Exploring Trends in Abundance of Young‐of‐the‐Year and Age‐1 Atlantic Croaker, Black Drum, Spot, and Weakfish in Relation to Salinity, Temperature, and Large‐Scale Climatic Signals in a Mid‐Atlantic Estuary

Abstract

Atlantic Croaker Micropogonias undulatus, Black Drum Pogonias cromis, Spot Leiostomus xanthurus, and Weakfish Cynoscion regalis have shown species‐specific, varying trends in abundance despite general declines in commercial landings throughout the Delaware River estuary. Identifying how environmental factors and climatic processes affect fishes at multiple life stages is needed to enhance the precision of regulatory actions for managed species. Species‐, area‐, and age‐specific indices were compared with depth, salinity, temperature, the Atlantic Multidecadal Oscillation (AMO), and the North Atlantic Oscillation (NAO) to explore potential relationships as well as temporal and spatial parameters. Our results demonstrate that station (15 indices), salinity (14 indices), the AMO and NAO (13 indices each), and depth and temperature (12 indices each) served as important components for models of abundance for 17 species‐, age‐, and area‐specific combinations from 1991 to 2016. Significant time series trends were detected in six of the modeled indices of abundance, including baywide indices of age‐1 Weakfish (decline) and age‐0 Atlantic Croaker (increase); age‐0 Atlantic Croaker (increase) and Weakfish (decline) in Delaware; and age‐1 Spot (decline) and Weakfish (increase) in Delaware. Our results demonstrate how multiple fixed‐station surveys can be combined to quantitatively assess environmental and climatic effects correlated with species‐, age‐, and area‐specific levels of abundance, suggesting that climatic signals are affecting smaller‐scale environmental variables that in turn affect relative abundance.

Environmental drivers of biogeography and community structure in a Mid-Atlantic estuary

“…We also used indices for two longer term regional climatological conditions, the Atlantic Multidecadal Oscillation (AMO) and the North Atlantic Oscillation (NAO). The AMO is a 65-to-80-year climate cycle in the North Atlantic driven by variability in ocean thermohaline circulation (Sutton and Hodson 2005 ) which has been previously linked to fluctuations in fish abundance of a number of marine species (Faillettaz et al 2019 ; McLean et al 2018 ; Mathews et al 2022 ). The NAO, another major source of interannual oceanic variability, represents the sea-level pressure difference between Iceland and the Azores, and has been linked to increased sciaenid abundance (Mathews et al 2022 ) and increased CPUE of tunas (Báez et al 2011 ).…”

“…The AMO is a 65-to-80-year climate cycle in the North Atlantic driven by variability in ocean thermohaline circulation (Sutton and Hodson 2005 ) which has been previously linked to fluctuations in fish abundance of a number of marine species (Faillettaz et al 2019 ; McLean et al 2018 ; Mathews et al 2022 ). The NAO, another major source of interannual oceanic variability, represents the sea-level pressure difference between Iceland and the Azores, and has been linked to increased sciaenid abundance (Mathews et al 2022 ) and increased CPUE of tunas (Báez et al 2011 ). Data for these oscillations were obtained from the National Oceanic and Atmospheric Administration’s Earth System Research Laboratory ( https://www.esrl.noaa.gov/psd/data/climateindices/ ).…”