Multi-decadal patterns in abundance and seasonal distribution of Hogchokers (Pleuronectiformes: Achiridae), an apparent trophic anomaly, in lower Chesapeake Bay and its tributaries

Abstract Objective We used data from a long-term trawl survey to describe multi-decadal variation in the spatial distribution and relative abundance of the Hogchoker Trinectes maculatus in Chesapeake Bay and its three southernmost tributaries in relation to abiotic factors for three different life stages. Additionally, we compared relative abundance of Hogchokers in Chesapeake Bay with that of other commonly captured species. Lastly, we described trophic interactions of Hogchokers as prey within the Chesapeake Bay food web. Methods We used 35 years of bottom trawl survey data from Chesapeake Bay and three of its southern tributaries from a stratified random sampling design that included fixed and random stations to estimate relative abundance of Hogchokers in the James, York, and Rappahannock rivers and the lower Chesapeake Bay. We used generalized additive models to examine life-stage-specific distribution in relation to abiotic variables and seasons. We evaluated the role of Hogchokers in the Chesapeake Bay food web through published and unpublished diet studies. Results From 1988 to 2022, more than 2,293,000 Hogchokers were captured. Abundance in the York River ranked first (1,124,978 individuals), followed by that in the James River (825,711), the Rappahannock River (307,022), and lastly the main stem of Virginia’s portion of Chesapeake Bay (36,016 individuals). Annual relative abundance varied by three orders of magnitude within Chesapeake Bay; even greater variability was observed in specific regions within the bay and tributaries. Indices of Hogchoker relative abundance showed nearly 100-fold differences among years in the James River, whereas abundance patterns in remaining sampling areas showed less dramatic variations. Bottom water temperature, depth, salinity, and dissolved oxygen explained most of the observed variation relative to abundance among the size-classes examined. Distribution patterns were related to fish size, with smaller individuals found in brackish–freshwater habitats, whereas larger Hogchokers resided in more saline habitats. The seasonal distribution of Hogchokers was life stage specific, with early juveniles occurring in the upper portions of tributaries in summer and winter and larger juveniles and mature individuals occurring in the tributaries in winter and throughout all regions in summer. Conclusions Hogchokers are widely distributed based on size, and their distribution is affected by water temperature, salinity, depth, and dissolved oxygen. Hogchokers consume benthic invertebrates, potentially forming an important link between benthic productivity and higher trophic levels, but investigations of potential fish predators revealed limited consumption of Hogchokers despite their high abundance. Thus, Hogchokers may represent a carbon and nutrient sink in Chesapeake Bay and other temperate estuaries.