Entrainment of Endangered Sturgeon by a Large Water Diversion: Rescue, Enumeration, and Conservation Opportunities

The Bonnet Carre’ Spillway diverts water from the Mississippi River through a floodway into Lake Pontchartrain to reduce river stages at New Orleans and prevent flood damages. Pallid Sturgeon, a federally listed species under the Endangered Species Act, and Shovelnose Sturgeon, listed under the Similarity of Appearance rule, are entrained through the Spillway structure and become trapped in the Spillway canals and other waterbodies. Five openings and corresponding rescue operations occurred between 2008 and 2019 after each Spillway closure. Operational parameters spanned a range of water temperatures and seasons with magnitude and duration of discharge varying across all openings. A total of 70 days with crew number ranging from 6 to 12 were expended to rescue 57 Pallid Sturgeon and 362 Shovelnose Sturgeon after the five openings that spanned 240 total days. More sturgeon were entrained at higher water temperatures, with greater numbers of bays opened, and for longer periods of time. Recovery of sturgeon is initially high but over time declines as sturgeon are depleted from the floodway, stranded in isolated waterbodies in the floodway, and/or displaced further downstream into Lake Pontchartrain during longer openings. Sturgeon that cannot find their way back to the floodway are unlikely to be rescued. Recent population studies indicate that less than 1% of the total population size in the Lower Mississippi River are entrained. However, this does not take into account those individuals entrained but not captured and the potential impacts of more frequent openings of the structure. Conservation recommendations are provided to increase catch efficiency and recovery of the endangered sturgeon.

The most southwestern locality and confirmed presence of Carabus (Carabus) vinctus (Weber, 1801) in Louisiana

New collection efforts led to re-discovery of Carabus (Carabus) vinctus (Weber) in Louisiana after the first record in 1874. The presumed range of the species in Louisiana is confined to the bottomland forests of the Lake Pontchartrain hydrological system including the lower flows of incoming streams. New locality extends the range of the species in the Gulf States almost 100 miles to the west and represents the most southwestern point of the whole range. Morphologically specimens from Louisiana are close to the Alabama specimens and belong to the var. georgiae Csiki.

Remotely sensed habitat assessment of bottomland hardwood and swamp habitat : West Shore Lake Pontchartrain Hurricane Storm Damage Risk Reduction System potential impact area

This study used remote sensing techniques to identify and assess the current condition of bottomland hardwood (BLH) and swamp habitats within the West Shore Lake Pontchartrain (WSLP) hurricane storm-damage risk reduction system (HSDRRS) project area. This effort provides baseline knowledge of the location and quality of these habitats prior to the construction of the WSLP HSDRRS project. The resultant products will assist the USACE—New Orleans District (MVN) by informing ecosystem decision-making related to environmental assessments.

Diet of Lesser Scaup Wintering on Lake Pontchartrain, Louisiana

The lesser scaup Aythya affinis has been a species of conservation concern since continental breeding populations began declining in the 1980s. The causes of this decline are likely multifaceted, but cross-seasonal effects are believed to play a prominent role: females unable to acquire sufficient nutrient reserves during winter and spring migration have poor survival and breeding success. Understanding scaup diet composition and prey selection can help managers not only diagnose mechanisms underlying wintering scaup distributions, but may also help direct management actions to increase forage availability and quality. We evaluated the diet of 60 scaup collected from a major wintering site in Louisiana, Lake Pontchartrain. Scaup consumed almost entirely mollusks, especially targeting medium-sized (6–16 mm) common rangia clams Rangia cuneata, which were strongly selected relative to their availability. Eighty-two percent of scaup consumed dark false mussels Mytilopsis leucophaeata and 57% consumed dwarf surf clams Mulinia lateralis; both foods were selected by scaup, but were uncommon in benthic samples. On the other hand, small snails Texadina sphinctostoma, Probythinella protera were common in dredge samples but were either avoided or consumed in proportion to their availability. We conclude that medium-sized common rangia clams and dark false mussels are the most consumed foods for scaup wintering on Lake Pontchartrain, and hypothesize that annual variation in prey populations may be an important proximate driver of scaup abundance.