In the United States, the commercially important bay scallop (Argopecten irradians) has declined in most of the Atlantic and Gulf coastal areas where it was abundant in the 20th century. Bay scallops are particularly susceptible to population fluctuations because they usually live for only 18-22 months and reproduce once. On Long Island, New York, populations of the northern subspecies (A. irradians irradians) were nearly driven to extinction due to direct mortality and recruitment failures during "brown tide" (Aureococcus anophageferrens) algal blooms from 1985 to 1987, and in 1995. Despite the absence of brown tides since 1995, bay scallop populations did not recover on their own over the next 12 years; commercial harvests during this period remained at 1-2 % of pre-brown tide levels and population densities in most areas were very low (< 0.1 individuals/m2). Our primary hypothesis for this lack of recovery was that local bay scallop densities and numbers were too low to permit high rates of successful fertilization of eggs during spawning.
In our current work, funded by Suffolk County, New York, we attempted to jump-start bay scallop populations by planting large numbers of hatchery-reared scallops at high densities (>75-100/m2) to ensure a high probability of fertilization success upon spawning. Since 2006, we have planted more than 5 million scallops (most >40 mm) – in lantern nets suspended in midwater as well as via free-planting to the bay bottom.
In the last 10 years, we have spent 1000’s of hours on and under the water monitoring the progress of our restoration efforts; by all accounts it is clear that our efforts have driven the resurgence of scallop populations in the Peconic Bays of eastern Long Island, as well as the commercial fisheries. Initially, levels of larval recruitment to "spat" collectors (mesh bags suspended above the bay bottom) only increased significantly in areas where we planted scallops, but in the next few years larval recruitment increased throughout the Peconic Bays as natural populations began to rebuild. In turn, commercial harvests have increased dramatically since 2008 (the first year when any benefit to the fishery from our restoration work could have been seen). Statistics from the NY State Department of Environmental Conservation show that average annual landings from 2010-2015 were 10-27x higher than annual pre-restoration harvests. Landings in 2014 were the highest in 30 years: ~89,000 lbs. Dockside value of the fishery since 2008 has increased by over $4 million; with economic multipliers, the total increase in value to the local economy resulting from the increased bay scallop harvest is >$40 million.
Recent Publications http://ccesuffolk.org/marine/aquaculture