Interactions of Atlantic salmon (Salmo salar) and trout (Salvelinus fontinalis and Oncorhynchus mykiss) in Vermont tributaries of the Connecticut River

Abstract

Competitive interactions among stream salmonids in resource-limited environments have been linked to reduced success for many species. Few studies have focused on interactions at scales larger than individual fish or stream reach. We chose to focus our study on these larger scales to provide information for managing species that have complex life histories transcending multiple scales. Our objective was to explore age-0 Atlantic salmon (Salmo salar) growth and survival in relation to trout abundance (introduced rainbow (Oncorhynchus mykiss) and native brook (Salvelinus fontinalis) trout) and prey resources at 24 stream reaches across two Vermont watersheds that flow into the Connecticut River. Simple linear and multilinear regressions were conducted on response and predictor variables related to fish and invertebrate prey. Age-0 Atlantic salmon survival was greatest at the site with highest trout abundance; however, no linear relationships to trout abundance were detected possibly because Atlantic salmon growth and survival were highly variable across sites. In contrast, a positive significant multivariate relationship was identified among age-0 Atlantic salmon survival, the abundance of age-1+ brook trout (i.e., 100–130 mm), and benthic prey abundance. These results suggest that stocking streams based on trout abundance may not increase Atlantic salmon growth and survival during the first summer of life.

Measurements of salmonid population performance in relation to habitat in eastern Newfoundland streams

“…No relationships between brook trout and Atlantic salmon, however, were detected (positively or negatively) suggesting that the two species do not directly limit one another’s abundance in the streams of TNNP. These findings are supported by those of Raffenberg & Parrish (2003), who found little evidence that the survival, growth and feeding of age 0 year Atlantic salmon were negatively affected by the presence of brook trout and rainbow trout in two rivers in Vermont.…”

Food consumption and growth of Atlantic salmonSalmo salarparr in sub‐Arctic rivers: empirical support for food limitation and competition

“…), furthermore, can reduce the food availability of stream‐living salmonids by cropping the benthic invertebrate community (Brocksen et al , 1968; Dahl, 1998). In addition to the diminished food consumption and somatic growth rates observed in the present study, the consequences of competition may also include reduced survival rates (Kocik & Taylor, 1995; Raffenberg & Parrish, 2003). In the River Reisa, the annual catches of S. salar in the river are low compared to related river systems (Gabler, 2000), and the presence of alpine bullheads may in several respects represent a problem for the management of the S. salar population in the watercourse.…”

“…Studies on resource competition have mainly been directed towards spatial relationships and habitat competition (Hearn & Kynard, 1986; Kennedy & Strange, 1986; Hearn, 1987; Heggenes et al , 1995; Fausch, 1998; Volpe et al , 2001). Competitive interactions for food resources have rarely been addressed, except for a few exceptions related to feeding interactions with other salmonids (Thonney & Gibson, 1989; Raffenberg & Parrish, 2003; Mookerji et al , 2004). In the sub‐Arctic River Reisa, northern Norway, a study of the resource partitioning between S. salar parr and a dense population of alpine bullheads Cottus poecilopus Heckel suggested that interspecific food competition may have a major impact on the S. salar population in the river (Gabler & Amundsen, 1999; Gabler, 2000).…”

Prey Selection of Subyearling Atlantic Salmon and Rainbow Trout Coexisting in a Natural Stream

“…Others have warned of potential effects of exotic Atlantic salmon invading native rainbow trout habitat in the Pacific Northwest (Volpe et al 2001). Surprisingly little information exists on the interactive ecology of the two species (see Gibson 1980, Hearn and Kynard 1986, Volpe et al 2001, Raffenberg and Parrish 2003, Stanfield and Jones 2003, Coghlan and Ringler 2005. Furthermore, we are not aware of any published studies that investigated partitioning of food resources between the two species in a natural setting.…”