Research leapt forward at the end of the 1980s, when we began taking biopsy skin samples. Skin biopsies taken in conjunction with photo-identification provide us the sex and genetic code of individuals, and enabled us to better understand social structure, reproduction, and eventually the genealogy of each species studied.
Skin samples can also be used to determine each individual's prey consumption. Using stable isotopes, lab analysis can indicate at which trophic level different species are feeding, which is important in understanding competition between species.
Because certain pollutants are lipid-soluble and accumulate in blubber over time, blubber collected in biopsy samples can be analyzed for concentrations of persistent contaminants such as PCBs, pesticides, and dioxins, amongst others. Certain of these substances, now banned in North America, have been found to cause severe health problems. By monitoring the levels of these substances in the animals we study, we can gain a better understanding of the degree of pollution in their habitat.
Blubber can also be used to determine pregnancy rates using hormones (progesterone), as well as testosterone and stress hormone levels. The latter are part of ongoing research projects, and skill in interpreting some aspects of the data are still being developed. An overview of current field projects is given below.
These samples are taken by firing a specially designed bolt and tip from a crossbow. The bolt is mounted by a stainless steel or titanium tip containing three retaining prongs, which penetrates the animal and holds the sample taken. A specially designed foam-rubber stopper keeps the tip from penetrating deeper than epithelial tissue and allows the bolt to rebound and float for easy retrieval. The tip is disinfected with alcohol before each use and every tip is used only once to avoid any chance of infection or cross DNA contamination. We usually obtain between 18 and 25 mm skin and blubber for each. Multiple worldwide studies have been conducted, without negative effect on the study species. Some individuals react to boat approaches and sometimes the bolt strike, but resume their previous behaviour within minutes. In fact humpback whales sometimes react more to misses than to actual hits.
Stainless steel tip and foam-rubber stopper (yellow)
Biopsy sample - skin (dark black) and blubber (red)