Seasonal changes in thyroid hormones and osmoregulation in mature male parr and 1- and 2-year-old immature parr of Baltic salmon (<i>Salmo salar</i> L.)

Rydevik, Magnus; Bergström, Eva; Lundqvist, Hans; Eriksson, Ljusk Ola

doi:10.1139/z89-137

Cited by 11 publications

(4 citation statements)

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“…Secondly, the non-smolting one-year old parr also exhibited surges in insulin during the period of parr-smolt transformation, although separated in time from those of the twoyear old fish. This finding is in contrast to what has been found for thyroxine (T 4 ), where plasma levels in both one-and two-year old fish peak at the same time during smoltification, although again, levels in the non-smolting one-year old parr are significantly lower than in the two-year smolts (Rydevik et al 1989). This supports the view that T 4 plays a pivotal role in the metabolic changes which occur during parr-smolt transformation.…”

Section: Discussioncontrasting

confidence: 85%

Plasma levels of insulin and liver glycogen contents in one- and two-year old Atlantic salmon (Salmo salar L.) during the period of parr-smolt transformation

Mayer

Borg

Plisetskaya

1994

Fish Physiol Biochem

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Plasma levels of insulin were measured by specific radioimmunoassay in 1-year and 2-year old Atlantic salmon (Salmo salar) parr during the period of parr-smolt transformation. The two-year old fish were of two different categories; silvering pre-smolts and previously mature male parr. If insulin plays an important role in parr-smolt transformation and/or subsequent osmoregulatory changes it was expected that the pre-smolts would show a different insulin profile compared to the mature male parr and one-year old parr, both of which show impaired hypoosmoregulatory ability compared to smolts. Measurements were taken during two separate years. Between January and April both categories of two-year old fish had generally higher plasma levels of insulin compared to the non-smolting one-year old parr. In the pre-smolts insulin levels ranged from 4.0 to 7.9 ng ml(-1), and from 7.8 to 16.7 ng ml(-1) in 1990 and 1992 respectively, while in the previously mature males the same respective values were from 4.3 to 10.0 ng ml(-1), and from 6.6 to 24.1 ng ml(-1). In the two-year old fish, whether pre-smolts or mature males, plasma insulin levels peaked between 1-2 months before final smoltification, after which insulin titers declined sharply. In 1990, the 1-year old parr showed a dual peak in plasma insulin. Insulin first peaked in February (7.8 ng ml(-1)), and then again in April-May (7.7 ng ml(-1)), while in 1992 the 1-year old parr showed a number of smaller transient peaks (5-7 ng ml(-1)) between March-May, followed by sharp elevation of insulin levels in June. Liver glycogen contents were at their highest (3.5-5.0 g 100 g(-1) I liver wet weight) in March in both 1-year and 2-year old fish. Glycogen levels were low during the later stages of parr-smolt transformation, before rising again in June in both the 1-year old and precociously mature parr, but not in the smolts.

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Section: Discussioncontrasting

confidence: 85%

Plasma levels of insulin and liver glycogen contents in one- and two-year old Atlantic salmon (Salmo salar L.) during the period of parr-smolt transformation

Mayer

Borg

Plisetskaya

1994

Fish Physiol Biochem

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“…In individuals maturing for the first time, the commmencement of gonadal development is evident by mid June to early July (Jones, 1959;Mitans, 1973;Rydevik et al, 1989;Berglund, 1991). Alm (1959) showed that early sexual maturation in several salmonids is positively correlated with growth rate.…”

Section: Introductionmentioning

confidence: 99%

“…Sexual maturation in male Atlantic salmon (Salmo salar L.) parr is a widespread phenomenon, both under natural and hatchery conditions (Jones, 1959;Osterdahl, 1969;Lundqvist, 1983). In individuals maturing for the first time, the commmencement of gonadal development is evident by mid June to early July (Jones, 1959;Mitans, 1973;Rydevik et al, 1989;Berglund, 1991). Alm (1959) showed that early sexual maturation in several salmonids is positively correlated with growth rate.…”

Section: Introductionmentioning

confidence: 99%

Effects of sexual maturation, castration, and androgen implants on growth in one‐ and two‐year‐old parr in a Baltic Atlantic salmon (Salmo salar L.) stock

Berglund

Mayer

Borg

1992

Journal of Fish Biology

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The effects of maturation, castration, and androgen implants on growth in 1-and 2-year-old Baltic salmon (Salmo salar L.) were studied in a stock originating from the Umealven (Ume river) in northern Sweden. 1 + male parr that later matured were larger than non-maturing parr in the spring. Later in the summer, during the period of gonadal growth, the growth rate of maturing parr was depressed compared to that of non-maturing males. Implantation of capsules with 11-ketoandrostenedione (OA) or testosterone (T) in sexually immature I-year-old fish, accelerated the specific growth rate in spring and early summer, particularly considering growth in weight, resulting in an increase in the condition factor. In contrast, the growth rate was depressed from late June onwards, the period when the gonads normally develop in 1 + parr. T, but not OA, also promoted sexual maturation. Castration or OA treatment did not affect total summer growth in 2-year-old salmon. This study suggests a causal relationship between androgens and the growth pattern observed in maturing 1 + male parr.

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“…The mechanism for the differences in colouration between the two groups of mature fish may be associated with other endocrine changes that occur during the spring. Rydevik et al (1989) found circulating levels of thyroid hormones to be highly variable in previously mature fish during the spring. Thyroid hormones have been shown to promote changes characteristic of smolting such as silvering (Miwa & Inui, 1985).…”

Section: Discussionmentioning

confidence: 97%

Seasonal changes in androgen levels in stream‐ and hatchery‐reared Atlantic salmon parr and their relationship to smolting

Shrimpton¹,

McCormick²

2002

Journal of Fish Biology

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In stream‐reared Atlantic salmon Salmo salar, plasma androgens were significantly greater in mature male parr than immature males and females in October, but had declined by January and did not differ significantly from immature fish throughout the spring. Immature fish in March were significantly larger and had greater gill Na+, K+‐ATPase activity than their previously mature counterparts. Bimodal growth distribution was seen in hatchery‐reared Atlantic salmon and a proportion of the male fish in the lower mode matured. Plasma testosterone (T) and 11‐ketotestosterone (11‐KT) were significantly elevated from September to December in mature male (1+ year) parr. In January, plasma androgens had declined in mature males and did not differ significantly from immature fish. By May all the hatchery fish were large enough to smolt and a proportion of the previously mature males had increased gill Na+, K+‐ATPase activity. Therefore elevated androgens in the previous autumn do not prevent smolting. Parr with higher plasma T and 11‐KT in April and May, that are presumably beginning to mature, had lower gill Na+, K+‐ATPase activity, indicating that future maturation and associated increases in androgens may inhibit smolting.

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Seasonal changes in thyroid hormones and osmoregulation in mature male parr and 1- and 2-year-old immature parr of Baltic salmon (Salmo salar L.)

Cited by 11 publications

References 0 publications

Plasma levels of insulin and liver glycogen contents in one- and two-year old Atlantic salmon (Salmo salar L.) during the period of parr-smolt transformation

Plasma levels of insulin and liver glycogen contents in one- and two-year old Atlantic salmon (Salmo salar L.) during the period of parr-smolt transformation

Effects of sexual maturation, castration, and androgen implants on growth in one‐ and two‐year‐old parr in a Baltic Atlantic salmon (Salmo salar L.) stock

Seasonal changes in androgen levels in stream‐ and hatchery‐reared Atlantic salmon parr and their relationship to smolting

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