Effects of Intermittent Formalin Treatment of Atlantic Salmon Juveniles on Growth, Condition Factor, Plasma Electrolytes, and Hematocrit in Freshwater and after Transfer to Seawater

Field studies have revealed that many ectotherms mature younger and smaller in warmer environments although they grow faster. This has puzzled ecologists because the direct effect of factors that accelerate growth is expected to be larger, not smaller size. We tested this experimentally for Atlantic salmon (Salmo salar) at two winter temperatures and diets. Logistic regression revealed that the probability of maturation during the second year in sea water, relative to the probability of older maturation, increased with temperature and growth rate during the first winter. Also, large size and high condition factor 1 year prior to maturation stimulated maturation. In females, a high lipid diet increased the probability of maturation as one-sea-winter fish, and there were significant interactions between winter temperature and food quality and between body size and condition factor the first autumn in sea water. Thus, if the direct effect of temperature on growth rate is the main effect of warming, salmon are likely to attain maturity younger and smaller. Also, richer food decreased age at maturation in females. This finding has consequences for interpretations of climate change impacts on age at maturity in Atlantic salmon and may also hold for many other ectotherm species.

Download Full-text

Changes in condition factor and gonadosomatic index in maturing and non-maturing Atlantic salmon (Salmo salar L.) in Bay of Fundy sea cages, and the effectiveness of photoperiod manipulation in reducing early maturation

Aquaculture Research ◽

10.1111/j.1365-2109.2005.01297.x ◽

2005 ◽

Vol 36 (9) ◽

pp. 882-889 ◽

Cited By ~ 15

Author(s):

Richard H Peterson ◽

Paul R Harmon

Keyword(s):

Atlantic Salmon ◽

Salmo Salar ◽

Condition Factor ◽

Gonadosomatic Index ◽

Bay Of Fundy ◽

Early Maturation ◽

Atlantic Salmon Salmo Salar ◽

Photoperiod Manipulation

Download Full-text

Physiological and endocrine changes in Atlantic salmon smolts during hatchery rearing, downstream migration, and ocean entry

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/cjfas-2012-0151 ◽

2013 ◽

Vol 70 (1) ◽

pp. 105-118 ◽

Cited By ~ 26

Author(s):

Stephen D. McCormick ◽

Timothy F. Sheehan ◽

Björn Thrandur Björnsson ◽

Christine Lipsky ◽

John F. Kocik ◽

...

Keyword(s):

Atlantic Salmon ◽

Condition Factor ◽

Anthropogenic Impacts ◽

Downstream Migration ◽

Endocrine Function ◽

Plasma Growth Hormone ◽

Data Set ◽

Hatchery Fish ◽

Igf I ◽

Freshwater Habitats

Billions of hatchery salmon smolts are released annually in an attempt to mitigate anthropogenic impacts on freshwater habitats, often with limited success. Mortality of wild and hatchery fish is high during downstream and early ocean migration. To understand changes that occur during migration, we examined physiological and endocrine changes in Atlantic salmon (Salmo salar) smolts during hatchery rearing, downstream migration, and early ocean entry in two successive years. Gill Na+/K+-ATPase activity increased in the hatchery during spring, increased further after river release, and was slightly lower after recapture in the ocean. Plasma growth hormone levels increased in the hatchery, were higher in the river, and increased further in the ocean. Plasma IGF-I remained relatively constant in the hatchery, increased in the river, then decreased in the ocean. Plasma thyroid hormones were variable in the hatchery, but increased in both river- and ocean-captured smolts. Naturally reared fish had lower condition factor, gill NKA activity, and plasma thyroxine than hatchery fish in the river but were similar in the ocean. This novel data set provides a vital first step in understanding the role and norms of endocrine function in smolts and the metrics of successful marine entry.

Download Full-text

Activity, Respiration, and Excretion of Ammonia by Atlantic Salmon (Salmo salar) Smolt and Postsmolt

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f89-098 ◽

1989 ◽

Vol 46 (5) ◽

pp. 790-795 ◽

Cited By ~ 22

Author(s):

A. J. Wiggs ◽

E. B. Henderson ◽

R. L. Saunders ◽

M. N. Kutty

Keyword(s):

Oxygen Consumption ◽

Atlantic Salmon ◽

Spontaneous Activity ◽

Salmo Salar ◽

Condition Factor ◽

Ammonia Excretion ◽

Initial Increase ◽

Atlantic Salmon Salmo Salar ◽

Substantial Change ◽

Increased Activity

Spontaneous activity, oxygen consumption, and excretion of ammonia by juvenile Atlantic salmon (Salmo salar) were measured over 17 wk as the appearance of the fish changed from early smolt to smolt and then postsmolt. A substantial change in routine oxygen consumption from 66 to 148 mL∙kg−1∙h−1 was primarily correlated with the increase in activity. An initial increase in ammonia excretion from about 5 to about 14 mL∙kg−1∙h−1 was largely correlated with the decline in condition factor from 0.99 to 0.79 suggesting that increased metabolic needs caused by the increased activity were not being met by the amount of food ingested. This is supported by the secondary increase in condition factor (C.F. = 0.93) and decrease in ammonia excretion (to about 7 mg∙kg−1∙h−1) that occurred after the meal size was increased.

Download Full-text