Effects of hydraulic characteristics on energy use and behaviour of adult upriver migrating sockeye (Oncorhynchus nerka) and pink (O. gorbuscha) salmon
Creators: name: Standen, Emily M.
Publisher: name: University of British Columbia
Year: 2009

description: Adult Pacific salmon (Oncorhynchus sp.) undertake upriver migrations to reach their spawning grounds. Because these fish cease feeding upon entry to freshwater they depend entirely upon energy reserves to complete their upriver spawning migration. In the past in situ salmon migration energetics and behaviour have been studied independently. Body constituency analysis has been used to assess energy use of migrating fish on a spatial-temporal scale of hundreds of kilometers (Idler and Clemens 1959; Gilhousen 1980; Leonard and McCormick 1999) and radio telemetry as well as visual observations have been used to study animal behaviour over distances of tens to thousands of metres (Ellis 1966a; Fretwell 1981). The recent advent of radio telemetry and underwater stereo videography has allowed coupling of behaviour with energy use of upriver migrating salmon in situ (Boisclair 1992; McKinley and Power 1992; Hughes and Kelly 1996; Hinch and Rand 2000). Very few studies to date have used EMG telemetry to estimate energy use of moving fish in situ and only one of these was done on salmon (sockeye salmon Hinch and Rand 1998; sturgeon McKinley and Power 1992). A limited number of studies have used underwater videography to study in situ juvenile fish movement (Boisclair 1992; Hughes and Kelly 1996) however, to date only one study has used underwater videography to analyze adult fish migration again on sockeye salmon (Hinch and Rand 2000). The objective of this thesis was to assess the affect of sex, species and river features on in situ energy use and behaviour of upriver migrating pacific salmon (Oncorhynchus nerka and O. gorbuscha). The first part of the project took place in the fall of 1999 and used EMG telemetry to describe activity levels and estimate energy use in 12 adult pink salmon during migration through a 7 km section of the Fraser Canyon which had a diversity of flow conditions. This data was then compared with similar data collected for sockeye salmon and provided the first in situ comparison of its kind. Across all reaches sockeye salmon tended to use more energy (0.93 J-m⁻¹) than pink salmon (0.26 J-m⁻¹; P=0.0986). Sockeye salmon swimming speeds were twice as variable (mean CV; 54.78) as pink salmon swimming speeds (mean CV; 22.54). In all analysis reach was a significant factor determining swimming speed, ground speed and energy use (PO.0009 for all ANOVAs). Within sex species groups all fish increased their activity levels when they migrated through constricted reaches compared with non-constricted reaches. Between sex-species groups differences in behaviour depended upon reach. The second part of the project was conducted the summer of 2000 and used underwater stereovideography to assess differences in energy use and behaviour of adult sockeye salmon as they migrated through a variety of small scale flow fields (1-5 m²) within the Seton River, British Columbia. The objective of this study was to compliment the work conducted in Part I by more accurately defining river conditions as well as the energy use and behaviour of fish migrating through these conditions. On average fish encountered velocities (44 cm-s⁻¹) which were less than the average site velocity (53 cm-s⁻¹). In addition swimming speed and ground speed were similar in low encountered velocity sites (&lt;0.13 m-s⁻¹) with a ratio of 1:1. In mid to high encountered velocity sites (0.35-1.27 m-s⁻¹) the ratio of swimming speed to ground speed stayed constant at 2:1 but both swimming speed and ground speed increased with increasing velocity. These projects suggest that although species and sex are relevant, river reach characteristics are the primary factors affecting energy use during upstream salmon migration in the Fraser River. Complex current patterns generated by river constrictions created confusing migration cues, which impeded the ability of salmon to locate appropriate pathways. When assessed with videography, at the majority of sites fish used low velocity flow fields to optimize migration. This thesis has been successful in confirming the importance of river reach characteristics in determining energy use and behaviour in upriver migrating salmon. These results suggest that river management, whose goal is to ensure successful fish passage, should focus on bank and bed characteristics that provide flow patterns and hydraulics that minimize energy use in migrating fish.