The Effects of Different Winter Feeding Regimens on Growth, Survival, and Fatty Acid Composition of Fathead Minnow and Golden Shiners

Abstract

Winter mortality is a common problem for Arkansas baitfish farmers that produce Fathead Minnow (FHM) Pimephales promelas and Golden Shiners (GS) Notemigonus crysoleucas. Winter feeding programs are a potential avenue to improve survival and condition and reduce weight loss of baitfish. Methods of winter feeding vary widely among producers, and currently there are no recognized best management practices. The impacts of different winter feeding regimens on FHM and GS survival, growth, and lipid storage were evaluated in temperature‐controlled aquarium systems. Fathead Minnow (mean ± SD = 0.88 ± 0.04 g) or GS (0.88 ± 0.02 g) were stocked at ambient water temperature, and the temperature was reduced to 6°C (FHM) or 8°C (GS) to mimic winter conditions. Three feeding regimens were implemented (3 tanks/regimen) that included ad libitum feeding twice per week (2×/week), once per week (1×/week), or once per month (1×/month). Significant differences in weight gain (loss), condition factor (K), and specific growth rate were observed after 13 weeks for FHM. Fish that were fed 2×/week gained nearly 3%, while fish that were fed 1×/week or 1×/month lost weight (2.3% and 10.1%, respectively). There were no significant differences in GS final weight (0.79–0.82 g), survival (65.0–88.3%), or weight gain (−6.84% to −9.50%) among treatments after 12 weeks. The GS from the 2×/week treatment had significantly higher K‐values than GS that were fed 1×/week or 1×/month. Fatty acid profiles of both species differed among treatments, showing a decline in saturated fatty acids from initial levels and an increase in polyunsaturated fatty acids (PUFAs) as feeding frequency decreased. Results suggest that fish may lose weight during the winter, but it does not appear to adversely affect survival, and both species alter their fatty acid compositions to optimize n‐3 PUFAs during cold water temperatures.

Weight Loss, Survival, and Fatty Acid Composition in Overwintered Juvenile Coppernose Bluegill Lepomis macrochirus purpurescens Cultured in Outdoor Tanks Using Different Feeding Regimens

“…This is the first published report on the effects of different feeding regimens on winter growth and FA composition of Coppernose Bluegill. Data from the present study indicated that all feeding regimes evaluated for winter-fed Coppernose Bluegill resulted in weight loss during the culture period, which is in agreement with previous reports on centrarchids and other fish species cultured in Arkansas (Roy et al 2017(Roy et al , 2019a(Roy et al , 2019b. However, unlike those reports, in which a constant low water temperature was maintained throughout the study, the present study was conducted in an outdoor setting with fluctuating ambient water temperatures.…”

“…Previously, it was postulated that winter mortality in some cultured species of fish might be due to reduced feeding of fish (i.e., a lower amount of feed administered by the producer, a lower feed intake by the fish, or both) and the concomitant adverse changes due to cold, reduced disease resistance and immunity, and changes in essential FAs (Roy et al 2017). With several published reports on winter feeding regimens for various species of sport fish and baitfish (Roy et al 2017(Roy et al , 2019a(Roy et al , 2019b), it appears highly likely that for most fish species investigated, this may not be an accurate hypothesis. Despite the weight loss exhibited by the fish, survival percentages were generally high in those studies.…”

“…Fish were weighed, lyophilized, and ground, and the ground homogenates were stored at −20°C until lipid extraction according to the method of Folch et al (1957). Analyses using gas chromatography were carried out according to Roy et al (2017Roy et al ( , 2019b. Briefly, to each extracted lipid tube, 100 μL of a C-13 solution (Nu-Chek Prep N-13A-A7-N) in hexane were added and evaporated to dryness under nitrogen using a nitrogen evaporator.…”

“…Winter losses of fish, particularly juvenile fish, have been routinely reported in the spring by Arkansas sport fish producers (Roy et al 2013(Roy et al , 2017(Roy et al , 2019a(Roy et al , 2019b. Winter mortality on commercial farms appears to be more prevalent in smaller fish, particularly those measuring less than 7.6 cm (3 in) TL (Roy et al 2013).…”

“…Thus, it appears that FA compositions during the winter tend to reflect preferential use of some FAs for energy and the preferential retention of other FAs for their critical functional properties in disease resistance, ionic balance, immunity, membrane fluidity, and inflammatory response (Castell et al 1972;Tacon 1996;Glencross 2009). It has been reported that decreases in saturates and monoenes occur in winter (Roy et al 2017(Roy et al , 2019a(Roy et al , 2019b. Oleic acid (OA; 18:1[n-9]) is reportedly used as an energy source during winter (Henderson and Sargent 1985;Roy et al 2017), but Tocher et al (1998 suggested that 18:1 (n-9) can be utilized as a substrate for PUFA synthesis.…”