Years of the North Atlantic Humpbacks (YoNAH)

The Years of the North Atlantic Humpback (YoNAH) project is an international collaboration to study North Atlantic humpback whales across most of their known range. It was conceived to address large-scale issues, such as the size and structure of the population, vital rates, migratory movement and the structure of the mating system.

The project involved two intensive years of field research. During the summers of 1992 and 1993, intensive photographic and genetic sampling was performed concurrently in five high-latitude feeding grounds: the Gulf of Maine (U.S.), Canada, Greenland, Iceland and Norway. During the winter months, field work was performed in the West Indies, a shared, low-latitude breeding ground. Sampling techniques were standardized within and between areas to ensure data comparability and to minimize sampling bias. A central archive was established for all photographs, tissue samples and data to facilitate analysis and to provide a valuable legacy for future investigators.

The YoNAH Research Team

The Center for Coastal Studies is primarily responsible for work performed in two areas: the Gulf of Maine feeding ground and the West Indies breeding ground. The following is a full list of primary YoNAH participants (in alphabetical order):

Summary of Major YoNAH Findings

Thanks to the large volume of data collected, YoNAH analyses are still on-going. Major findings to date are summarized below.

Population Estimate

The YoNAH project produced the first estimate of the size of the entire North Atlantic population--approximately 10,600 animals. Population estimates are important to the management and conservation of endangered species like the humpback whale. The YoNAH estimate will serve as a baseline against which to evaluate whether the population is increasing or decreasing over time.

Population Structure

YoNAH also provided detailed information on exchange between high-latitude feeding grounds and low latitude breeding grounds (see image, right). For example, prior to this study it was assumed that whales from Norway mated and gave birth in the eastern North Atlantic (the Cape Verde Islands). We now know that at least some of these whales mingle with whales from the western North Atlantic on the Caribbean breeding grounds. Individuals were tracked between Norway and the Caribbean both by photographs of natural marks (see Stevick et al. 1998, below) and "genetic tags."

Known feeding and breeding grounds of the North Atlantic humpback whale. Lines indicate exchange between areas, not actual migration routes.