Uncovering the Ecology of Ocean Sunfish with Beneath The Waves

DISCOVERY Vessel Jax
Cape Cod, Massachusetts
August 1 - 6, 2025

Project Overview

Ocean sunfish (Mola mola) are the world’s largest bony fish, yet many aspects of their biology remain poorly understood, particularly in temperate regions such as the northwest Atlantic. While they are globally distributed and frequently observed laying at the ocean’s surface sideways apparently 'sunning' themselves, key questions remain about their behavior, movement patterns, and ecological role in this region.

To address these knowledge gaps, researchers from Beneath The Waves have launched a multi-year study focused on the biology and ecology of Mola mola in the northwest Atlantic. The project applies a suite of non-lethal techniques, including bio-logging, tissue sampling, and microbiome analysis, to investigate short and long-term movements, habitat use, genetics, diet, and parasite loads. These efforts aim to establish foundational knowledge of the species’ life history and inform future conservation strategies.

SeaKeepers has supported this research since its inception in 2022 by providing vessel access and logistical coordination through our DISCOVERY Program. Continued collaboration has enabled scientists to expand their dataset, refine field methods, and monitor the seasonal presence of sunfish in the region.

Application

Discovering more about the Mola mola will allow us to further understand this ancient fish and how its adaptations have survived over evolutionary time. These ancient adaptations provide insight into historic life strategies and the pathways of fish evolution which enabled such a gentle giant to persist despite environmental change. The data collected will enhance scientific understanding of Mola mola ecology in temperate waters and may inform future conservation and management strategies. This work could support broader marine biodiversity and ecosystem health initiatives and may serve as a foundation for student research projects at both the undergraduate and graduate level.

Expedition Summary

From August 1 - 6, 2025, SeaKeepers assisted researchers from Beneath The Waves in studying the ecology of Mola mola in the waters off Cape Cod, Massachusetts with collaborating research teams from MIT, Harvard, Tufts, and KAUST. SeaKeepers connected this research team with vessel support from DISCOVERY Vessel Jax, a local Cape Cod fishing charter that generously donated their time and shared their local knowledge to support this research.

Over the course of the week, researchers processed six ocean sunfish and successfully deployed satellite tags with video monitoring capabilities and biologgers on three individuals, which were later recovered. Spotters aboard the vessel and in helicopters were used to locate and intercept target animals. Once encountered, each fish was measured, sampled for genetics and parasites, and tagged with both PIT (Passive Integrated Transponder) tags and external spaghetti tags to enable individual identification and monitor future recapture or resighting.