Reginald B. Blaylock

Amyloodinium ocellatum causes epizootics in marine fish hatcheries. Frozen, wild fish, often used as food in aquaculture, could introduce the disease. We investigated the parasite's ability to survive, reproduce and infect a host after freezing. Infected gills were frozen at −20°C for either 0, 24, 36, 48, or 72 h. Parasite viability was assessed first by placing thawed infected gills into tanks with naïve fish. Gills of the exposed fish were examined on day 0 and on days 4 and 7 post‐exposure. Tomonts from infected gills in all freeze durations produced infections. However, dinospore production decreased and infections took longer to establish in fish exposed to tomonts from the 72 h treatment. Second, eight tomonts from each freeze duration were placed in 5 mL of 25 ppt artificial seawater at 22°C in individual wells of a 12‐well plate and monitored for hatching. Ninety seven percent of tomonts from all treatments hatched. Tomonts frozen for up to 72 h survived, reproduced and infected fish, but dinospore production decreased as freeze duration increased. Extrapolation from the rate of reduction in dinospore production over the freeze durations tested suggests that a freeze duration of 237 h could inactivate all tomonts.

The Journal of Parasitology publishes on basic or applied aspects of general, veterinary, or medical parasitology, and epidemiology.

Culture models and facilities for large‐scale, commercial production of popular Gulf of Mexico species are unavailable. The spotted seatrout (Cynoscion nebulosus) is one of the most popular recreational fishes in the Gulf of Mexico. Seatrout culture techniques were adapted from red drum (Sciaenops ocellatus) protocols developed in the 1970s. Broodstock husbandry, spawning, and extensive pond rearing techniques using fertilized and bloomed brackish ponds were well‐established by the 1980s. By 2018, approximately 80 million 25–30‐day old seatrout had been produced, mainly for stock enhancement. Cannibalism and poor nutrition hindered intensive tank culture. Between 2005 and 2015, an intensive tank‐rearing protocol that reduced cannibalism and intracohort variability and increased average survival to almost 50% was developed using algal concentrate, rotifers, brine shrimp (Artemia sp.), and microencapsulated feeds. Preliminary results suggested that a 500 g fish could be produced in approximately 10 months. Nevertheless, interest in commercialization has remained low. Zootechnical performance throughout the latter stages of culture, the economics of production, consumer preferences/perceptions, and market capacity must be documented to complete the assessment of the spotted seatrout as a species for commercial aquaculture. The optimization of aquafeeds specific for seatrout and a domestication program is warranted to further facilitate industry growth.

Unless humanity achieves United Nations Sustainable Development Goals (SDGs) by 2030 and restores the relatively stable climate of pre-industrial CO₂ levels (as early as 2140), species extinctions, starvation, drought/floods, and violence will exacerbate mass migrations. This paper presents conceptual designs and techno-economic analyses to calculate sustainable limits for growing high-protein seafood and macroalgae-for-biofuel. We review the availability of wet solid waste and outline the mass balance of carbon and plant nutrients passing through a hydrothermal liquefaction process. The paper reviews the availability of dry solid waste and dry biomass for bioenergy with CO₂ capture and storage (BECCS) while generating Allam Cycle electricity. Sufficient wet-waste biomass supports quickly building hydrothermal liquefaction facilities. Macroalgae-for-biofuel technology can be developed and straightforwardly implemented on SDG-achieving high protein seafood infrastructure. The analyses indicate a potential for (1) 0.5 billion tonnes/yr of seafood; (2) 20 million barrels/day of biofuel from solid waste; (3) more biocrude oil from macroalgae than current fossil oil; and (4) sequestration of 28 to 38 billion tonnes/yr of bio-CO₂. Carbon dioxide removal (CDR) costs are between 25–33% of those for BECCS with pre-2019 technology or the projected cost of air-capture CDR.

The corticosteroid hormone cortisol is the central mediator of the teleost stress response. Therefore, the accurate quantification of cortisol in teleost fishes is a vital tool for addressing fundamental questions about an animal’s physiological response to environmental stressors. Conventional steroid extraction methods using plasma or whole-body homogenates, however, are inefficient within an intermediate size range of fish that are too small for phlebotomy and too large for whole-body steroid extractions. To assess the potential effects of hatchery-induced stress on survival of fingerling hatchery-reared Spotted Seatrout (Cynoscion nebulosus), we developed a novel extraction procedure for measuring cortisol in intermediately sized fish (50–100 mm in length) that are not amenable to standard cortisol extraction methods. By excising a standardized portion of the caudal peduncle, this tissue extraction procedure allows for a small portion of a larger fish to be sampled for cortisol, while minimizing the potential interference from lipids that may be extracted using whole-body homogenization procedures. Assay precision was comparable to published plasma and whole-body extraction procedures, and cortisol quantification over a wide range of sample dilutions displayed parallelism versus assay standards. Intra-assay %CV was 8.54 %, and average recovery of spiked samples was 102 %. Also, tissue cortisol levels quantified using this method increase 30 min after handling stress and are significantly correlated with blood values. We conclude that this modified cortisol extraction procedure provides an excellent alternative to plasma and whole-body extraction procedures for intermediately sized fish, and will facilitate the efficient assessment of cortisol in a variety of situations ranging from basic laboratory research to industrial and field-based environmental health applications.

Stock enhancement programs rely on the ability to recapture and identify stocked fish to evaluate stocking effectiveness. Since 2006, the Seatrout Population Enhancement Cooperative (SPEC) has released almost 600,000 Spotted Seatrout Cynoscion nebulosus, about 100 mm TL, tagged with opercular coded wire tags (CWTs) into coastal Mississippi waters. However, only about 50 fish have been recaptured and initial retention of the opercular CWT has rarely exceeded 75%. This study first evaluated the suitability of visible implant alpha (VIA) and visible implant elastomer (VIE) tags for use in juvenile Spotted Seatrout. The VIA tags performed poorly. Based on those results, the study evaluated the effects of tagging site and fish size on survival, growth, and retention of CWTs and VIE tags and VIE tag fragmentation in juvenile Spotted Seatrout. Three separate growth experiments with juvenile Spotted Seatrout that had mean initial TLs of 93, 138, and 152 mm, respectively, were conducted to assess the effects of tagging. Each growth experiment had nine treatments consisting of a control, fish with either an opercular CWT, a dorsal muscle CWT, a ventral caudal fin VIE tag, or a jaw VIE tag, and four false‐tagged treatments corresponding to each tagged treatment. Dorsal CWTs were retained better than opercular CWTs; VIE tags were equally retained regardless of body location. However, VIE tag quality was affected over the long term by pigmentation overlap and fragmentation. Growth rates and survival were not different within any size‐class experiment or among treatments. This study has shown that CWTs and VIE tags are effective marking methods for juvenile Spotted Seatrout. Received October 11, 2012; accepted May 16, 2013

Kudoa hypoepicardialis n. sp. infects the space between the epicardium and the compact myocardium and, in intense infections, the pericardial chamber of man-of-war fish (Nomeus gronovii) (Nomeidae) (the type host), blue runner (Caranx crysos) (Carangidae), Warsaw grouper (Epinephelus nigritus) (Serranidae), Atlantic tripletail (Lobotes surinamensis) (Lobotidae), northern red snapper (Lutjanus campechanus) (Lutjanidae), black drum (Pogonias cromis) (Sciaenidae), and bluefish (Pomatomus saltatrix) (Pomatomidae) in the northern Gulf of Mexico. This is the first report of a Kudoa sp. from the heart of a fish in the Gulf of Mexico, and of these hosts, only the bluefish was previously identified as a host for a species of Kudoa. Spores of the new species varied slightly in size among these hosts but were regarded as conspecific based on their nearly identical (99.9%) small-subunit (SSU) ribosomal DNA (rDNA) sequence. The new species differs both from the 4 nominal species of Kudoa reported from fishes in the Gulf of Mexico and from K. pericardialis, an allopatric species that infects the pericardial cavity, by the combination of having a large spore, a small polar capsule, and a polar filament with a single coil. The new species is morphologically and genetically most similar to K. shiomitsui, an allopatric species that infects the heart and pericardial cavity, but is distinguished from it based on a 4.2% difference in the SSU rDNA sequence. Heart lesions primarily were restricted to the vicinity of plasmodia and included a layer of fibrinous inflammation characterized by lymphocytes, macrophages, and granulomas as well as epithelioid encapsulations around plasmodia. Heavily infected hosts had melanin-like deposits and adipose cells beneath the epicardium. and the epicardium was discontinuous and apparently breached by plasmodia in some regions. Cardiac muscle, gill, liver, spleen, intestine, and kidney were normal.