Brian Gause

Chemical and Electrical Approaches to Sedation of Hybrid Striped Bass: Induction, Recovery, and Physiological Responses to Sedation

Abstract Currently, in the United States, there are few sedatives available to fisheries professionals that are safe, effective, and practical. Chemical sedatives, including tricaine methanesulfonate (MS-222), carbon dioxide (CO2), benzocaine, and eugenol may be used to sedate fish, though none of these compounds are currently approved by the U.S. Food and Drug Administration as immediate-release fish sedatives. Another option is the use of electricity to temporarily immobilize fish. Few studies have assessed the efficacy of these options for immediate-release sedation in side-by-side comparisons. We evaluated the use of MS-222 (150 mg/L), CO2 (∼400 mg/L), benzocaine (150 mg/L), eugenol (60 mg/L), and a commercially available electrosedation unit (30 Hz pulsed DC, 60 V, 25% duty cycle, 3-s exposures) to induce hybrid striped bass (white bass Morone chrysops × striped bass M. saxatilis; 510 ± 12 g [mean ± SE]) to stage IV anesthesia or sedation. Induction times were shortest (0.2 ± 0.1 min) when electrosed...

Replacement of Fish Meal with Ethanol Yeast in the Diets of Sunshine Bass

Abstract Increasing demand and rising costs of fish meal (FM) coupled with static landings of reduction fisheries have made continued use of FM-rich aquaculture feeds environmentally and economically unsustainable. Animal- and plant-derived proteins have been investigated as alternatives to FM, with variable success. Observed limitations of commonly used alternative proteins have led nutritionists to investigate new alternatives to FM. Ethanol yeast, a co-product of bioethanol production and potential new alternative protein source, was evaluated as a FM replacement in the diets of sunshine bass (female white bass Morone chrysops × male striped bass M. saxatilis). Five diets were evaluated, including a control diet containing 30% FM and four experimental diets (22.5, 15, 7.5, and 0% FM) in which 25, 50, 75, or 100% of the FM content was replaced with ethanol yeast. Juvenile sunshine bass (∼16 g) were fed twice daily to apparent satiation for 45 d. Production performance of sunshine bass was not impaired b...

Induction, Recovery, and Hematological Responses of Largemouth Bass to Chemo- and Electrosedation

Abstract Sedating fish before handling minimizes the risk of injury to both fish and handler and may also minimize the fishs stress response. We conducted two experiments to quantitatively compare induction and recovery times of largemouth bass Micropterus salmoides sedated with tricaine methanesulfonate (MS-222), eugenol, benzocaine, carbon dioxide (CO2), or electrosedation (pulsed DC).We also assessed the fishs hematological profile following sedation with MS-222, eugenol, and electrosedation. Induction times varied significantly among the sedatives evaluated; electrosedation yielded the fastest inductions (0.2 ± 0.1 min; mean ± SE) and CO2 yielded the slowest (3.6 ± 0.1 min). Times to recovery of equilibrium and responsiveness to tactile and visual–auditory stimuli also varied, ranging from 1.8 ± 0.3 to 3.7 ± 0.3 min and from 2.3 ± 0.3 to 4.0 ± 0.3 min, respectively, depending on the sedative used. Plasma cortisol concentrations were elevated at 0.5 h postsedation among fish sedated with eugenol and ...

Selective Fatty Acid Metabolism, Not the Sequence of Dietary Fish Oil Intake, Prevails in Fillet Fatty Acid Profile Change in Sunshine Bass

Abstract Increasing prices of fish oils (FOs) that are rich in long-chain (LC) polyunsaturated fatty acids (PUFAs) have led to increased implementation of plant-derived oils in aquaculture feeds. Use of diets that contain alternative lipids will affect the fillet fatty acid (FA) profile; therefore, the fish may be “finished” to augment fillet LC-PUFA content before harvest. Understanding tissue FA profile change and selective metabolism of FAs in sunshine bass (female white bass Morone chrysops × male striped bass M. saxatilis) may allow finishing strategies to be optimized for this taxon. We evaluated whether the sequence of dietary LC-PUFA provision affects tissue composition of sunshine bass and whether profile change is similar after a switch to or from an LC-PUFA-rich feed. Sunshine bass were fed practical feeds (∼45% protein, ∼14% lipid) containing FO (rich in LC-PUFAs) or corn oil (CO; rich in medium-chain [MC] PUFAs) according to four regimens: FO feed exclusively, CO feed exclusively, or switchin...

Production Performance and Stress Tolerance of Sunshine Bass Raised on Reduced Fish Meal Feeds Containing Ethanol Yeast

Abstract Ethanol yeast (EY) has been shown to be an effective alternative to fish meal (FM) in diets of sunshine bass (female white bass Morone chrysops × male striped bass M. saxatilis). Diets containing blends of FM and EY yield production performance similar or superior to that of diets containing no EY. Complete replacement of FM with EY, however, reduces feed palatability, impairs production performance, and may affect other aspects of livestock vigor. Accordingly, the objectives of this study were to determine the effects of dietary EY inclusion (with or without a palatant) on the feed intake, growth performance, and physiological robustness of sunshine bass after stressor exposure. Formulations were developed containing 15, 7.5, and 0% FM with EY as the primary alternative protein source. Experimental diets were prepared according to these formulations with and without the addition of 1% soluble canola protein concentrate as a palatant. Replicate tanks of juvenile sunshine bass (∼4.4 g) were fed th...

Amending reduced fish-meal feeds with marine lecithin, but not soy lecithin, improves the growth of juvenile cobia and may attenuate heightened responses to stress challenge

Sparing of marine resources in aquafeeds can be environmentally and economically advantageous; however, fish meal (FM) replacement can affect the production performance and physiological competence. Phospholipids are increasingly understood to be involved in maintaining growth and vigour in fish and may be deficient in reduced FM formulations. Accordingly, we evaluated the growth and stress tolerance of juvenile cobia fed typical (50% FM) or reduced FM feeds (12% FM) with or without phospholipid amendment [1% marine lecithin (12% FM + Marine PL) or soy lecithin (12% FM + Soy PL)] for 6 weeks in triplicate tanks (N = 3) in a recirculation aquaculture system. The 50% FM feed yielded significantly superior growth and growth efficiency in comparison with the 12% FM and 12% FM+ Soy PL feeds, but the 12% FM+ Marine PL feed yielded comparable results to 50% FM feed. A low-water stress challenge induced elevated plasma glucose, cortisol and lactate levels in all treatments. However, a significant interaction (diet × stress) effect suggested a lesser cortisol response among fish fed the 12% FM+ Marine PL and 50% FM diets. These findings demonstrate that growth performance and, perhaps, resilience of cobia raised on reduced FM feeds may be improved by the addition of marine-origin phospholipid to the diet.

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...