Microspectrophotometry of rod photoreceptors was used to follow variations in visual pigment vitamin A1/A2 ratio at various life history stages in coho salmon. Coho parr shifted their A1/A2 ratio seasonally with A2 increasing during winter and decreasing in summer. The cyclical pattern was statistically examined by a least-squares cosine model, fit to the 12-month data sets collected from different populations. A1/A2 ratio varied with temperature and day length. In 1+ (>12 month old) parr the A2 to A1 shift in spring coincided with smoltification, a metamorphic transition preceding seaward migration in salmonids. The coincidence of the shift from A2 to A1 with both the spring increase in temperature and day length, and with the timing of seaward migration presented a challenge for interpretation. Our data show a shift in A1/A2 ratio correlated with season, in both 0+ (<12 months old) coho parr that remained in fresh water for another year and in oceanic juvenile coho. These findings support the hypothesis that the A1/A2 pigment pair system in coho is an adaptation to seasonal variations in environmental variables rather than to a change associated with migration or metamorphosis.

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On the west coast of Vancouver Island, Canada, in the Treaty Settlement Lands of the Huu‐ay‐aht First Nation, a causeway isolating the southern portion of the Sarita River estuary was breached in 2018 to enhance juvenile salmon and tidal water access into the southern portion of the estuary. Short‐term goals of breaching were to: (1) enhance juvenile salmon access through the causeway; (2) promote colonization of Chinook and Chum Salmon in pools, while retaining Coho Salmon; (3) monitor the entire estuary fish community, including non‐salmonids, to assess breaching success; and (4) homogenize water chemistry in pool and channel ecosystems currently fragmented by the causeway. Immediately following the breach, both fish community and water chemistry measurements indicate that these goals were achieved. Chinook and Chum Salmon utilization increased inside and outside of the causeway following breaching. Similarly, Chinook and Chum salmon were observed in pool ecosystems, and Coho Salmon were also retained in pools following breaching. Water chemistry was homogenized post‐breach, primarily due to increased saltwater penetration. While continued monitoring is required, short‐term indicators suggest that breaching was effective in increasing connectivity of the Sarita Estuary, allowing access to 1.4 km2 of habitat that had previously been inaccessible to juvenile salmon.

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Productivity of temperate streams and lakes is often limited by availability of key nutrients, and nutrient-poor habitats are termed oligotrophic. Oligotrophic streams and lakes occur naturally, but often are a product of human activities (cultural oligotrophication), such as the creation of dams. Cultural oligotrophication has resulted in declining productivity in streams and lakes, a condition that can manifest itself in collapsing salmonid fish stocks. To counteract lost productivity as part of restoration or compensation measures, managers often add nutrient via fertilizers to enhance fisheries production. However, these programs are not always successful, and this article reviews available literature to identify patterns that may influence success of nutrient enhancement programs. Overall fertilization of lakes and streams will almost certainly increase primary producer and invertebrate populations. While it is likely that fertilization will also increase fishery production, it is far from certain. The magnitude of this change is unpredictable, and the success of a fertilization program will vary greatly between years, habitat, and microhabitats. Regardless, if fertilization is coupled with holistic monitoring of the food web and ecosystem, then it is likely to be an effective technique to enhance fishery productivity in active restoration of compensation programs. However, the benefits of fertilization will not outlast the fertilization project, and care must be exercised when ceasing active fertilization. When compared to other restoration/compensation strategies such as fish ladders or trap and transport, fertilization may be a cost-effective method to enhance fishery production. Finally, recommendations are discussed to increase the probability of fertilization success.

The Kaouk River estuary is located on the northwest coast of Vancouver Island, British Columbia, Canada, in the Treaty Settlement Lands of the Ka:'yu:'k't'h'/Che:k'tles7et'h First Nations. Stretching across the widest point of this estuary is a causeway providing road access to Fair Harbour. This causeway was observed to decrease habitat connectivity throughout the estuary, specifically limiting juvenile salmon access to high-quality rearing habitat in the tidal marsh. As such, the causeway was breached in 2019 and a bridge was installed. Juvenile salmon were observed using the new connection and were captured both up and downstream of the causeway immediately following breaching. Postbreach water chemistry (dissolved oxygen, pH, salinity, and temperature) near the causeway was recorded within the range of values observed throughout the estuary. Use of the breach by juvenile salmon and homogenized water chemistry indicate the project succeeded in improving habitat connectivity within the Kaouk River estuary and has enhanced juvenile salmon access to 2.7 km 2 of wetland rearing habitat.

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