Habitat use of lake trout (Salvelinus namaycush) following species introduction

Abstract

Although introductions of prey species have the potential to significantly alter habitat use by top predatory fish, this aspect has rarely been directly quantified. Introduction of yellow perch (Perca flavescens), a littoral-pelagic prey species, to a small boreal lake previously dominated by littoral cyprinids provided a unique opportunity to examine how a change in forage base influenced habitat use by the sole top predator, lake trout (Salvelinus namaycush). We monitored lake trout pelagic and spatial distribution using acoustic telemetry before (2001) and after (2008) the introduction of perch to determine whether habitat use reflected a deeper, offshore prey community. After accounting for differences in water temperature and dissolved oxygen concentrations between years and the inclusion of a control lake, our data suggest that lake trout habitat use changed after the introduction of yellow perch. Lake trout, on average, were 1.4 m deeper (P < 0.01), reduced their use of littoral habitat by 55% (P = 0.03) and experienced a 71% decrease in home range size (P < 0.01), consistent with a greater offshore habitat overlap between predator and prey after the introduction of yellow perch. This study illustrates how introduced prey species may have a significant influence on habitat use by top predatory fish, while also showing the importance of using direct measurements to quantify behavioural changes.

Life at the top: Lake ecotype influences the foraging pattern, metabolic costs and life history of an apex fish predator

“…Each study lake contains a different prey community (Figure , Appendix S2): (a) Lake 373 has abundant (~13 per m 3 , Paterson, Podemski, Wesson, & Dupuis, ), cold‐water invertebrate prey Mysis diluviana, or Mysis hereafter; (b) Lake 626 has yellow perch Perca flavescens (introduced ca. 2005—Wall & Blanchfield, ), a forage fish of moderate size, with a preferred temperature (~18°C—Hasnain et al., ) that exceeds the preferred temperature for lake trout by an amount sufficient to ensure that it is typically found in epilimnetic and/or littoral habitats that are thermally hostile to lake trout in summer; (c) Lake Louisa has no alternate prey; consequently, lake trout diet is dominated by zooplankton and littoral minnows (Konkle & Sprules, ; Morbey et al., ); and (d) Lake Opeongo has abundant (~0.03 per m 3 —Moryk, ) cisco Coregonus artedi , a large pelagic, cold‐water planktivore which is a preferred prey for lake trout—Matuszek et al., ; Shuter et al., ), along with yellow perch. Prey resources in Lakes 626 and Louisa are similar in that larger vertebrate prey (perch, minnows) are found in epilimnetic/littoral environments that were thermally hostile to lake trout during the study period (Figure ).…”

Mercury Elimination by a Top Predator, Esox lucius

“…Fish were marked with PIT tags (Passive Integrated Transponder; Biomark, Inc.) to identify individuals upon recapture. Northern pike not previously surgically implanted with acoustic temperature-sensing transmitters (22 g in air, 62 mm × 16 mm diam, Model CTT-83-3, 3 y battery life, Sonotronics) underwent this procedure following standard methods . Pike recovered from anesthesia in a tub of fresh lake water before being released into Lake 240.…”

Energetic costs of activity in wild lake trout: a calibration study using acceleration transmitters and positional telemetry

“…interval. The movement of organisms must be modeled on a very short spatial-temporal scale for the straight-line assumption to be biologically correct (Turchin 1998). However, D r a f t the increased frequency of data collection may result in simultaneous reporting ('collisions') by multiple transmitters, leading to information loss; autocorrelation and location error may also obscure the biological significance of the results (Fieberg and Ditmer 2012).…”

“…However, D r a f t the increased frequency of data collection may result in simultaneous reporting ('collisions') by multiple transmitters, leading to information loss; autocorrelation and location error may also obscure the biological significance of the results (Fieberg and Ditmer 2012). Therefore, substantial error may stem from violation of the assumption that fish move in a linear path over relatively long time periods (~4 min) -real organisms rarely behave in such a simple fashion (Turchin 1998;Rowcliffe et al 2012). This issue is further explained below.…”