Over 40 years of research surveys result in one of the most substantial pools of shark data in the world
For decades, the EAF-Nansen Programme has collected data and information on demersal and pelagic sharks across the globe, creating one of the largest pools of shark records in the world that can be critical to better understanding these fascinating and valuable, yet poorly understood, marine predators, and improve the conservation and management of these vulnerable species.
It all started in 1975, when the first research vessel Dr Fridtjof Nansen was launched. Since then, the Nansen Programme has carried out research surveys in waters of about 60 countries in East and West Africa, parts of Southeast Asia, the Eastern Central Pacific, and the Caribbean.
In the beginning, surveys focused on investigating largely unknown areas to ascertain the distribution, composition, magnitude, and status of the fish stocks in those waters. Over the years, the scope of the activities has broadened to collect data and information on other marine resources, including sharks.
“Sharks that are caught as by-catch in the demersal and pelagic trawls during the research surveys are counted, weighed and identified down to the lowest category possible on the taxonomic scale, before those who are still alive are released back at sea”, said Edoardo Mostarda, a fisheries and biodiversity expert of the EAF-Nansen Programme.
In some selected areas, mainly Angola, data on length, sex and maturity, and rough stomach content for some species have also been opportunistically recorded, largely based on the efforts of Diana Zaera-Perez, a technician from the Norwegian Institute of Marine Research (IMR). As a result, a vast dataset consisting of more than 25 000 records of about 110 shark species has taken form over the years. Based on its size, taxonomic resolution, spatial and temporal coverage, it can be considered one of the most substantial shark data sets in the world.
There are more than 550 species of sharks, some of which are at risk from increasing fishing efforts that have led to concerns over the consequences for the populations of some of the species in several areas of the ocean.
“Sharks lack the ability to recover from overfishing due to their slow growth rate and reproductive potential in comparison to bony fishes”, Edoardo Mostarda explained, adding that more information is required to better understand when, and which, management action is needed. This issue is particularly relevant to the demersal sharks that are often missed by many researchers as the focus globally is on pelagic sharks.
The EAF-Nansen Programme's pool of data can provide knowledge on species distributions, describe how species abundance has changed over time and space, and understand the complex interactions between different species in a community, for informed decisions on fisheries management and environmental conservation efforts.
EAF-Nansen Programme embarks on first examination of the data
Despite the importance and possibilities of this dataset, specific studies making use of these data have never been carried out. For this reason, the EAF-Nansen Programme is developing projects in collaboration with partner countries for the next phase of the Programme (2024-2028).
In January 2023, 20 scientists came together to start examining the data and work on proposals for studies to be done. “To kick-start the analysis of the vast data records, we invited the experts from Angola, Namibia, South Africa and Mozambique to work on proposals and start a preliminary examination of the data for the research that can be done in their region”, said Rishi Sharma, Lead Technical Officer of the EAF-Nansen Programme. As southern African countries (Benguela Current Convention area) have been most frequently surveyed, and therefore have the fewest gaps in annual surveys, the initial focus was put on this region, he explained.
The proposals focused on characterizing shark species ‘hotspots’ in each country, investigating the distribution and structure of the shark communities, analyzing trends in population size of the shark demersal species, and updating national checklists and range maps.
Given the expected time and effort required to standardize and analyze the data, the EAF-Nansen Programme envisages supporting either current or prospective MSc and PhD students to complete these proposals for the next phase.
"Working with these strongly motivated students will help us advance the analyses, while building capacities and creating synergies with their institutions and countries," said the coordinator of the EAF-Nansen Programme, Merete Tandstad, and expressed excitement for seeing the data come to use in the next phase which will have a stronger focus on governance and the science-management policy nexus.
The EAF-Nansen Programme is a longstanding partnership between the Food and Agriculture Organization of the United Nations (FAO) and Norway, dating back to 1975. It is executed by FAO in close collaboration with the Norwegian Institute of Marine Research (IMR) and funded by the Norwegian Agency for Development Cooperation (Norad).
In collaboration with 32 countries across Africa and the Bay of Bengal, the Programme is improving fisheries policies and management practices in line with the ecosystem approach to fisheries (EAF), and developing the capacity of fisheries institutions to ensure sustainable fisheries management.
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