Insights Into Temporal Patterns of Late Season Spawning and Other Biological Parameters in Bay Scallop Populations Over a 30-year Period

Stephen T. Tettelbach^1,*, Dennis M. Bonal², Harrison Tobi¹, Stephen Tomasetti³, and Raymond Czaja Jr.⁴

¹Marine Program, Cornell Cooperative Extension, Southold, NY 11971. ²Department of Medicine at the Alpert Medical School of Brown University, Providence, RI 02912. ³Department of Natural Sciences, University of Maryland Eastern Shore (UMES), Sarbanes Coastal Ecology Center, Berlin, MD 21811. ⁴National Center for Ecological Analysis and Synthesis, University of California, Santa Barbara, CA 93101. *Corresponding author.

Northeastern Naturalist, Volume 33, Issue 3 (2026): 431–461

First published early online: 20 September 2026

Abstract
Information on life-history strategies and seasonal patterns of reproduction is essential to management of wild fisheries. In this study, we documented temporal trends in shell metrics (total shell height, height of the single annual growth ring, shell growth after the first winter) and other biological parameters (adductor muscle weight, incidence of parasitic pea crabs, percentage of scallops that were reproductively mature) for adult (1+ yr) Argopecten irradians irradians (Bay Scallop) harvested in the Peconic Bays, NY, over a 30-year period. Of 10,620 scallops examined, <1% were 2+ years of age. For scallops 1+ yr of age, the product of fall spawns the prior year, 21.4% had annual growth rings ≤20 mm. These fall-spawned scallops are of particular interest because they may survive to spawn in a second year; extended reproduction of a given year class beyond the usual 1 year may serve to buffer dramatic annual fluctuations in recruitment. Temporal trends in the prevalence of fall-spawned adults were not correlated with mean water temperatures or their degree of change during the prior year. The relationship between scallop shell growth after the first winter versus annual growth-ring size was inverse and highly significant, confirming prior work that demonstrated compensatory growth in this species. Average scallop meat weight increased during 2 time periods with different opening dates for the harvest season (1990–2004, 2005–2019), perhaps due to rising temperatures. There were no obvious trends in the prevalence of Tumidotheres maculatus (Squatter Pea Crab) throughout the time series despite the observed increase in average water temperature. Reasons for spatial and temporal variability in prevalence of fall-spawned scallops (0–100%) are not yet clear, but further study is warranted given their importance to the sustainability and growth of Bay Scallop populations.

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