Large-scale movements of spawning female blue crabs in the Gulf of Mexico
Zachary Darnell School of Ocean Science and Technology, The University of Southern Mississippi March 01, 2020 Goals
1. To examine large-scale movements of spawning female blue crabs within and among estuaries and offshore waters of the Gulf of Mexico using a large-scale, Gulf-wide mark- recapture study.
2. To assess condition, reproductive potential, and reproductive output of spawning blue crabs in the Gulf of Mexico.
3. Use existing datasets from both state and regional management agencies to examine the temporal and spatial dynamics of the Gulf of Mexico spawning stock.
Total number tagged: 19,621
Tagging locations. Top panel shows actual tagging locations, with each point representing a location where at least one tagged crab was released. Note that many points overlap. Bottom panel shows the same data represented as a heat map, with darker red colors indicating a greater number of crabs tagged at that location. Number State tagged Texas 1,583 Louisiana 7,966 Mississippi 3,994 Alabama 688 Florida 5,390 TOTAL 19,621 2404 recaptures reported ~12.3% recapture rate
Number of recaptures Percentage Sector reported of total Commercial crabber 1930 84.9% Commercial shrimper 59 2.6% Commercial finfisher 4 0.2% Recreational fishing (any) 203 8.9% Miscellaneous non-fishing 77 3.4% TOTAL 2273 100.0% Gulf-wide movement statistics
27.28 ± 1.05 d 18 ± 0.6 km 1.30 ± 0.04 km d-1 range = 1–548 d range = 0–446 km range = 0–20.74 km d-1 median = 11 d) median = 17 km median = 0.57 km d-1)
75% of all recaptures occurred within 24 d of tagging and 90% of all recaptures occurred within 64 d of tagging Recapture locations
Recapture locations. Each symbol represents a single recapture report, with symbol color indicating the state where the crab was tagged.
90.2% recaptured in the same state where tagged. Basin delineations for analysis
Tagging regions used in analyses. Lower Laguna Madre (region 1), Corpus Christi Bay/Upper Laguna Madre (2), Aransas/Copano Bays (3), San Antonio Bay (4), Matagorda Bay (5), Galveston Bay (6), Sabine Lake (7), Lake Calcasieu (8), Vermillion-Teche (9), Terrebonne (10), Barataria (11), Pontchartrain/Western Mississippi Sound (12), Eastern Mississippi Sound/Mobile Bay (13), Perdido/Wolf/Pensacola (14), St. Andrew Bay (15), Apalachicola/St. George Sound (16), Steinhatchee (17), and offshore Gulf of Mexico (crabs tagged outside of the delineated inshore regions). Recaptures by region
Recapture Region Tagged Recaptured rate Lower Laguna Madre 65 0 0.0% Corpus Christi Bay/ULM 104 1 1.0% Aransas/Copano Bays 77 0 0.0% San Antonio Bay 572 6 1.0% Matagorda Bay 407 8 2.0% Galveston Bay 144 5 3.5% Sabine Lake 105 4 3.8% Lake Calcasieu 86 5 5.8% Vermillion-Teche 187 5 2.7% Terrebonne 925 190 20.5% Barataria 1880 304 16.2% Pontchartrain/WMS 7078 939 13.3% EMS/Mobile Bay 2127 249 11.7% Perdido/Wolf/Pensacola 263 48 18.3% St. Andrew Bay 3564 192 5.4% Apalachicola 47 0 0.0% Steinhatchee 1776 443 24.9% Offshore Gulf 214 5 2.3% TOTAL 19621 2404 12.3% Region where recaptured Teche - LLM CCB/ULM Aransas/Copano Antonio San Bay Bay Matagorda Bay Galveston Lake Sabine Calcasieu Lake Vermillion Perdido/Wolf/Pens. Andrew St. Bay Apalach./SGS Steinhatchee Gulf Offshore Terrebonne Barataria Pont./WMS Bay EMS/Mobile
LLM CCB/ULM 1 Aransas/Copano San Antonio Bay 1 Matagorda Bay 0.87 0.13 Galveston Bay 1 Sabine Lake 1 Lake Calcasieu 0.8 0.2 Vermillion-Teche 1 Terrebonne 0.83 0.14 0.01 0.03 Barataria 0.08 0.88 0.01 0.03
Region where tagged where Region Pont./WMS 0.01 0.93 0.06 0.01 EMS/Mobile Bay 0.01 0.98 0.01 Perdido/Wolf/Pens. 0.06 0.94 0 St. Andrew Bay 0.98 0.02 Apalach./SGS Steinhatchee 0.02 0.48 0.5 Offshore Gulf 0.2 0.2 0.2 0.2 0.2 Matrix showing the region of recapture for crabs tagged in each region. Values represent proportions. Zero values have been removed. Recaptures by region
Recapture Region Tagged Recaptured rate Lower Laguna Madre 65 0 0.0% Corpus Christi Bay/ULM 104 1 1.0% Aransas/Copano Bays 77 0 0.0% San Antonio Bay 572 6 1.0% Matagorda Bay 407 8 2.0% Galveston Bay 144 5 3.5% Sabine Lake 105 4 3.8% Lake Calcasieu 86 5 5.8% Vermillion-Teche 187 5 2.7% Terrebonne 925 190 20.5% Barataria 1880 304 16.2% Pontchartrain/WMS 7078 939 13.3% EMS/Mobile Bay 2127 249 11.7% Perdido/Wolf/Pensacola 263 48 18.3% St. Andrew Bay 3564 192 5.4% Apalachicola 47 0 0.0% Steinhatchee 1776 443 24.9% Offshore Gulf 214 5 2.3% TOTAL 19621 2404 12.3% Focal regions for further analyses
Recapture Region Tagged Recaptured rate Lower Laguna Madre 65 0 0.0% Corpus Christi Bay/ULM 104 1 1.0% Aransas/Copano Bays 77 0 0.0% San Antonio Bay 572 6 1.0% Matagorda Bay 407 8 2.0% Galveston Bay 144 5 3.5% Sabine Lake 105 4 3.8% Lake Calcasieu 86 5 5.8% Vermillion-Teche 187 5 2.7% Terrebonne 925 190 20.5% Barataria 1880 304 16.2% Pontchartrain/WMS 7078 939 13.3% EMS/Mobile Bay 2127 249 11.7% Perdido/Wolf/Pensacola 263 48 18.3% St. Andrew Bay 3564 192 5.4% Apalachicola 47 0 0.0% Steinhatchee 1776 443 24.9% Offshore Gulf 214 5 2.3% TOTAL 19621 2404 12.3% Seasonal movement rates (all focal regions)
Movement rates were Box-Cox transformed prior to analysis. Bars represent back- transformed least-squares means and 95% confidence intervals. Seasonal movement rates (each focal region)
All Steinhatchee tagging during Spring
Movement rates were Box-Cox transformed prior to analysis. Bars represent back- transformed least-squares means and 95% confidence intervals. Regional movement rates (all seasons)
Movement rates were Box-Cox transformed prior to analysis. Bars represent back- transformed least-squares means and 95% confidence intervals. Texas, Calcasieu, Vermillion-Teche
Region where tagged Perdido/Wolf/ Pensacola Terrebonne
Recaptured inside Terrebonne
Rayleigh test, P = 0.013
Recaptured outside Terrebonne
Tagging (gray) and recapture (red) locations tagged in Terrebonne. Note that the coastline basemap is an Rayleigh test, P < 0.001 approximation, given the rapidly changing Louisiana coastline. Barataria
Recaptured inside Barataria
Rayleigh test, P < 0.0001
Recaptured outside Barataria
Tagging (gray) and recapture (red) locations tagged in Barataria. Note that the coastline basemap is an approximation, Rayleigh test, P < 0.001 given the rapidly changing Louisiana coastline. Pontchartrain/Western MS Sound
Recaptured inside Pont./WMSS
Rayleigh test, P < 0.001
Recaptured outside Pont./WMSS
Tagging (gray) and recapture (red) locations tagged in Pontchartrain/Western MS Sound.
Rayleigh test, P < 0.0001 Eastern MS Sound/Mobile Bay
Recaptured inside EMSS/MB
Rayleigh test, P = 0.003
Recaptured outside EMSS/MB
Tagging (gray) and recapture (red) locations tagged in Eastern MS Sound/Mobile Bay.
n = 6 St. Andrew Bay
Recaptured inside St. Andrew Bay
Rayleigh test, P < 0.001
Recaptured outside St. Andrew Bay
n = 3 Tagging (gray) and recapture (red) locations tagged in St. Andrew Bay. Steinhatchee
Rayleigh test, P < 0.001
Tagging (gray) and recapture (red) locations tagged in Steinhatchee. Summary
• 85% of recaptures from commercial crabbers, ~10% recreational. • Seaward movements within estuaries • Relatively low movement rates • This study: 1.30 ± 0.04 km d-1 • Aguilar et al. 2005 (Chesapeake): 3.3 ± 0.35 km d-1 • Potentially due to differences in tides, estuary size, salinity gradients.
• Most crabs recaptured within same estuary where tagged, but some movements between estuaries. ~10% crossed state lines. • Few recaptures in Gulf waters reduced ability to determine movement patterns once out of the estuary.