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COSEWIC assessment and status report on the American Eel in Canada

FEA4 - Atlantic Islands (Newfoundland)

Indices of Juvenile Abundance

Available data series from the eel components of Newfoundland are limited to electrofishing surveys conducted for salmonids on two rivers, Northeast Brook and the Highlands River. These sites have no commercial eel fisheries; therefore these data should not be influenced by any local harvesting. The methods used in both rivers are considered consistent through time (K.D. Clarke, DFO, pers. comm.). Methods employed varied but the longest data set is based on five electrofishing stations located on the main stem. Each station was isolated with barrier nets and depletion electrofishing was conducted with a minimum of 3 sweeps. American eel abundance was relatively stable within Northeast Brook from 1984 to 1990 (Figure 22). With the exception of 1986, which had low eel abundance, average catches of eels ranged from a low of 4.5 per station to a high of 8 per station. Data post-1990, with the exception of 1992, suggest lower overall abundance of eels in the electrofishing stations. Average eel catches in this period, excluding 1992, ranged from 1 to 2.8 eels per station. For the Highlands River, data are discontinuous with only two sampling years in the early 1980s but concur with the trends observed in Northeast Brook (Figure 22).

Figure 21.  Data sites within the ecological freshwater area FEA4, Atlantic Islands.

Figure 21.  Data sites within the ecological freshwater area FEA4, Atlantic Islands.

Figure 22.  Mean number of eels caught (± 95% confidence intervals) per 100 m² in two rivers of Newfoundland, estimated from electrofishing surveys (from K.D. Clarke, DFO): (A) NorthEast Brook (1984-1996); and, (B) Highlands River (1980-1981; 1993-1999).

Figure 22.  Mean number of eels caught (± 95% confidence intervals) per 100 m² in two rivers of Newfoundland, estimated from electrofishing surveys (from K.D. Clarke, DFO): (A) NorthEast Brook (1984-1996); and, (B) Highlands River (1980-1981; 1993-1999).