Technology including the use of robots is aiding researchers in understanding daily habits of the endangered Mediterranean sperm whale.
Scientists at the University of East Anglia (UEA) used unmanned underwater gliders equipped with acoustic monitors and recorded sperm whale sounds, or ‘clicks’, over several months and 1000s of kilometres of ocean.
Sperm whales are highly vocal, producing distinct types of clicks for both echolocation and social interaction purposes. The study, published in the Endangered Species Research, focused on the extremely powerful and highly directional ‘usual clicks’ produced while foraging.
Continuous day and night monitoring during winter months suggested that there were different foraging strategies between different areas. In the Ligurian Sea,for example, mobile and scattered individual whales forage at all times of day.
In contrast to this in the Gulf of Lion larger groups of sperm whales were less active foraging at dawn.
The study involved researchers from UEA and the Centre for Environment, Fisheries & Aquaculture Science (CEFAS), the Scottish Association for Marine Science (SAMS), University of Gothenburg and Sorbonne University.
Pierre Cauchy, a postgraduate researcher at UEA’s Centre for Ocean and Atmospheric Sciences (COAS) and CEFAS, said:
“Increasing observation efforts, particularly in winter months, will help us better understand habitat use, and identify key seasonal habitats to allow appropriate management of shipping and fishing activities.
“The clear daily pattern identified in our results appear to suggest that the sperm whales are adapting their foraging strategy to local prey behaviour. The findings also indicate a geographical pattern to their daily behaviour in the winter season.”
The use of the robotic oceanographic gliders will enable the scientists to study areas and at times of the year which would not normally be possible. Better understanding of the Mediterranean sperm whale could lead to eliminating some of the threats currently endangering them.
There are fewer than 2500 mature individual Mediterranean sperm whales and threats to them include being caught as bycatch in fishing nets, ship strike, ingestion of marine debris, disturbance by human-made noise and whale watching activities.
Record Levels of Toxins Found In Whales and Dolphins
A study of chemicals in stranded whales and dolphins that washed ashore in Florida and North Carolina recorded the highest levels yet of mercury and arsenic. The stranded animals included 11 different species, providing the first evidence for two rarer species: white-beaked dolphin and Gervais’ beaked whales.
Beyond the toxins found in plastics, such as bisphenol-A, Prof A. Page-Karjian and team of the Harbor Branch Oceanographic Institute at Florida Atlantic University, in the United States, also measured heavy metals such as arsenic, lead, and mercury, which can damage animals’ immune, reproductive, and nervous systems at high concentrations.
Assistant Professor Annie Page-Karjian said:
“Marine mammals are ecosystem sentinels that reflect anthropogenic threats through their health — which has implications for human health as well.
“For example, many of the species in this study prey upon fishes that are also preferred species for human consumption — so monitoring concentrations of contaminants in these animals provides a relatively low-cost snapshot of the potential exposure risk in humans, as well as other marine animals.”
Reporter: Fiona Grahame