Geology topics

Leslie R. Wedge

Publications and source records attributed to Leslie R. Wedge.

3 recordsLinked to original sources

USGS2001

Relationships between thiamine content of eggs and concentrations of lead and other heavy metals in water and survival of Atlantic salmon fry

Atlantic salmon (Salmo salar) were extirpated in much of New York state by the late 1800s. Currently, Atlantic salmon from Little Clear Pond (Saranac Lake, NY) are stocked in Cayuga Lake (Ithaca, NY) and Lake Ontario to support a fishery, but reproduction is severely impaired by thiamine deficiency in Cayuga Lake and probably in Lake Ontario--apparently caused by adults feeding on prey fish high in thiaminase. One study suggested that survival of these fry may be reduced by phosphorus, calcium, magnesium, copper, or lead in water. Thiamine deficiency is known to increase lead toxicity. Bringing gravid Atlantic salmon from Little Clear Pond and Cayuga Inlet into the laboratory, we examined the effect of exposing their fertilized eggs during water-hardening to water with and without added lead (0.1 to 100 mg lead·liter-1) and to other contaminated waters (from New York State) on the survival of their eggs and fry. Our results showed no significant influence of our water-hardening treatments on survival of eggs or fry; therefore, it appears that exposure of eggs (during water-hardening) to lead in water (concentrations up to 100 mg lead·liter-1) or to several contaminated waters was not detrimental to the survival of eggs or fry of Atlantic salmon. We also determined the mineral and heavy metal content of dried eggs and found that eggs from Cayuga Lake salmon had significantly higher concentrations of copper (1.9 vs. 0.5 mg·g-1) than did eggs from salmon from Little Clear Pond. All concentrations of copper appeared to be within the range observed in other normal salmon. There were no other significant differences in concentrations of other minerals tested. Concentrations of copper in Cayuga Lake water (mean, 1.16 mg·liter-1) were significantly higher than in Little Clear Pond water (mean, 0.17 mg·liter-1). The effect of copper in eggs of thiamine-deficient salmon is not known.

Conference Paper↗

USGS2000

Effects of thiamine on reproduction of Atlantic salmon and a new hypothesis for their extirpation in Lake Ontario

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.

Transactions of the American Fisheries Society↗

USGS1999

Interspecific competition in tributaries: Prospectus for restoring Atlantic salmon in Lake Ontario

Historically, Lake Ontario may have supported the world's largest freshwater population of Atlantic salmon (Salmo salar). However, by the late 1800's, salmon were virtually extinct in the lake due to the damming of tributaries, overharvest, deforestation, and pollution. Of these factors, the building of dams on tributaries, which precluded access by the salmon to natal spawning streams, was probably the most detrimental. Since the extirpation of Atlantic salmon in the Lake Ontario watershed over a century ago, considerable change has occurred throughout the lake and tributary ecosystem. The changes within the ecosystem that may have the most profound effect on Atlantic salmon restoration include the presence of exotic species, including other salmonines, and reduced habitat quality, especially in tributaries. These changes must be taken into account when considering Atlantic salmon restoration.

Great Lakes Research Review↗