MARLIN App Helps Indian Fishers Document Marine Biodiversity

It’s a matter of fact that no marine photographer or documentarian has witnessed the richness of ocean biodiversity like a fisher has. Despite most fishers in India owning a smartphone these days, they hardly ever visually document their fishing expeditions. Other than a lack of interest or skill, they had no reason to do so—that is, until a team of scientists in the country gave them one.

In 2024, the Indian Council of Agricultural Research-Central Marine Fisheries Research Institute (ICAR-CMFRI) developed the Marine Fishery Machine Learning Routines of Indian Exclusive Economic Zone (MARLIN) Android mobile app. The initiative aims to build a comprehensive visual marine database as fishers across the country upload high-quality digital images and videos related to the fish they see and catch, strengthening compliance with fishing laws and marine conservation efforts.

An App to Document Indian Marine Life

The conception of MARLIN was quite accidental, said Eldho Varghese, a senior scientist at ICAR-CMFRI with a background in statistics and computer science and the brain behind the app. While working with ICAR previously, Varghese’s team developed an AI tool that used visual analysis methods to count the number of spikes or heads in a wheat plant passing through a conveyor belt. After transferring to CMFRI, the marine division under ICAR, he was motivated to try the same idea to create a database and identification system for fish.

Despite increased efforts in nature and biodiversity documentation, India’s marine data remain mostly undocumented, scattered, and methodologically inconsistent. As a citizen-science effort, MARLIN could help Indian fishers to properly identify marine species, including the deep-sea ones, to abide by India’s Wildlife Department rules and regulations as well as fill in the missing marine biodiversity data.

MARLIN allows users, who are mostly fishers, to effortlessly upload photos of marine fish species they encounter in the Indian EEZ, thus creating a nationwide visual repository. Since MARLIN’s launch, the CMFRI has reported that the app is a success. By analyzing the data the team has received so far, they see a rich variety of marine biodiversity that the fishers have been able to visually capture and an increasing frequency of data inputs. MARLIN also allows users to geotag their photos, enabling users to pinpoint the exact location where each marine species was caught, which provides crucial information for researchers and conservationists studying the distribution patterns of various species.

At present, MARLIN allows the submission of marine data in five categories: Fish, Jellyfish, Algal Blooms, Sharks and Rays, and Fishing Crafts and Invertebrates. The fishers can either type details or drop an accompanying voice note elaborating on the visuals they upload. The voice option was developed keeping in mind the challenge many Indian fishers may have with typing in English. The app doesn’t provide an option for the public to download its data yet; this restriction aims to prevent any misuse of the data by the general public. The latter is important, Varghese said, because of the scope of monetization of such visuals through social media. “Just because our fishers aren’t content creators, it doesn’t mean that stealing their intellectual property is any less serious,” he added.

MARLIN’s More Than 150,000 Images and Counting

A 10-member team currently runs MARLIN, including five fish taxonomists who screen the media uploaded onto the app and provide a final filtered version of the visual data. Although MARLIN’s taxonomy team currently takes care of transcribing the voice notes left by fishers, an AI tool that can perform this function is under development. The next major step for the MARLIN team is to implement the automated identification of a marine species from the visual data, Varghese said.

“We have over 150,000 images in the database right now, which is considerably increasing each day,” Varghese said.

MARLIN's role in helping researchers understand the marine ecosystem of Indian seas is vital to conservation projects and actions as well. For example, CMFRI has joined hands with the Wildlife Trust of India to visually document whale shark sightings and landings through MARLIN. Varghese has also represented CMFRI at various international marine conferences and presented on the app as well as demonstrated the extent of data MARLIN has collected so far.

“Some of the fishers have been consistent contributors to MARLIN since the time of its launch,” Varghese said. “We are presently planning to host a seminar for fishers across the country and provide certificates and economic incentives to those who have provided MARLIN with significant data and visual material crucial for enriching our knowledge of the ocean.”