Troutlodge (United States)

Previously accurate genomic predictions for Bacterial cold water disease (BCWD) resistance in rainbow trout were obtained using a medium-density single nucleotide polymorphism (SNP) array. Here, the impact of lower-density SNP panels on the accuracy of genomic predictions was investigated in a commercial rainbow trout breeding population. Using progeny performance data, the accuracy of genomic breeding values (GEBV) using 35K, 10K, 3K, 1K, 500, 300 and 200 SNP panels as well as a panel with 70 quantitative trait loci (QTL)-flanking SNP was compared. The GEBVs were estimated using the Bayesian method BayesB, single-step GBLUP (ssGBLUP) and weighted ssGBLUP (wssGBLUP). The accuracy of GEBVs remained high despite the sharp reductions in SNP density, and even with 500 SNP accuracy was higher than the pedigree-based prediction (0.50-0.56 versus 0.36). Furthermore, the prediction accuracy with the 70 QTL-flanking SNP (0.65-0.72) was similar to the panel with 35K SNP (0.65-0.71). Genomewide linkage disequilibrium (LD) analysis revealed strong LD (r2 ≥0.25) spanning on average over 1Mb across the rainbow trout genome. This long-range LD likely contributed to the accurate genomic predictions with the low-density SNP panels. Population structure analysis supported the hypothesis that long-range LD in this population may be caused by admixture. Results suggest that lower-cost, low-density SNP panels can be used for implementing genomic selection for BCWD resistance in rainbow trout breeding programs.

Benzocaine, 2-phenoxyethanol and MS-222 were tested as anaesthetics for several handling procedures with spotted rose snapper Lutjanus guttatus broodstock. Significant differences in time for induction and recovery were found with specific doses, as well as a direct correlation between the dose and the induction time. Each procedure demanded specific anaesthesia levels where the stage of deep anaesthesia should not be surpassed. The most effective agent for inducing deep anaesthesia was MS-222, with the least amount of time required for induction and recovery when using 100 mg l-1. It was followed by 250 µl l-1 of 2-phenoxyethanol, which was less costly.

World trade in live salmonid embryos (eyed eggs) has grown in response to increased global salmon production, particularly in South America, and parallels international trade in farmed salmonid products. Rainbow trout (Oncorhynchus mykiss), Atlantic salmon (Salmo salar) and coho salmon (O. kisutch) are the most commercially important species. In 1992, the Food and Agriculture Organization of the United Nations estimated world production of rainbow trout at 300,000 tonnes, while the production of Atlantic salmon was estimated at 250,000 tonnes and coho salmon at 50,000 tonnes. One can estimate that roughly 3 billion, 150 million and 30 million eggs, respectively, were required to produce this yield. Broodstock are cultivated world-wide, using a wide variety of water sources, including the marine environment, riverine water containing anadromous fish, and ground water free of migrating fish. As many as 70% of all coho eggs are derived from feral fish. Approximately 50% of all commercial salmonid eyed eggs are produced in Europe, and approximately 15% are produced in the state of Washington, United States of America. Conditions which are ideal for commercial salmonid grow-out are not necessarily ideal for the cultivation of salmonid broodstock; this is one reason why international egg trade is necessary. The trend of current salmonid health regulations is towards facilitating egg commerce on a regional level, in an attempt to control disease transmission. Regulations controlling egg importation often include pathogens which are not vertically transmitted. This serves only to increase egg prices, in compensation for the cost of laboratory tests. Genetic improvements have been the cornerstone of increasing commercial production of all agricultural commodities. Fish health regulations are sometimes instituted in an effort to protect the local industry, but in fact they act more often to restrict the flow of genetic material and may actually serve to reduce industry productivity and profitability.