How to Obtain Artificial Brown Trout (Salmo trutta L.) eggs

Comparison of the physical properties of real and artificial salmonid eggs and of their performance when drifting in an experimental stream channel

“…The present study gives values of 1.068 to 1.076 for eggs of Teesdale trout and Atlantic salmon and published estimates are 1.069 + 0.038 (95% C.L.) for Teesdale trout (Ottaway, 1981) and 1.064 _+ 0.003 for rainbow trout (Salmo gairdneri Richardson), chinook salmon (Oncorhynchus tschawytscha (Walbaum)) and coho salmon (0. kisutch (Walbaum)) (Bonham, 1976). It is, therefore, likely that the same nylon material could be used to simulate the eggs of a wide range of salmonid species.…”

“…Weight, volume, density, shape and surface texture of eggs Artificial eggs These were described by Ottaway (1981) as moulded spheres of 'Grilon BT 40' (a variant of 'nylon 6') of 0.5 cm diameter and specific gravity 1.07 g ml -' (temperature not stated). Therefore each egg should have a volume of 0.065 ml and a weight of 0.070 g.…”

“…Durable, artificial brown trout eggs which can be batch marked by dyeing and/or individually numbered with an indelible felt-tipped pen were briefly described by Ottaway (1981). Such eggs have a wide variety of possible uses including field studies on the washout of salmonid eggs during spates, the distance drifted by displaced eggs and the types of locations in which displaced eggs resettle.…”

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The paper compares three batches of brown trout (Salmo trutta Linnaeus) eggs, two batches of Atlantic salmon (Salmo salar Linnaeus) eggs and the artificial trout eggs described by Ottaway (1981), in terms of their measurable physical characteristics. Attention was given to the effects of temperature and of the stage of development of the real eggs.

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