Investigating fish hydraulic habitat preferences using a passive integrated transponder antenna network: Scope on spatial scales and individual mobility
Abstract
Flow velocity is a major feature of fluvial fish habitat. It affects swimming energy expenditures, resource distribution and efficiency of prey capture, thus exerting a major influence on fish distribution. Preferences of juvenile salmonids for ranges of flow velocity are well documented. Preference curves are usually generated by comparing velocities measured at the precise location of captured fish (nose velocity) with velocities measured at random locations where fish are absent. However, these preferences tend to be specific to sites and rivers and show important variability with time. Recent biotelemetry studies have revealed that juvenile salmonids are more mobile than previously assumed and use larger home ranges and multiple micro-habitats. Therefore, fish might select habitats based on the characteristics of a microhabitat, but also based on the properties of the surrounding area. Furthermore, mobile fish could present temporal variability in their habitat preferences. Recent advances in biotelemetry provide new ways to monitor fish locations and to obtain habitat preferences both at the individual and the population levels at high temporal and spatial resolutions for extended periods. In this study, we seek to identify the most relevant spatial scales defining habitat preferences of juvenile Atlantic salmon. We emphasize both the group and individual temporal variability in hydraulic habitat preferences. During a three month period, we monitored the location and movements of 61 juveniles marked with 23-mm passive integrated transponders (PIT) using a network of 186 antennas buried into the bed of a natural river reach in Saguenay, Canada. Each antenna was scanned every 33 seconds to detect and record the presence or absence of tagged fish. The reach was 70 m long and 9 m wide on average and presented a very clear morphological sequence consisting of two pools separated by a riffle. Mean flow velocity and turbulent flow properties were measured at 3500 velocity locations across the reach with ADVs on a regular grid at 10 cm above the bed at low flow. We examined fish preferences at the microhabitat scale (nose velocity), at the feeding habitat scale (1.5 X 1.5 m), at a scale of surrounding feeding habitats (2.5 X 2.5 m) and at a scale of morphological units (pools and riffles). Over the study period, the antenna grid generated 106208 detections. Fish monitoring revealed a variability of spatial behaviors among individuals, some fish showing strong attachment to a small number of adjacent micro-habitats whereas others used a large number of micro-habitats located far apart, in both pools and riffles. Juvenile salmon exhibited preferences for medium to high velocity micro-habitats. However, fish presented hydraulic habitat preferences occurring at the scale of flow patches (≈ 6 m2). Furthermore, juvenile Atlantic salmon also showed an active habitat selection dynamics, where temporal individual preference curves for several hours were similar to that of the entire group of fish for a short time period. These observations highlight the importance of patch scale habitat features which provide valuable information for fish management.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2009
- Bibcode:
- 2009AGUFM.H51D0788R
- Keywords:
-
- 1813 HYDROLOGY / Eco-hydrology;
- 1825 HYDROLOGY / Geomorphology: fluvial;
- 1860 HYDROLOGY / Streamflow