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

American Fisheries Society – Louisiana Chapter 2014 Annual Meeting, Thibodaux, LA

May 29th – 30th, 2014

Andreas Moshogianis, Theryn Henkel*, John Lopez, and Andrew Baker

LAKE PONTCHARTRAIN BASIN FOUNDATION

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 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) X X

Spotted gar (Lepisosteus oculatus) X X

Longnose gar (Lepisosteus osseus) X X

Channel catfish (Ictalurus punctatus)  X  X X X

Blue catfish (Ictalurus furcatus) X X

Redear sunfish (Lepomis microlophus) X X

American eel (Anguilla rostrata) X

Bluegill (Lepomis macrochirus) X

Spotted sunfish (Lepomis punctatus) X

Longear sunfish (Lepomis megalotis) X

River carpsucker (Carpiodes carpio) X

Threadfin shad (Dorosoma petenense) X

Inland silverside (Menidia beryllina) X

Red-eared slider (Trachemys scripta elegans)  X X

Brackish/Saltwater Species

Speckled seatrout (Cynoscion nebulosus) X

White perch (Pomoxis annularis) X

Striped mullet (Mugil cephalus) X X

Gizzard shad (Dorosoma cepedianum) X X

Red fish (Sciaenops ocellatus) X X

Skipjack shad (Alosa chrysochloris) X X

Ladyfish (Elops saurus) X

White bass (Morone chrysops) X X

Gulf menhaden (Brevoortia tyrannus) X

Gafftop catfish (Bagre marinus) X 

Fat sleeper goby (Dormitator maculatus) X

Bay anchovy (Anchoa mitchilli) X

Leatherjacket (Oligoplites saurus) X

Striped bass (Morone saxatilis) X  X

Atlantic croaker (Micropogonias undulates) X

Grass shrimp (Palaemonetes spp.) X

Blue crab (Callinectes sapidus) X  X X

X

 X

X

Cast net

X

X

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

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 ACommon 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 B

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 ACommon 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 B

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 9Crab trap 22.5 3

Gill net 21.75 118Trot line 14.25 3Hoop net 10.25 2

Crawfish trap 9 0Cast net 4.5 101

Pinfish trap 5.75 0Electroshocking 0.25 309

List of each gear type with respective total effort and catch

Observed Species

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

Observed Species in Mardi Gras Pass

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