Artificial Maturation as a Technique for Investigating Adaptations for Migration in the European Eel, Anguilla Anguilla (L.)

Pankhurst, Neville William

doi:10.1007/978-1-4613-2763-9_10

Cited by 6 publications

(6 citation statements)

References 34 publications

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“…As American eels Anguilla rostrata Lesueur approach sexual maturity they undergo a suite of morphological and physiological changes that are thought to be adaptive for their pelagic migration to their presumed spawning grounds in the Sargasso Sea, similar to those of the European eel Anguilla anguilla (L.) (Pankhurst, 1984). Some of the changes that have been associated with the metamorphosis from resident juvenile yellow phase eel to the migratory adult or silver phase eel in anguillids include increased eye diameter (Pankhurst, 1982; 0Present address: Beak International, 14 Abacus Road, Brampton, Ontario L6T 3G1, Canada.…”

Section: Introductionmentioning

confidence: 99%

Plasma non‐esterified fatty acid profiles and 17β‐oestradiol levels of juvenile immature and maturing adult American eels in the St Lawrence River

Ccottrill

McKinley

Kaak

et al. 2001

Journal of Fish Biology

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American eels Anguilla rostrata, collected from three distinct locations along the St Lawrence River (Lake St Lawrence, Quebec City and Kamouraska), were thought to consist entirely of out-migrating adults at Quebec City and Kamouraska and of both resident and migrants at Lake St Lawrence. The mean plasma levels of 17 -oestradiol closely paralleled the trend observed with gonadosomatic index (I G ) and oocyte development. The highest levels of 17 -oestradiol and I G were observed in Quebec City and Kamouraska, while the levels observed in the resident eels from Lake St Lawrence were very low. Generally, the concentration of total plasma non-esterified fatty acids (NEFA) appeared to follow the trend of 17 -oestradiol and I G and increased with sexual maturity. However, the most sexually mature group, eels from Kamouraska, had the lowest total plasma NEFA levels. The reason for the drop is not clear at present. In addition, a number of shifts in the plasma NEFA profiles of American eels did occur during their migration in a downstream direction, with several fatty acids either increasing or decreasing in relative abundance. The ratio of n3 : n6 fatty acids declined with increasing sexual maturity as most n3 fatty acids became less abundant. Although the correlation between gonadal development and the relative concentration of individual fatty acids was not always clear, both arachidonic acid (20 : 4n6) and docosahexaenoic acid (22 : 6n3) were significantly higher in the plasma of out-migrating adults than in resident yellow phase eels. 2001 The Fisheries Society of the British Isles

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Section: Introductionmentioning

confidence: 99%

Plasma non‐esterified fatty acid profiles and 17β‐oestradiol levels of juvenile immature and maturing adult American eels in the St Lawrence River

Ccottrill

McKinley

Kaak

et al. 2001

Journal of Fish Biology

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“…Sexual development in freshwater eels is halted when these fish are held in captivity (Dufour et al 1988), but this arrest can be overridden by hormone treatment. Accordingly, experimentation has been repeatedly undertaken: ( 1 ) to mimic "natural" sexual development in captive eels, allowing morphological, biochemical, and physiological changes occurring during the spawning migration to be inferred (e.g., Pankhurst 1984); and (2) to obtain mature gametes for fertilisation and study of resulting developmental stages (e.g., Yamauchi et al 1976;Yamamoto 1981). The first successful results using exogenous hormone treatments in eels date from the 1930s, when male European eels (Anguilla anguilla) were injected with urine from pregnant women (e.g., Fontaine 1936).…”

Section: Introductionmentioning

confidence: 99%

Induced spawning and early ontogeny of New Zealand freshwater eels{Anguilla dieffenbachiiandA. australis)

Lokman

Young

2000

New Zealand Journal of Marine and Freshwater Research

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Knowledge on the reproductive biology of New Zealand freshwater eels (Anguilla australis Richardson and A. dieffenbachii Gray) is limited to changes associated with gametogenesis in the adults; details pertaining to embryonic and larval development are not available, but are of obvious benefit for a better understanding of the eel life history and for artificial propagation programmes, whether for aquaculture or conservation purposes. Therefore, eels were artificially matured and eggs fertilised with sperm from either species to investigate early ontogeny. Only eggs from A. australis hatched successfully after c. 45 h of incubation at room temperature, yielding larvae of c. 2.5 mm in length. Larvae survived for up to 5 days, by which time they had attained a length of 5.3 mm. Scanning electron microscopy of 1-and 2-day-old larvae revealed the presence of prominent free neuromasts on the head and along the flanks. Although hatching of New Zealand eels was achieved for the first time, it is strongly recommended that hormone treatment be initiated immediately following capture, well before ovarian atresia starts.

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“…Because the eels were close in size, the doses were not weightspecific. These dosages of hCG and salmon pituitary approximated those used in our previous maturation experiments with females (Pankhurst, 1984;Pankhurst & Sorensen, 1984). Previous studies of male maturation (Boetius & Boetius, 1967;Todd, 198 I; Sorensen & Winn, 1984) also employed this dose of hCG.…”

Section: Fish Capture Husbandry and Treatmentmentioning

confidence: 91%

“…Unfortunately, fully mature adult Anguillu have never been captured (Tesch, 1977) and knowledge of their reproductive biology is based on artificial maturation experiments using migratory females. Artificially matured female European eels experience both radical structural changes in retinal organization, skin structure and skeletal muscle (Pankhurst, 1984) and a marked degeneration of their intestine (Pankhurst & Sorensen, 1984) and olfactory epithelium (Pankhurst & Lythgoe, 1983). The intestine of mature female American eels also degenerates (Pankhurst & Sorensen, 1984).…”

Section: Introductionmentioning

confidence: 99%

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Histological changes in the gonad, skin, intestine and olfactory epithelium of artificially‐matured male American eels, Anguilla rostrata (LeSueur)

Sorensen

Pankhurst

1988

Journal of Fish Biology

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Migratory (silver) male American eels were injected weekly for 5 weeks with human chorionic gonadotropin (hCG), salmon pituitary extract, hydrocortisone 21 -hemisuccinate (cortisol), or saline to determine the effects of induced maturation on the histology of their gonads, skin, intestines and olfactory epithelia. Treatment with hCG induced full sexual maturity, salmon pituitary evoked only limited spermatogenesis, and neither hydrocortisone nor saline had any effect on the gonad. Eels injected with hCG and salmon pituitary experienced no changes in skin morphology, but the epidermal thickness of saline-and hydrocortisone-treated fish decreased. Intestinal morphology did not change in any of the treatment groups. Both the presumed sensory and non-sensory portions of the olfactory epithelium of hCG-and pituitary-treated males exhibited a decrease in thickness, structural degeneration, and non-significant reductions in mucous cell density. Some of these changes in maturing male eels are similar to those previously observed in maturing females but others are different; it appears likely that maturing Anguillu are sexually dimorphic and that these changes are adaptive and not artifacts of the hormone treatments.

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Artificial Maturation as a Technique for Investigating Adaptations for Migration in the European Eel, Anguilla Anguilla (L.)

Cited by 6 publications

References 34 publications

Plasma non‐esterified fatty acid profiles and 17β‐oestradiol levels of juvenile immature and maturing adult American eels in the St Lawrence River

Plasma non‐esterified fatty acid profiles and 17β‐oestradiol levels of juvenile immature and maturing adult American eels in the St Lawrence River

Induced spawning and early ontogeny of New Zealand freshwater eels{Anguilla dieffenbachiiandA. australis)

Histological changes in the gonad, skin, intestine and olfactory epithelium of artificially‐matured male American eels, Anguilla rostrata (LeSueur)

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