Center for Conservation Biology

North Atlantic right whale

Research overview

Data chart showing estrogen and progestin levels highest in pregnant right whales over non-pregnant

Fecal estrogen and progestin levels in pregnant and non-pregnant females. Click image to enlarge.

The North Atlantic right whale is one of the most endangered whales in the world.

Approximately 300 individuals remain. In the past decade, birth rates declined steeply for unknown reasons, and death rates increased due to entanglement in fishing nets and perhaps propeller injuries from large ships. We collaborated with Rosalind Rolland and Scott Kraus of the New England Aquarium to address these problems by monitoring stress and reproductive hormones in whale feces.


We developed the first pregnancy test for free-living baleen whales using fecal progesterone and estrogen measures. These hormones are thousands of times greater in pregnant than in non-pregnant females.

We also developed the first test ever for age of sexual maturity in baleen whales, solving a long-standing puzzle of whale biology. In both sexes, mature whales have significantly higher levels of reproductive fecal hormones (estrogen, progesterone, testosterone) than immature whales. These data have shown that right whales reach sexual maturity four years later than previously assumed. Such information is critical to developing more effective population models in this and other species. (Figure 1)

Image with three data charts showing reproductive hormones for female (estrogen, progesterone) and male (testosterone) right whales of varying ages

Figure 1. Right whale reproductive hormones.

Recent stressful events were monitored using fecal stress hormones (glucocorticoids). The high glucocorticoid levels in feces of a whale that became fatally entangled in a fishing line in 2001 illustrates this approach. (Figure 2)

Data chart with photograph of whale entangled in net. Image depicts a right whale named Chruchill entangled in a net with text that reads: "Right whale Churchill after several months of net entanglement, showing signs of physiologic stress (emancipation and skin parasites). Numerous disentanglement efforts failed." Chart shows stress levels for immature, mature, and lactating right whales compared to much higher stress hormones from "Churchill".

Figure 2. Glucocorticoids in stressed right whale.

Despite our successes, one problem remained. Observers were unable to collect a sufficient sample size to adequately test their multiple hypotheses for the population decline. We applied the scat detection dog method to this problem, training detection dogs to locate right whale scat off the bow of the small boat. Dogs detected samples as far as a nautical mile from the source, and located 3-5 times the number of samples per unit effort than were collected by human observers.

Rolland continues to use these combined tools to help identify the timing and cause(s) of reproductive failure and mortality in this species, with hopes of informing mitigation efforts aimed at facilitating right whale recovery. In 2011, this work led to analysis of right whale behavior during the shipping lull following September 11, 2001. We found a decrease in stress due to the dramatic decrease in noise during this time period. For further information regarding this data read our recently published paper, “Evidence that ship noise increases stress in right whales (see below).”


  • Rosalind M. Rolland, SE Parks, KE Hunt, M Castellote, PJ Corkeron, DP Nowacek, SK Wasser and SD Kraus. 2011. Evidence that ship noise increases stress in right whales. Proceedings of the Royal Society, Biological Sciences
  • Rolland, R, P Hamilton, S Kraus, B Davenport, R Gillett, S Wasser. 2006. Fecal sampling using detection dogs to study reproduction and health in North Atlantic right whales (Eubalaena glacialis). Journal of Cetacean Research and Management 8(2):121-125.