At the beginning of the new year, a medium-sized van carrying several units of deep-ocean scientific research equipment departed from Qingdao and headed toward the South China Sea for deployment, aiming to conduct surveys of marine mammal populations in China’s waters. Shortly after the equipment was deployed in the South China Sea, additional scientific instruments were also deployed in the coastal waters near Qingdao.

The deployment of these devices marks the beginning of a long-term investigation into marine mammal populations in China’s oceans, which is scheduled to continue until June 2028. The initiative is led by a Unmanned Surface Vehicle research team jointly formed by HydrovoX (hereinafter referred to as “HydrovoX Technology”) and Ocean University of China.

Unmanned Surface Vehicles Equipped with Sonar Systems Explore Marine Mammals in the South China Sea

Marine mammal acoustic intelligent identification has long been a highly challenging research topic. In China, issues such as low population density, limited spatial distribution, and severely insufficient acoustic datasets for endangered marine mammals persist, with some species even lacking any available samples. The rational development and utilization of marine biological resources are of great significance for strengthening ecological environmental protection, accelerating the construction of China as a “maritime power,” and enhancing international discourse in ocean affairs.

New Year Begins: Deep-Sea Exploration Enters the Blue Ocean

At the beginning of the new year, the Unmanned Surface Vehicle research team entered a busy deployment phase.

“After the holiday, another batch of equipment was transported to the South China Sea and deployed for operation,” said a project representative. “All pre-deployment preparations must be carefully completed—there must be no mistakes.”

Once all preparations were completed, a medium-sized van arrived at HydrovoX (HydrovoX). HydrovoX serves as an important testing site for Unmanned Surface Vehicle marine observation equipment developed by the research team. The equipment used in this marine mammal exploration mission was developed and assembled at this facility.

After loading was completed, the cargo vehicle carrying this mission-critical equipment departed from the Qingdao Marine Science and Technology Innovation Center and traveled over 2,000 kilometers over two days to reach a major port in the South China Sea region.

For researchers, time was of the essence. On the following day, under favorable weather conditions, this batch of high-tech mobile marine platforms was deployed into the vast waters of the South China Sea by professional operators.

Only a few days after deployment in the South China Sea, another set of equipment from the same batch was transported out of HydrovoX in Qingdao and delivered to a key coastal port near Qingdao.

“Several devices have also been deployed in the coastal waters near Qingdao,” said a project representative. “After deployment, these units will autonomously navigate along predefined trajectories to monitor marine mammals potentially present in the Yellow Sea and Bohai Sea regions.”

Qingdao-Made Technology Enables Breakthrough Innovation

Marine mammal acoustic intelligent identification has long been a highly challenging research problem. While abundant acoustic datasets exist for common species with large populations and wide distribution, data for low-density and spatially restricted species remain severely limited. For endangered species, in some cases, no usable samples are available at all. This imbalance in data availability remains one of the key challenges in marine bioacoustic intelligent recognition research.

Unmanned Surface Vehicle-Borne Sonar System for Marine Mammal Monitoring

A representative from HydrovoX stated that China possesses rich marine mammal biodiversity, with a total of 39 recorded species, including various whales, dolphins, seals, and sea lions. The rational development and utilization of marine biological resources are of great significance for achieving sustainable socio-economic development, strengthening ecological conservation, accelerating the construction of China as a “maritime power,” and enhancing the country’s influence in global ocean governance.

Based on this background, a five-year program scheduled to run until June 2028 has been launched to investigate the baseline inventory of marine mammals. The program is led by the Unmanned Surface Vehicle research team of Ocean University of China, in collaboration with multiple domestic marine mammal research institutions, industry associations, and non-governmental organizations. The survey covers the South China Sea, the Western Pacific Ocean, as well as coastal waters near Qingdao, aiming to provide real-time in situ acoustic data for marine mammal research and conservation in China.

According to the project representative interviewed on March 7, the deployed system mainly consists of two integrated components. One is an unmanned surface observation platform operating at the sea surface, while the other is a sonar acquisition system suspended beneath the platform. The onboard surface platform is equipped with imaging and video recording systems for capturing visual data of marine mammals at or near the sea surface. Meanwhile, the subsurface sonar module collects acoustic signals emitted by marine mammals above and below the sea surface, including those from deeper ocean layers. The collected acoustic and visual data are transmitted to shore-based systems via the Unmanned Surface Vehicle, where they are analyzed to identify species composition, population distribution, and abundance.

Undoubtedly, the utilization of acoustic information collected through sonar systems represents a new generation of artificial intelligence-enabled Unmanned Surface Vehicle technology, marking a disruptive innovation in marine observational capabilities.

Sonar System Previously Detected Whales in Coastal Waters Near Qingdao

The recent deployment of observation equipment in the South China Sea and nearshore waters of Qingdao is not the first of its kind.

According to the project team, exploratory deployments were already conducted last year in regions including the South China Sea and coastal Qingdao waters. During those trials, acoustic datasets collected from marine mammals were analyzed, revealing that spectral characteristics at different time periods reflect the full process of marine mammals approaching and then moving away from the Unmanned Surface Vehicle. These results indicate that marine mammal acoustic signals exhibit distinct harmonic structures in their frequency spectra.

All acoustic data collected during these exploratory missions were transmitted back to shore-based control systems via satellite communication. These results demonstrate that the Unmanned Surface Vehicle developed by Ocean University of China has achieved stable long-duration and wide-area acoustic observation capability for marine mammals in real marine environments.

Spectral Characteristics of South China Sea Acoustic Detection by Unmanned Surface Vehicles at Different Time Periods

Spectral Characteristics of Acoustic Detection in the South China Sea by Unmanned Surface Vehicles at Different Time Periods

In fact, the research team began deploying self-contained hydrophones mounted on Unmanned Surface Vehicles as early as 2018, conducting sea trials in the coastal waters around Qingdao.

“At that time, we captured a rather unusual sound in the Qingdao sea area,” said a project representative. “We highly suspected that this unusual sound came from a marine mammal, but based on our knowledge and experience at the time, we were unable to clearly identify or confirm it.”

Dr. Yang Zhiguo, who had previously been a visiting scholar at the University of Southampton and the UK National Oceanography Centre, later took the recorded acoustic data to the United Kingdom for analysis. The results confirmed that the sounds detected in the Qingdao coastal waters were from either orcas (killer whales) or false killer whales. Although large marine mammals had not been systematically surveyed in the region for years in terms of species, population, and migration behavior, this acoustic evidence confirmed their presence in the nearshore waters of Qingdao, albeit in low abundance.

This discovery was subsequently validated. In August 2020, photographs of whales spotted near the Third Bathing Beach in Qingdao sparked widespread attention and discussion.

The project representative further noted that both orcas and false killer whales are large marine mammals with strong social behavior. They typically live in groups and rely on acoustic signals for communication, and even when isolated, they continue to emit vocalizations.