Introduction
This project is part of an initiative undertaken since 2010 by the ministère de la Faune et des Parcs (MFFP) and its many partners to update knowledge about Québec Muskellunge and optimize its management. To measure the current state of the Muskellunge sport fishery in the St. Lawrence River and the des Deux-Montagnes Lake, a survey of the catches was conducted from 2010 to 2013, with the collaboration of three professional fishing guides. In the section of the river located between Montréal and Sorel and in Lake Saint-Pierre, the lower abundance of young specimens harvested by sport fishermen suggested lower recruitment of young Muskellunge in these two bodies of water, compared to Lakes Saint-Louis and des Deux-Montagnes (see Carrier et al. in the present issue for more details).
Some anthropogenic activities have a negative impact on the St. Lawrence ecosystem. They have recently resulted in a deterioration of aquatic habitats, particularly in Lake Saint-Pierre. Nearly 5 000 ha of fish breeding, nursery, and growth habitats in the floodplain has been altered due to the intensification of agricultural practices over the last three decades (de la Chenelière et al. 2014). The loss of large areas of submerged aquatic vegetation beds since the mid-2000s (Figure 1; Magnan et al. 2017) and the proliferation of benthic cyanobacteria (Hudon et al. 2012), which develop on the bottom of Lake Saint-Pierre, have also been documented. These wetlands represent growth habitats and refuges for several fish species. This situation raises fundamental questions about the potential effects of habitat loss on a large predator species such as Muskellunge. In addition, critical breeding and growth habitats of juvenile Muskellunge have never been identified in Lake Saint-Pierre, which limits our ability to properly protect and restore habitats of this species. A study was therefore initiated to monitor adult Muskellunge movements during the spawning and growth seasons, to determine habitat characteristics selected by fish and to locate breeding and rearing areas of juveniles.
Methodology
The identification of movement patterns and the precise location of Muskellunge has been made possible through the use of advanced telemetry technologies.
Two types of transmitters have been inserted into the fish abdomen: an acoustic transmitter, which is detected by stationary receivers at strategic locations in the St. Lawrence River and its tributaries (Figure 2) and a radio transmitter including an external antenna visible on the ventral portion of the fish, allowing precise location of the specimens using a mobile receiver, operated from a plain or a boat (Figure 3). In spring 2017 and spring 2018, a total of about 80 fixed receivers were deposited annually near the waterbed between Montréal and the Gentilly sector (Figure 4). These receivers, recovered at the end of each autumn, continuously record the passage of tagged fish. The number of the individual, the date and time of passage are then extracted and used for migration analysis purposes.
This information provides information on habitat use and residence time of Muskellunge in various sections of the St. Lawrence River and its tributaries. They also help defining the periods and patterns of seasonal migration of the species. In addition, accurate, real-time fish telemetry locations provide information on the location and characteristics of adult staging sites during spring breeding and during summer and fall growth seasons.
Preliminary results
A total of 21 Muskellunge were caught by sport fishing thanks to the valuable collaboration of two professional anglers, Mr. Mike Lazarus and Mr. Marc Thorpe, and to the MFFP wildlife technicians. The fish were surgically fitted with transmitters during the fall of 2016 and fall of 2017. Females and males ranged from 38 to 52 inches in size (Figure 5). The implementation of the transmitters carried out by the wildlife technicians of the MFFP went very well. All Muskellunge were located on at least one occasion, approximately 6 to 18 months after being tagged, indicating that all individuals survived after surgery.
Ten individuals tagged in the fall of 2016 were followed by boat and plain between April 25 and May 24, 2017. During this period, which includes migration to breeding sites and spawning activities, 112 locations of individual Muskellunge were noted. The habitat selected by each individual was also characterized (vegetation, substrate, temperature, current velocity, oxygen concentration, depth, etc.). The locations recorded in the spring of 2017 showed that all Muskellunge tagged at Lake Saint-Pierre during the previous fall used the Lake Saint-Pierre area to reproduce. The data revealed that 38 % of radio tagged individuals used Lake Saint-Pierre tributaries during the breeding season (April-May). Specimens were located in the du Loup, Saint-François and Nicolet Rivers, as well as in the Chenal Tardif (a section of the Saint-François River). After breeding, these individuals migrated to feeding habitats in the St. Lawrence River. The rest of the individuals used Lake St. Pierre wetlands during the spawning season. In the spring, Muskellunge were found at depths ranging from 0.6 to 8.2 m (mean : 3.1 m), in low current velocity, mostly lower than 0.1 m/s. In the majority of cases, Muskellunge were found in habitats showing submerged vegetation of moderate to high abundance.
The analysis of movements recorded in 2017, based on data collected by dozens of fixed receivers, showed that after the breeding season, the majority of fish tagged in the fall of 2016 in Lake Saint-Pierre spent some time in this area during the summer and fall of 2017. However, during summer, 60% of the individuals made large-scale migrations towards the stretch of the river located between Montréal and Sorel. Some Muskellunge even reached the stations located near the Jacques Cartier Bridge in Montréal.
In order to track the movements of the 21 tagged individuals, the telemetry monitoring work will continue in 2018 and 2019. All the results collected during this project will enable to identify and map the preferential habitats for Muskellunge, particularly for reproduction, which could be protected or restored as needed. The preliminary results of 2017 already underline the role of the shallow marshes of Lake Saint-Pierre and some of its tributaries for the reproduction of the species. It will be important to validate these observations over the next few years, to estimate the contribution of these various sectors to the recruitment of the species and to evaluate the state of health of habitats. In addition, the long-distance migrations reported in 2017 emphasize that the management of Muskellunge and its habitats must be done at the scale of the entire studied fluvial section, including the downstream portion of the tributaries. This finding is supported by the results of the genetic structure of populations, which demonstrated the homogeneity of the genetic signature of the Muskellunge population in the St. Lawrence stretch located between Lake Saint-Louis and Lake Saint-Pierre (see Rougemont et al. in the present issue for details on population genetics).
Warning to anglers
If you catch a marked Muskellunge, you must release it after noting the fish and telephone number written on the tag that is inserted at the base of the dorsal fin (it is often necessary to scrape the surface of the label to clearly see the numbers therein). Be careful, it is important to avoid taking the specimen out of the water and to limit the handling time. Moreover, these tips apply to all Muskellunge catches, whether tagged or not. Then contact a MFFP biologist at the number written on the tag to provide the date, location of capture, and, if possible, pictures of the ventral portion of the fish.
Acknowledgements
We would like to thank all the partners who participated in the financing and the realization of the telemetry work. Special thanks to professional fishermen Mike Lazarus and Marc Thorpe for their support throughout the development of the study and for their participation in the capture of the specimens. Thanks also to Florent Archambault, Nicolas Auclair, Rémi Bacon, Virginie Boivin, Chantal Côté, Charles-Étienne Gagnon, Guillaume Lemieux, Yves Paradis, and René Perreault for their support and for all efforts in the field. The project is made possible by the collaboration and financial support of the ministère des Forêts, de la Faune et des Parcs, of the Comité ZIP du lac Saint-Pierre, of Muskies Canada, of the Fondation de la faune du Québec, of Thomas marine, of the Fondation héritage faune (Fédération québécoise des chasseurs et des pêcheurs) and of some private donors.
References
De la Chenelière, V., P. Brodeur et M. Mingelbier (2014). Restauration des habitats du lac Saint-Pierre : un prérequis au rétablissement de la perchaude. Le Naturaliste canadien. 138 (2) : 50-61.
Hudon, C., A. Cattaneo, A.-M. Tourville Poirier, P. Brodeur, P. Dumont, Y. Mailhot, Y.-P. Amyot, S.-P. Despatie and Y. De Lafontaine (2012). Oligotrophication from wetland epuration alters the riverine trophic network and carrying capacity for fish. Aquatic Sciences. 74 : 495-511.
Magnan, P., P. Brodeur, É. Paquin, N. Vachon, Y. Paradis, P. Dumont et Y. Mailhot (2017). État du stock de perchaudes du lac Saint-Pierre en 2016. Comité scientifique sur la gestion de la perchaude du lac Saint-Pierre. Chaire de recherche du Canada en écologie des eaux douces, Université du Québec à Trois-Rivières et ministère des Forêts, de la Faune et des Parcs. vii + 34 pages + annexes.