The Oyster is Your World

This presentation shows the results of aquaculture production models of the U.S. oyster aquaculture. U.S. aquaculture data from 1984 to 2019 are compiled from previous annual reports and online sources. The NOAA Fisheries data are reported in pounds of meat annually valued in dollars. FAO FishStat provides a more detailed breakdown by species and regions. FAO oyster production data are reported live weight and valued in dollars up to 2020. Annual U.S. oyster aquaculture production since 1984 is shown in Fig. 1. The blue bars show annual oyster aquaculture production reported by NOAA Fisheries from 1984 to 2019. The green curve shows the farmgate values of oyster production for the same period. 





The U.S. Aquaculture Production Assessment Model (APAM) assumes that annual production is defined as follows: Q = A + B[X] + E, where Q - aquaculture production (lb/yr), A and B are coefficients, X- matrix of independent variables, and E- error term. The U.S. Aquaculture Farmgate Value Assessment Model (AFVAM) for oyster aquaculture assumed that the annual farmgate value is defined as follows: R = A + B[X] + E, where R - aquaculture farmgate value ($/yr), A and B are coefficients, X- matrix of independent variables, and E- error term. Results showed that global pandemics and recessions disrupted the marketplace and production space and caused oyster aquaculture production to fall. These models are useful in determining future trends in the industry. Annual production has been growing during the past decade and is expected to expand further in the coming decade. 

We analyze public preferences for oyster reef restoration, focusing on the U.S. Gulf Coast, one of the leading oyster-producing regions in the U.S. We administer a contingent-valuation survey to 4,690 households across the region using a web survey instrument employing videos to convey key information and follow-up questions to mitigate hypothetical bias. We test for status quo and scope effects, and compare a restricted sample of "high-quality" responses that are internally consistent against the full sample. We provide estimates of both household and aggregate willingness to pay and place these in the context on ongoing oyster restoration efforts and commercial landings. Results indicate that public support for oyster restoration, in terms of willingness to pay, exceeds current restoration expenditures and is consistent with the current market value of oysters. We also find that preferences are driven strongly by those who eat oysters as well as those who are saltwater anglers.

Empirical and mechanistic models have been used for the quantitative assessment of oyster resources for decades by resource managers. Various models have been applied for numerous purposes including fisheries management, impact assessment, aquaculture applications and for restoration planning. Empirical modeling approaches rely on the statistical relationships from observational data and are excellent predictors when sufficient data are available and conditions driving the resources are not changing outside of historic bounds. Mechanistic models are based on "first principles" and are mathematical representations of complex systems to describe real-world phenomena. Empirical models have modest data requirements as compared to mechanistic models which often have complex equations with large data requirements. Thus, empirical models are most useful when data are limited and conditions remain in the range of previously observed ecological bounds, whereas mechanistic models are most useful when more data are available, and the need to predict system behavior when conditions are changing, such as climate change. This presentation provides an overview of modeling approaches including the evolution of empirical approaches using empirical methods such as habitat suitability models. The development of mechanistic models from the simplest von Bertalanffy growth model to more complex models such as dynamic energy budget (DEB) models and food chain models are also presented with recent applications in the Gulf Coastal region.

This presentation shows the results of a state-wide analysis of the cultch planting activities at the Mississippi public oyster reefs. Commercial oyster landings in Mississippi were compiled from the NOAA Fisheries website. Fisheries data are reported in pounds annually and valued in dollars. Annual cultch planting activities were compiled from the Mississippi Department of Marine Resources oyster publication and information requests.
 From 1997 to 2004, when the total Mississippi public oyster reefs were about 12,000 acres, annual oyster landings averaged 3.0 million pounds of meat, valued at $3.0 million. The public oyster reefs planted with clutch materials averaged 138 acres per year. Despite the massive cultch planting activities shown in Fig. 1, oyster annual harvests have significantly fallen due to a series of natural, technological, and man-made disasters in 2005, 2010, 2011, and 2019. 



Figure 1. Mississippi commercial oyster landings and acres of public reefs planted with cultch materials.


An Oyster Economic Cultch Planting-Harvesting Model (OECPHM) has been developed to simulate the impacts of these disasters on the state oyster industry. Results showed significant relationships during the pre-disaster period and were used to estimate the expected harvests should the disasters not have occurred in recent years. Initial results indicate that cultch planting activities positively impact oyster harvests for multiple years.
The Oyster Economic Cultch Planting-Harvesting Model is defined as follows:
Oyster harvested = F( year, current and past acres planted with cultch materials, diesel price, unemployment rates, cubic yards of water released by the Bonnet Carre Spillway, recession, Covid-19, trade war months, and disaster days). 
The OECPHM estimated expected oyster harvests as future cultch planting activities are undertaken, assuming no disasters occur in the forecasting period. These results do not include any valuation on the benefits associated with future harvests and costs of cultch planting.