Muskellunge (Esox maquinongy) declined during the first half of the 20th century in Québec portion of the St. Lawrence River. Muskellunge stocking was conducted from 1950 to 1977 in order to support the recreational fishery. This study aimed to monitor the muskellunge fishery using angler diaries. Fishing effort and success, as well as fish length and sex, were noted from 2010 to 2013 in five sectors of the St. Lawrence River. A total of 2,619 individuals were captured with an angling effort of 12,503 rod hours. Angling success varied from 0.17 to 0.30 muskellunge/rod hour, depending on sector. Based on historical data, size of angled fish increased over the past century. The proportion of catch larger than 44 inches increased from 19% in 1918-1927 to 53% in 2010-2013. However, the proportion of catch smaller than n35 inches (88.9 cm) was low in the downstream sectors of the river, suggesting recruitment failure in recent years. The status of muskellunge stocks appears healthy in the upstream sectors of the St. Lawrence River but remains fragile downstream. In the context of large scale habitat losses observed during the past decade, studies are needed to measure genetic structure of populations and to identify, restore and protect critical spawning, nursery and growth habitats. Angler diaries have proved to be an effective management tool that should be maintained or expanded in the future.