2012-2014 Research Projects: Sustainable Fisheries and Aquaculture
Project: Development of a Novel Genetic Approach to Rapidly Detect and Quantify Fish Eggs of Economically Important Species: A New Tool for Fisheries Management
Dianne Greenfield, Belle W. Baruch Institute for Marine and Coastal Sciences, University of South Carolina
Indices of fish egg production are essential for understanding recruitment and developing stock assessment models for species management. Traditional methods of enumerating and identifying planktonic fish eggs entail time-consuming microscopy. Furthermore, eggs of different species are often morphologically indistinguishable leading to erroneous population assessments that affect management decisions. We aim to develop a rapid, cost-efficient, and novel molecular tool that will facilitate fish egg identification and quantification using the economically important species red drum (Sciaenops ocellatus) as our target organism. Sandwich hybridization assay enables rapid, direct detection of large subunit rRNA sequences using two DNA oligonucleotides (signal and capture) in a 96-well plate, and results are determined at A450 and A650 nm.
The research team plans to (1) identify a LSU rRNA region of interest and design corresponding capture probes specific to S. ocellatus, (2) validate probe specificity against a variety of fish species, (3) refine the assay for quantification of S. ocellatus eggs through generating standard curves against known egg abundances, (4) validate assay quantification against natural field samples, and (5) transfer the technology through workshops and peer-reviewed literature for the purpose of enhancing end-user monitoring and research activities.
Contact for Questions
Dianne Greenfield (email@example.com)
Project: Managing Reproductive Behavior in Fisheries and on Fish Farms: A Joint N.C./S.C. Sea Grant Project
Robert Chapman, South Carolina Department of Natural Resources
Persistent poor egg quality is a major problem in finfish aquaculture that has remained intractable and of unknown cause(s) despite decades of attention by researchers around the world. In the national breeding program for the striped bass, which supports a major fish-farming industry in the Carolinas and nationwide as well as important recreational fisheries, half of females fail to reproduce even though their oocytes/eggs are morphologically indistinguishable from those of good spawners. Our recent research has strongly implicated dysfunction of the ovarian transcriptome as a root cause of the problem. We developed a microarray to simultaneously measure expression of virtually all of the thousands of genes present in ovarian biopsies taken from female striped bass before the breeding season. Using a novel approach to analysis of microarray data based on artificial neural networks and machine learning tools, we then modeled the profiles of gene expression and their relationship to egg quality. This research could lead to more efficient production of hybrids for growout facilities and have important implications for fisheries management policies.
We aim to discover patterns of ovarian gene expression associated with high and low egg quality in striped bass. This will identify the specific physiological functions that are impaired and point the way toward changes in husbandry practices that can optimize egg quality. We will extend the analysis to wild caught individuals and evaluate the capacity of gene expression profiling as a tool for assessing the egg quality among age cohorts.
Contact for Questions
Robert Chapman (ChapmanR@dnr.sc.gov)
Project: Development of a Sustainable, Minimal-Water Exchange, Polyculture Biofloc-Based, Mariculture Production System
John Leffler, South Carolina Department of Natural Resources
New technologies are needed to improve environmental sustainability and economic viability of mariculture in the United States. If successful, this work could facilitate an important diversification of mariculture products that can be grown year-round with low environmental impacts and in inland areas adjacent to profitable markets that value fresh, year-round seafood.
In this first year, the investigators will (1) determine a minimal biomass load of each of the three livestock species such that nitrogen species, dissolved oxygen, and solids levels are within pre-defined benchmarks, (2) achieve growth rates for shrimp, oysters, and fish equal to pre-defined benchmarks, (3) to incrementally increase the biomass of each high-value livestock species until double the minimal biomass loading is achieved in a stable system, (4) identify flow rates and other management protocols that accomplish the other objectives, and (5) engage our collaborators during the development of this proposal. During the second year of the project, the objectives are to (1) test protocol repeatability among systems in regard to the biomass production of each of the high value livestock species and FCRs for the shrimp and fish, (2) develop a simple parameterized economic model of the costs involved in the production of all three livestock species, and to work with our collaborators to collect market prices and product acceptance for the livestock species produced, and (3) work with collaborators to summarize the results of the entire project, especially with regard to the economic feasibility of the enterprise, and to jointly develop and disseminate several information products.
Contact for Questions
John Leffler (LefflerJ@dnr.sc.gov)