Goliath Grouper preference for artificial reefs: Relief and volume are predictors of abundance Angela B. Collins, Ph.D. abcollins@ufl.edu Florida Sea Grant, UF IFAS Extension Florida Fish and Wildlife Conservation Commission
Study species: Goliath grouper E. itajara
Geographic range South Atlantic, GoMex Historical center of abundance: SW Florida
Life history characteristics Large, long-lived (2.5 m; 37+ y) Late maturity (4-6 y; >1 m TL) Protogynous* Sedentary Predictable aggregations at high relief habitat Accessible to people
Current Status of the Stock Increasing juvenile abundance in nursery habitats (Koenig et al. 2007; Cass-Calay and Schmidt 2009) Adult numbers are increasing offshore (Porch et al. 2004, 2006; Koenig et al., 2011; Anecdotal diver and angler reports) Stock assessments continue to fail due to a lack of information (SEDAR6, 2004; SEDAR23, 2011, FWC 2016) Estimates regarding population recovery are dependent upon directed research efforts
Study area: Nov 2007 present Visual surveys: 441 Depth range: 7 48 m
Methods Visual Survey Year-round video surveys Presence, abundance Size distribution Seasonal patterns Habitat characterization Artificial vs. Natural Relief Volume (artificial habitats only)
Measuring fish 20 cm 120 cm TL
Conventional and Acoustic Tagging External ID tags allow reports of resightings (divers) &/or recaptures (anglers) Acoustic tags provide detailed info Site fidelity, movement, survival after C&R
Results
Presence by habitat, depth, season Proportion of surveys present 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 Artificial Deep (>20 m) Artificial Shallow(<20m) Natural Deep Natural Shallow 20 1 13 Winter Spring Summer Fall Goliath grouper presence: Habitat: p < 0.0001** Depth: p = 0.23 Season: p = 0.02* (PROC GLIMMIX, Presence modeled as a binomial distribution) 33 4 23 10 10
Collins et al., 2015 Proportion of surveys present 1.0 0.8 0.6 0.4 0.2 Presence by habitat relief Artificial Natural B C A B low relief high relief < 1.5 m > 1.5 m
Abundance: Artificial reefs 30 25 Overall mean = 4.5 Goliath observed (n) 20 15 10 5 0 Oct Feb Jun Oct Feb Jun Oct Feb Jun
Abundance: Natural reefs 30 25 Overall mean = 0.4 Goliath observed (n) 20 15 10 5 0 Oct Feb Jun Oct Feb Jun Oct Feb Jun
Collins et al., 2015 Number observed 25 20 15 10 5 0 Abundance by vertical relief A Artificial reefs B Natural reefs High Low High Low > 1.5 m < 1.5 m > 1.5 m < 1.5 m B C
Abundance by site volume 25 Shallow < 20 m Deep > 20 m *Artificial only Number observed 20 15 10 5 D D C B A 0 na Low Medium High 1000 m 3 1000 10,000 m 3 10,000 m3
Overall size distribution of Goliath grouper Frequency 160 140 120 100 80 60 40 20 0 ~ 5 15 years 20-40 40-60 60-80 80-100 100-120 120-140 140-160 160-180 180-200 200-220 Total length (cm) shallow deep This study: TL range: 35 213 cm Median = 121 cm TL (age ~ 7 y) Bullock et al. (1992): TL range: 8 216 cm Median = 168 cm TL (age = 13 y) 67 cm @ Mexican Pride, 80 km from shore and 39 m deep
Gulf of Mexico 12 shipwrecks The acoustic array
Acoustic array Continuous monitoring of sites (10 40 m) 2 4 Vemco receivers anchored 50 100 m from center of each site (Detection tests = >98% detection success)
Methods Recreational fishing (rod & reel or handline) to 40 m Measure, photos, DNA, vent Pressure sensitive acoustic tags Pinger ( rate: every 1 3 minutes; with pressure sensor, battery life ~ 2 years) ID Tag (ongoing visual surveys, recap hotline for anglers)
Results 39 Goliath grouper were acoustically tagged in array Size range 105 206 cm TL Handling times ranged from 3 62 minutes (mean = 10 min) Immediate mortality was not observed
Goliath grouper ID 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 5761 5762 5763 5764 5765 5766 5767 5768 5769 5770 5771 5772 5773 5774 5775 5776 5777 5778 5779 5780 5782 5783 138 139 140 5785 Residence and site fidelity # ## # # # # # # # #### # TMP 18 950 days (µ = 444 days) Residence time: 18-736 days 6 recaptures Forays (72%) demonstrated capacity to home (> 400 days; mean = 41) Seasonal departure (> 65% of individuals) Apr2011 Aug2011 Dec2011 Apr2012 Aug2012 Dec2012 Apr2013 Aug2013 Dec2013
And this is just cool! GG: 202 cm TL Capture depth = 30 m Barotrauma = 3 160 km in 3 days! 174 km
Movement between sites
Great Goliath Grouper Count Florida Sea Grant, FWC/FWRI and volunteers Broad geographic coverage in short time frame Snapshot of Goliath grouper abundance Citizen science provides incorporation of their observations into management
Great Goliath Grouper Count 300+ surveys since 2010 20+ volunteers assisted FSG agents and FWRI biologists statewide Sites surveyed (n) 70 60 50 40 30 20 10 0 2010 2011 2012 2013 2014
Great Goliath Grouper Count Total number observed per year : 190 360 Average number of fish per survey is ~5 (artificial reefs) Highest numbers in SW FL Total number of Goliath grouper observed 400 300 200 100 0 2010 2011 2012 2013 2014
You can join the fun! Contact your local Florida Sea Grant Agent. www.flseagrant.org
Goliath Grouper Web Module http://portal.gulfcouncil.org/goliathgrouper.ht ml
For more details on these results Collins, A.B., Barbieri, L.R., McBride, R.S., McCoy, E.D. and Motta, P.J. 2015. Habitat relief and volume are predictors of Goliath grouper presence and abundance in the eastern Gulf of Mexico. Bulletin of Marine Science 91: 399 418. Collins, A.B. 2014. An investigation into the habitat, behavior and opportunistic feeding strategies of the protected Goliath grouper (Epinephelus itajara). PhD Dissertation, University of South Florida, Tampa, Florida. Collins, A.B. and Barbieri, L.R. 2014. An evaluation of the effects of catch and release angling on survival and behavior of Goliath grouper (Epinephelus itajara) with additional investigation into residence and longterm movement patterns. NOAA/NMFS Final Report # NA10NMF4330115. 52 pp.
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Acknowledgements St. Petersburg Underwater Club (CRP partner) D. O Hern & R. Taylor S. Bratic, C. Barnes, W. Butts, J. DeLaCruz, C. Gardinal, C. Grauer, B. Hardman, S. Hooker, I. Lathrop, S. Lucas, K. Ludwig, M. Joswig, D. Palmer, H. Scarboro and E. Walker. NOAA/NMFS MARFIN and CRP programs Bob Sadler, Todd Kellison, David McClellan, Jose Castro Staff: Kyle McWhorter. Jamie Williams, Josh Taylor, Carlos Monzon- Aguirre, Brittany Barbara Motta Ichthyology Lab: Maria Laura Habeggar, Porter Fund Advice and good GG conversation: Chris Koenig, Don DeMaria, Lew Bullock FWRI Divers&Anglers: Fish Bio, Molluscs, FIM, FDM, SA, HAB, SERF Stats Help: Melanie Parker, Erin Leone, Wade Cooper Image Analysis Program: Janet Tunnell Early reviews: Jim Colvo, Janet Ley