GCRL s Catch More Fish with Science Spotted Seatrout Read Hendon Center for Fisheries Research & Development & Capt. Matt Tusa Shore Thing Charters
Spotted Seatrout, Cynoscion nebulosus a.k.a. speckled trout member of the drum family Sciaenidae common throughout southeastern U.S. bays and estuaries most popular inshore coastal species in MS
Current Fishery Information
MS Recreational Harvest Estimates 1,000,000 900,000 800,000 Estimated Numbers of Fish 700,000 600,000 500,000 400,000 300,000 200,000 100,000 0 Spotted Seatrout "White Trout" "Ground Mullet" Croaker Red Drum Estimated NUMBERS of Fish Harvested in Mississippi Waters, MRIP, 2014 Data
MS Recreational Harvest Estimates 700,000 600,000 500,000 Estimated Pounds of Fish 400,000 300,000 200,000 100,000 0 Spotted Seatrout "White Trout" "Ground Mullet" Croaker Red Drum Estimated POUNDS of Fish Harvested in Mississippi Waters, MRIP, 2014 Data
MS Recreational Harvest Estimates 1,200,000 Estimated No. of Spotted Seatrout Harvested 1,000,000 800,000 600,000 400,000 200,000 0 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 Estimated Spotted Seatrout Recreational Harvest in Mississippi over Time, MRIP
MS Recreational Effort Estimates 2,500,000 Estimated No. of Angler Trips 2,000,000 1,500,000 1,000,000 500,000 0 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 Estimated Total Number of Recreational Trips in Mississippi (non-specific), MRIP
The Science Behind the Fishery
Fishery-Independent Data ( F-I )
F-I Annual Abundance 450 400 350 Annual Abundance 300 250 200 150 100 50 0 93 94 95 96 97 98 99 00 01 02 03 01 05 06 07 08 09 10 11 12 13 14 Year GCRL Fixed Stations
F-I Spatial Distribution 53 146 97 241 253 177 59 395 63 58
F-I Monthly Distribution 200 180 160 Number of Spotted Seatrout 140 120 100 80 60 40 20 0 J F M A M J J A S O N D Month
Temperature Influence on Abundance 140 120 Number of Spotted Seatrout 100 80 60 40 20 0 46 48 50 52 54 55 57 59 61 63 64 66 68 70 72 73 75 77 79 81 82 84 86 88 90 91 Surface Water Temperature (F)
Salinity Influence on Abundance 8.0 7.0 6.0 Average Abundance 5.0 4.0 3.0 2.0 1.0 0.0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 33 Surface Salinity (ppt)
Age & Growth
Determining Fish Age GSMFC GSMFC The most abundant fish in GCRL monitoring samples are ages 1 & 2.
Length at Age - Males ObsTL PredTL TL (inches) 28 26 24 22 20 18 16 14 12 10 8 6 4 2 0 0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 Biological Age
Length at Age - Females ObsTL PredTL TL (inches) 28 26 24 22 20 18 16 14 12 10 8 6 4 2 0 0 1.0 2.0 3.0 4.0 5.0 6.0 Biological Age
Length-Weight Relationship 8 7 6 Total Weight (lbs) 5 4 3 2 1 0 5 10 15 20 25 30 Total Length (inches)
Reproduction
Spotted Seatrout Reproduction Most females sexually mature by end of first year 65% mature at 13-in and 100% at 14-in Spawning season in MS = April to September Seagrass beds, island passes, reefs but, little is known about local spawning habitat.
Using Courtship Sounds to Identify Spawning Habitat Male trout produce species-specific courtship sounds, i.e. drumming Acoustic receiver can detect and record the courtship sounds FWRI
Spawning Habitat Study Objectives Use male courtship sounds to identify spawning habitat in two Mississippi bays Biloxi Bay Grand Bay NERR Biloxi Bay Impacted Estuary Grand Bay Pristine Estuary
Conducted weekly passive acoustic survey May to September 2008-09 1830-0200 hr Hydrophone Survey Estimated the group size and distance from hydrophone Size : 1-2, 3-5, small group, large group Distance to trout: On Top Of, Close By, In The Distance
Biloxi Bay Survey 356 Stations
Grand Bay Survey 348 Stations
Male Courtship Sounds Most prevalent in June and July More prevalent in Grand Bay than Biloxi Bay Preferred spawning habitat for males*: Depth >2 meters Temp >80 F Salinity >15 ppt * for On Top Of or Close By detections
Movements & Migrations
Movements & Migrations angler-cooperative tagging program 15,206 spotted seatrout tagged 408 (2.7%) recaptured 84% of fish = 10-14 inches total length
Where Were Fish Tagged? Zone I = 45% Zone II = 20% Zone III = 33% Zone IV = <1% 0 40 80 Kilometers N Harrison County Jackson County Louisiana Hancock County ZONE Zone 1I Bay St. Louis Pass Christia n Gulfport Biloxi Zone 1I ZONE II Ship I. Cat I. Ocean Springs ZONE Zone 1VIV ZONE Zone III III Gautier Horn I. Pascagoul a Petit Bois I. Alabama Gulf of Mexico
How Long Were Fish Out After Tagging? 300 250 Number of Spotted Seatrout 200 150 100 50 0 0 4 8 12 16 20 24 28 32 36 40 44 48 52+ Weeks at Liberty (4-week Intervals)
How Far Did Fish Move After Tagging? Number of Spotted Seatrout 350 300 250 200 150 100 82% traveled less than 2 miles 92% traveled less than 6 miles distance not related to fish size or time at liberty 50 0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30+ Miles Traveled
Longest Distances Traveled Exceptions to the Rule 35 miles in 212 days; 12.0 in
Longest Distances Traveled Exceptions to the Rule 40 miles in 138 days; 12.0 in
Longest Distances Traveled Exceptions to the Rule 45 miles in 200 days; 14.0 in
Feeding
Feeding Overstreet and Heard (1982) 373 spotted seatrout; 340 contained food Percent Occurrence = the % of stomachs in which a particular prey type occurs Fish Size Range (Total Length, Inches) Prey Type 4.0-11.75 12.0-18.5 18.75-24.5 Polychaetes 2.0% 9.8% 6.3% Crustaceans 47.0% 34.4% 31.3% Fishes 65.0% 76.3% 75.0%
Feeding Category Species % Polychaete Neanthes succinea 5.6 Shrimp Farfantepenaeus aztecus 7.4 Litopenaeus setiferus 3.8 unidenfied penaeids 7.1 Palaemonetes pugio 3.5 Crab Callinectes sapidus 8.8 Fish Anchoa mitchilli 14.4 Brevoortia patronus 11.8 Membras martinica 3.8 Microponias undulatus 2.9 unidenfied fish parts 38.8 Bay Anchovy Gulf Menhaden Clam Worm Brown Shrimp Blue Crab
Hooking Mortality
Hooking Mortality Do the fish that I release survive? 72-hour mortality study
Hooking Mortality 90 Live Dead n = 88 80 70 60 Number of Fish 50 40 30 20 10 0 Start No. 0 hours 24 hours 48 hours 72 hours
Moving Forward Continue the monthly monitoring in conjunction with MDMR Stock assessment in progress with 2014 data being included Feeding analyses to begin this summer with implementation of new program Potential to expand acoustic network to better define habitat use
More fishing info can be found at: http://www.usm.edu/gcrl/ Special thanks to our primary research sponsors!