Lake Nipissing Sturgeon Adult Population Assessment

By Todd C. Eastman
Former NOTO Research Analyst

Early in June I had the opportunity to spend a day with North Bay MNR Management Biologist Richard Rowe, and Project Biologist Shaun Roberts, netting sturgeon on the South River off of Lake Nipissing. This year marked the third year of a 6-year Sturgeon Adult Population Assessment being conducted by North Bay Ministry of Natural Resources (sturgeon spawn every 6 years so theoretically speaking a 6 year study should reflect the adult population of Lake Nipissing). The project is attempting to assess the remnant adult sturgeon population of Lake Nipissing. Historical habitat destruction, commercial exploitation, and very slow reproductive rates are considered to be key factors responsible for the decline in sturgeon numbers.

The study takes place every spring from early May to mid June when sturgeon are spawning in the rivers off Lake Nipissing. Sturgeon are known to spawn in three rivers off of the lake: the fish swim up stream until they encounter something that prevents them from swimming any further (e.g. rapids). It is at these spots where the fish spawn.

On this day we travelled by boat up the South River to Chapmans Chutes. From the base of the falls we set a 250 foot long by 8 foot high lead-weighted-large-mesh gill net. The gill net was left on the base of the river for one hour. After the hour expired the net was retrieved. Fish were identified as having been caught before by the absence or presence of a magnetic chip in their scute (hard plate) on the dorsal surface behind their head.

If the sturgeon had not been caught before it was tagged and the sex, weight, and total length were recorded. Also a sample from the dorsal fin was taken and brought back to the lab in order that the age of the fish could be determined. At the end of the day we had set two nets and captured 23 sturgeon. 7 of the sturgeon were new fish not having been captured in the first two years of the study. The largest sturgeon netted was 141 lbs, 1700 mm in length.

The MNR study is providing the essential data required to accurately assess the remnant adult sturgeon population of Lake Nipissing. Through this study, and other monitoring initiatives, MNR will be able to determine the current and future needs of this once abundant species. 

This article was taken from page 15 of NOTO's "The Outfitter" publication, September/October 2003 Issue


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