A contribution to the biology of the American eel (Anguilla Rostrata (Leseur)) in certain areas of Newfoundland
Some aspects of the growth, relative growth, sex differentiation and distribution and stomach contents were investigated in the American eel in brackish water and freshwater environments from four different areas in Newfoundland. Some aspects of the silver or migrating stage of the American eel were...
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| Format: | Thesis |
| Language: | English |
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Memorial University of Newfoundland
1969
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| Online Access: | https://research.library.mun.ca/7128/ https://research.library.mun.ca/7128/1/Gray_RonaldWalter.pdf https://research.library.mun.ca/7128/3/Gray_RonaldWalter.pdf |
| Summary: | Some aspects of the growth, relative growth, sex differentiation and distribution and stomach contents were investigated in the American eel in brackish water and freshwater environments from four different areas in Newfoundland. Some aspects of the silver or migrating stage of the American eel were also studied. -- The growth of young eels was slow, especially in brackish water habitats. However, as the eels became older, their growth rate improved. The fastest growth was observed in eels from Burnt Berry Brook, followed by those from Indian Pond, Topsail Barachois and Main Brook. -- The data on relative growth indicate that differences occur in the growth of certain body parts between brackish and freshwater populations of eels. Bertin's hypothesis on broad-nosed and sharp-nosed eels, however, does not appear to apply to the eels studied in the present investigation. -- An abnormal sex ratio was present in eel populations studied in Newfoundland. Females were universal in their distribution throughout the sampling areas, however, only one male was observed. -- The food taken by eels in the present investigation varied considerably between brackish water and freshwater habitats. Clams, shrimp, gammarids, brittle stars, adult dragonflies, fish eggs, sticklebacks, and eels were present in the stomachs of eels in brackish water. Adult dragonflies, dragonfly nymphs, adult mayflies, adult hemipterans, beetle pupae, adult beetles, dipteran larvae, adult dipterans, stonefly nymphs, freshwater snails, freshwater clams, salmonid eggs, salmonids, and eels were present in the stomachs of eels in fresh water. -- The migrating eels examined in this study exhibited characteristics typical of the silver eel described by European authors. Data on color, body measurements, internal changes and state of maturity as determined by ova diameters would seem to indicate that they approach the condition observed in the European eel prior to its migration to sea. |
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