Nanaimo River

Nanaimo River Study Area

Figure 1. Nanaimo River Study Map showing hatchery chinook releases (purple) and PIT array location (red). Map is interactive

PIT Tags Deployed in Nanaimo River Salmonids

PIT tagging Nanaimo River Chinook and coho began in the winter of 2020/2021 when the first microtrolling occurred (September 2020). The first hatchery Chinook and coho were tagged in the early spring of 2021 (5,000 each). Annual tagging has continued since.

Figure 2. PIT tags deployed in Nanaimo River Fall Chinook

Figure 2. PIT tags deployed in Nanaimo River Fall Chinook

Figure 3. PIT tags deployed in Nanaimo River Summer Chinook

Figure 3. PIT tags deployed in Nanaimo River Summer Chinook

Figure 4. PIT tags deployed in Nanaimo River Coho

Figure 4. PIT tags deployed in Nanaimo River Coho

Nanaimo River Juvenile Chinook Outmigration Timing

A mainstem PIT array (comprised of two 20 ft HDPE Biomark Antennas) was installed in August of 2022 to detect outmigrating juvenile and returning adult Coho.

Figure 5. Nanaimo River Hatchery Freshwater Release Outmigration Detections 2022.

Figure 5. Nanaimo River Hatchery Freshwater Release Outmigration Detections 2022.

Figure 6. Nanaimo River Hatchery Freshwater Release Outmigration Detections 2023.

Figure 6. Nanaimo River Hatchery Freshwater Release Outmigration Detections 2023.

Figure 7. Nanaimo River Hatchery Freshwater Release Outmigration Detections 2024.

Figure 7. Nanaimo River Hatchery Freshwater Release Outmigration Detections 2024.

Nanaimo River Mainstem PIT Array Detection Efficiency for Adult Returns

The Nanaimo River PIT array is comprised of two antenna transects that span the entire width of the river. Each transect is made up of 1 - 30 ft HDPE Biomark antenna. For return years 2022 and 2023 the array detection efficiency was calculated by unique tags detected on transect 1 compared to those detected on transect 2. These data were combined and then compared to PIT tags detected during mobile scanning and broodupdated_stock collection.

Table 1.Nanaimo River Mainstem PIT Array Summary of Unique Detection’s and Detection Efficiency for Chinook salmon 2023.
[1] 71 [1] 71 [1] 19 [1] 0.788888888888889 [1] 90 [1] 90 [1] 0 [1] 1 [1] 1
Nanaimo River Chinook Adult Return Detection Efficiency 2023
Unique Tags Detected Detection Efficiency
Nanaimo Mainstem Lower 71 0.79
Nanaimo Mainstem Upper 90 1.00
Table 2.Nanaimo River Mainstem PIT Array Summary of Unique Detection’s and Detection Efficiency for Chinook salmon 2024.
[1] 49 [1] 49 [1] 35.4468085106383 [1] 0.580246913580247 [1] 81 [1] 81 [1] 3.4468085106383 [1] 0.959183673469388 [1] 0.982867220962459
Nanaimo River Chinook Adult Return Detection Efficiency 2024
Unique Tags Detected Detection Efficiency
Nanaimo Mainstem Lower 49 0.58
Nanaimo Mainstem Upper 81 0.96

Nanaimo River Detections Through Time

Detections of tagged salmon movements within the Nanaimo River are shown below (Figure 9).These are movements of fish filtered to one distinct detection per day.

Figure 8. Detections Through Time at the Nanaimo River Mainstem Array.

Figure 8. Detections Through Time at the Nanaimo River Mainstem Array.