Response of Juvenile Salmonids to Stream-Estuary Ecotone Habitat Restoration Projects in Humboldt Bay, CA

There has been a growing understanding of the importance of estuaries to juvenile coho (Oncorhynchus kisutch) salmon.  This has resulted in multiple habitat restoration projects being implemented in the stream-estuary ecotone (SEE) of Humboldt Bay tributaries.  The California Department of Fish & Wildlife (CDFW) is monitoring selected projects to assess their performance and to provide information to help design and improve future projects.  CDFW sampled restoration sites in the SEE of Humboldt Bay to describe water quality and determine fish use at these sites.  Preliminary results show that juvenile coho salmon and steelhead trout moved into restored sites and reared there for months.  The restoration sites provided over-winter and spring rearing habitat but low stream flows in the summer and fall resulted in warm brackish water unsuitable for salmonids. Specific results showed the return of juvenile coho to historic rearing sites; the immediate use of and extended rearing of juvenile salmonids from throughout the basin in newly constructed off channel ponds; and large numbers of tidewater goby (Eucyclogobius newberryi) establishing populations in the restored sites.  Improving connections between small tributaries and creating off channel habitat in the SEE appears to benefit juvenile salmonids.