Location: Harry K. Dupree Stuttgart National Aquaculture Research Cntr
2020 Annual Report
Objectives
1. Improve the performance of hybrid striped bass (HSB) fingerlings in intensive production systems.
1.A. Develop fish stocking and dissolved oxygen and dissolved inorganic nitrogen management strategies for intensive production of HSB.
1.B. Optimize production of advanced HSB fingerlings in the biofloc technology production system.
1.C. Determine the nutritional value of alternative ingredients and supplemental exogenous enzymes for HSB.
1.D. Evaluate practical fishmeal-free (FMF) and plant-based diets for HSB performance and nutrient (N & P) retention in intensive production systems.
1.E. Determine optimum feeding regime, live feed enrichment, and feasibility of microparticulate diets to increase growth, survival, condition, and fatty acid composition in moronid larvae.
2. Reduce on-farm mortalities to pathogens in HSB aquaculture.
2A-D. Perform controlled challenges with white bass (WB), striped bass, palmetto and sunshine HSB to establish their susceptibility to emerging pathogens. Detect genetic variation for resistance to disease in host, and identify genes and pathways critical for pathogenesis in microbe; Evaluate the innate and adaptive immune response and determine the efficacy of vaccines to emerging pathogens.
2.E. Develop methods for harmful algal bloom control.
3. Develop and implement technologies that enhance genetic improvement of HSB.
3.A. Create and release a first-generation white bass genome and transcriptome assembly.
3.B. Optimize a photo thermal manipulation protocol for offseason (fall) spawning of WB and create even/odd year class base populations for selective improvement of important production traits.
3C. Identify phenotypic differences in WB for growth and utilization of plant protein- and plant oil-based diets and determine the genetic variation in protein, lipid and carbohydrate utilization for the identified traits.
3.D. Develop methods for the production of triploid HSB.
Approach
Develop fish stocking and dissolved oxygen and dissolved inorganic nitrogen management strategies for intensive production of hybrid striped bass utilizing both traditional and split-pond production systems; Optimize production of advanced hybrid striped bass fingerlings in biofloc technology production system; Determine the nutritional value of alternative ingredient mixes and supplemental exogenous enzymes for hybrid striped bass. Evaluate practical fishmeal-free and plant-based diets for hybrid striped bass performance and nutrient (Nitrogen and Phosphorus) retention in intensive production systems; Determine optimum feeding regime, live feed enrichment, and feasibility of microparticulate diets to increase growth, survival, condition, and fatty acid composition in moronid larvae; Determine optimum larval feeding regime for larval Morone using live feeds to increase growth, survival, and larval quality through metamorphosis; Determine the influence of live feed enrichment on growth, survival, condition, and fatty acid composition of Morone larvae; Determine the feasibility of replacing live feeds with formulated microparticulate diets from first feeding in moronid larvae; Perform controlled challenges with white bass, striped bass, palmetto and sunshine hybrid striped bass to establish their susceptibility to emerging pathogens; Detect genetic variation for resistance to disease in moronids. Identify microbial genes and pathways critical for pathogenesis in moronids; Evaluate the innate and adaptive immune response in moronids and determine the efficacy of vaccines to emerging pathogens; Develop methods for harmful algal bloom control; Create and release a first-generation white bass genome and transcriptome assembly; Optimize a photo thermal manipulation protocol for offseason (fall) spawning of white bass and create even/odd year class base populations for selective improvement of important production traits; Identify phenotypic differences in white bass for growth and utilization of plant protein- and plant oil-based diets and determine the genetic variation in protein, lipid and carbohydrate utilization for the identified traits; Develop methods for the production of triploid hybrid striped bass.
Progress Report
A range-finding study initiated in late June in outdoor biofloc tanks evaluated the effect of stocking 150 to 350 1-gram fish per square meter of tank water surface on fingerling growth and yield. This study will continue through the summer until a projected harvest in October.
ARS researchers have determined that white bass and striped bass, the parental species to hybrid striped bass, display large differences in susceptibility to the bacterium Flavobacterium columnare. We are currently creating F2 backcross hybrid striped bass by mating F1 hybrid striped bass with parental white bass to be used as a mapping population for disease resistance quantitative trait locus (QTL) studies. This research will aid in the development of disease-resistance genetic markers.
Research is ongoing to determine optimum hybrid striped bass larval feeding regimes using live feeds. Scientists at Stuttgart National Aquaculture Research Center, Stuttgart, Arkansas, have been seeking to determine the earliest time that Morone larvae can be converted to a prepared diet by minimizing the time spent on live food items while maximizing larval growth and survival. Hybrid striped bass (HSB) larvae typically spend the first portion of exogenous feeding in tank production consuming rotifers (Brachionus sp.) before moving on to larger Artemia nauplii, and finally weaning onto manufactured diets. Previous research in this lab feeding rotifers demonstrated that minimizing the number of days larvae were fed before transitioning to larger Artemia nauplii maximized growth. Current studies are further refining Artemia feeding protocols as well as optimizing the timing of feeding, analysis, and enrichment of live food items with the goals of driving down the costs of production and providing a more abundant, year-round supply of seedstock for HSB producers.
Research is ongoing to determine the feasibility of early weaning of hybrid striped bass larvae onto manufactured microdiets. Scientists at Stuttgart National Aquaculture Research Center, Stuttgart, Arkansas, have been seeking to determine the earliest time that HSB larvae can be converted to a manufactured microdiet (MD). HSB larvae typically spend the first portion of exogenous feeding in tank production consuming live food items (rotifers and Artemia nauplii) before being weaned onto MDs,which are both more cost-effective and can be formulated to meet all nutritional requirements. Additionally, replacing live feed with a MDs require no special skills or facilities, as are required for live feeds, would greatly facilitate year-round fingerling production, and help to drive down the high costs of indoor larval production, the bulk of which are attributed to the costs associated with live feeds. Other finfish species thought to require live feeds have had mixed success with MDs, therefore it is imperative that we determine the feasibility/suitability of HSB to weaning and/or replacement of live feeds with a high-quality MD. Data analysis is ongoing to determine the MD that best maximizes larval growth and survival as compared to a typical live feed regime. Future research will focus on MD formulation, MD/live feed cofeeding strategies, and larval digestive enzyme assays.
We continued a collaboration with researchers at the University of Arkansas at Pine Bluff (Pine Bluff, Arkansas) and Keo Fish Farm (Keo, Arkansas) to produce triploid (sterile) hybrid striped bass. In a 2-year-old cohort produced via heat-shock on eggs, we determined growth rates and morphology of these triploid fish as compared to diploid (normal) fish. We also developed an experimental hatching system at Keo and screened 12 compounds to find a superior method to prevent eggs from sticking together. The industry typically uses a 4-minute treatment of tannic acid, but it is costly and if left too long, will form a hard layer which prevents embryos from breaching the chorion when hatching. We determined that evaporated milk and whole milk were just as efficient at preventing stickiness but were inexpensive and safer for the eggs. Next year the hatchery at Keo Fish Farm plans to use evaporated milk and whole milk exclusively to prevent eggs from sticking together.
We continued a collaboration with researchers at the Freshwater Institute (Shepherdstown, WV) and Hood College (Frederick, MD) on the toxicity of peracetic acid to early life stages of Atlantic salmon. This collaboration is also investigating the use of peracetic acid in recirculating aquaculture systems to treat these systems to eliminate pathogens.
We continued collaborating with researchers in Denmark, Germany and the US, to establish the importance of the potent disinfectant peracetic acid to the global aquaculture industry. After evaluating our research, the major manufacturer of peracetic acid in the US (PeroxyChem) and another company that retails fishery products (AquaTactics) have gained EPA Registrations to use their products in the aquaculture industry as a disinfectant.
In an on-going common-garden trial, a subset of juveniles from 15 families from the odd (2019) yearclass of white bass families are being fed a fish meal control or an all-plant protein diet. The families used represent a portion of the crosses derived from each of the wild and domestic strains of white bass currently being used to develop a new line of white bass by single-pair mating of wild caught and domestic fish. Results of this study will determine whether white bass can be selected for better performance traits on an all-plant protein diet.
Streptococcus iniae (Strep) is a common gram-positive bacterial pathogen that causes mortality loss in the hybrid striped bass industry. Efforts to minimize antibiotic use and antimicrobial resistance (AMR) are being examined across animal agriculture, including aquaculture. In collaborative work funded by the ARS Antimicrobial Resistance (AMR) or Alternatives to Antibiotics (ATA) Program with scientists at the ARS SGPGRU (Hagerman, ID), the USFWS Bozeman Fish Technology Center (MN), and the University of Idaho, we are examining the efficacy of two promising antimicrobial feed additive classes: organic acids (OAs) and plant essential oils (EOs) for antimicrobial properties and improved dietary nutrient utilization in hybrid striped bass and rainbow trout. Ten diets containing different combinations of extracts from cinnamon, thyme, garlic, and oregano as well as the organic acids sodium diformate and sodium butyrate are being fed to juvenile hybrid striped bass for approximately three months after which growth performance, nutrient utilization, resistance to disease challenge by Strep, and expression of key genetic markers of disease resistance will be assessed.
Accomplishments
