In 1983, the lower Spanish River from Espanola downstream to Spanish (where it meets Lake Huron by way of the river delta at Whales Back Channel) suffered a massive biological blow when an accidental release of sewage and other chemical compounds devastated the fish population with hundreds of thousands of fish killed. Through the efforts of many individuals, government and non-government organizations, corporations and partnerships the rehabilitation of the Lower Spanish Rivers fishery has been one of this area's greatest good news stories. Unfortunately there are still a few high profile species of fish that were flagged by international agencies as having unsustainable numbers and not in recovery.

Fish species listed as not in recovery by an International Joint Commission (IJC) were Channel Catfish, Muskellunge and Lake Sturgeon. Over several years of rehabilitation, stocking efforts, and assessment and monitoring, the MNR was able to remove the River from the AOC list and add it to the in recovery list. During this time, the MNR developed a protocol for assessing the presence of Juvenile Musky and Riverine Assessment of Lake Sturgeon with the end result being an indication that the river and all species of concern had re-established self sustaining populations and the River could be removed from the AOC list.

Great Lakes Environmental Services was retained by the Lake Huron Management Unit of the MNR to undertake an assessment of the Spanish River. Our biologist's spent a week aboard an electrofishing boat in search of the ever elusive juvenile Musky. They were hoping to locate and sample 20 specimens of juvenile Musky during the week which would have constituted a successful assessment. By weeks end, they had sampled a total of 77 different juvenile Musky, far exceeding what they were hoping to find and indicating that there is most definitely a self sustaining population of Musky in the Lower Spanish River.