as ocean currents and noise pollution, affect their presence and behaviour in these waters. To do this, he spends hours observing whales and dolphins from a boat, documenting their behaviour, where they move and what they do. He also uses their calls to determine when they arrive, whether they’re feeding or mating, and where they come from. This information can help identify new behaviours and important areas that need protection.
This study uses long-term reef fish survey data, by underwater visual census, from 2011 – 2017. Sarah will use the dataset to investigate differences in the reef fish community at different sites around the islands and assess annual changes in patterns of abundance at the site, considering which factors are causing these variations, with particular consideration of extreme climate events (ocean warming event in 2016).