In the eastern North Pacific Ocean, the harbor porpoise ranges from Point Barrow, along the Alaskan coast, and down the West Coast of North America to southern California (Gaskin 1984). The harbor porpoise is basically an inshore species, frequenting coastal waters and the mouths of large rivers, harbors, and bays, sometimes ascending freshwater streams. Relatively high densities of harbor porpoise have been recorded along the coasts of Washington, and Northern Oregon and California; yet, distinct seasonal changes in abundance in these areas have been noted, possibly due to a shift in distribution to deeper offshore waters during winter

Visit the Endangered Species Home Page put out by U.S. Fish and Wildlife. An awesome site!

Persistent: 1. Refusing to give up or let go; persevering obstinately. This definition has a negative connotation, and in this case, very true.

Marine: 1. Of or pertaining to the sea

Debris: 1. The scattered remains of something broken or destroyed; ruins.

So, working backwards to develop the definition; persistent marine debris is something broken or destroyed, located in the sea, that refuses to go away. This defines trash, not readily biodegradable, including metals, plastics, and rubber products. Metals and rubber products are serious problems but once in the marine environment, they sink to the bottom and pose less of a threat than the third item our list, plastics.

The introduction of synthetic materials, or "plastics", is one of the most important technological advancements for modern society. The superior qualities of these synthetic materials make them an almost universal substitute for natural materials. However, it is these qualities - light weight, strength, durability, and low cost - which make plastics so prevalent and potentially damaging in the marine environment. This debris degrades coastal areas and injures or kills many marine animals including commercial fish and shellfish, birds, marine mammals, and sea turtles. It also interferes with vessel operations and safety by entangling propulsion and steering systems and may damage machinery by blocking seawater intakes.

Carwardine, M. 1995. Whales, Dolphins and Porpoises. Dorling Kindersley Publishing, Inc., 95 Madison Ave., NY 10016. 256p.

Jefferson, T.A., S. Leatherwood and M.A. Webber. 1993. Marine Mammals of the World. Food and Agriculture Organization (F.A.O.) of the United Nations, Viale delle Terme di Caracalla, 00100 Rome, Italy. 320p.

Jefferson, T.A., S. Leatherwood, L.K.M. Shoda, R.L. Pitman. 1992. Marine Mammals of the Gulf of Mexico. A Field Guide for Aerial and Shipboard Observers. Texas A & M University Printing Center, College Station, TX 77843. 92p.

Katona, S.K., V. Rough and D.T. Richardson. 1993. A Field Guide to Whales Porpoises and Seals From Cape Cod to Newfoundland. Fourth Edition. Smithsonian Institution Press, Washington, DC. 316p.

Katona, S.K., V. Rough and D.T. Richardson. 1983. A Field Guide to the Whales, Porpoises and Seals of the Gulf of Maine and Eastern Canada - Cape Cod Bay to Newfoundland. Third Edition. Charles Scribner's Sons, NY. 255p.

Katona, S., D. Richardson and R. Hazard. 1975. Whales and Seals of the Gulf of Maine. Maine Coast Printers, Rockalnd, ME [ISBN 0-916080-01-3]. 97p.

Leatherwood, S. and R.R. Reeves. 1983. The Sierra Club Handbook of Whales of Dolphins. Sierra Club Books, San Francisco, CA. 302p.

Leatherwood, S., D.K. Caldwell and H.E. Winn. 1976. Whales, Dolphins and Porpoises of the Western North Atlantic. NOAA Tech. Rept. NMFS CIRC-396, Seattle, WA. For sale by: Supt. Of Documents, Printing Office, Washington, DC. [Stock no. 003-020-00119-0] 176p.