Northwest Fisheries Science Center

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Document Type: Chapter or Section
Center: NWFSC
Document ID: 8847
Type of Book: Technical
Section or Chapter Title: A review of seal and sea lion entanglement in marine fishing debris
Book Title: Proceedings of the North Pacific Rim Fishermen's Conference on Marine Debris, 12-16 October 1987. Kailua-Kona, Hawaii
Author: Charles W. Fowler
Editor: Dayton Lee Alverson, J. A. June (Eds.)
Publication Year: 1988
Pages: 1-44

Plastic debris, much of which has its origins in commercial fishing operations, are found entangled on individuals of a number of species of seals.  Ten of the 16 species of otariid seals have been observed entangled in such debris.  By comparison, six of the 14 species of phocid seals have been observed entangled.  Individual phocid species tend to show lower entanglement rates than do the otariids.  This apparent difference between phocids and otariids has not been explained but may be related to body shape, habitat, and behavior.  Entanglement in debris is thought to contribute to the mortality of individuals through starvation, suffocation, infection in resulting wounds, exhaustion, bleeding,ยท drowning, and possibly increased predation.  Studies indicate entanglement may be contributing significantly to the decline of the northern fur seal population.  Because the population is already at low levels, entanglement may pose some threat to the Hawaiian monk seal population.  Entanglement may be a potential problem for immature northern sea lions (known to be experiencing a decline) and the South African fur seal (some colonies of which have experienced declines) populations.