Horse Lake Rainbow Trout Natural and Fishing Mortality Analysis 2017

2018-02-15

The suggested citation for this analytic report is:

Dalgarno, S.I.J. and Thorley, J.L. (2018) Horse Lake Natural and Fishing Mortality Analysis 2017. A Poisson Consulting Analysis Report. URL: https://www.poissonconsulting.ca/f/168266338.

Background

Horse Lake supports a recreational fishery for stocked Rainbow Trout and Kokanee and wild Lake Trout. To provide information on the natural and fishing mortality, Lake Trout were caught by angling and tagged with acoustic transmitters and/or reward tags.

Methods

Data Preparation

The outing, receiver deployment and fish capture and recapture information were provided by the Ministry of Forests, Lands and Natural Resource Operations.

The data were imported into a custom SQLite database and manipulated for plotting using R version 3.4.3 (R Core Team 2017).

Data Assumptions

Receivers were assumed to have a detection range of 500 m. Seasons were defined as: December - February (Winter); March - May (Spring); June - August (Summer); September - November (Autumn).

Results

Tables

Captures

Table 1. Number of fish captured by year, species and size class. Any fish > 500mm is classified as ‘large’.

Year Species Large Small Total
2017 Kokanee 0 23 23
2017 Lake Trout 7 154 161
2017 Rainbow Trout 0 3 3
Total 7 180 187

Recaptures

Table 2. Recapture rate (total tagged fish/recaptured fish).

Fish Captured and Tagged Fish Recaptured Recapture Rate
150 2 0.01

Table 3. Recaptures to date.

Date Capture Species Fork Length (mm) Date Recapture External Tag Number 1 External Tag Number 2 Harvested
2017-05-20 Lake Trout 405 mm 2017-09-08 86 337 Yes
2017-06-06 Lake Trout 445 mm 2017-07-07 278 544 Yes

Figures

Captures

figures/capture/CaptureHistogram.png
Figure 1. Captures by fork length, year, species and tag type.
figures/capture/CaptureMap.png
Figure 2. Capture location by species and tagging.
figures/capture/CaptureRate.png
Figure 3. Capture rate by species and date.

Receiver Coverage

figures/receiver/ReceiverMap.png
Figure 4. Location of deployed receivers and coverage (500m radius). Although receivers move slightly over time and after being redeployed, the centroid of all known locations for each receiver is shown.

Detections

figures/detection/detection-overview.png
Figure 5. Date of detections by species for each acoustically tagged fish. Grey segments indicate estimated tag life from capture date. No acoustically tagged fish were recaptured.
figures/detection/DetectionMap.png
Figure 6. Percent of Lake Trout detections by receiver and season.

Mobile Survey

figures/mobile/DetectionSummary.png
Figure 7. Number of Lake Trout detected at each survey location. Colour indicates date surveyed. Each location was surveyed for approximately 12 minutes.
figures/mobile/FishSummary.png
Figure 8. Location and date of detection by transmitter number. Each transmitter represents an individual acoustically tagged Lake Trout.

Recommendations

  • Data management
    • Record X/Y coordinates for all captures.
    • Record boat for all outings and fish.
    • Record start and end time for all outings.
    • Record ‘activity’ for all outings (Capture or Deployment).
    • Record ‘capture method’ for all captures (Rod or Net).
    • Use consistent factor levels (e.g. boat names, capture method).
    • Use https://poissonconsulting.shinyapps.io/horse-exploit-upload/ to upload future detection, capture, outing and recapture data.
  • Mobile survey
    • Mobile surveys should be conducted every three months and each should be finished within a week.

Acknowledgements

The organisations and individuals whose contributions have made this analysis report possible include:

  • Ministry of Forests, Lands and Natural Resource Operations
    • Russell Bobrowski
    • Scott Horley

References

R Core Team. 2017. “R: A Language and Environment for Statistical Computing.” Vienna, Austria: R Foundation for Statistical Computing. https://www.R-project.org/.

Horse Lake Rainbow Trout Mortality Exploitation