Effects of Thiamine on Reproduction of Atlantic Salmon and a New Hypothesis for Their Extirpation in Lake Ontario

Abstract

Previous researchers demonstrated that a mortality in fry (called Cayuga syndrome) of Atlantic salmon Salmo salar from Cayuga Lake (New York) was associated with low levels of thiamine. They reduced the mortality of fry by bathing or injecting fry with thiamine. We injected four to six gravid female Atlantic salmon with either physiological saline (PS) or PS plus thiamine (7 mg/kg weight) 14-23 d before eggs were stripped, fertilized, and incubated in individual lots. Chemical analyses showed that eggs from control and treated salmon contained 1.1 and 1.6 nmol thiamine/g, respectively. Thiamine injections had no significant effect on the percentage of eggs that hatched. Between 700 and 800 Celius degree-days postfertilization, control fry (saline) showed signs of Cayuga syndrome and a 45% incidence of mortality; in contrast, mortality was only 1.9% for fry that received thiamine. By 1,078 degree-days postfertilization, mean mortality of control fry was 98.6%, whereas that for thiamine-injected salmon was 2.1%. This study showed that thiamine injections of prespawning female salmon from Cayuga Lake increased thiamine content of their eggs and prevented the Cayuga syndrome and subsequent mortality of fry. Historically, overfishing, pollution, and building of dams and barriers to spawning migration were suggested as possible causes of the decline of the Atlantic salmon in Lake Ontario and Cayuga Lake. Based on our findings and other reports, we suggest another possible contributing cause of the extirpation of landlocked Atlantic salmon in Lake Ontario and some other inland waters of New York: the entrance of alewives Alosa pseudoharengus containing thiaminase, which induced thiamine deficiency in eggs and increased mortality in fry of the predatory salmon.Atlantic salmon Salmo salar, which were once

Landlocked Fall Chinook Salmon Maternal Liver and Egg Thiamine Levels in Relation to Reproductive Characteristics

“…However, this value (2.75 nmol/g) was slightly less than the 2.99 nmol/g total thiamine value reported to produce 20% mortality in Lake Ontario Chinook Salmon eggs [31], but the overall high survival of the fry, and the lack of substantial post-hatch mortality, from this spawn appears to indicate that mortality due to thiamine deficiency did not occur. Of the 99 spawns sampled in this study, only three showed survival of less than 90% between hatch and swim-up, which is the most lethal period for thiamine deficiency complex [28]. Of these, the lowest concentration of total egg thiamine was 9.25 nmol/g, much greater than the concentration considered the upper end of the thiamine deficiency complex [28,31], making it unlikely that a lack of thiamine was the cause of fry mortality.…”

“…Of the 99 spawns sampled in this study, only three showed survival of less than 90% between hatch and swim-up, which is the most lethal period for thiamine deficiency complex [28]. Of these, the lowest concentration of total egg thiamine was 9.25 nmol/g, much greater than the concentration considered the upper end of the thiamine deficiency complex [28,31], making it unlikely that a lack of thiamine was the cause of fry mortality. The adequacy of thiamine levels in Lake Oahe Salmon observed in this study is further supported by the similar hatch to swim-up survival rates of Lake Oahe Salmon eggs to eggs treated with supplemental thiamine from populations with a history of thiamine deficiency complex [15,16,20].…”

“…Survival to the eyed-egg stage of development has been reported from 83% to 98% from Chinook Salmon in their native range [3,28,52,53]. Egg survival in 2003 and 2005 was also dramatically lower than that previously reported for Lake Oahe Chinook Salmon [1].…”

“…Perhaps of more interest, with the exception of 2001, mean maternal liver total thiamine levels were less than the level of total liver thiamine (6.3 nmol/g) in healthy Atlantic Salmon [18], and very similar to Great Lakes Salmonids producing progeny with Thiamine Deficiency Complex [44]. These relatively low levels may not be lethal, but lower thiamine levels can impact adult fish neurological function [19,45], metabolic rates [15,28], and muscle weakness [34], thereby potentially decreasing foraging efficiency and subsequently contributing to smaller body sizes [22,28]. Similar to that reported by other authors [14,17,30,46], free thiamine was the most prevalent form of thiamine in Lake Oahe Chinook Salmon eggs.…”

Five year trends in the egg-thiamine status of Atlantic salmon from the St. Marys River, Michigan

“…Mortality in fish is brought about by depletion of available thiamine resulting in early mortality syndrome (EMS) (Honeyfield et al, , 2005b. Thus, dietary thiaminase from alewife consumption has been suggested as a major cause of fry mortality in salmonid culture, reproductive failure by stocked lake trout, and extirpation of landlocked Atlantic salmon in Lake Ontario after alewife invasion (Ketola et al, 2000). Recent work has helped strengthen the connection between the affect of alewife consumption and the incidence of EMS in Great Lakes salmonids (Riley et al, 2007(Riley et al, , 2008.…”