8:45 AM – 9:35 AM Research Update Distribution and Habitat Associations Philip Stevens, Research Scientist, FWRI Spawning Dynamics Joy Young, Biological Scientist, FWRI Research - Population/Behavioral traits What is it that Snook do and why do they do it?
Habitat Use Spawning
Diet Movement
Phil Stevens Joy Young Common Snook habitat use and diet
Philip Stevens, Erick Ault, Dave Blewett, Ross, Boucek, Jenn Rehage, Alexis Trotter, Beau Yeiser, Joy Young, and Jim Whittington Habitat use and diet
Movement
Diet
Estuary Residence River Offshore Residence Residence
Data for Stock Assessment are largely centered on the estuary
What is going on in other habitats, namely offshore reefs and rivers?
To what extent do fish move between habitats and why do they move? Offshore Reefs SE Florida Study Sampling Area
Ft. Pierce Inlet
St. Lucie Inlet 65 Km (40 Miles) Coastline About 5-12 km (3-8 miles) offshore
Jupiter Inlet Offshore Life History
2011-2014 Offshore Specimen Length Frequencies
Males (n=149) Females (n=202)
80
70
60
50 70% of Observed
40
30
20 Total Numberof Specimens 10
0 500 600 700 800 900 1000 1100 Total Length (mm)
Average TL = 949 mm (37 inches) for females and 885 mm (35 inches) for males Maximum TL = 1093 mm (43 inches) Age range = 4 -19 years; average ~10 years Diet and genetics Offshore Life History Cont.
Underwater Observations Roving Count (Opportunistic) Group Size (Number of Fish) Length Distribution (TL) Regional Bias Condition Limited
2009 - 2014 Observation Data
Region Group (Average) Group (Maximum) TL (mm) Avg TL (mm) Max
Ft. Pierce 24 140 835 1150
St. Lucie 29 250 827 1150
Jupiter 18 50 759 1080 Offshore Movement Patterns
Acoustic Telemetry
Of snook originally tagged inshore (n=186), eleven moved offshore
Snook that were tagged offshore (n=61), mostly remained offshore (high residency to reef tract)
Once offshore, very little movement back to inlets and inshore waters (only 4 fish bounced back and forth) Offshore Reproduction
Sampling and hydrated female locations
Sampling occurred in evening hours when active spawning is known to occur
99% of females were spawning capable # hydrated females caught or regressing None 1 2 11% of females had hydrated eggs (Imminent spawning) 3 Ft. Pierce Inlet
St. Lucie Inlet
Jupiter Inlet Use of offshore habitat has been documented throughout the state. Are these areas important at the population scale? Rivers Mexico
Mexico
Mexico Costa Panama Rica Spring-fed rivers
Tampa Bay
SE Florida Charlotte Harbor
Everglades Luiz Barbieri, Jim Estes, Tom Champeau, Bill Acknowledgements Johnson, Bill Pouder, and Ron Taylor
Southwest Florida Water Management District; FWC St Pete, Charlotte Harbor, Lakeland, State Wildlife Grant; Sport Fish Restoration Gainesville, Melbourne, Everglades (FIU) How do we sample rivers? - electrofishing Stuns the fish – Allows researchers to take measurements and release Charlotte Harbor Electrofishing 2004-05
Myakka River
Peace River
Freshwater Fisheries
Caloosahatchee River Charlotte Harbor Rivers - Seasonality
2.5 A Peace River Myakka River 2.0 Caloosahatchee River
1.5
1.0
0.5
0.0 ) -1 -0.5
2.5 B Fall04 Win05 Spr05 Sum05 Fall05 Win06 Spr06 Sum06
2.0 All rivers combined 1.5
CPUE (fish minute 1.0
0.5
0.0
-0.5
Fall04 Win05 Spr05 Sum05 Fall05 Win06 Spr06 Sum06 Season Blewett et al. 2009 What drives seasonal movements of snook into the rivers? 26 Estuary 24 River 22 Canal 20 18 16 14 Temperature cue? Not the whole story. 12
10 Water temperatures of the Water temperatures of the 8 habitats “spread” for three habitats do not differ days post-cold front leading6 into winter 1/7/2008 1/14/2008 1/21/2008 1/28/2008 26 Estuary Date River 24 Canal 22 20 18 16
14 2 °C 12 Temperature (°C) 10 8 6 1/5/2009 1/12/2009 1/19/2009 1/26/2009 26 Blewett et al. 2014 Date 24 22 20 18 16 14 12 10 8 6 1/4/2010 1/11/2010 1/18/2010 1/25/2010 Date Appear to cue on river flow
Summer/fall abundance of snook 12 100 Fish abundance Actual river flow 10 80
8 60 /s) 3 6 40 4 Flow (m Flow 20
Fish/100 m shoreline Fish/100 2 0 0
F04 S05 F05 S06 F06 S07 F07 S08 F08 S09 F09 S10 F10 S11 F11 S12 F12 S13 F13 W05SP05 W06SP06 W07SP07 W08SP08 W09SP09 W10SP10 W11SP11 W12SP12 W13SP13
Season
Estuary = 3 fish per haul in 183-m seine * gear efficiency of 30% = 10 snook/100m shoreline Rivers (summer) = ~1.5 fish per 100m in electrofishing * gear efficiency of 15% = 10 snook/100m shoreline Annual snook abundance vs. flow
2.2
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6 2
Common snook abundanceCommon (ln) R = 0.90
0.4
0.2 1.5 2.0 2.5 3.0 3.5 4.0 4.5 River flow (ln) More Flow = More Snook Peace River – summer Peace River – mid fall Estuary Prey River Prey
Blewett et al. 2006 Stevens et al. 2010 By late summer/early fall
Summer resident snook
Post-spawning fish from the bay Everglades Study system: ecotonal sites in Everglades National Park
Boucek and Rehage 2013 Study system: ecotonal sites in Everglades National Park
Marsh stage Sampling window Marsh drying
60
40
20 0 Marsh Depth (CM) Marsh 0 Marsh water depth (CM) -20 Dec Jun Dec Jun Dec Jun Dec Jun 2009 2010 2011 2012 2013 2014 Sunfishes are the dominantil prey items Snook and sunfish abundance increases in the dry season, but varies across years
16 14 Snook Push into river occurs 12 in April/May 10 8 6 4 2 # of snook per 100 meters 100 per of snook # 350 Sunfishes 30 25 20 15 10
# of sunfish per 100m per of sunfish # 5 0 Dec Jun Dec Jun Dec Jun Dec Jun Tampa Bay Southwest Florida Rivers
Dry Wet Transition Winter/Spring Summer Fall
Tampa Bay’s rivers
Tampa Bay Rivers
6.00 2014 2015 5.00 4.00 Year-round occurrence; no 3.00 seasonal changes apparent. 2.00
Catch per 100 sampled m 1.00
0.00 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month
Tampa Bay Rivers The rivers in TB appear to be an 3.5 extension of the estuary habitat 3 2.5
2
1.5
1
Snook per 100 m shoreline of 0.5 There are about 15 snook per 100m of shoreline (the length of a football field) in both estuary and river habitats 0 Dec-Feb Mar-May Jun-Aug Sep-Nov Estuary = 5 fish per haul in 183-m seine * gear efficiency of 30% Rivers = 2.6 fish per 100m shoreline in electrofishing * gear efficiency of 15% SE Florida Indian River Lagoon Rivers
Year-round occurrence; no seasonal changes apparent.
The rivers in IRL appear to be an extension of the estuary habitat Fat Snook
There are about 15 snook per 100m of shoreline (the length of a football field) in the estuary and 9 snook per 100m in the rivers.
However, other snook species (e.g., fat snook) boost numbers of “snook” per 100m of shoreline to that comparable to the estuary.
Estuary = 5 fish per haul in 183-m seine * gear efficiency of 30% Common Snook Rivers = 1.3 fish per 100m shoreline in electrofishing * gear efficiency of 15% Spring-fed rivers
Overwintering is apparent at this latitude
(Picture from observation bubble at Homosassa Springs)
<50 deg F Gulf temp vs. 72 deg F spring temp 2013 2015
Abundance in rivers less than half that of lower latitudes
0.2-0.6 snook/100m * gear efficiency of 15% =<4 snook/100m Conclusions Population traits will vary based on the size and shape of the estuary, habitat types, and prey presented to the species
Movement
Diet
Estuary Residence River Offshore Residence Residence Thank you!