Reproductive Failure of Landlocked Atlantic Salmon from New York's Finger Lakes: Investigations into the Etiology and Epidemiology of the “Cayuga Syndrome”

We describe a disease syndrome that afflicts larval, landlocked Atlantic salmon Salmo salar from Cayuga Lake, one of central New York's Finger Lakes. Mortality associated with the “Cayuga syndrome” is 98–100%. Death usually occurs between 650 and 850 centigrade degree-days after fertilization, approximately 2–4 weeks before yolk resorption is complete. Although there is minor temporal variation in the onset of the Cayuga syndrome in progeny from individual females, all sac fry eventually succumb. Incubation of embryos and sac fry under constant, ambient, or reduced temperature regimens slightly alters the degree-day timing of syndrome onset, but does not improve survival. Based on mortality rate, manifestation of the Cayuga syndrome has not changed in the past 10 years, even though incubation waters of varying chemistry and temperature have been used. Mortality of the negative control stocks used for these studies never exceeded 10% from hatching to first feeding. Findings from reciprocal crossbreeding experiments indicate the problem is associated with ova only. A noninfectious etiology is indicated by the lack of consistently identifiable fish pathogens from syndrome-afflicted sac fry and by the failure to transmit the condition horizontally. Suspect contaminants were eliminated as potential causative factors. Epidemiological studies on the viability of other Finger Lakes stocks indicate that Atlantic salmon from Keuka and Seneca lakes are also afflicted (100% mortality). yet those from Skaneateles Lake are not. The cause of this syndrome appears to be nutritional.This is the publisher’s final pdf. The published article is copyrighted by the American Fisheries Society and can be found at: http://www.tandfonline.com/toc/uahh20/current#.Ug5ocnfAF8E

Distribution of an Invasive Aquatic Pathogen (Viral Hemorrhagic Septicemia Virus) in the Great Lakes and Its Relationship to Shipping

Viral hemorrhagic septicemia virus (VHSV) is a rhabdovirus found in fish from oceans of the northern hemisphere and freshwaters of Europe. It has caused extensive losses of cultured and wild fish and has become established in the North American Great Lakes. Large die-offs of wild fish in the Great Lakes due to VHSV have alarmed the public and provoked government attention on the introduction and spread of aquatic animal pathogens in freshwaters. We investigated the relations between VHSV dispersion and shipping and boating activity in the Great Lakes by sampling fish and water at sites that were commercial shipping harbors, recreational boating centers, and open shorelines. Fish and water samples were individually analyzed for VHSV using quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and cell culture assays. Of 1,221 fish of 17 species, 55 were VHSV positive with highly varied qRT-PCR titers (1 to 5,950,000 N gene copies). The detections of VHSV in fish and water samples were closely associated and the virus was detected in 21 of 30 sites sampled. The occurrence of VHSV was not related to type of site or shipping related invasion hotspots. Our results indicate that VHSV is widely dispersed in the Great Lakes and is both an enzootic and epizootic pathogen. We demonstrate that pathogen distribution information could be developed quickly and is clearly needed for aquatic ecosystem conservation, management of affected populations, and informed regulation of the worldwide trade of aquatic organisms

Diseases and Parasites of Scallops

Knowledge of the diseases and parasites of scallops has continued to change since the second edition of this book (McGladdery et al., 2006). Advancements in the field of scallop health research have followed the broader improvements in the ability to identify disease agents in other aquatic animals. Significant progress has been made in diagnostic capability, particularly the ability to distinguish between infectious pathogens and cryptic histopathological lesions in scallops using molecular techniques. Evidence of this is the progress made in combating opportunistic infections of larvae and juveniles of several scallop species reared under hatchery conditions. There are an increasing number of investigators who pursue the unexplained mortalities in the bivalve hosts using a new generation of diagnostic tools. The diversification of scallop species being brought into stock enhancement and aquaculture programs on a global scale has led to increased contributions from our Asian colleagues. Parallel development of remote underwater photography technology for surveillance and stock assessment purposes as well as suspension culture techniques has greatly improved our capability to detect health challenges in many scallop species, challenges which previously evaded direct observation in the scallop\u27s benthic domain.The present review follows that of Getchell (1991), dividing sections by taxonomic group of pathogen. The updating of these taxonomic divisions attempted to keep up with changes made over the last decade. The listing of pathogens by scallop species also has been continued in Table 1, to facilitate scallop-specific cross-referencing. The infectious agents described in detail in the prior two editions remain to ensure as comprehensive a reference as possible. For clarity, a more encompassing definition of the term pathogen has been embraced as a microorganism capable of causing host damage (Paillard et al., 2004). The general approach is to first discuss the aetiology of the scallop disease, then cover the pathogenesis or host syndromes associated with the disease and finally, describe the mode of action of the pathogen (pathogenicity) if known (Paillard et al., 2004). The components of pathogen virulence emphasised are the genetic, biochemical and structural features that enable it to damage the host. © 2016 Elsevier B.V

Complementary approaches to diagnosing marine diseases: a union of the modern and the classic

Linking marine epizootics to a specific etiology is notoriously difficult. Recent diagnostic successes show that marine disease diagnosis requires both modern, cutting-edge technology (e.g. metagenomics, quantitative realtime PCR) and more classic methods (e.g. transect surveys, histopathology and cell culture). Here, we discuss how this combination of traditional and modern approaches is necessary for rapid and accurate identification of marine diseases, and emphasize how sole reliance on any one technology or technique may lead disease investigations astray. We present diagnostic approaches at different scales, from the macro (environment, community, population and organismal scales) to the micro (tissue, organ, cell and genomic scales). We use disease case studies from a broad range of taxa to illustrate diagnostic successes from combining traditional and modern diagnostic methods. Finally, we recognize the need for increased capacity of centralized databases, networks, data repositories and contingency plans for diagnosis and management of marine disease

Fish analyzed for VHSV and number of fish determined to be positive with data on fish sizes and known vulnerability to VHSV.

<p>1. VHSV susceptibility is reported by the U.S. Department of Agriculture, Animal and Plant Health Inspection Service <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0010156#pone.0010156-Center1" target="_blank">[12]</a> although other species can be infected.</p

Detection of VHSV in fish and water and the presence of VHSV positive fish at sampling sites in and outside of invasion hotspots shown in Figure 1.

<p>Detection of VHSV in fish and water and the presence of VHSV positive fish at sampling sites in and outside of invasion hotspots shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0010156#pone-0010156-g001" target="_blank">Figure 1</a>.</p

Distribution of VHSV positive fish in the Great Lakes from 2003 through 2008 as reported by the U.S. Department of Agriculture Animal and Plant Health Inspection Service [12] and the distribution of documented invasion hotspots [18], [27].

<p>Distribution of VHSV positive fish in the Great Lakes from 2003 through 2008 as reported by the U.S. Department of Agriculture Animal and Plant Health Inspection Service <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0010156#pone.0010156-Center1" target="_blank">[12]</a> and the distribution of documented invasion hotspots <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0010156#pone.0010156-Grigorovich1" target="_blank">[18]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0010156#pone.0010156-Cangelosi1" target="_blank">[27]</a>.</p

VHSV detection in fish and water using qRT-PCR and cell culture assays shown by site, type of site, and number of fish tested.

<p>VHSV detection in fish and water using qRT-PCR and cell culture assays shown by site, type of site, and number of fish tested.</p

Distribution of VHSV positive fish and water at sites classified as commercial shipping harbors, recreational boating centers, and open shoreline.

<p>Distribution of VHSV positive fish and water at sites classified as commercial shipping harbors, recreational boating centers, and open shoreline.</p