Assessing movement patterns of the highly invasive Western Mosquitofish (Gambusia affinis)
Abstract
The Western Mosquitofish is among the top 100 invaders in the world, yet continues to be introduced globally for mosquito control. This study investigates the movement patterns of the Western Mosquitofish and develops movement predictions for their continued invasion. Our results reveal that small-scale and short-term movements by invasive Western Mosquitofish are predictable using existing statistical models. However, movement over larger scales and longer timelines was consistently underpredicted by existing models, suggesting our current understanding of invasion capacity by Western Mosquitofish is limited. We used sensitivity and optimization methods to identify parameter adjustments that make existing statistical models relevant for broader-scale invasions, and we illustrate the improved inference gained from this approach by modelling the future spread of a recently invaded region. Our results provide quantitative estimates of Western Mosquitofish invasion across a range of contexts and can direct conservation and management actions aimed at improving invasion monitoring, predicting risk of secondary spread, and understanding invasion dynamics at multiple spatiotemporal scales. Data includes GPS data and movement of fish through manmade systems, first-order streams, and larger-order rivers. Data utilizes the fish move model to predict and analyze the mosquitofish movement.
Notes on missing data
Cells containing “n/a” or left blank indicate unavailable values. The overall dataset structure, column names, and sheet formats were preserved exactly to maintain compatibility with the analysis code provided (Ch3.R).
Files included in this dataset
- CH3.xlsx — Primary data file containing mark–recapture data collected across four movement studies in College Station, Texas.
- Ch3.R — R code containing all analyses and functions used in the paper.
Sheet names and variables
- wc1 — Mark–recapture data for fish in White Creek (spring season).
- h1 — Mark–recapture data for fish in Hensel Creek (spring season).
- h2 — Mark–recapture data for fish in Hensel Creek (summer season).
- w2 — Mark–recapture data for fish in White Creek (summer season).
- allnew — Combined dataset for all mark–recapture events across sites and seasons.
- exp_obs — Expected and observed distances moved for recaptured fish.
- meso — Fish movement data from Cote et al. (2010).
- meso_obs — Expected and observed distances moved (m) (Cote et al. 2010).
- nebraska — Movement data from Lynch (1988).
- Perkin_idea_revisions — Augmented movement data used to generate improved model predictions for large river systems.
Variables included in this dataset
- stream: stream where fish were collected
- code: unique ID for each recaptured fish denoting stream, season, recapture event, recapture seine haul, and number of fish recaptured in each seine haul
- date: date recaptured
- color: colour and body location of Visible Implant Elastomer (VIE) tag on each recaptured fish
- lat: GPS latitude coordinates
- long: GPS longitude coordinates
- M/R: M denotes the row is the GPS coordinates for where a specific colour of the VIE fish was marked; R denotes the row is the GPS coordinates for a specific recapture event of a fish
- sex: sex of the recaptured fish
- time(d): number of days between tagging a fish and when it was recaptured
- time_d: number of days between tagging a fish and when it was recaptured
- dir_moved: direction recaptured fish had moved (upstream or downstream)
- dis_moved: distance a recaptured fish had moved (m)
- TL: total length of recaptured fish (cm)
- SL: standard length of recaptured fish (cm)
- BH: body height (cm)
- BA: body area (no units, as measurement is relative to body size)
- HD: head depth (cm)
- CPL: caudal peduncle length (cm)
- CPD: caudal peduncle depth (cm)
- CFH: caudal fin height (cm)
- CFA: caudal fin area (no units, as measurement is relative to body size)
- RBH: relative body height (no units, as measurement is relative to body size)
- RCFA: relative caudal fin area (no units, as measurement is relative to body size)
- ARC: caudal fin aspect ratio (no units, as measurement is relative to body size)
- BLS: body lateral shape (no units, as measurement is relative to body size)
- CPT: caudal peduncle throttling (no units, as measurement is relative to body size)
- RPL: relative peduncle length (no units, as measurement is relative to body size)
- dis_day: rate of movement (m/d)
- season: season the fish was recaptured during
- component: whether the subset of fish is part of the mobile or stationary component of the population
- mean: average distance moved (m) by the mobile or stationary component of a population
- lower: lower bound of distance moved by mobile or stationary component (95% CI)
- upper: upper bound of distance moved by mobile or stationary component (95% CI)
- exp_or_obs: whether the given distance was from the observed mark–recapture study or expected movement predicted using the movement model
- up_or_down: whether fish movement was in the upstream or downstream direction
- order: river order (stream order from 1-9)
- time_y: time (years)
- direction: direction recaptured fish had moved (upstream or downstream)
- distance_m: distance moved (m)
- augment: augmented prediction of fish movement (m) to account for increased movement in large-order rivers
- obs_mean: mean distance moved (m) from observed data
- obs_lower: low boundary of distance moved (m) from observed data
- Obs_upper: upper boundary of distance moved (m) from observed data
- exp_mean: mean distance moved (m) from expected data
- exp_lower: low boundary of distance moved (m) from expected data
- exp_upper: upper boundary of distance moved (m) from expected data
- model_from_RW: output of movement distance (m) from Randinger and Wolter Fishmove Model
- back_transformed: distance moved (m) once accounted for steam size and time
- site: specific stream that fish were collected from
- time: time (d) between release and recapture of fish in the mesocosm study
- river: specific river fish were tracked in in Nebraska case study
- SO: stream order of various collection sites (stream order from 1-9)
- number: arbitrary number given to each of the data points for graphing