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

Visual surveys: 441

Depth range: 7 – 48 m

Study area: Nov 2007 – present

Methods – Visual Survey• Year-round video surveys

– Presence, abundance – Size distribution– Seasonal patterns

• Habitat characterization– Artificial vs. Natural– Relief– Volume (artificial habitats only)

20 cm

120 cm TL

Measuring fish

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

20

33

1

13

4

10

23

10

Winter Spring Summer Fall

Pro

po

rtio

n o

f su

rvey

s p

rese

nt

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0Artificial Deep (>20 m)

Artificial Shallow(<20m)

Natural Deep

Natural Shallow

Presence by habitat, depth, season

Goliath grouper presence:Habitat: p < 0.0001**Depth: p = 0.23Season: p = 0.02*(PROC GLIMMIX, Presence modeled as a binomial distribution)

low relief high relief

Pro

po

rtio

n o

f su

rvey

s p

rese

nt

0.2

0.4

0.6

0.8

1.0Artificial

Natural

Presence by habitat relief

BB

C

A

< 1.5 m > 1.5 m

Collins et al., 2015

Abundance: Artificial reefs

Oct Feb Jun Oct Feb Jun Oct Feb Jun

Go

liath

ob

serv

ed (

n)

0

5

10

15

20

25

30

Overall mean = 4.5

Date

Oct Feb Jun Oct Feb Jun Oct Feb Jun

Go

liath

ob

serv

ed (

n)

0

5

10

15

20

25

30

Col 37 vs Col 38

Col 37 vs Col 38

Abundance: Natural reefs

Overall mean = 0.4

High Low High Low

Nu

mb

er o

bse

rved

0

5

10

15

20

25

Abundance – by vertical reliefNaturalreefs

Artificialreefs

A

B

B C

> 1.5 m < 1.5 m > 1.5 m < 1.5 m

Collins et al., 2015

Low Medium High

Nu

mb

er o

bse

rved

0

5

10

15

20

25

Shallow < 20 m

Deep > 20 m

Abundance – by site volume

D D

C

BA

≤ 1000 m3 ≥ 1000 – 10,000 m3 ≥ 10,000 m3

*Artificial only

na

Total length (cm)

20-40

40-60

60-80

80-100

100-120

120-140

140-160

160-180

180-200

200-220

Freq

uen

cy

0

20

40

60

80

100

120

140

160shallow

deep

~ 5 – 15 years

Overall size distribution of Goliath grouper This study:TL range: 35 – 213 cm Median = 121 cm TL (age ~ 7 y)

Bullock et al. (1992):TL range: 8 – 216 cmMedian = 168 cm TL(age = 13 y)

67 cm

@ Mexican Pride, 80 km from shore and 39 m deep

The acoustic array

Gulf of

Mexico

12 shipwrecks

– 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)

Acoustic array

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

Apr2011 Aug2011 Dec2011 Apr2012 Aug2012 Dec2012 Apr2013 Aug2013 Dec2013

798081828384858687888990919293

5761576257635764576557665767576857695770577157725773577457755776577757785779578057825783

138139140

5785

############################# ################################################################################# ################ ############################################################################################# ########

Residence and site fidelityG

olia

th g

rou

per

ID

–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)

And this is just cool!

GG: 202 cm TLCapture depth = 30 m

Barotrauma = 3

174 km

160 km in 3 days!

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

2010 2011 2012 2013 2014

Site

s su

rve

yed

(n

)

0

10

20

30

40

50

60

70

Great Goliath Grouper Count

2010 2011 2012 2013 2014Tota

l nu

mb

er o

f G

olia

th g

rou

per

ob

serv

ed

0

100

200

300

400

• Total number observed per year : 190 – 360

• Average number of fish per survey is ~5 (artificial reefs)

• Highest numbers in SW FL

You can join the fun!

Contact your local Florida Sea Grant Agent….www.flseagrant.org

Goliath Grouper Web Module

http://portal.gulfcouncil.org/GoliathGrouper.html

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 long-term movement patterns. NOAA/NMFS Final Report # NA10NMF4330115. 52 pp.

Thanks for listening…Questions?

AcknowledgementsSt. 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