NOAA Fisheries Marine Mammal Stock Assessments

BARNSTABLE – Assessing marine mammal stocks gives NOAA fisheries a valuable information on population trends, productivity rates, estimates of human-caused mortality, and other sources of serious injury.

These assessments allow NOAA to evaluate the effectiveness of conservation and recovery measures, and to adjust management approaches as needed.

The Marine Mammal Protection Act defines a marine mammal stock as a group of individuals “of the same species or smaller taxa in a common spatial arrangement that interbreed when mature.”

Stock assessment reports for all marine mammals in the U.S. waters were first required when the MMPA was amended in 1994.

Since that time, all stocks have been reviewed at least every three years or as new information becomes available.

Stocks that are designated as “strategic” are reviewed annually.

Each draft stock assessment report is peer-reviewed by one of three regional Scientific Review Groups and revised and published after a public comment period.

Data collection, analysis, and interpretation are conducted through marine mammal research programs at each of NOAA’s Fisheries Science Centers and by other researchers.

The U.S. Fish and Wildlife Service prepares SAR’s for marine mammals under their jurisdiction including polar bears, sea otters, walruses, and manatees.

Each report includes a description of the stock’s geographic range, minimum population estimate, current population estimates, current and maximum net productivity rates, potential biological removal levels, status of the stock, estimates of annual human-caused mortality and serious injury by source, and a description of other factors that may be causing a decline or impeding the recovery of strategic stocks.

The information contained in stock assessment reports is used to identify and evaluate the status of marine mammal populations and the effects of human activities upon them, authorize the “taking” of marine mammals incidental to human activities, design and conduct appropriate conservation measures, and evaluate the progress of each fishery in reducing its incidental mortality and serious injury to insignificant levels approaching a zero mortality and serious injury rate.

To learn more about NOAA stock assessments, visit

About Luke Leitner

Luke Leitner grew up in Watertown Massachusetts and now lives in West Yarmouth on the Cape. He has been a part of the news team in the News Center since the spring of 2019. He studied business communications at Western New England University.
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