The ocean quahog, Arctica islandica, is the longest-lived metazoan with a single individual, nicknamed Ming, having an estimated age at collection of 508y. Despite this extraordinary age, Ming was comparatively small with a shell length (SL) of 86.9 mm from a live collection off Iceland in 2006. Small but old specimens of this species are not rare. Large individuals (90-120 mm SL) are regularly retained in fishery surveys in the U.S. Mid-Atlantic and Georges Bank regions. Large size is not always associated with older age. Ropes & Murawski (ICES report 1983) describe 3 large individuals from NOAA-NMFS surveys: a 132 mm SL at 157 y from Central New Jersey; a 130 mm SL at 53y also from Central New Jersey; and a 130 mm SL at 93 y from Georges Bank. These animals represent over 100 years variation in age but were comparable in size. A perusal of NEFSC and other industry supported surveys over the past 40 years indicate that individuals exceeding 130mm SL are rare. We report herein on a recent collection and examination of the largest individual ocean quahog for which we can find a record.
A single left valve from a live specimen of 141 mm SL was collected in a commercial hydraulic dredge on August 14, 2023 at 40.18.60oN and 73.19.20oW. This location is on the north side of the Hudson Canyon at ~50 m depth, in a region where the inshore limit of the bottom seasonal cold pool abuts warmer water above the seasonal thermocline. This inshore limit is, in successive years, gradually retreating to deeper water, and an ecotone of mixed surf clam (Spisula solidissima) and ocean quahog benthic dominants is developing in this transition region. The collection depth of this large specimen is in this expanding ecotone.
The valve was embedded in clear polyester resin, sectioned through the axis from hinge to growing edge, and the exposed edge polished prior to acquiring reflected light images of the hinge region and entire section from hinge to the growing edge. Initial low-definition images suggest an age at collection of between 62-65 years (to be updated as higher definition images are acquired after the abstract submission date). We discuss the growth history of this specimen in relation to both the local environment of the collection site and the general long term warming of the Mid Atlantic with climate change.
This work was supported by the National Science Foundation (NSF) Science Center for Marine Fisheries (SCEMFIS, www.scemfis.org) and an NSF Veteran Research Experience Award to Cohn as the presenting author.