The Bonnet Carré Spillway (BCS) is a flood control structure on the Mississippi River (MR) that has recently been operated for 3 years in a row in 2018, 2019, and 2020; and for twice in a calendar year (2019) for the first time. The amount of MR water diverted into Lake Pontchartrain during BCS openings varies depending on the duration of the openings, and the number of gates opened. BCS openings impact the salinity, temperature and water quality of the Mississippi Sound and Bight (MSB). In this study, we investigate the impact of recent BCS openings on fish and shellfish species in the MSB by using a coupled modeling approach. We hypothesized that modifying the BCS openings by reducing the number of gates opened per day and the maximum number of gates opened during an opening may reduce the impacts of BCS openings on coastal and estuarine fish and shellfish species. To test this hypothesis, the Coupled Ocean Atmosphere Wave Sediment Transport modeling system for MSB (msbCOAWST) is used to hindcast past BCS openings (2018, 2019 and 2020), and to simulate varying opening scenarios such as: 2019 without the second opening; 2019 with shorter second opening; openings reducing the MSR discharge to 1.2 million cfs and 1.25 million cfs; and slower-paced openings with 10 bays opened per day. A new Ecospace model was developed using Ecopath with Ecosim (msbEcospace) and loosely coupled to msbCOAWST to evaluate effects on fish and shellfish in the same region. The msbCOAWST salinity and temperature output is used to simulate the effect of the above-mentioned scenarios on 35 fish and shellfish species at different life stages. Preliminary results show that impacts and reduction of impacts by reducing the pace and amount by which salinity is reduced varies by species, and is more pronounced in sessile species such as eastern oyster, and less pronounced in nektonic species such as white and brown shrimp.