John C. Bowzer

Chemical and Electrical Approaches to Sedation of Cobia: Induction, Recovery, and Physiological Responses to Sedation

Abstract To support the growing interest in marine fisheries research in areas such as biotelemetry, tagging, and tracking, we assessed the ability of various sedatives to facilitate this research in juvenile cobias Rachycentron canadum (∼300 g), namely, tricaine methanesulfonate (MS-222; 150 mg/L), carbon dioxide (CO2; ∼750 mg/L), eugenol (60 mg/L), benzocaine (150 mg/L), and pulsed-DC electrosedation (100 V, 30 Hz, 25% duty cycle, 5-s exposure). Induction times (CO2 [z] > benzocaine [y] > eugenol [y] > MS-222 [y] > electrosedation [x]), recovery of equilibrium (CO2 [z] > eugenol [z] > MS-222 [y] > benzocaine [y] > electrosedation [x]), and responsiveness to tactile stimulus (eugenol [z] > MS-222 [y] > benzocaine [y] > CO2 [xy] > electrosedation [x]) differed significantly among the sedative treatments (treatments with the same letters are not significantly different). Total handling time from initial sedative exposure to recovery differed among the sedatives as well (CO2 [z] > eugenol [y] > benzocaine [x] > MS-222 [x] > electrosedation [w]), with cumulative means ± SEs of 5.9 ± 0.2 min for CO2, 4.1 ± 0.2 for eugenol, 2.7 ± 0.2 min for benzocaine and MS-222, and 1.0 ± 0.2 min for electrosedation. Physiological responses differed significantly over time, with transient increases in plasma Cortisol, glucose, osmolality, and lactate that were resolved within 6 h. The overall magnitude of the physiological responses differed among sedatives, depending on the response variable; however, in each case, CO2 elicited the greatest response. Although variations in induction and recovery times were observed, it is likely that these differences can be reasonably accommodated within the context of typical research by adjusting the sedative treatments or allowing for longer induction and recovery times as needed.

Having Your Omega 3 Fatty Acids and Eating Them Too: Strategies to Ensure and Improve the Long-Chain Polyunsaturated Fatty Acid Content of Farm-Raised Fish

For most of the human population, seafood represents the primary source of beneficial long-chain polyunsaturated fatty acids (LC-PUFA) (1). Historically, capture fisheries were able to meet demand, but the current state of fisheries portends a “sea change” in how we feed a seafood- and LC-PUFA-hungry world. The Food and Agriculture Organization of the United Nations (FAO) has stated that of those marine fisheries for which statistics are available, 53% are fully exploited, 28% are over exploited, and 4% are depleted or recovering from depletion; only 15% are considered under exploited, or capable of sustaining greater harvest pressure (2). Although rates of decline have been slaked in some instances, the future of many fisheries remains uncertain (3), and some researchers have gone so far as to predict the collapse of many fisheries unless significant changes are made to current resource management approaches (4–6). As capture fisheries have reached maximum sustainable yields, global demand has continued to grow: global fisheries landings including aquaculture in 1950 was approximately 20 million metric tons (MMT); landings in 2008 topped 140 MMT, of which approximately 115 MMT were used for direct human consumption (2). Increasing demand is a function of human population growth, as well as increasing per capita consumption: annual fish consumption has grown by more than 70% since the 1960s, reaching 17 kg per capita in 2007, the highest recorded to date (2).

Potential of Asian Carp from the Illinois River as a Source of Raw Materials for Fish Meal Production

Abstract Incentivizing overfishing through the creation of high-value markets for Silver Carp Hypophthalmichthys molitrix and Bighead Carp H. nobilis has been proposed as a management strategy for controlling Asian carp in the Illinois River. Asian carp may be rendered into a protein-dense fish meal, and one of the most attractive, high-value end uses for such a product is aquafeed manufacturing. However, the nutritional content and shelf stability of Asian carp as a raw material must be determined to assess its suitability for rendering and subsequent use as a protein source in aquafeeds, which was the focus of this study. To determine seasonal, geographical, and species variation in body composition, fatty acids, and oxidative stability, Asian carp were collected from five reaches of the Illinois River during the fall, spring, and summer (up to 12 individuals of each species per reach per season) and analyzed. Slight geographical, seasonal, and species variation exists in the body composition and fatty ...

Feeding Rate and Frequency Affect Growth of Juvenile Atlantic Spadefish

Abstract The Atlantic spadefish Chaetodipterus faber is an excellent candidate for aquaculture development, but success will depend on the identification of proper feeds and feeding regimens for this species. Accordingly, we evaluated the growth performance of juvenile Atlantic spadefish (3.60 ± 0.03 g [mean ± SE]) fed at rates of 3, 5, or 7% of body weight (BW) per day, either in a single feeding (1×) or in three equal feedings (3×). Weight gain, specific growth rate, feed conversion ratio, and feed intake were significantly affected by both feeding rate and frequency. Weight gain and the specific growth rate increased significantly with feeding rate, and growth was generally greater and more efficient in the 3× groups than in the 1× groups. Fish fed at higher feeding rates accumulated significantly more lipid within the body and had associated decreases in moisture, protein, and ash content, but carcass composition was unaffected by feeding frequency. We suggest that the growth of juvenile Atlantic spad...

Developing Rested Harvest Strategies for Rainbow Trout

AbstractHarvesting fish for slaughter commonly elicits a generalized stress response, which can negatively affect meat quality and processing efficiency. Sedatives used before or during harvest (i.e., “rested harvest”) can minimize these effects. Use of chemical sedatives is regulated by the U.S. Food and Drug Administration and, unfortunately, none are approved for rested harvest. Electrosedation technology is not currently subject to the same regulatory constraints as chemosedation, but its effectiveness in the context of rested harvest has not been adequately tested. Accordingly, we tested the influence of chemo- and electrosedation rested harvest protocols on Rainbow Trout Oncorhynchus mykiss. Marketable-sized fish (~500 g/fish) were subjected to 3 min of crowding and chasing directly after capture (control) or following treatment with eugenol (10 mg/L) or one of five DC electrosedation protocols. After the challenge, fish were sampled to determine blood chemistry profiles or slaughtered by dewatering...

Extrusion Temperature and Pellet Size Interact to Influence Growth Performance of Hybrid Striped Bass Fed Industrially Compounded Aquafeeds

AbstractThe objective of this experiment was to jointly assess the possible influences of aquafeed extrusion temperature and pellet size and uniformity on growth performance of juvenile hybrid Striped Bass (White Bass Morone chrysops × Striped Bass M. saxatilis). A diet formulated to meet or exceed the nutritional requirements of hybrid Striped Bass was coupled with different feed manufacturing strategies to yield a range of compositionally identical but physically distinct feeds. Batches of feed were extruded at 107 ± 6°C or 127 ± 3°C through dies estimated to yield pellets that were “small” (3 mm), “recommended” (4 mm), or “large” (5 mm) relative to the size ranges suggested for the target fish size. Portions of the uniformly small and large feeds were combined (25:75, 50:50, and 75:25 ratios of small : large pellets) to create additional mixed-sized feeds. Fish were stocked in a recirculating aquaculture system (fish size: 19.6 ± 0.7 g [mean ± SE]; 10 fish/tank) comprising thirty-six 119-L circular tan...