Food web

Puget Sound hosts more than 100 species of seabirds, 200 species of fish, 15 marine mammal species, hundreds of plant species, and thousands of invertebrate species. These species do not exist in isolation, but rather interact with each other in a variety of ways: they eat and are eaten by each other; they serve as vectors of disease or toxins; they are parasitic; and they compete with each other for food, habitat, and other resources.

--Source: Sound Science 2007 

Overview

The health of an ecosystem is tied closely to the health of its food webs. This article provides an overview of the concept, origin, and characteristics of a food web and how predator and prey relationships are shaped in the Salish Sea.  

Bear eats salmon. Photo: Robert Voors (CC BY-NC-ND 2.0) https://www.flickr.com/photos/robert_voors/1303192433

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With a population growth of about 10 percent per year in inland waters, harbor porpoises are having an undetermined but growing effect on food dynamics in Puget Sound.

Pacific herring are a pelagic fish species found from northern Baja California to northern Honshu Island, Japan. They are found throughout the Puget Sound basin and are a mix of “resident” and “migratory” stocks. 

As the region's population grows, scientists say we can expect to see increasing amounts of nitrogen and other elements flowing into Puget Sound. Known as “nutrients” these elements are naturally occurring and even necessary for life, but officials worry that nutrients from wastewater and other human sources are tipping the balance. That could mean big problems for fish and other marine life, gradually depleting the water of oxygen and altering the food web.

High amounts of elements such as nitrogen can cause blooms of phytoplankton that sometimes trigger perturbations throughout the food web. This occurs most often in the spring and summer after the long, dark, cloudy days of winter begin to fade.

As wildlife managers work to recover Puget Sound’s diminished Chinook population, a proposed white paper is expected to review the impacts of some of the salmon's chief predators. The study would include a section on potential management of seals and sea lions, prompting open discussion of a long taboo subject: Could officials seek to revise the Marine Mammal Protection Act — or even conduct lethal or non-lethal removal of seals and sea lions in some cases? Such actions are hypothetical, but we look at some of the ongoing discussions around the issue as prompted by a new resolution from the Puget Sound Leadership Council. 

Increased consumption of Chinook salmon by seals and sea lions in the Salish Sea “could be masking the success of coastwide salmon recovery efforts,” according to a new study published in the journal Scientific Reports. Endangered resident orcas are said to be declining in part due to a lack of available Chinook, the orcas' preferred prey.