Bird watching found to be a critical factor in monitoring fisheries
The researcher’s work has focused on observing the diet, health and population dynamics of crested terns, a small fish-eating seabird living in marine waters of South Australia.
“My data shows that information collected from crested terns can be used to monitor marine ecosystem health, such as the abundance of sardines in the ocean,” says Dr McLeay, of the South Australian Research and Development Institute.
The number of sardines in Australian waters is currently estimated by weighing up the active biomass, based on the production of eggs by female adult fish, against fisheries’ catch data.
This technique, however, does not take into account the ecological interactions sardines have with many species, including terns.
To develop a new approach to measuring fish abundance, Dr McLeay focused on two major sardine mortality events of the 1990s, when approximately 70% of adult sardines in South Australian waters died due to a virus.
The researcher found that terns rely on sardines in their diet—a factor that can be monitored by recording their vomit—and that the survival of tern chicks is related directly to sardine abundance.
Using GPS tracking devices, he also found that adult terns have a restricted foraging range, making them particularly vulnerable to losses in local sardine numbers.
“My data shows that we can use terns to help us inform conservation strategies and manage marine resources better,” Dr McLeay says.
He now hopes that terns will provide a tool for enhancing management practices for Australia’s largest fishing ground, the South Australian sardine fishery.