Thiamine Levels in Muscle and Eggs of Adult Pacific Salmon from the Fraser River, British Columbia

Abstract

Multiple species and stocks of Pacific salmon Oncorhynchus spp. have experienced large declines in the number of returning adults over a wide region of the Pacific Northwest due to poor marine survival (low smolt-to-adult survival rates). One possible explanation for reduced survival is thiamine deficiency. Thiamine (vitamin B ) is an essential vitamin with an integral role in many metabolic processes, and thiamine deficiency is an important cause of salmonid mortality in the Baltic Sea and in the Laurentian Great Lakes. To assess this possibility, we (1) compared muscle thiamine content over time in a holding experiment using Fraser River (British Columbia) Sockeye Salmon O. nerka to establish whether adults that died during the holding period had lower thiamine levels than survivors, (2) measured infectious loads of multiple pathogens in held fish, and (3) measured egg thiamine content from four species of Pacific salmon collected on Fraser River spawning grounds. Chinook Salmon O. tshawytscha had the lowest egg thiamine, followed by Sockeye Salmon; however, egg thiamine concentrations were above levels known to cause overt fry mortality. Thiamine vitamers in the muscle of Fraser River adult Sockeye Salmon shifted over a 13-d holding period, with a precipitous decline in thiamine pyrophosphate (the active form of thiamine used in enzyme reactions) in surviving fish. Survivors also carried lower loads of Flavobacterium psychrophilum than fish that died during in the holding period. Although there is no evidence of thiamine deficiency in the adults studied, questions remain about possible thiamine metabolism-fish pathogen relationships that influence survival.

Model for estimating thiamine deficiency-related mortality of Atlantic salmon (Salmo salar) offspring and variation in the Baltic salmon M74 syndrome

“…The proportion and concentration of monophosphorylated thiamine derivative TMP were lowest among the thiamine components in the eggs, regardless of THIAM or TotTH concentration. A similar observation has been reported for other salmonines (Czesny et al 2009;Welch et al 2018;. However, the TMP concentration had a stronger negative relationship with YSFM than the concentration of TPP.…”

“…Compared to River Tenojoki salmon, several Oncorhynchus species that had been feeding in the Pacific Ocean contained thiamine in eggs in even higher concentrations when they returned for spawning (TotTH 10.9-19.5 nmol g −1 ). In them, THIAM (8.0-18.4 nmol g −1 ) was by far the largest component (73-94%) of TotTH in the eggs (Welch et al 2018).…”

“…In several landlocked salmonine species, the THIAM concentration and proportion of muscle were similarly low (mean values 0.07-0.20 nmol g −1 and 1.28-3.36%) . In sockeye salmon (O. gorbuscha) that had been feeding in the Pacific Ocean, the reported concentration and proportion of THIAM in the muscle (3.7 nmol g −1 and 30%, respectively,) were much higher than in Baltic salmon, as was the TotTH concentration (12.2 nmol g −1 ) (Welch et al 2018).…”

“…Unlike most Baltic salmon, the salmon of the rivers flowing into the Gulf of Riga and feeding there on a more diverse diet containing no sprat are not known to suffer from M74 (Karlsson et al 1999). Nor have Atlantic salmon feeding in the Atlantic Ocean or other ocean-feeding salmonines displayed thiamine deficiency (Pickova et al 1998(Pickova et al , 2003Welch et al 2018).…”

High Lipid Content of Prey Fish and n−3 PUFA Peroxidation Impair the Thiamine Status of Feeding-Migrating Atlantic Salmon (Salmo salar) and Is Reflected in Hepatic Biochemical Indices

“…Consistently, the proportion of TPP in muscle was larger in BS salmon (mean ± SE: 84 ± 1%, range: 83-86%) than in BPr salmon (64 ± 4%, 37-75%), whereas it was smallest in GoF salmon (47 ± 5%, 22-67%). After feeding in the Pacific Ocean, the proportion of TPP in the muscle in sockeye salmon (Oncorhynchus nerka Walbaum), 48 ± 6%, was similar to GoF salmon [87]. In BS salmon, the muscle TPP proportion was near those observed in the muscle of salmon at spawning (78-90%), and that of the single M74 female of M74 monitoring in 2004 was 89% [71].…”