National Park Service

South Florida/Caribbean I&M Network (SFCN)

Invasive/Exotic Animals Monitoring

Lionfish
Lionfish (Pterois volitans/miles).

Brochures

Protocol

The SFCN Invasive/Exotic Fish in Canals protocol is currently under development.

Importance/Issues

Invasive fauna are a serious threat to maintaining ecosystem integrity, with at least 61 exotic species found within SFCN parks and many more throughout south Florida. Some of the most problematic species include pythons, hogs, rats, mice, mongoose, Mayan cichlid, Cuban treefrogs, free-roaming and feral livestock, Mexican weevil, lac lobate scale, and fire ants (for complete list see Appendix N). These species displace and prey upon native fauna and can alter food webs. Tracking the distribution and level of control of known invasive species is important to assessing the health of the ecosystem for supporting native species. Detecting new species with the potential to become invasive while they are still in small controllable populations and/or outside park boundaries is important to cost-effective management. Island food-webs are particularly susceptible to invasive species, but also offer opportunities for successful control as has been demonstrated by BUIS and VIIS exotic control programs. Executive Order 13112 deals with the introduction, spread, control, and monitoring of invasive species on federal lands.

Monitoring

  • What exotic animal species are present in the parks and which ones are considered invasive or otherwise problematic?
  • What is the distribution of the species?
  • Where have new invasive/exotic species been detected in or near the parks?

Status and Trends

Non-Native Fish in Canals

Figure 1. (Left) SFCN Data Manager Brian Witcher holds a 47 cm Largemouth Bass (<em>Micropterus salmoides</em>) caught in the L31W-South canal during night electrofishing. (Right) SFCN biological technician Robert Muxo holds a 35.5 cm Butterfly Peacock Bass (<em>Cichla ocellaris</em>) caught in the L31W-North canal during night electrofishing.  Overall difference was statistically significant, with night sampling yielding more fish (p = 0.024)
Figure 1. (Left) SFCN Data Manager Brian Witcher holds a 47 cm Largemouth Bass (Micropterus salmoides) caught in the L31W-South canal during night electrofishing. (Right) SFCN biological technician Robert Muxo holds a 35.5 cm Butterfly Peacock Bass (Cichla ocellaris) caught in the L31W-North canal during night electrofishing.

The SFCN monitors the canals adjacent to Everglades National Park (EVER) for the purpose of detecting the new exotic species of fish. Introductions of exotic fish can lead to adverse effects on the aquatic food web by altering community structure over time. The SFCN conducts sampling in the canals by way of electrofishing, an efficient technique for assessing fish populations. A protocol for the annual sampling of the canals bordering EVER is being developed, based on pilot work conducted by the SFCN and baseline data provided by Florida International University (FIU). The protocol will address specific electrofishing methods for detecting new and rare species in the canals. Early detection and reporting of a new exotic fish species, that can potentially harm the aquatic ecosystems in our parks, would allow resource managers to respond quickly and efficiently to the threat.

Figure 2. Bar graphs illustrating electrofishing depletion studies conducted for both the L31W-South canal (A) and the L31W-North canal (B). The bars represent the total number of fish collected for each subsequent pass. An initial nine passes were completed at each station to attempt depletion. Four subsequent passes were completed at each station, approximately two weeks later, to assess fish community structure following depletion. Electrofishing was conducted both at daytime and at nighttime. A yellow star above a pass indicates that a new species was collected during that pass.
Figure 2. Bar graphs illustrating electrofishing depletion studies conducted for both the L31W-South canal (A) and the L31W-North canal (B). The bars represent the total number of fish collected for each subsequent pass. An initial nine passes were completed at each station to attempt depletion. Four subsequent passes were completed at each station, approximately two weeks later, to assess fish community structure following depletion. Electrofishing was conducted both at daytime and at nighttime. A yellow star above a pass indicates that a new species was collected during that pass.

In 2013, SFCN conducted its second year of electrofishing in the canals along the periphery of Everglades National Park (EVER). Last year's initial pilot study determined that nighttime electrofishing yields higher fish abundance and higher species richness. However, total species richness for any one canal bordering EVER still needed to be determined. This information is important since the goal of the vital sign is to detect the new species of exotic fish as early as possible. Standard electrofishing techniques use a single-pass approach at a location to characterize the fish community present. This year's continuing pilot study set out to investigate alternative electrofishing methods that would indicate if total species richness can be determined for a particular canal. There were two primary objectives for this year's sampling. The first objective was to conduct multi-pass electrofishing at a fixed location (multiple passes at the same location) to see if new species would continue to appear after the first pass and to determine whether depletion was feasible. The second objective was to conduct sequential passes within a continuously similar habitat (see insert in Figure 3, B) to determine how species composition varied along a spatial transect. This method required that passes not overlap and not have a lapse between them.

Efforts were focused on the north and south sections of the L31W canal, from here on referred to as the L31W-North and the L31W-South. A water control structure separating those sections restricts the passage of fish. The fish community in the L31W-South is composed mostly of native species. The fish community in the L31W-North is composed mostly of exotic species, which at times exceed 80% of the catch therein (Figure 2, B). Electrofishing was conducted during the end of the dry season, when water levels in the adjacent marsh are at their lowest. Based on electrofishing data collected by Florida International University (FIU), this is also the time when fish concentration in the canals is greatest, and the probability of encountering a new exotic species is theoretically the highest. Electrofishing was conducted at daytime and at nighttime, based on last year's results. For the multi-pass portion of the study, nine passes of electrofishing were conducted at a specific location for each of the two canal sections: station 1 in the L31W-South and station 24 in the L31W-North. All catch was removed, processed, and relocated approximately 200 meters downstream after each pass. During the daytime, catch per unit effort (CPUE) at each station was significantly reduced after two consecutive passes. At sunset, fish abundance greatly increased for both stations (Figure 2, A and B). During nighttime, new species were collected all the way into the ninth pass at both stations. Subsequent visits to station 24 indicated a decrease in exotic fish species, due to their relocation two weeks prior, and a significant shift toward a more native-dominated community composition (Analysis of Similarity, Global R = 0.442, P = 0.0015)(Figure 3, A).

Figure 3. (A) Ordination graph created by non-metric multi-dimensional scaling (NMDS), representing fish community structure in the L31W-South (station 1) and the L31W-North (station 24), based on species relative abundance for all repetitive passes. Note the dissimilarity in species relative abundance between the initial electrofishing passes conducted in station 24 on April 2 and the subsequent visits to that same station on April 16 (dashed circle). (B) NMDS graph representing species relative abundance for sequential bouts. Note insert with aerial imagery, showing location of five sequential bouts conducted along station 8 in the L31W-South canal.
Figure 3. (A) Ordination graph created by non-metric multi-dimensional scaling (NMDS), representing fish community structure in the L31W-South (station 1) and the L31W-North (station 24), based on species relative abundance for all repetitive passes. Note the dissimilarity in species relative abundance between the initial electrofishing passes conducted in station 24 on April 2 and the subsequent visits to that same station on April 16 (dashed circle). (B) NMDS graph representing species relative abundance for sequential bouts. Note insert with aerial imagery, showing location of five sequential bouts conducted along station 8 in the L31W-South canal.

For the sequential-pass portion of the study, sequential passes were conducted along several stations encompassing homogeneous habitats along the L31W-North and L31W-South canals. As with the multi-pass study, all catch was relocated approximately 200 m downstream after each pass. Sequential passes along the L31W-South were similar in species composition and relative abundance; with 60% similarity between most of the day and night catches. Sequential passes along the exotic-dominated L31W-North were not as similar in species composition and relative abundance for both day and night catches (Figure 3, B). In last year's pilot study, it was determined that day and night electrofishing yield different results; this trend was also confirmed in this year's study. This year's pilot study revealed small-scale spatial variability (which may be due to the presence of exotics) which proved to be even more marked than the differences between day and night electrofishing. Sequential passes along a homogeneous habitat were expected to yield similar results (species composition and relative abundance), and this was the case in the L31W-South, which is the native-dominated portion of the canal. This is not the case, however, in the exotic-dominated L31W-North portion of the canal (Figure 3, B). SFCN data management created a working fish database, combining the 2012 and 2013 SFCN pilot sampling data with most of the FIU electrofishing data. Dr. Jennifer Rehage from FIU provided an Excel file with three years of electrofishing data. This large dataset was carefully converted to a Microsoft Access database that was consistent with the Natural Resource Database Template. The process of adding referential integrity to the new tables provided a great opportunity to discover and correct errors that had been perpetuated by entry into an Excel worksheet. Microsoft Access data entry forms were also added to allow the entry of the first year of SFCN electrofishing data. The final geodatabase combines fish, habitat, and geospatial data in a way that should make data analysis and reporting much simpler. FIU will provide the SFCN with the remaining early- and late-dry season data once it has undergone their QA/QC process. The SFCN staff spent 427 field-hours working on this vital sign.

In 2014, the SFCN will design its Non-Native Fish Monitoring Program and begin its implementation in the canals adjacent to EVER in a coordinated effort with EVER staff. Sampling will consist of daytime/nighttime electrofishing and multiple passes at each location. Additional sampling methodology will be determined based upon data analyses from the combined SFCN and FIU sets. The final invasive/exotic fish protocol will be in draft form by the end of July 2014.

Lionfish

Lionfish (Pterois volitans/miles), the first successful invasive marine reef fish species, are quickly overtaking the Western Atlantic. These venomous fish feed on anything and have been found to especially target juvenile grunts, snapper, and grouper. Lindsay Jones was hired on as a Student Conservation Association Intern to survey for lionfish in South Florida parks and to remove any fish that were discovered. Lionfish surveys accompanied Rapid Habitat Assessments (RHA), Reef fish Visual Censes (RVC) and Coral Monitoring surveys in order to begin immediate monitoring in BISC, DRTO, VIIS/VICR and BUIS in 2009. A 40m by 10m belt transect was conducted by divers swimming with a dive light checking the reef and cryptic habitat. Zero lionfish were encountered in 2009, however, the number of lionfish sightings significantly increased at the start of the 2010 calendar year.

Reports came in rapidly from local sport divers and spear-fishers. In response, an educational pamphlet was made to provide information on the biology, negative ecological influences, and danger of lionfish to the public. Search and recovery trips were taken to sites where lionfish had been reported and we worked with local spear-fishers to analyze specimens that they had collected and try to combine collection efforts. Lindsay gave a webinar put on by the Water Resources Division of the NPS to describe our lionfish survey methodology. We also coordinated with the USDA's National Invasive Species Program to create lionfish footage for an invasive species documentary series.

The 2010 field season was shortened by weather and the oil spill response, so lionfish were only surveyed for during the standard RVC surveys, Coral Monitoring and opportunistically by staying alert for the invasive species while doing any underwater work. In 2011, 198 sites in DRTO were surveyed with 3 lionfish found there and 112 sites in BISC have been surveyed with 5 lionfish found. In addition, 1 lionfish was reported during monitoring of 5 coral monitoring index sites and 170 fish monitoring sites in and around VIIS/VICR and 2 coral monitoring sites and 122 fish monitoring sites in and around BUIS.

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Approach

SFCN will annually contact the major animal community monitoring programs and Park Resource Management personnel to develop and then update a list of exotic species within the parks and gather any new information regarding new exotic species detected and specific locations if possible (e.g., monitoring programs for fish, seagrass, amphibians, birds, coral, etc). This is intended to be a very basic list and specificity of locations may vary widely. This will be used to update the new web page being developed by the CISMA (Cooperative Invasive Species Management Area; www.evergladescisma.org) for exotic animal location reporting similar to their exotic plant page already in operation. This web page will also be queried to update the list. SFCN will immediately inform Park Resource Management and the Exotic Plant Management Specialist about new exotic species found within their parks. SFCN will also assist in getting the word out about this new web page and will maintain a link to this web page from the SFCN web site. As CISMA becomes better known, SFCN may cease contacting major monitoring groups and instead pull new species from the CISMA.

Monitoring canals annually along the eastern border of Everglades which commonly overwash into the park plus canals nearby have been identified as a priority invasion hotspot for monitoring (L31W, L31N, C111). SFCN will work in cooperation with EVER park personnel (Jeff Kline) to use electrofishing and other sampling techniques (seine nets, dip nets, etc.) in these canals to detect new problematic fish species which can then be targeted for control by a multi-agency team that is scheduled to be developed soon. Some additional sites to monitor would be the L29 and L67 extension on the northern boundary of EVER, plus some canals in BICY (Tamiami canal, L-28, L31W, Loop road). Monitoring timing is preferably early and late dry season.

If there is sufficient SFCN and BISC staff time, the effort may be expanded to BISC canals which empty into Biscayne Bay.

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Last Updated: March 27, 2017 Contact Webmaster