Yutaka Watanuki

Studying Changes of the Marine Environment through the Perspective of Seabirds

Yutaka Watanuki , Professor

Faculty of Fisheries Sciences/ Graduate School of Fisheries Sciences

High school : Nagano High School

Academic background : Doctorate at Hokkaido University

Research areas
behavioral ecology, marine ecology
Research keywords
marine ecology, changes to the marine environment, bio-logging, monitoring

What are you aiming to achieve?

Seabirds are the only marine organisms that we are able to observe over the sea surface. You sometimes see gulls floating in line on the sea surface. If you look closely, you may also see foam and rubbish such as cans also floating there, and you may find that the color of the ocean or the formation of waves changes suddenly just at that point. This is a front between currents, caused by seawater flowing in different directions. Sea birds show us these fronts very clearly. Thus by studying seabirds as indicator, it is possible to recognize the changes of the marine environment. This is my research topic.

We use the ocean in many ways, not just fishing. As a result, however, we have reduced fish stocks of large predatory fish such as tuna, polluted the ocean with PCBs, plastic and others, and reduced biodiversity. We need to understand how the marine environment is changing, and particularly changes of the ecosystem, as quickly as possible. Buoys and satellites are very useful to gathering physical information such as water temperature and salt content, etc. In addition to information gained from survey ships and fishermen, seabirds are general indicators of the marine ecosystem, because they eat a range of organisms from plankton to sardines. Studying their behavior and ecology tells us a lot about the ocean.


What sort of equipment do you use to perform what type of experiments?

Seabirds breed colonially on isolated islands. We camp there, and examine what they are eating, how many eggs they lay, and how many chicks they are rearing, each year, as part of our monitoring project. All you need for this project are binoculars, a pair of boots, a field notebook, a spring balance and a vernier caliper (Fig. 3). By taking some of the food provided for the chicks, we learn about what they are eating. We also take minute samples of blood and fat from both parents and chicks. The chemical composition of these tissues tells us about their food habits. These samples also tell us the extent to which seabirds are being affected by PCBs, plastic and other marine pollutants. Over a long period of time, this study shows changes in the marine ecosystem and the pollution.

This observation is not enough, however, to understand the behavior of seabirds on the ocean. In order to understand behavior I have spent hours and hours on a boat with binoculars, surveying how many of each different type of sea bird is present. Still, I have been unable to continually follow their behavior at the sea. More recently I have caught some seabirds in their nesting grounds and attached data loggers (devices that record water temperature and water depth etc.) or radio wave transmitters on their back before releasing them, and then captured them again when they returned to the islands in order to collect the behavioural data stored in the data-loggers, and investigate their behavior and movement over the ocean in more detail. This technique is known as Bio-logging (Fig. 4).

Fig. 3 Measuring the weight of rhinoceros auklets on Teuri island. Each year, the speed of development of the chicks varies significantly, reflecting the availability of the fish on which they feed.

Fig. 4 Attaching data loggers and VHF radio transmitters to Adelie penguins, which breed near the Showa Base. This makes it possible to continually record when, where, and how far they dive to get food.



What are you aiming for next?

We will continue our monitoring of seabirds, and aim to be able to detect if there is a change in local marine ecosystems. It is not glamorous work, but I believe that it is one of the ways that we will be able to analyze the impact of long-term climate change on ecosystems. Another project is to estimate the changes in marine pollution levels and changes of the ecosystems in the area where each seabird has travelled. We can map the routes travelled by each individual in detail using Bio-logging technology, and are aiming to establish a “behavioral landscape approach”, which links ocean currents and marine productivity. It is also possible to determine levels of pollution and feeding habits using the pollutant and stable isotope in the blood, feather and wax secreted from the base of the birds’ tail-feathers. Now we are working on short-tailed shearwaters, which breed in Tasmania, travel as far as the Antarctic Ocean to find food when rearing their young, and then cross the Pacific to the Baring Sea to winter, as a potential tools to monitor the environmental changes in the Pacific from north to south on a global scale.



(1) Watanuki, Y. (author), Behavior and Ecology of Sea Birds, Seibutsu Kenkyusha (2010)
(2) Japanese Society of Bio-logging Science (Ed.), Bio-logging – Homing in on the Mysterious Behavior of Animals, Kyoto Tsushinsha (2009)