Understanding the composition, utilization and coexistence of fresh and saltwater species in Mardi Gras Pass: A new and evolving distributary of the Mississippi River in SE Louisiana Andreas Moshogianis, Theryn Henkel*, John Lopez, and Andrew Baker LAKE PONTCHARTRAIN BASIN FOUNDATION American Fisheries Society Louisiana Chapter 2014 Annual Meeting, Thibodaux, LA May 29 th 30 th, 2014
The Bohemia Spillway 11.8 mile reach east bank of MS River located 45 miles downriver of New Orleans Created in 1926; MS River levees removed Re-estabished more natural conditions of overbank flow across the natural levee
Mardi Gras Pass
Development of MGP February 8, 2012
February 24, 2012
February 24, 2012
Mixing of fresh Mississippi River water with saline estuarine water
June 29, 2012
August 13, 2012
September 4, 2012
What about the biology?
This goal of this study was to investigate the biological communities present in MGP in order to better understand the utilization of MGP by aquatic species
Survey Dates November 8, 2012 December 6, 2012 January 15, 2013 March 23, 2013 5-month high-water event; not ideal for sampling August 22, 2013 (cast net only) November 14, 2013 December 13, 2013 Gear types used varied by date, depending on conditions (high velocity, low velocity, cold water, warm water, etc.)
Methods Gill nets Trot lines (deployed horizontally) Jug lines (deployed vertically) Crab traps Minnow traps Crawfish traps Hoop nets Pinfish traps Rod and reel Electrofishing * Water quality parameters were measured at each gear deployment
Water Quality Conditions Throughout the duration of the sampling, the surface salinity ranged from 0.1 to 0.7 ppt, while bottom salinity ranged from 0.2 to 0.8 ppt. Although this is freshwater environment, a number of brackish/saltwater species have been captured in MGP. The Secchi depth ranged from 15 cm to 80 cm. The river stage varied from 0.91 ft to 2.88 ft on the eight survey dates (US Army Corps of Engineers, 2013).
Species Freshwater Species Gill Net Cast net Trot-line Jug-line Crab Trap Minnow Trap Crawfish Trap Pinfish Trap Hoop net Rod and Reel Electroshocking Black crappie (Pomoxis nigromaculatis) Largemouth bass (Micropterus salmoides) Spotted gar (Lepisosteus oculatus) Longnose gar (Lepisosteus osseus) Channel catfish (Ictalurus punctatus) Blue catfish (Ictalurus furcatus) Redear sunfish (Lepomis microlophus) American eel (Anguilla rostrata) Bluegill (Lepomis macrochirus) Spotted sunfish (Lepomis punctatus) Longear sunfish (Lepomis megalotis) River carpsucker (Carpiodes carpio) Threadfin shad (Dorosoma petenense) Inland silverside (Menidia beryllina) Red-eared slider (Trachemys scripta elegans) Brackish/Saltwater Species Speckled seatrout (Cynoscion nebulosus) White perch (Pomoxis annularis) Striped mullet (Mugil cephalus) Gizzard shad (Dorosoma cepedianum) Red fish (Sciaenops ocellatus) Skipjack shad (Alosa chrysochloris) Ladyfish (Elops saurus) White bass (Morone chrysops) Gulf menhaden (Brevoortia tyrannus) Gafftop catfish (Bagre marinus) Fat sleeper goby (Dormitator maculatus) Bay anchovy (Anchoa mitchilli) Leatherjacket (Oligoplites saurus) Striped bass (Morone saxatilis) Atlantic croaker (Micropogonias undulates) Grass shrimp (Palaemonetes spp.) Blue crab (Callinectes sapidus) Gear Type List of captured species and gear types used
August 22, 2013 While conducting a bathymetry survey of MGP a cast net was deployed Nearly 50 juvenile gulf menhadden, seven black crappie, four lady fish, and three spotted gar, were captured in one cast of the cast net This suggests MGP is a suitable nursery for some fresh and saltwaer species of fish
Electroshocking Methodology 900 seconds of shocking, split between two locations (A and B) A start point, turn-around, and end point
September 25, 2013
Electrofishing Survey - Transect A Common Name Scientific Name Count Largemouth bass Micropterus salmoides 4 Spotted gar Lepisosteus oculatus 1 Longnose gar Lepisosteus osseus 1 White bass Morone chrysops 2 Ladyfish Elops saurus 1 Skipjack herring Alosa chrysochloris 2 Fat sleeper Dorminator maculatus 2 Bay anchovy Anchoa mitchilli 64 Striped mullet Mugil cephalus 48 Threadfin shad Dorosoma petenense 1 Gulf menhaden Brevoortia patronus 1 Gizzard shad Dorosoma cepedianum 35 Leatherjack Oligoplites saurus 1 Electrofishing Survey - Transect B Common Name Scientific Name Count Largemouth bass Micropterus salmoides 19 Channel catfish Ictalurus punctatus 2 American Eel Anguilla Rostrata 1 Leatherjack Oligoplites saurus 1 Redear sunfish Lepomis microlophus 2 Bluegill Lepomis macrochirus 5 Striped mullet Mugil cephalus 26 Spotted sunfish Lepomis punctatus 10 Longear Sunfish Lepomis Megalotis 4 Fat sleeper Dorminator maculatus 4 Spotted gar Lepisosteus oculatus 1 River Carpsucker Carpiodes Carpio 4 Gizzard shad Dorosoma cepedianum 66 Inland silverside Menidia beryllina 1
Electrofishing Survey - Transect A Common Name Scientific Name Count Largemouth bass Micropterus salmoides 4 Spotted gar Lepisosteus oculatus 1 Longnose gar Lepisosteus osseus 1 White bass Morone chrysops 2 Ladyfish Elops saurus 1 Skipjack herring Alosa chrysochloris 2 Fat sleeper Dorminator maculatus 2 Bay anchovy Anchoa mitchilli 64 Striped mullet Mugil cephalus 48 Threadfin shad Dorosoma petenense 1 Gulf menhaden Brevoortia patronus 1 Gizzard shad Dorosoma cepedianum 35 Leatherjack Oligoplites saurus 1 Electrofishing Survey - Transect B Common Name Scientific Name Count Largemouth bass Micropterus salmoides 19 Channel catfish Ictalurus punctatus 2 American Eel Anguilla Rostrata 1 Leatherjack Oligoplites saurus 1 Redear sunfish Lepomis microlophus 2 Bluegill Lepomis macrochirus 5 Striped mullet Mugil cephalus 26 Spotted sunfish Lepomis punctatus 10 Longear Sunfish Lepomis Megalotis 4 Fat sleeper Dorminator maculatus 4 Spotted gar Lepisosteus oculatus 1 River Carpsucker Carpiodes Carpio 4 Gizzard shad Dorosoma cepedianum 66 Inland silverside Menidia beryllina 1
Cumulative list of freshwater fish Fourteen different species of freshwater fish have been captured in MGP: channel catfish (Ictalurus punctatus) largemouth bass (Micropterus salmoides) spotted gar (Lepisosteus oculatus) longnose gar (Lepisosteus osseus) channel catfish (Ictalurus punctatus) blue catfish (Ictalurus furcatus) redear sunfish (Lepomis microlophus) American eel (Anguilla rostrata) bluegill (Lepomis macrochirus) spotted sunfish (Lepomis punctatus) longear sunfish (Lepomis megalotis) inland silverside (Menidia beryllina) river carpsucker (Carpiodes carpio) black crappie (Pomoxis nigromaculatis)
Saltwater Fish Fifteen different species of saltwater fish have been captured in MGP: speckled seatrout (Cynoscion nebulosus) white perch (pomoxis annularis) striped mullet (Mugil cephalus) gizzard shad (Dorosoma cepedianum) red drum (Sciaenops ocellatus) skipjack shad (Alosa chrysochloris) ladyfish (Elops saurus) white bass (Morone chrysops) gafftop catfish (Bagre marinus) fat sleeper goby (Dormitator maculatus) bay anchovy (Anchoa mitchilli) leatherjacket (Oligoplites saurus) striped bass (Morone saxatilis) Atlantic croaker (Micropogonias undulates) gulf menhaden (Brevoortia tyrannus)
During the eight surveys, the total amount of effort (or soak-time) was 138.75 hours with a total of 546 fish/aquatic species captured Gear Type Effort (hours) Catch (# of fish) Minnow trap 25.75 1 Jug line 24.75 9 Crab trap 22.5 3 Gill net 21.75 118 Trot line 14.25 3 Hoop net 10.25 2 Crawfish trap 9 0 Cast net 4.5 101 Pinfish trap 5.75 0 Electroshocking 0.25 309 List of each gear type with respective total effort and catch
Observed Species Observed Species in Mardi Gras Pass Common Name Scientific Name Common Name Scientific Name Alligator gar (Atractosteus spatula) Beaver (Castor canadensis) Flathead catfish (Pylodictis olivaris) White heron (Ardea alba) River Shrimp (Macrobrachium ohione) Great blue heron (Ardea herodias) Needle fish (Strongylura marina) Snowy egret (Egretta thula) Crawfish (Procambarus sp.) Double Crested Cormorant (Phalacrocorax auritus) Fiddler Crab (Uca sp.) Belted Kingfisher (Megaceryle alcyon) Deer (Odocoileus virginianus) White pelican (Pelecanus erythrohynchos) Nutria (Myocastor coypus) Brown pelican (Pelecanus occidentalis) River otter (Lontra canadensis) Various snakes, lizards, and frogs
Recreational Fisherman Utilization MGP is a fertile fishing ground for recreational fresh (largemouth bass) and saltwater species (redfish & speckled trout) Short-cut to other fishing grounds by way of the MS River
Discussion MGP is a very dynamic system At high stages, freshwater, rich in nutrients and sediment from the MS River flows into wetlands While at low stages, the flow can be reversed Numerous species, both aquatic and avian are utilizing MGP as a navigable route to and from fresh- and salt-water ecosystems, suggesting coexistence of various fresh and saltwater species
Future Work There is a need to conduct more frequent seasonal sampling to get a better estimate of population shifts that may occur as a result of high- and low-water events Further work is needed to better understand the entire biological assemblage of MGP Expanding our survey methods to capture avian, mammal, reptile, and amphibian species will give us a better understanding of the biological community, coexistence between species, and food-web dynamics
Acknowledgements, and Thank you! Funding for this project Surdna Foundation Electrofishing resources LA Department of Wildlife and Fisheries, Inland Fisheries District 8 Tim Ruth, Gary Vitrano, Jeffrey Thompson, Matthew Duplessis LPBF for assistance sampling David Baker, Eva Hillmann, and Iain Kelly