Abundance and Distribution of Arctic Grayling in the Upper Little ...

More documents

Recommendations

Info

summer of 2007 to estimate abundance of Arctic grayling in the upper Little Smoky River in order to provide resource managers with current data that will aid in the development of management plans for the Little Smoky watershed. 1.2. Study objectives Our study addressed the following objectives: i. Using sample angling, calculate catch rates of Arctic grayling (≥ 150 mm fork length; FL) and legal‐sized Arctic grayling (> 350 mm TL) at 29 locations distributed along a 235‐km section of the upper Little Smoky River; ii. At a subset of locations (n = 7), estimate angling capture efficiency of Arctic grayling using capture‐mark‐recapture (CMR) techniques; we defined efficiency as the proportion (or percentage) of fish in a given area that were captured during sampling; iii. Model abundance and spatial distribution of Arctic grayling, including legal‐sized Arctic grayling, for the entire study area in the Little Smoky River mainstem; and iv. Determine the size structure of the Arctic grayling population in the Little Smoky River study area. 2.0 STUDY AREA The Little Smoky River is located in west‐central Alberta and flows approximately 550 km from its headwaters in the East Slopes of Alberta to its confluence with the Smoky River. The upper third of the river is characterized by moderate gradient, abundant aquatic vegetation and clear but slightly stained water (Sterling and Hunt 1989). Sport fish species in the upper Little Smoky River include Arctic grayling, mountain 2
whitefish (Prosopium williamsoni), bull trout (Salvelinus confluentus) and northern pike (Esox lucius) (Sterling and Hunt 1989). The lower two‐thirds of the river is characterized by reduced gradient and turbid water, with walleye (Sander vitreus) and northern pike as the primary sport fish (Sterling and Hunt 1989). Based on Arctic grayling movement studies (Stanislawski 1997), we defined our study area as the 235 km of the Little Smoky River upstream of the road bridge crossing located 42 km downstream of the mouth of Tony Creek (Figure 1). 3.0 MATERIALS AND METHODS 3.1. Inventory data We collected Arctic grayling abundance data by sample angling (Gresswell el al. 1997) at 27 of 29 sampling sites along the 235‐km study area (Figure 1). We excluded sites 27 and 28 from the study as we captured no Arctic grayling at sites immediately upstream and downstream of these locations (i.e., sites 26 and 29). Initially, we planned to use electrofishing as our primary method of fish capture. However, based on very low observed electrofishing capture efficiencies and poor site access, we chose angling methods over electrofishing to maximize capture efficiency and the number of inventory sites that could be sampled in the study area. We sampled sites in random order when river conditions permitted. We georeferenced the start and end of each site in the field using a hand‐held Global Positioning System (NAD 83, Zone 11U). We calculated site length with hydrographic layers and the site start and end waypoints in a geographic information system (GIS). Site length ranged from 1,340 to 2,550 m (average 2,123 m) and was dictated by the amount of stream that angling crews could survey during the course of one day. Crews of two or three angled in an upstream direction using fly fishing and spinning gear to capture fish. Fishing effort was evenly distributed across all available habitats. We collected data on stream wetted‐ and rooted‐widths (m), measured with a rangefinder at a right angle to river flow every 500 m along a site. We also recorded angling hours (0.25 h accuracy) and FL (mm) of all fish captured. Site location, length, and rooted‐width and wetted‐width data are provided in Appendix 1. We measured fish TL for a subsample of captured Arctic grayling. We developed a linear regression relationship between FL and TL that was used to estimate TL where only FL data were collected (Appendix 2). 3
Page 1 and 2: Abundance and Distribution of Arcti
Page 3 and 4: Abundance and Distribution of Arcti
Page 5 and 6: EXECUTIVE SUMMARY During summer 200
Page 7 and 8: TABLE OF CONTENTS EXECUTIVE SUMMARY
Page 9 and 10: LIST OF TABLES Table 1. Table 2. Ar
Page 11: 1.0 INTRODUCTION 1.1. Background Th
Page 15 and 16: 3.2. Population modeling We used th
Page 17 and 18: Smoky River at the Town of Little S
Page 19 and 20: efficiency of large fish was 2.4 ti
Page 21 and 22: Fish abundance per 2 km 800 700 600
Page 23 and 24: 4.4. Summary Legal‐sized fish in
Page 25 and 26: Department of Biological Sciences,
Page 27 and 28: 6.0 APPENDICES Appendix 1. Date, lo
Page 29 and 30: Appendix 2. Fork length‐total len
Page 31 and 32: Appendix 4. Historical and 2007 wat
Page 33 and 34: CONSERVATION REPORT SERIES

Abundance and Distribution of Arctic Grayling in the Upper Little ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?