Brown Trout Spawn Timing, Redd Locations, and Stream Characteristics in Spearfish Creek within Spearfish, South Dakota, USA

Shaylee Martling,Michael E Barnes,Greg Simpson,Jeremy L Kientz,Alex J Rosburg

doi:10.4236/oje.2020.104012

Abstract

This study documented brown trout (Salmo trutta) spawning locations, redd construction timing, and associated environmental variables in an 850-m long mainstem section and a 400-m long diversion channel of Spearfish Creek within the city limits of Spearfish, South Dakota, USA in 2019. The first redds were observed on October 15, with no new redds observed after November 12. Redd construction peaked during the first week of November, when 23 redds were observed in the mainstem section and 50 in the diversion channel. Substrate size was significantly smaller, water temperatures significantly higher, and water velocities significantly greater in redd versus non-redd locations in both the mainstem reach and the diversion channel (P ˚C), but significant, increase in water temperature from the rest of the channel locations. This is the first study to document redd locations in Spearfish Creek and will provide a baseline to evaluate future spawning activity, particularly as it may be affected by likely future anthropogenic changes potentially affecting the stream environment.

Highlights

Brown trout (Salmo trutta) are an important recreational fish species and are considered to be an indicator of aquatic ecosystem health [1]
Redd construction peaked during the first week of November, when 23 redds were observed in the mainstem section and 50 in the diversion channel
Hotspots were associated with a small (0.1 ̊C), but significant, increase in water temperature from the rest of the channel locations. This is the first study to document redd locations in Spearfish Creek and will provide a baseline to evaluate future spawning activity, as it may be affected by likely future anthropogenic changes potentially affecting the stream environment

Summary

Introduction

Brown trout (Salmo trutta) are an important recreational fish species and are considered to be an indicator of aquatic ecosystem health [1]. Hills of South Dakota (USA), brown trout are not native and were introduced in 1890 [2]. They quickly became naturalized, with naturally-reproducing and self-sustaining populations in most of the 1287 km of Black Hills streams where appropriate habitat is present [3] [4] [5]. Redd location is predicated on stream characteristics, including morphology, substrates, and water velocity [12]. Brown trout prefer faster-moving water over coarse gravel in shallower stream reaches [7] [13]. The location and number of redds within a stream may be useful to assess the environmental impacts of changes in water flows or temperatures [19]

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Conclusion