Assessment of the Introduced Lionfish in Everglades and Dry Tortugas National Parks

Transcription

1 Assessment of the Introduced Lionfish in Everglades and Dry Tortugas National Parks Tracy A. Ziegler, Ph.D. Fisheries Biologist National Park Service

2 Problem Sightings of lionfish at Dry Tortugas (DRTO) & Everglades National Parks (EVER) increasing since 2009 Variety of threats to invaded ecosystem o Negative impact on native species through competition, predation, niche takeover o Few predators eat lionfish o Likely to establish w/in stressed areas within Florida Bay o Venomous spines could harm visitors

3 Limited Monitoring and Removal Efforts at EVER & DRTO Respond to sightings in visitor use areas Remove all lionfish reported or observed doing other natural resource work Biscayne National Park lionfish interns visited DRTO for 10 days in dives completed; 118 lionfish removed Still, no full time lionfish management efforts at DRTO or EVER

4 Special Circumstances for DRTO RNA (research natural area) Lionfish could dramatically affect the performance measures of the RNA e.g., snapper and grouper size and abundance may be influenced by lionfish

5 Reef Visual Census June lionfish reported

6 Florida Current

7 Project Goals Minimize ecological impacts of lionfish to the marine resources within the parks by removing lionfish Improve visitor experience and reduce threats to visitor safety

8 Methods Conducted timed surveys (total search time) via SCUBA or snorkel Search time began upon decent or when searcher could see the bottom/habitat Slow, steady lionfish-focused search of all habitat during the dive or snorkel All lionfish observed were removed or documented in not captured, with size estimates

9 Results DRTO: 141 timed surveys totaling 1493 min total search time (24.8 hours!) were conducted 78 lionfish TOTAL were removed 117 observed and not captured EVER: 31 timed surveys totaling 1019 min (16.9 hours underwater) 12 lionfish removed NONE were left behind

10 Habitat Type Distribution DRTO - Lionfish were found: High Relief Coral Reef 52% Low Relief Coral Reef 44% Other 4% EVER - Lionfish were found: Hard Bottom 56% Seagrass 28% Sandy/Mud Bottom w/ Ledge 8% Artificial Structure 8% Low Relief Coral

11 Dry Tortugas National Park Total number of fish captured = 78 Surveys conducted at 47 sites

12 Dry Tortugas National Park Total number of fish observed but NOT captured = 117

13 Everglades, Florida Bay Area Total number of fish captured = 12 Surveys conducted at 31 sites

14 DRTO: Hot Spots Identified Large groups of lionfish were found on high relief coral sites such as Texas Rock (pinnacle formation) and areas of White Shoal with high relief coral

15 EVER: Hot Spots Identified 7 of the 12 lionfish found in Florida Bay were removed from Arsenicker Bank and the southwestern portion of Florida Bay

16 Conclusions: Dry Tortugas Relatively small number of lionfish removed suggest that the presence of large predators (e.g., goliath grouper, groupers, snappers, sharks, etc.) may be influencing the number of lionfish Possible predation? o TWO reports from fisherman that caught groupers at DRTO found lionfish in their guts

17 Conclusions: Everglades Many more lionfish were collected in Florida Bay than were expected Lionfish were found in NON-TRADITIONAL HABITATS (seagrass beds, hard bottom, etc.) Lionfish were found in areas with high salinity (between ppt) and at shallow depths (anywhere from 2 4 ft)

18 Science Need Hypotheses to test in the near future: Presence of larger, more abundant predators at DRTO are keeping lionfish population numbers low. Lionfish will recruit to stressed areas (e.g., high salinity, poor habitat) within Florida Bay in EVER

19 THANK YOU!! South Florida National Parks Trust Grant Funding for interns Vanessa McDonough, Ph.D., Fisheries Biologist ALL our fabulous interns! Including Kara Wall, Amanda Lawrence, Ryan Lind, Lee Qi, Marc Fruitema David Fowler, District Ranger from Everglades Kayla Nimmo, Jason Osborne, Zach Fratto Numerous Volunteers!

20 Any Questions? Catch and eat lionfish!!!