Fishery Bycatch and Human-Caused Mortality and Serious Injury


The Marine Mammal Protection Act (MMPA) requires the National Oceanic and Atmospheric Administration (NOAA), National Marine Fisheries Service (NMFS), to document human-caused mortality, non-serious injury (NSI), and serious injury (SI) of marine mammals as part of assessing marine mammal stocks and to evaluate human-caused injury and mortality levels in the context of potential biological removal (PBR) levels calculated under the MMPA (Wade 1998). NMFS defines SI as “any injury that will likely result in mortality.” While recognizing mortality is straightforward, distinguishing NSI from SI requires reliable data on injury severity and animal condition, often in challenging environments where thorough examination of injuries is not possible. NMFS updated its SI designation and reporting process, which uses guidance from previous SI workshops (Angliss and DeMaster 1998, Andersen et al. 2008), expert opinion, and analysis of historic injury cases to develop new criteria for distinguishing SI from NSI (NOAA 2012, Moore et al. 2013).

Records of serious injury and mortality are used to prepare Pacific Marine Mammal Stock Assessments prepared by the Southwest Fisheries Science Center and Pacific Islands Science Center.


Andersen,M. S., K. A. Forney, T. V. N. Cole, T. Eagle, R. Angliss, K. Long, L. Barre, L.Van Atta, D. Borggaard, T. Rowles, B. Norberg, J. Whaley, and L. Engleby.  2008. Differentiating serious and non-seriousinjury of marine mammals: report of the serious injury technical workshop,10-13 September 2007, Seattle, Washington. U.S. Dep. Commer., NOAA Tech. Memo.NMFS-OPR-39.94 p.

Angliss,R.P. and D.P. DeMaster. 1998. Differentiating serious and non-serious injury ofmarine mammals taken incidental to commercial fishing operations. NOAA Tech.Memo.NMFS-OPR-13, 48 pp.

Carretta, J.V., J.E. Moore, and K.A. Forney. 2017. Regression tree and ratio estimates of marine mammal, sea turtle, and seabird bycatch in the California drift gillnet fishery: 1990-2015. NOAA Technical Memorandum, NOAA-TM-NMFS-SWFSC-568. 83 p. doi:10.7289/V5/TM-SWFSC-568.

Carretta, J. V., S. M. Wilkin, M. M. Muto, and K. Wilkinson. 2013. Sources of human-related injury and mortality for U.S. Pacific west coast marine mammal stock assessments, 2007-2011. U.S. Dep. Commer., NOAA Tech. Memo. NMFS-SWFSC-514, 83 p.

Carretta, J.V. and J. Barlow. 2011. Long-term effectiveness, failure rates, and “dinner bell” properties of acoustic pingers in a gillnet fishery. Marine Technology Society Journal 45:7-19.

Carretta, J.V., T. Price, D. Petersen, and R. Read. 2004. Estimates of marine mammal, sea turtle, and seabird mortality in the California drift gillnet fishery for swordfish and thresher shark, 1996-2002. Marine Fisheries Review 66(2):21-30.

NOAA. 2012.  Federal Register 77:3233. National Policy forDistinguishing Serious From Non-Serious Injuries of Marine Mammals.

Moore, M.J., Barco, S.G., Costidis, A.M.,Gulland, F.M., Jepson, P.D., Moore, K.T., S. Raverty, & McLellan, W.A.2013. Criteria and case definitions for serious injury and death of pinnipedsand cetaceans caused by anthropogenic trauma. Diseases of aquatic organisms, 103(3),229-264.

Wade,P.R. 1998.  Calculating limits to theallowable human-caused mortality of cetaceans and pinnipeds.  Marine Mammal Science 14:1-37.