Brazil has a long and rich history of marine exploitation, dating back to pre-colonial times when indigenous peoples relied on fishing and shellfish gathering for their subsistence.
Over the centuries, the coastal and oceanic resources of Brazil have attracted the interest of European colonizers, immigrants, and traders, who developed various forms of commercial fisheries and aquaculture.
Today, Brazil is one of the largest fish producers and consumers in the world, with a diverse and complex marine sector that involves millions of people and generates billions of dollars.
However, the increasing demand for marine products has also led to the depletion and degradation of many marine ecosystems and species, threatening their ecological, economic, and social values.
To understand and address these challenges, it is essential to have reliable and comprehensive data on the historical trends and patterns of marine exploitation and biodiversity.
Unfortunately, such data are often scarce or incomplete, especially for the periods before the establishment of official statistics and monitoring programs.
A recent study by researchers from the Institute of Environmental Science and Technology at the Universitat Autònoma de Barcelona (ICTA-UAB) in Spain and their collaborators in Brazil has found a novel and valuable source of historical information on marine biodiversity: newspapers.
Newspapers as historical archives
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The study, published in PLOS ONE, analyzed over 20,000 newspaper articles published between 1840 and 2019 in the state of Santa Catarina, one of the most important fishing regions in Brazil.
The study revealed how newspapers can provide insights into the changes in marine animal diversity and abundance over the past 180 years.
Newspapers are widely available and accessible sources of information that reflect public perceptions and opinions on various topics, including marine issues, as per Phys.org.
Newspapers can also document events and phenomena that are not recorded by other sources, such as scientific reports or government statistics.
Therefore, newspapers can serve as historical archives that complement and enrich other types of data on marine biodiversity.
The researchers collected newspaper articles from three online databases that cover different periods of time: Hemeroteca Digital Brasileira (1840-1920), Biblioteca Nacional Digital Brasil (1920-1999), and Google News Archive (2000-2019).
They searched for articles that mentioned any marine animal species (fishes, sharks, rays, crustaceans, mollusks, echinoderms, cnidarians, mammals, reptiles, birds) in relation to fishing or aquaculture activities in Santa Catarina.
They then extracted information on the species names, dates, locations, contexts, and frequencies of occurrence from each article.
The researchers found that newspapers reported on more than 250 marine animal species over the past 180 years, and also found that newspapers reflected changes in the ecological, socio-cultural, economic, and market importance of different marine animal species over time.
For example, some species that were abundant and valuable in the past became rare and less relevant in recent decades due to overfishing or environmental degradation.
Conversely, some species that were previously ignored or discarded became more appreciated and exploited due to changes in consumer preferences or technological innovations.
One of the most striking findings of the study was that newspapers revealed a shift in the trophic structure of marine animal diversity over time.
Trophic structure refers to the distribution of species across different levels of the food chain, from primary producers to top predators.
It is an important indicator of ecosystem health and function, as it reflects the energy flow and nutrient cycling within an ecosystem.
The researchers analyzed the frequency of occurrence of different trophic groups in newspapers over time.
They found that high trophic level species, such as groupers and sharks, were more common in newspapers between the late 19th and mid-20th centuries.
However, these species became less frequent in more recent newspapers, while low trophic level species, such as mollusks and crustaceans, increased.
This suggested that there was a decline in the abundance and diversity of high trophic level species and a rise in the abundance and diversity of low trophic level species over the past 180 years.
This shift in trophic structure is consistent with the phenomenon of fishing down the food web, which occurs when fishing pressure reduces the biomass and diversity of large predatory fish and shifts the catch composition towards smaller and less valuable species.
Fishing down the food web can have negative consequences for marine ecosystems, such as reducing their productivity, stability, and resilience.
The researchers attributed the shift in trophic structure to several factors, such as changes in fishing technology, market demand, environmental conditions, and management policies.
They also noted that newspapers may not reflect the actual catch composition or abundance of different species, but rather their perceived importance or availability to consumers and fishers.
Therefore, newspapers should be interpreted with caution and complemented with other sources of data to reconstruct the historical baselines of marine biodiversity.
