Early sexual maturation in males of wild sea trout, <i>Salmo trutta</i> L., inhibits smoltification

Dellefors, Claes; Faremo, Ulo

doi:10.1111/j.1095-8649.1988.tb05519.x

Cited by 100 publications

(79 citation statements)

References 11 publications

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“…, using 1 year old sea-run brown trout. These generally migrate to sea at age 2 yr (Bohlin et al 1994), but a varying proportion, mainly males, mature early (from age 1.5 yr) and remain stream-resident throughout their lives (Dellefors & Faremo 1988).…”

Section: Introductionmentioning

confidence: 99%

The cost of catching up: increased winter mortality following structural growth compensation in the wild

Johnsson

Bohlin

2006

Proc. R. Soc. B.

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Although laboratory and observational studies suggest that many animals are capable of compensatory growth after periods of food shortage, few field experiments have demonstrated structural growth compensation in the wild. Here, we addressed the hypotheses that (i) food restriction can induce structural compensatory growth in free-living animals, (ii) that compensation is proportional to the level of body size retardation and (iii) that compensation induces mortality costs. To test these, wild brown trout (Salmo trutta) yearlings were brought to the lab, tagged individually, subjected to four levels of food deprivation (including a control), released back into the native stream and recaptured after one, five and ten months. Brown trout fully restored condition and partially restored mass within a month, whereas compensation in structure (i.e. body length) was not evident until after five months, supporting hypothesis 1. As the level of growth compensation was similar among the three deprived groups, hypothesis 2 was not supported. A final recapture after winter revealed delayed mortality, apparently induced by the compensatory response in the deprived groups, which is consistent with hypothesis 3. To our knowledge, this is the first field experiment demonstrating structural compensatory growth and associated costs in a wild animal population.

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Section: Introductionmentioning

confidence: 99%

The cost of catching up: increased winter mortality following structural growth compensation in the wild

Johnsson

Bohlin

2006

Proc. R. Soc. B.

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“…Sexual differentiation is faster in larger fish [1] and their gonadogenesis is faster as well [2]. According to numerous authors, precocious maturation, common in salmonid males at the parr stage (juveniles mature prior to their first descent to the sea) occurs in the largest individuals [3][4][5][6][7][8][9][10][11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Body size versus gonad maturation form in under-yearling precocious males of the sea trout (Salmo trutta m. trutta L.)

Dziewulska

Domagała

2006

Reprod. Nutr. Dev.

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-The study was aimed at analysing body size in relation to form of gonad maturation (amount of mature germ cells) in 329 under-yearling sea trout males. The fish, aged 7 months, were caught in late October-early November in 3 streams located in north-western Poland. Each stream supported fish belonging to a different sib group. Standard histological techniques and a computer image analysis programme were used to detect the class of gonad maturation and percentage of the gonad area occupied by tubules with active spermatogenesis. Gonad maturation forms were distinguished based on the latter criteria. Gonads with developing germ cells occupying less than 90% of gonad area were classified as incomplete forms of gonad maturation, others as complete maturation forms. In each sib-groups analysed, even the smallest individual were already precocious, their gonads being incompletely mature. The smallest maturing male measured 7.1 cm in length. The average size of an incompletely maturing individual was slightly smaller than that of the completely mature one but the difference lacked statistical significance (P > 0.05). The sib-group of smaller fish contained less precocious, and the gonads of the more precocious were incompletely mature, compared to the sib-group of larger fish (P < 0.001). It seems that the incomplete form of gonad maturation (defected maturation) occurs at a smaller critical fish size than the complete gonad maturation form. Incomplete maturation is more frequent smaller individuals and possibly in among slow-growing groups of fish.Salmo trutta / testis / precocious / incomplete maturation / partial maturation / attempted maturation

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“…In coastal streams, the migrants are anadromous (migrating between fresh and salt water) whereas the residents stay in fresh water throughout life (Jonsson 1985;Dellefors & Faremo 1988). The residents may be mere dwarfs compared with their anadromous counterpart.…”

Section: Introductionmentioning

confidence: 99%

Energy allocation in polymorphic Brown Trout

Jönsson

1997

Functional Ecology

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1. To evaluate differences in energy allocation to gonadal development of resident and anadromous Brown Trout, Salmo trutta, we analysed tissue composition and energy contents of adults of the two morphs from three small streams in southernmost Norway. Somatic energy per unit mass of anadromous spawners (5·0 ± 0·6 kJ g–1 wet weight) was 1·1 times that of the residents. This difference was chiefly due to a 1·4 ‐times higher lipid content in anadromous (4·9 ± 1·5%) than resident trout. The somatic protein and carbohydrate contents per unit mass were higher in resident than anadromous fish. 2. Somatic energy content per unit mass increased linearly with body length in resident but not anadromous fish. This increase was due to a significant increase in lipid content with fish size in resident contrary to anadromous trout. 3. The mass‐specific energy content of the ovaries was higher for residents (8·4 ± 0·4 kJ g–1 wet weight) than anadromous (7·81 ± 0·5 kJ g–1 wet weight) trout. This was due to higher lipid and protein contents per unit mass in resident than anadromous females. In males, no similar differences between morphs were found (5·9 ± 0·8 kJ g–1 wet weight). The mass‐specific energy content of the ovaries was c. 1·4 higher than that of the testes, mainly caused by a 2·3–2·6 higher lipid content per unit mass of eggs. 4. The mean gonadosomatic index (kJ %) was higher in anadromous (34·0 ± 9·4) than resident (28·6 ± 5·5) females, but not in males (≈ 3%). In females, but not in males, gonadal energy increased linearly with increasing somatic energy of the fish. 5. Female gonadal energy at corresponding somatic energies was higher than that of males. On average, the energetic investment in gonads relative to soma of first‐time spawners in the year of maturation was estimated at 11% in males and 67% in females.

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Early sexual maturation in males of wild sea trout, Salmo trutta L., inhibits smoltification

Cited by 100 publications

References 11 publications

The cost of catching up: increased winter mortality following structural growth compensation in the wild

The cost of catching up: increased winter mortality following structural growth compensation in the wild

Body size versus gonad maturation form in under-yearling precocious males of the sea trout (Salmo trutta m. trutta L.)

Energy allocation in polymorphic Brown Trout

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