Weight loss, survival, and fatty acid composition in over-wintered juvenile coppernose bluegill (Lepomis macrochirus purpurescens) cultured in outdoor tanks using different feeding regime

Authors: ROY, LUKE - Auburn University; Rawles, Steven - Steve; QUINTERO, HERBERT - University Of Arkansas At Pine Bluff; KELLY, ANITA - Auburn University; PARK, JEONGHWAN - Pukyong National University; Webster, Carl

Submitted to: North American Journal of Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/20/2021
Publication Date: 8/3/2021
Citation: Roy, L.A., Rawles, S.D., Quintero, H.E., Kelly, A.M., Park, J., Webster, C.D. 2021. Weight loss, survival, and fatty acid composition in over-wintered juvenile coppernose bluegill (Lepomis macrochirus purpurescens) cultured in outdoor tanks using different feeding regime. North American Journal of Aquaculture. 84(1):42-52. https://doi.org/10.1002/naaq.10213.
DOI: https://doi.org/10.1002/naaq.10213

Interpretive Summary: Commercial producers raising centrarchids (bluegills and largemouth bass) in Arkansas routinely report winter mortality because fish could be susceptible to harsh winter (cold) water temperatures. The foodfish and sportfish industry in the southern U.S. often report unexplained mortality during winter months (winter kill). Coppernose bluegill (Lepomis macrochirus purpurescens) is a popular sportfish for recreational fishing and currently, there are no recommended best management practices for winter feeding of this species. To investigate the effect of different feeding regimens on winter performance of coppernose bluegill, an outdoor feeding trial was conducted. Four feeding regimens were used: feeding twice per week (2x/week), once per week (1x/week), twice per month (2x/month), or once per month (1x/month). Twenty-five coppernose bluegill (initial weight 2.59 g) were stocked per tank (16 tanks, 4 replicates). Water temperatures ranged from 0–16 deg C during the trial. After 95 d, there were no differences in final weight or condition factor of the fish in any of the treatments. Fish fed 2x/week or 1x/week had higher survival percentages than those fed 2x/month or 1x/month. It appears that winter feeding frequency did not influence fatty acid profiles in coppernose bluegill. Total polyunsaturated fatty acids (PUFA), n-3 and n-6, levels were higher in fish at the conclusion of the study compared to initially. n-3 PUFA are the "heart-healthy" fatty acids that are important to good cardiovascular condition in humans. This study indicates that (1) overwintering and infrequently-fed coppernose bluegill preferentially conserve PUFA, and (2) feeding once or twice per week may be a beneficial strategy for sportfish producers to increase survival of coppernose bluegill during the winter.

Technical Abstract: Commercial producers raising centrarchids in Arkansas routinely report winter mortality. Juvenile centrarchids are susceptible to harsh winter conditions. Coppernose bluegill (Lepomis macrochirus purpurescens) is a popular sportfish for recreational fishing and there are no recommended best management practices for winter feeding of this species. To investigate the effect of different feeding regimens on performance of coppernose bluegill, an outdoor trial was conducted. Four feeding regimens were implemented that included feeding twice per week (2x/week), once per week (1x/week), twice per month (2x/month), or once per month (1x/month). Twenty-five coppernose bluegill (initial weight 2.59 +/- 0.19 g) were stocked per tank (16 tanks, 4 replicates). Temperatures ranged from 0–16 deg C during the trial. After 95 d, there were no differences (P > 0.05) in final weight, weight loss, or condition factor. Fish fed 2x/week or 1x/week had higher survival (P < 0.05) than those fed 2x/month or 1x/month. Fatty acid profiles of initial fish were distinctly different from those of post winter-fed bluegill, whereas winter feeding frequency did not appear to influence fatty acid profiles in coppernose bluegill. Concentrations of saturates were higher in initial fish than in post-winter fish. Monosaturates 16:1 and 18:1n-9 were higher in initial fish than in post-winter fish. Initial fish contained lower levels of 18:2n–6, 20:4, and 22:6n–3 than post-winter fish. Total polyunsaturated fatty acids (PUFA), n-3 and n-6 levels were also lower in initial fish than post-winter fish, while the ratio n-6/n-3 fatty acids did not differ significantly among initial and post winter-fed fish. Data indicate that 1) overwintering and infrequently fed coppernose bluegill preferentially conserve PUFA, and 2) feeding once or twice per week may be a beneficial strategy for sportfish producers to increase survival of coppernose bluegill during the winter.