Marine Mammals

Population Assessments

Population assessments provide the foundation for evaluating status of and threats to marine mammals managed by NOAA Fisheries under the U.S. Endangered Species Act and Marine Mammal Protection Act. Ideally, these assessments include synthesis and analysis of scientific information on a species or stock’s population structure, life history characteristics and vital rates, abundance, and threats, particularly those caused by human activities. 

Production of complete protected species assessments at regular intervals by NOAA Fisheries is necessary for informing agency decisions related to a species’ ESA listing status, federal or federally-funded activities that may impact a species or its habitat, acceptable bycatch levels, and scientific research and incidental take permits issued to agencies, scientific and academic institutions, and industry. Additionally, such information is vital to NOAA Fisheries fulfilling its supportive and advisory role in state- and tribal-managed coastal areas and providing scientific and policy leadership and guidance to regional and international bodies such as multi-state marine fishery commissions, U.S. Fishery Management Councils, international fishery management organizations, and the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).

Without assessment data, precautionary and often severely restrictive regulatory measures are put in place  that are likely to impede commercial fisheries, development and exploratory activities, and stall conservation efforts to recover species as current and reliable science is unavailable.

How many animals are there? How do they change from year to year and from area to area? These basic questions allows managers to make decisions about when, where, and how an activity can be conducted without undue harassment of protected species frequently occurring in areas of high human activity. 

The NOAA Fisheries Office of Science and Technology’s marine mammal population assessment activities focus on improving the quality, type, and frequency of assessments, including:

  • Work with Science Centers to develop technical tools and criteria to improve our assessments of marine mammal stocks.
  • Monitor the status of the stocks through current Government Performance Results Act (GPRA) measures and other performance metrics. These metrics are often used to inform research and budget planning for protected species science and our ability to completely or partially assess protected species stocks. An electronic monitoring system for the status of our stocks (Protected Resources - Species Information System, PR-SIS) is currently in development.
  • Work with science centers to develop strategies to increase survey efficiency and design, as well as leverage internal and external resources to conduct broad-scale and integrated ecosystem surveys using a variety of observation platforms including advanced technology such as unmanned systems, acoustic recorders, wave gliders, etc.
  • Work with science centers and protected resources regional and national management offices to help better prioritize our assessments given mission-critical management needs.

More Information

Note: A "Strategic Stock" is defined by the MMPA as a marine mammal stock:
  1. For which the level of direct human-caused mortality exceeds the potential biological removal level;
  2. Which, based on the best available scientific information, is declining and is likely to be listed as a threatened species under the ESA within the foreseeable future; or
  3. Which is listed as a threatened or endangered species under the ESA, or is designated as depleted under the MMPA.


Marine Mammal Population Survey

Ship-based and aerial surveys are critical to achieving NMFS’ marine mammal population assessment goals, which include abundance estimation and examination of trends and human impacts relative to management objectives. A limited number of marine mammal surveys are conducted and managed by the six NMFS Science Centers. These often involve more than one center, as well as internal and external collaborators. The number of protected species surveys conducted each year is dependent on funding and available ship time allocated at the national level.

Marine mammal-related surveys conducted and/or participated in by NMFS during 2012 included:

 PSSB at sea

For more information on surveys in which NMFS participates, see:

ribbon seal

Adult male ribbon seal (Histriophoca fasciata) released with a satellite transmitter. Photo: Josh London, NOAA/AFSC. Marine Mammal Permit: 15126