# Presentation: 577640

## Barrens Topminnow Monitoring 

- January 10 -14, 2006

## Personnel

- Brad Bingham – FWS
- Geoff Call – FWS
- Steve Alexander – FWS
- Paul Benton – TTU
- Jacob Westhoff - TTU

## Methods

- Dipnets
- 15” opening with 1/8”delta mesh
- Seines
- 10 x 4 x 1/8” delta mesh
- 20 x 4 x 1/8”delta mesh
- 30 x 4 x 1/8” delta mesh

## Data Collected

- Species encountered
- Relative abundance of Western Mosquitofish (*Gambusia affinis*) (MF) and Barrens Topminnows (*Fundulus julisia*) (BTM)
- Total length for all BTMs
- Number of samples taken
- General site notes

## Slide 5

| Site Name | Date | # Samples | MF Detected? | # BTMs | Evidence of BTM reproduction? |
| --- | --- | --- | --- | --- | --- |
| Smithville Pond | 1-10-2006 | 12 | No | 78 | Yes |
| Herndon | 1-10-2006 | 6 | Yes | 12 | No |
| Bridges | 1-10-2006 | 6 | No | 0 | No |
| Crooks | 1-10-2006 | 15 | Yes | 7 | No |
| Rose Creek | 1-12-2006 | 11 | Yes | 2 | No |
| Merkle | 1-12-2006 | 7 | No | 3 | Maybe |
| Faris Springs | 1-12-2006 | 11 | No | 19 | Yes |
| Hasty Springs | 1-12-2006 | 11 | No | 5 | No |
| Markum | 1-14-2006 | Dipnets | No | 77 | Yes |
| Collier | 1-14-2006 | 8 | No | 8 | Yes |

## BTM length-frequency histograms

- Smithville Pond

- Marcum Site

- Faris Springs

- N = 19
- Mean TL = 47 mm
- Range = (28-61 mm)

- N = 77
- Mean TL = 40 mm
- Range = (23-73 mm)

- N = 78
- Mean TL = 40mm
- Range = (17-64 mm)

## Length-frequency histogram of MF at Rose Creek 

- Length-frequency histogram of MF at Rose Creek

- N = 177
- Mean TL = 27 mm
- Range = (13-49 mm)

## Summary

- Population estimates
- Sampling issues
- 10 sites sampled
- BTMs found at 9 sites
- MF found at 3 sites
- BTM reproduction at 4
-    (maybe 5) sites
- No BTM reproduction
-     when found with MF
- Future efforts

## Mechanisms for co-existence of the introduced western mosquitofish (Gambusia affinis) and native Barrens topminnows (Fundulus julisia) with emphasis on density and artificial habitat

**Jacob Westhoff**
**Tennessee Tech University**

## Three approaches

- Biological Control of MF
- Habitat complexity
- Controlling MF density

## Objectives

- 1. Design and validate an artificial habitat matrix/refuge that allows for recruitment of Barrens topminnow fry to adults in the presence of western mosquitofish
- 2. Determine a density ratio at which adult Barrens topminnows will choose to co-inhabit “prime” habitat with western mosquitofish when given the choice of a less desirable habitat

## Habitat Complexity

- Rakes (1989)
- Filamentous algae important to reproduction
- Johnson (2004)
- Negative relationship between BTM stocking success and vegetative cover
- Recommended stocking sites with < 80% vegetative cover
- Laha (2004)
-  BTM juveniles and fry susceptible to adult MF predation

## Natural Habitat Complexity

## Artificial Habitat Matrix (AHM)

## Fenced Refuge

## Artificial Habitat Matrix/Refuge

_**Pros**_
- One time installation
- Control size of refugia
- Exclude adult MF
- Installed at any site
- Immediate field application

_**Cons**_
- BTMs must use it
- Adequate food and growth
- Maintenance
- Interspecific competition

## Experimental Design

**Compare BTM growth, survival, and condition between treatments with refugia and treatments without refugia using several densities of MF**

## Expected Results

**BTM survival will be greater in treatments with an artificial habitat matrix**

## Field Implications

-  Identify sites where artificial habitat matrices should be used
- Adapt laboratory model of artificial habitat matrix to a field version
- Install and validate field model of artificial habitat matrix

## Controlling MF Density

- Meffe (1984)
- Natural processes allow for co-existence
- Goldsworthy (2005)
- MF densities  of 0-66 per/m2 (N= 17)
- Median = 5
- Mean=11

## Experimental Design

- Two controls
- 10 adult MF
- 10 adult BTMs
- Two treatments
- 5 adult MF and
-     5 adult BTMs
- 20 adult MF and
-     5 adult BTMs

## Expected Results

- MF and BTMs in both controls will prefer the “prime” habitat

## Expected Results

- BTMs will use the “prime” habitat less frequently in the presence of MF

## Expected Results

## Field Implications

- BTM sites harboring MF can be managed to create a desirable density of MF
- Potential stocking sites can be identified based on current MF densities (Density should be determined from multiple sampling trips)
- If MF invade the entire Barrens Plateau, managers will have a mechanism for co-existence

## Other Possible Investigations

- Use ArcGIS software to identify land-use changes in the Barrens Plateau of Tennessee that may be impacting BTMs
- Examine current field sites where co-existence occurs for mechanisms already in place (Pond Springs)

## Summary

- Habitat complexity
- Density ratio
- Other possible
-    investigations