Goldstream

Goldstream River

The Goldstream River, located on Vancouver Island, British Columbia, Canada, hosts several species of salmon, including Chinook, Coho, and Chum salmon.The Goldstream River watershed covers an area of approximately 39 square kilometers (15 square miles). The Goldstream River watershed is located in a temperate rainforest region on Vancouver Island. It experiences a coastal temperate climate characterized by mild, wet winters and relatively dry summers. The region receives a significant amount of rainfall throughout the year, with the heaviest precipitation occurring during the fall and winter months. The Goldstream River itself is relatively short, with a length of about 16 kilometers (10 miles) from its headwaters to its confluence with the Strait of Juan de Fuca. However, it is important to note that the Goldstream River is just one part of the broader Goldstream Watershed, which includes various tributaries and streams that contribute to its overall flow.

Goldstream River Hatchery*

The Goldstream River Hatchery plays a vital role in the conservation and enhancement of salmon populations within the Goldstream River watershed. The hatchery’s methods involve the collection of adult salmon returning to the river during their spawning runs. Female and male salmon are carefully selected, and their eggs and milt (sperm) are manually extracted, then fertilized and incubated in controlled environments. Once the salmon fry have hatched, they are reared in hatchery tanks, where water temperature, flow, and quality are closely monitored to ensure optimal conditions for growth. As the fry develop, they are gradually acclimated to the natural conditions of the river, preparing them for eventual release into the wild. Monitoring and tracking of released smolts play a crucial role in assessing the hatchery’s success and contribution to the overall health of the Goldstream River salmon populations.

Goldstream River coho returns typically begin mid-September but peak towards to beginning of November.

Goldstream River Study Area

The key locations for the Goldstream River and the Bottlenecks Program is the Goldstream River Enhancement Hatchery located ~ 4 km from the ocean and the location of the mainstem PIT array located at tidewater (Figure. 1)

Figure 1. Goldstream River Study Map showing sampling and PIT antenna/array locations

PIT Tags Deployed in Goldstream River Salmonids

PIT tagging in the Goldstream River began in the winter of 2022 when the first test group of hatchery Coho were pit-tagged. Coho were pit-tagged in 2023 and will eb tagged again in 2024.

Table 1. PIT Tags Deployed in Goldstream River Coho salmon.

Goldstream River Juvenile Coho Outmigration Timing

A mainstem PIT array was installed in August of 2022 to detect returning adult Coho as well as outmigrating Coho juveniles in future study years.

Figure 2. Goldstream River Coho Outmigration Detections 2023.

Goldstream River Mainstem PIT Array Detection Efficiency for Adult Returns

The Goldstream 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 broodstock collection.

Table 2.Goldstream River Mainstem PIT Array Detection Efficiency for Coho salmon.

	Goldstream Mainstem 1	Goldstream Mainstem 2	Mobile Scans	System
Unique Tags Detected	214	235	12	249
Tags Detected on Mainstem Array	202	202	202	202
Total Unique Tags Detection	249	249	249	249
Expanded Unique Tags	257	282	14	249
Transect Detection Efficiency	0.86	0.94	0.83	1.00

Goldstream River Detections Through Time

Figure 3. Detections Through Time at the Goldstream River Mainstem Array.

Table 3. Detections Through Time at the Goldstream River Mainstem Array.

year_detected	species	fork_length_group	system	stock	period	tally
2022	ck	outmigration	Cowichan	COWICHAN_RIVER	hatchery	2
2022	ck	return	Cowichan	COWICHAN_RIVER	hatchery	1
2022	co	outmigration	Goldstream	Goldstream_R	hatchery	3
2023	ck	return	Cowichan	COWICHAN_RIVER	river	1
2023	co	outmigration	Goldstream	Goldstream_R	hatchery	3934
2023	co	outmigration	Millstream	Goldstream_R_TRANSPLANT	hatchery	1
2023	co	return	Goldstream	Goldstream_R	hatchery	216

Goldstream River Coho Adult Returns

The figures in the below section summarize the age class and stock composition of returned PIT tagged fish to the Goldstream River. These data only represent the data from the Bottlenecks to Marine Survival Program and do not represent the entire stock composition of adult Coho returns.

Figure 18. Age class (right) and stock composition (left) of returning adult Coho to the Goldstream River For Return Year 2022

Figure 19. Age class (right) and stock composition (left) of returning adult Coho to the Goldstream River For Return Year 2023

Straying in the Goldstream River

Due to the large number of PIT tags being deployed in multiple systems and salmon stocks along the East Coast of Vancouver Island is the ability to detect straying of other stocks into systems where PIT arrays are located. Throughout the inaugural four years of the Bottlenecks Study a number of systems have shown to have other stocks entering and staying in non-natal rivers (Table 4)

Table 4. Non-Goldstream Species Detected at the Goldstream River Mainstem Array.

outmigration_year	year_detected	species	stock	system	period	tally
2021	2022	ck	COWICHAN_RIVER	Cowichan	hatchery	1
2022	2022	ck	COWICHAN_RIVER	Cowichan	hatchery	2
2022	2023	ck	COWICHAN_RIVER	Cowichan	river	1
2023	2023	co	Goldstream_R_TRANSPLANT	Millstream	hatchery	1

Goldstream River Coho Adult Return Timing

Developing clear return timing graphs, is important in understanding the influences of climate change and how long summer droughts may impacts the in-river timing of fish. Return timing graphs for Goldstream River Coho are presented in Figures

Figure 5. Goldstream River Coho Spawn Migration Detections and Escapement Curves.