Spring climate warming is associated with earlier spawn timing of an adfluvial trout population

Phenological shifts are being observed in salmonid fish in response to climate change. Between 1961 and 2021, daily spawner counts have taken place during the spawning season, and climate and hydrologic measurements have been measured continuously near the spawning site for Gerrard Rainbow Trout in British Columbia, Canada. Trend and multiple regression analysis was conducted to determine phenological shifts and associated climate and hydrology metrics. Over the 61-year time series, the timing of peak spawning shifted earlier by 7.7 days and the duration of the spawning period shortened by 12.3 days due to the spawning season ending earlier; the timing of the start of the spawning season did not change. The shift in peak spawn timing was associated most strongly with an increase in early spring (March-April) air temperature (2.2 °C), an increase in water temperature (1.3 °C), and less strongly with hydrology metrics. Mountainous regions are experiencing earlier and warmer springs. Adflu..., , , # Spring climate warming is associated with earlier spawn timing of an adfluvial trout population

[https://doi.org/10.5061/dryad.wwpzgmsw1](https://doi.org/10.5061/dryad.wwpzgmsw1)

## Description of the data and file structure

Observational data on Rainbow Trout spawn timing, abundance and water temperature was collected at the outlet of Trout Lake on the Lardeau River. Flow data was publicly available from the Water Survey of Canada's website. Air temperature data was publicly available on Environment Canada's website.

### Files and variables

#### File: Dataset\_used\_in\_analysis.xlsx

**Description:** Data used in regression analysis

##### Variables

* Spawn period duration (days)
* Spawner abundance estimate
* Julian date peak spawn
* Julian Date start spawn
* Julian Date end spawn
* Mar-apr mean air temperature (°C)
* Julian day freshet start (estimated from kaslo 1996-2002)
* Water temperature Apr 24-May 20 avg (°C)
* Mar-Apr mean Lardeau flow (m3/s) (estimated from kaslo 19...,