PS 53-203 - The abundance and distribution of Sciaenidae and Callinectes sapidus in relation to channel dredging

Wednesday, August 17, 2022

5:00 PM – 6:30 PM EDT

Located in: ESA Exhibit Hall

Presenting Author(s)

SB

Samai A. Bhojwani

Doris Duke Conservation Scholars Program, United States

Coauthor(s)

ML

Melissa LaCroce

NC State's Center for Marine Science and Technology, United States
DB

Daniel Bowling

NC State's Center for Marine Science and Technology, United States
DE

Dave Eggleston

NC State's Center for Marine Science and Technology, United States

Background/Question/Methods

Channel dredging is the act of excavating material from marine environments. Dredging is common in the winter months to protect marine mammals, sea turtles, and important commercial fisheries, though the demand for dredging has increased due to how frequent the ports are used and the abundance of storms. Dredging has been linked to sedimentation stress, toxic contaminants, and noise pollution negatively impacting marine environments. In Beaufort Inlet, North Carolina, a trawling pilot project was conducted to determine the abundance and distribution of Sciaenidae and Callinectus sapidus relative to dredged channels. This study focuses on Sciaenidae and Callinectus sapidus as they are both important fisheries and shellfish in NC. Negative impacts of dredging are still being evaluated for many species, and no existing work has explored how Sciaenidae and Callinectus sapidus are being affected. A pilot study utilizing trawling has been developed and conducted to fill that knowledge gap. Trawling is the act of towing a fishing net through the water behind the boat to collect species. This allows for data to be collected on the abundance of species at individual points in time while testing water quality.

Results/Conclusions

Trawling was completed at an active dredging site and a control site. There were five trawls conducted in the active site, which are East and West of the Inlet, and six trawls in the controlled site. Five-minute trawls were conducted based on GPS points between two buoys over 16 days. When a trawling line was complete, the net was brought up and the species were identified, measured, and released. Collected quantitative data were used to generate two-tailed T-tests. The T-tests were used to assess the difference in abundance of Sciaenidae and Callinectus sapidus between the dredged and control site.The p-values calculated were significantly larger than our alpha p-value of 0.05. For the total Sciaenidae abundance the p-value was 0.02247 and for the Callinectes sapidus it was 0.5386, therefore the null-hypothesis is accepted - active dredging does not decrease the abundance of Sciaenidae and Callinectus sapidus. Due to conditions in the inlet sample sizes were small and there is significant variability in the abundance data. Incorporating more trawling lines, additional sites,and conducting monthly tests would allow researchers to determine if and how the active dredge zone evolves and better assess the influence of dredging on Sciaenidae and Callinectus sapidus.