Gros Morne National Park of Canada

Monitoring Juvenile Salmonid Surveys in Gros Morne National Park

Background

Electrofishing plot, Trout River
© Parks Canada / Tom Knight

Juvenile salmonid surveys are commonly performed to monitor the status of fish populations. Managers need this information to make informed decisions and develop fishing regulations to protect native species. The salmonids in Gros Morne National Park of Canada include Atlantic salmon, brook trout, arctic char, and rainbow trout, a non - native invasive species.

Juvenile salmonid surveys done this year were complementary to the stock assessment and fish fence monitoring on the lower Trout River, providing additional data on fish populations in the Trout River Pond watershed.

A fourth stream, Wallace Brook, was chosen to monitor as this brook receives substantial, though unquantified, fishing pressure. The status of fish populations in the brook are unknown.

Goals

• Assess the population status (determine juvenile densities) of Atlantic salmon and brook trout in Wallace Brook and Trout River Pond watershed.

• Monitor the occurrence of rainbow trout in Gros Morne National Park of Canada.

Project Description

Electrofishing
© Parks Canada / Tom Knight

Surveys of juvenile salmonids were conducted by electro-fishing during July and August when water levels were low. Two sites were chosen on Wallace Brook, one on the Trout River Feeder, and one site each on the two streams flowing into the east end of Trout River Pond. The technique used to evaluate juvenile fish populations in rivers is called electrofishing. Barrier nets are set up to contain a section of a brook and fish are temporarily stunned using a battery operated electric charge. The fish are weighed, measured and counted, then released outside the plot. When the nets are removed they go back to their spot in the river. The density of young fish can then be calculated for the survey plot. This gives us an index to monitor changes in populations.

Brook trout parr
© Parks Canada / Tom Knight

A number of preliminary findings were made, including:

• Densities of all species of juvenile salmonids are very low in all the plots surveyed (2.1/100m² - 14.3/100m²).

• Atlantic salmon and brook trout were caught at all our sample sites.

• Juvenile rainbow trout were only found inThe Feeder brook.

• Other species caught included three spined sticklebacks and American eels.

• The work needs to continue.

Project Team (GMNPC)

• Jennifer Hoffman
• Scott Taylor
• Steve Anderson
• Tom Knight