A study recently published in PLoS One journal reveals the decline of important fish stocks in Arraial do Cabo, Rio
de Janeiro state, Brazil. Arraial do Cabo is a typical fishing community established for decades essentially around
the artisanal fishing activity. Fishing in this site has become diverse from the perspective of fishing gears used as
well as diversity of catch composition. To understand changes in the region’s fish stocks over time, researchers at
Universidade Federal Fluminense (UFF), Universidade Federal de Santa Catarina (UFSC) and Macquarie University
in Australia, gathered and assessed the quantity of fish landed decades ago, as well as in the present days. In
addition, they conducted underwater diving observations and interviews with community fishermen. Yes,
conversations with fishermen. Studies based on knowledge and experiences reported by fishermen, or other
traditional community members, have become more frequent in science. This is because these fishermen,
especially older ones, have an extensive experience and knowledge of its surrounding environment. They can share
unique information on the diversity and abundance of fish stocks in the past, and, in most cases this is the only
reference source on environmental past conditions.

All sources of information - dives, interviews and fish landings - reveal a drastic decline in the amount and diversity
of fish in the region. The interviews show that four species groupers, and large parrotfish species, had their
populations reduced in the last six decades. Landing data reveal the same pattern for the bluefish, Pomatomus
saltatrix, in a 16-year monitoring period; and underwater fish counts shows reductions in the abundance of
groupers and parrotfishes, including the Greenbeak parrotfish Scarus trispinosus, the largest species of the family,
and endemic to the Brazilian coast.

Despite the significant decline of these species, the younger and less experienced fishers had a hard time
recognizing them as abundant and important resources in the past. This baseline shift of younger fishermen
highlights the importance of rescuing historical data on the environment and its transformations, in an attempt to
understand the changes and preserve what is left.

This type of research is a powerful tool to enhance public awareness on marine natural resources. Rescuing
historical data on the past abundance of fisheries is essential to show/ uncover how the uncontrolled exploitation
quickly changed fish stocks and marine ecosystems. It also highlights the importance of ecosystem services.