Egg‐to‐fry survival of the sea trout in some streams of Gotland

Abstract

The quality of the surface water of Gotland (Sweden) streams was good, and did not limit sea trout egg-to-fry (ETF) survival. The oxygen concentration of the interstitial water was positively correlated to the permeability of the stream bed, and to the geometric mean diameter of the substratum. When the oxygen at 15 cm inside the stream bed was undiminished from surface values, the permeability of the stream bed was at least 6000 cm h 1 and the geometric mean diameter of the substratum at least 15·0 mm. When the interstitial oxygen concentration increased, the interstitial ammonium concentration decreased, the NO 2 concentration remained stable and the NO 3 concentration increased. The ETF survival up to hatching was highly dependent upon the oxygen concentration of the interstitial water. For survival from hatching to emergence, the geometric mean diameter of the substratum was the most important factor. ETF survival >50% was observed where the interstitial oxygen concentration averaged at least 10 mg l 1 , the substratum permeability at least 2000 cm h 1 and the substratum geometric mean diameter at least 15 mm. Other factors, such as overdigging and drying out of the spawning grounds could increase the ETF mortality. 1996 The Fisheries Society of the British Isles

Dissolved oxygen concentration and emergence of sea trout fry from natural redds in tributaries of the River Rhine

“…In northern Germany, Hartmann (1988) found no living trout eggs in natural redds with DO levels <7·7 mg l 1 , and after hatching rainbow trout survival in redds was negligible below 5·2 mg l 1 (Sowden & Power, 1985). Survival of brown trout eggs in artificial egg pockets planted in an Idaho stream increased with intragravel DO concentrations >8 mg l 1 (Maret et al, 1993) and an even higher lethal limit of 10 mg l 1 was determined for sea trout in Gotland streams by using artificial incubation boxes (Rubin & Glimsäter, 1996). This difference might be related to a better percolation for eggs in natural redds than in egg boxes, which require a higher DO concentration to guarantee the survival of eggs       in the artificial environment (Silver et al, 1963).…”

“…The survival of salmonid eggs and fry has been associated in laboratory and field studies with the dissolved oxygen concentration, gravel size, permeability, and the seepage velocity in the intragravel environment during the long incubation period (Wickett, 1954;Chapman, 1988). Critical limits of dissolved oxygen for egg-to-fry survival have been established in field studies using trout eggs placed into incubation boxes and buried into the gravel of salmonid spawning rivers (Ingendahl et al, 1995;Rubin & Glimsäter, 1996). The same approach, which was used in studying reproductive success of salmonids in tributaries of the River Rhine, resulted in a very low survival rate for salmon and sea trout eggs placed into Whitlock-Vibertboxes (Ingendahl, 1999).…”

The effects of stream substratum composition on the emergence of salmonid fry

“…The river bed is the key habitat for the reproduction of lithophilic spawners. Several authors have stressed the importance of stream substratum characteristics for the hatching success of salmonids (Rubin & Glimsäter 1996;Acornley & Sear 1999;Soulsby et al 2001;Heywood & Walling 2007). The substratum requirements of salmonids change during different phases of the reproduction process and the substratum suitability must be specifically assessed in the period from the nest digging by females to the emergence of fry (Kondolf 2000).…”

Delayed Phenotypic Expression of Growth Hormone Transgenesis during Early Ontogeny in Atlantic Salmon (Salmo salar)?

“…The vulnerability of salmonid embryos to low oxygen conditions has been demonstrated previously [9], [49], [50]. If GH transgenesis were to affect the basal metabolic rate of Atlantic salmon embryos, there could be survival differences during embryo incubation relative to non-transgenic individuals [24], [51].…”