Shellstring Manual

Shellstring (Spatfall) Survey Step by Step Methods A shellstring survey is developed for a waterbody to provide an estimate of a particular area within the waterbody, or the waterbody as a whole’s potential for receiving a “strike” or settlement (set) of oysters on the bottom. It can provide an estimate of larval supply in a given system and helps describe the timing of settlement events in a given year

The Status of Virginia\u27s Public Oyster Resource 2016

This report summarizes data collected during 2016 in the Virginia portion of the Chesapeake Bay. The report is composed of two parts, part one, oyster recruitment (shell string) in Virginia and part two, dredge survey of selected oyster bars in Virginia

The Status of Virginia’s Public Oyster Resource 2020

The Virginia Institute of Marine Science (VIMS) monitors recruitment of the Eastern oyster, Crassostrea virginica (Gmelin, 1791), annually from late spring through early fall, by deploying spatfall[1] (settlement and recruitment of larval oysters to the post metamorphic form termed spat) collectors (shellstrings) at various sites in three Virginia western Chesapeake Bay tributaries. The survey provides an estimate of a particular area’s potential for receiving a strike or settlement (set) of oysters on the bottom and helps describe the timing of recruitment events in a given year. Information obtained from this monitoring effort provides an overview of long-term recruitment trends in the lower Chesapeake Bay and contributes to the assessment of the current oyster resource condition and the general health of the Bay. These data are also valuable to parties on both the public side (Virginia Marine Resources Commission (VMRC), Conservation Replenishment Department) and private industry who are interested in potential timing and location of shell plantings in order to optimize recruitment of spat on bottom cultch (shell that is available for larvae to settle on). [1] A number of terms are used to describe various stages of the settlement (behavior, larvae seeking the substrate), metamorphosis (irreversible change in morphology accompanying transition from larval to attached form), and subsequent growth to the juvenile (attached, small version of the adult) progression of oysters. Spat is commonly used to describe the early post metamorphic attached form. Spatfall “set” or “strike” is commonly used to describe the continuum resulting in spat. For the current report we use the common term spatfall to reflect the end point of settlement and metamorphosis on shellstrings, and recruitment to reflect survival of juvenile oysters on bottom substrate (cultch) in the following fall surveys. Results from spatfall monitoring reflect the abundance of ready-to-settle oyster larvae in an area, and thus, provide an index of oyster population reproduction as well as development and survival of larvae to the settlement stage in an estuary. Environmental factors affecting these physiological activities may cause seasonal and annual fluctuations in spatfall, which are evident in the data. Data from spatfall monitoring also serve as an indicator of potential oyster recruitment into a particular estuary. Survival of spat on bottom cultch is affected by many factors, including physical and chemical environmental conditions, the physiological condition of the larvae when they settle, predators, disease, and the timing of these various factors. Abundance and condition of bottom cultch also affects the settlement process and survival of spat on the bottom. Therefore, spatfall on shellstrings may not directly correspond with recruitment on bottom cultch at all times or places. This report summarizes data collected during the 2020 settlement season in three tributaries in the Virginia portion of the Chesapeake Bay

The Status of Virginia\u27s Public Oyster Resource 2013.

This report summarizes data collected during 2013 in the Virginia portion of the Chesapeake Bay. The report is composed of two parts, part one, oyster recruitment (shell string) in Virginia and part two, dredge survey of selected oyster bars in Virginia

The Status of Virginia’s Public Oyster Resource 2017

This report summarizes data collected during 2017 in the Virginia portion of the Chesapeake Bay. The report is composed of two parts, part one, oyster recruitment (shell string) in Virginia and part two, dredge survey of selected oyster bars in Virgini

The Status of Virginia\u27s Public Oyster Resource 2013.

This report summarizes data collected during 2013 in the Virginia portion of the Chesapeake Bay. The report is composed of two parts, part one, oyster recruitment (shell string) in Virginia and part two, dredge survey of selected oyster bars in Virginia

Decadal Scale Changes In Seasonal Patterns Of Oyster Recruitment In The Virginia Sub Estuaries Of The Chesapeake Bay

Reproductive periodicity of sessile estuarine invertebrates reflects local seasonality of environmental (temperature, salinity) and biologic (food) parameters. Estuaries are ephemeral features in geologic time but considered somewhat constant in the course of recent human history (decadal time scales). Analyses of long-term trends in eastern oyster (Crassostrea virginica) settlement periodicity since 1960 in three major Chesapeake Bay rivers (James, Piankatank and Great Wicomico Rivers) of the Chesapeake Bay show marked changes within the 4-decade time frame. The 50th percentile of cumulative recruitment occurs between day 194 and 250 of the year depending on year and location. Significant coherence in interannual variation is observed across a wide range of sites. These patterns are related to pre and post disease (both Haplosporidium nelsoni and Perkinsus marinus) events, periods characterized by high and low river flow, varying harvest pressure, and trends arguably associated with directed climate change

The Status of Virginia\u27s Public Oyster Resource 2011

This report summarizes data collected during 2011 in the Virginia portion of the Chesapeake Bay. The report is composed of two parts, part one, oyster recruitment (shell string) in Virginia and part two, dredge survey of selected oyster bars in Virginia

Oyster Reef Broodstock Enhancement In The Great Wicomico River, Virginia

The Great Wicomico River is a small, trap-type estuary on the western shore of the Chesapeake Bay that once supported substantial oyster populations. These populations were essentially eliminated by the combined effects of Tropical Storm Agnes in 1972, and subsequent disease mortalities related to Perkinsus marinus and Haplosporidium nelsoni. Oyster broodstock enhancement was initiated in June 1996 by the construction of a three-dimensional intertidal reef with oyster shell, followed by the seeding, in December 1996, of that reef with high densities of large oysters from disease-challenged populations in Pocomoke and Tangier Sound. Calculations of estimated fecundity of the reef population suggest that oyster egg production from this source is within an order of magnitude of total egg production in the Great Wicomico River prior to Tropical Storm Agnes. Field studies in 1997 indicate spawning by reef oysters from July through September. P. marinus prevalence increased from 32% in June to 100% in July, whereas intensity increased from June to September; H. nelsoni was absent. Plankton rows recorded oyster larval concentrations as high of 37,362 +/- 4,380 m(-3) on June 23. Such values are orders of magnitude higher than those typically recorded in Virginia subestuaries of the Chesapeake Bay in the past three decades, and lend support to a premise that aggregating large oysters may increase fertilization efficiency. Drifter studies suggest strong local retention of larvae, a suggestion reinforced by marked increases in local oyster spatfall on both shellstring collectors and bottom substrate compared with years prior to 1997. In locations where local circulation promotes larval retention, the combination of reef construction with broodstock enhancement may provide an accelerated method for oyster population restoration