Production Diseases and Other Disorders
10
Abstract
Production related diseases and disorders cover a large area that the authors believe
deserves increased attention, although for some areas we cannot cover the subject in
great depth. These refer to a wide range of conditions that may or not be attributed to a
biological agent with examples discussed in this chapter covering environmental related
conditions, vaccination, developmental and congenital abnormalities and disorders, dietary
imbalance, disorders affecting the heart and the eye, general skeletal abnormalities, and
deformities among eggs and fry and predators.
Keywords
Production diseases Abnormality Salmon Trout
Production related diseases and disorders refer to a wide
range of conditions with often multifactorial origin, and
therefore they require a multidisciplinary approach in their
management. Unspecific mortality varies from rather
obscure causes like ‘loser syndrome’ or ‘failed smolt’
(Fig. 10.1), to other more specific causes such as poor
smoltification, handling, transport, negative treatment
effects and also certain infectious agents. A significant proportion of the mortalities can occur early post transfer to sea
water and in some cases, might be linked to the quality of the
smolt at the time of transfer, something that can and should
be managed.
Overall, production related diseases and disorders cover
a large area that the authors believe deserves increased
attention, although for some areas we cannot cover the
subject in depth. Examples discussed in this chapter cover
environmental related conditions, vaccination, developmental and congenital abnormalities and disorders, dietary
imbalance, disorders affecting the heart and the eye, general
skeletal abnormalities, deformities among eggs and fry and
predators.
10.1 Environment
10.1.1 Water Quality and Husbandry
Poor water quality is an obvious detrimental factor for any
aquatic species including wild and farmed fish, with induced
hypoxia being one of the major associated risks. Gill
neuroepithelial cells (NECs) provide the sensory mechanisms
for low oxygen detection, conversely, hyperoxia causes a
decline in NECs number. These changes are concurrent with
marked vascular distension, increased gill mucous, hyperplasia, elongation of respiratory lamellae and eventually, metabolic acidosis and death.
Fish excrete ammonia, and to a lesser amount, urea into
the water as waste. Ammonia is highly toxic and exposure is a
hazardous issue in fish farming resulting in a significant
increase in oxygen consumption, with higher ventilation
volume and respiratory distress. This can lead to acute mortality while the long term exposure results in reduced growth.
Histologically, a severe branchial hyperplasia and associated
widespread lamellar fusion, particularly at the tips, can be
D.W. Bruno et al., A Colour Atlas of Salmonid Diseases,
DOI 10.1007/978-94-007-2010-7_10, # Springer Science+Business Media B.V. 2013
151
10
Abstract
Production related diseases and disorders cover a large area that the authors believe
deserves increased attention, although for some areas we cannot cover the subject in
great depth. These refer to a wide range of conditions that may or not be attributed to a
biological agent with examples discussed in this chapter covering environmental related
conditions, vaccination, developmental and congenital abnormalities and disorders, dietary
imbalance, disorders affecting the heart and the eye, general skeletal abnormalities, and
deformities among eggs and fry and predators.
Keywords
Production diseases Abnormality Salmon Trout
Production related diseases and disorders refer to a wide
range of conditions with often multifactorial origin, and
therefore they require a multidisciplinary approach in their
management. Unspecific mortality varies from rather
obscure causes like ‘loser syndrome’ or ‘failed smolt’
(Fig. 10.1), to other more specific causes such as poor
smoltification, handling, transport, negative treatment
effects and also certain infectious agents. A significant proportion of the mortalities can occur early post transfer to sea
water and in some cases, might be linked to the quality of the
smolt at the time of transfer, something that can and should
be managed.
Overall, production related diseases and disorders cover
a large area that the authors believe deserves increased
attention, although for some areas we cannot cover the
subject in depth. Examples discussed in this chapter cover
environmental related conditions, vaccination, developmental and congenital abnormalities and disorders, dietary
imbalance, disorders affecting the heart and the eye, general
skeletal abnormalities, deformities among eggs and fry and
predators.
10.1 Environment
10.1.1 Water Quality and Husbandry
Poor water quality is an obvious detrimental factor for any
aquatic species including wild and farmed fish, with induced
hypoxia being one of the major associated risks. Gill
neuroepithelial cells (NECs) provide the sensory mechanisms
for low oxygen detection, conversely, hyperoxia causes a
decline in NECs number. These changes are concurrent with
marked vascular distension, increased gill mucous, hyperplasia, elongation of respiratory lamellae and eventually, metabolic acidosis and death.
Fish excrete ammonia, and to a lesser amount, urea into
the water as waste. Ammonia is highly toxic and exposure is a
hazardous issue in fish farming resulting in a significant
increase in oxygen consumption, with higher ventilation
volume and respiratory distress. This can lead to acute mortality while the long term exposure results in reduced growth.
Histologically, a severe branchial hyperplasia and associated
widespread lamellar fusion, particularly at the tips, can be
D.W. Bruno et al., A Colour Atlas of Salmonid Diseases,
DOI 10.1007/978-94-007-2010-7_10, # Springer Science+Business Media B.V. 2013
151