The lateral line system and its innervation in the masu salmon Oncorhynchus masou masou (Salmonidae)

Because captive-bred animals gradually adapt to artificial rearing environments due to evolving life history traits, such individuals sometimes show lessened performance in natural environments. The lateral line system, one of the principal sensory organs of fishes, varies according to habitat environments, sometimes differing even within the same species. A reduction in lateral line elements may also occur in successive generations of captive-bred fish. Such a reduction, involving neuromasts over the entire body, was examined for the first time in captive-bred masu salmon Oncorhynchus masou masou. The total number of neuromasts in captive-bred fish was ca. 10% lower than in wild-caught and F1 fishes, suggesting that the system in captive-bred fish had reduced in number due to domestication. Furthermore, differences in total neuromast numbers between captive-bred and wild fish were greater than between anadromous and fluvial populations of the species. The lower number of neuromasts could be one of the reasons behind the lower survival of captive-bred fish in natural environments.

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“…Terminology. The terminology of each element of the lateral line system of masu salmon follows Nakae & Hasegawa (2022 22 ; see also Fig. 1).…”

Section: Methodsmentioning

confidence: 99%

Domestication of captive-bred masu salmon Oncorhynchus masou masou (Salmonidae) leads to a significant decrease in numbers of lateral line organs

Nakae

Hasegawa

Miyamoto

2022

Sci Rep

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“…After each observation, the number of lateral line organs was counted. The lateral line organs on both the head and body were counted on fish stained with DiAsp and anaesthetized (and euthanized) with a ca 0.1% solution of FA 100 (4-Allyl-2-methoxyphenol: eugenol) (see [ 26 ] for detailed procedures). The number of replicates, the body size of each experimental fish and the experimental periods are summarized in table 1 .…”

Section: Methodsmentioning

confidence: 99%

Effects of domestication and captive breeding on reaction to moving objects: implications for avoidance behaviours of masu salmon Oncorhynchus masou

2023

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Domestication and captive breeding can compromise the obstacle- and predator-avoidance capabilities of animals in the wild. Whereas previous studies only examined these effects in combination, here we examine them individually by comparing the abilities of wild, F1 (offspring of wild parents) and captive-bred (approx. F15) masu salmon Oncorhynchus masou to avoid a falling object under experimental conditions. Rates of avoidance failure were low (wild, 12.5%; F1, 10.7%; captive-bred, 8%) under light conditions, but increased under dark conditions (wild, 11.1%; F1, 32.1%; captive-bred, 60.0%). We attribute the elevated avoidance failure rate among F1 fish to the lack of learning opportunities in hatchery environments (i.e. domestication), and the further elevation of avoidance failure rate among captive-bred fish to the degradation of sensory organ function (i.e. captive breeding). These results imply reduced survival rates for F1 and captive-bred fish in the wild and are consistent with the low stocking efficiencies reported for captive-bred masu salmon.

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Development of the cranial lateral line system of Brook Trout, Salvelinus fontinalis (Teleostei: Salmonidae): Evolutionary and ecological implications

Jones,

Rizzato,

Webb

2024

Journal of Morphology

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The mechanosensory lateral line (LL) system of salmonid fishes has been the focus of comparative morphological studies and behavioral and physiological analyses of flow sensing capabilities, but its morphology and development have not been studied in detail in any one species. Here, we describe the post‐embryonic development of the cranial LL system in Brook Trout, Salvelinus fontinalis, using vital fluorescent staining (4‐Di‐2‐ASP), scanning electron microscopy, µCT, and clearing and staining to visualize neuromasts and the process of cranial LL canal morphogenesis. We examined the relationship between the timing of LL development, the prolonged life history of salmonids, and potential ecological implications. The LL system is composed of seven canals containing canal neuromasts (CNs) and four lines of superficial neuromasts (SNs) on the skin. CNs and SNs increase in number and size during the alevin (larval) stage. CN number stabilizes as canal morphogenesis commences, but SN number increases well into the parr (juvenile) stage. CNs become larger and more elongated than SNs, but the relative area occupied by sensory hair cells decreases during ontogeny in both types of neuromasts. Neuromast‐centered canal morphogenesis starts in alevins (yolk sac larvae), as they swim up into the water column from their gravel nests (~4 months post‐fertilization), after which yolk sac absorption is completed and exogenous feeding begins. Canal morphogenesis proceeds asynchronously within and among canal series and is not complete until ~8 months post‐fertilization (the parr stage). Three characters in the LL system and associated dermal bones were used to identify their homologs in other actinopterygians and to consider the evolution of LL canal reduction, thus demonstrating the value of salmonids for the study of LL evolution. The prolonged life history of Brook Trout and the onset of canal morphogenesis at swim‐up are predicted to have implications for neuromast function at these critical behavioral and ecological transitions.

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The lateral line system and its innervation in the masu salmon Oncorhynchus masou masou (Salmonidae)

Cited by 5 publications

References 39 publications

Domestication of captive-bred masu salmon Oncorhynchus masou masou (Salmonidae) leads to a significant decrease in numbers of lateral line organs

Domestication of captive-bred masu salmon Oncorhynchus masou masou (Salmonidae) leads to a significant decrease in numbers of lateral line organs

Effects of domestication and captive breeding on reaction to moving objects: implications for avoidance behaviours of masu salmon Oncorhynchus masou

Development of the cranial lateral line system of Brook Trout, Salvelinus fontinalis (Teleostei: Salmonidae): Evolutionary and ecological implications

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