Mariculture in the Strait of Juan de Fuca

 
PDF Files

 

 

Finfish mariculture has existed in the Pacific Northwest for over forty years, but for the past approximately 25 years most effort has focused on culture of Atlantic salmon as this species is in many aspects a better species to culture in net pens and coincidentally results in much lower ecological risks in the Pacific Northwest than culturing Pacific Salmon according to NOAA risk assessment and biological studies. Initially in the 1970s Pacific salmon were cultured mostly in backwater bays, inlets and restricted locations but the pens were relocated by design and regulation to more suitable main basins and channels that are considered less nutrient sensitive or insensitive in terms of nitrogen excretion of the fish affecting phytoplankton production. The Strait of Juan de Fuca (the "Strait") is a large area with sparse development in some regions and several apparent advantages for mariculture using offshore fish culture technology. The culture could be with salmon or marine fish using surface or submerged net pen systems. The latter are preferable for aesthetic considerations but in some locations the former may be more suitable for technical reasons.

This website provides an overview of pertinent hydrographic conditions and possible impacts of marine or salmonid finfish culture in the Strait for commercial harvest or marine fish stock rehabilitation.

Circulation studies, current and wave meter deployments, acoustic Doppler current profiles and phytoplankton assessments were conducted in three different regions distributed throughout the Strait near the southern shore.  Results were compared to existing inshore fish farms nearby and analyzed with a new simulation model that accounts for growth and metabolic oxygen demands of caged fish and the response of phytoplankton to nutrients and grazing.

Previously undetected and persistently lower sea surface temperatures were observed in satellite imagery for the central Strait region, especially during the summer and early fall.

Surface-layer water temperature was positively correlated with dissolved oxygen concentration during the same season. Accordingly, there could be significantly reduced dissolved oxygen content of surface waters of the central Strait during this period. Eastern and western areas of the Strait may be marginally better for fish culture on this account, depending on fish species cultured. Although the dissolved oxygen anomaly was discovered in our 2003 study, no follow-up research has been conducted so the full geographic extent, duration and dynamics of this phenomenon remains to be determined.

We conclude that low or no impact marine fish mariculture is technically feasible in the Strait. The high energy environment and lack of adverse nutrient enrichment effects from net pens in the Strait of Juan de Fuca would result in very minimal or no adverse effects from future, properly-planned and operated net-pen operations. Since this study was commenced in 2001, a decade of rapid advances in net pen facility design and construction allow for operation in the Strait. Ten years ago it was technically less feasible. At the same time, capture fisheries are approaching or past sustainable-yield levels. Worldwide aquaculture is now responsible for production of over half the seafood consumed by humans. This trend will not reverse, but the question remains: will the United States will sit on the sidelines and let other developed and developing countries lead the way in the effort to ecologically and sustainably produce seafood in coastal seas? Similarly, will the U.S. continue to import most of our seafood rather than produce it domestically? Importation raises safety, sustainability, economic and national security issues that are not easily addressed. The National Oceanic and Atmospheric Administration is leading a national discussion of these topics.

This study was sponsored in part by funding from NOAA Office of Oceanic and Atmospheric Research. Many individuals and organizations contributed in kind support, including the Washington Fish Growers Association and members, The Makah Tribal Nation, and several residents of Clallam County Washington who aided in field work and sampling.

Sunrise at Cypress Island

photo courtesy of Michael Womer, Anacortes, Washington