Fish Monitoring Network - Data Information


The Fish Monitoring Network's (FMN) sampling plan was designed to cover both the lentic and lotic habitats of each of every sector on both sides of the navigation channel, (Figure 2). Two fishing rigs are used: shore seine for coastal lentic habitats and experimental gillnets for lentic and lotic habitats (depth> = 2 m). The average distance between gillnet fishing stations is about 1 km. The seine fishing stations are spread along the shore and set at a target depth of 0.5 m. The distance between these stations is about 1 km.

Figure 2. The fish monitoring network's (FMN) sampling plan was designed to cover the lentic habitats of the coastal zone (seine sampling) as well as the deeper lentic and lotic habitats (gillnet sampling) on both sides of the navigation channel.

Gillnets are made of transparent monofilament line. Each net has eight panels that measure 1.8 m in height by 7.6 m in length, with increasing dimensions of stretched mesh (25, 38, 51, 64, 76, 102, 127 and 152 mm). At each station, in order to reduce mixing and clogging, two nets separated by a 20 meter rope are set end-to-end, and installed at the bottom, parallel to the current (Figure 3). Fish abundance is expressed in catch per unit effort (CPUE; number of fish per 24 hours fished).

Figure 3. At each station, two nets end-to-end, separated by a 20 meter rope are installed at the bottom, parallel to the current.

Beach seine fishing
The dimension of a beach seine rig is 12.5 m long by 4 m high and has a mesh size (stretched) of 3.2 mm. Fish abundance is expressed in catch per unit effort (CPUE). This unit effort represents a seine rig of about 120 m².

Table 1. Efforts deployed in the fish monitoring network for various sectors of the St. Lawrence River on a yearly basis. Hydrological conditions during sampling are also presented for informational purposes.

Since 2009, a lighter version of the FMN fish monitoring network protocol has also been used in some areas. This simplified inventory, called the FMNLV, is comprised only of gillnet sampling and aims at a small number of stations (about one in three FMN stations; Figure 4). This simplified approach has been implemented in order to increase the sampling frequency in the different sectors allowing for a more frequent assessment of the stock status of having a predominant sportfishing interest (walleye, sauger, yellow perch, northern pike, smallmouth bass, yellow sturgeon, etc.). Because the sampling frequency is higher than the five-year RMN protocol, it is easier to identify abundance fluctuations and the response of sportfishing specific species in regard to newly implemented management procedures. The sampling effort of this complementary network is mainly geared toward the St. Lawrence sectors where the pressure of sportfishing is strongest; (Lake St. Peter, Lake St. Louis, Lake St. Francis). Certain sectors presenting potential fishery resources (e.g., Lake of Two Mountains) can also be sampled in order to assess the state of fish stocks.

Figure 4. Example of sampling efforts in Lake Saint-Pierre in the context of both fish monitoring networks (FMN: intensive seine and gillnet sampling / FMNLV: reduced net only protocol).