Sperm characteristics and competitive ability in farmed and wild cod

Skjæraasen, Jon Egil; Mayer, Ian; Meager, Justin J.; Rudolfsen, Geir; Karlsen, Ørjan; Haugland, Thomas; Kleven, Oddmund

doi:10.3354/meps07774

Cited by 41 publications

(28 citation statements)

References 68 publications

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“…It might be argued that the position of farmed males over the spawning arena and the midwater spawning location reflects an alternative spawning strategy, with 'satellite' males rushing in to release milt after a mated pair has spawned (Hutchings et al 1999). In our laboratory experiment, we were unable to identify such males, and the results of a concurrent study suggest that such a strategy is unsuccessful for farmed males because they performed poorly in sperm competition against wild cod (Skjaeraasen et al 2009). …”

Section: Vertical Dynamics and Reproductive Behaviourmentioning

confidence: 65%

Vertical dynamics and reproductive behaviour of farmed and wild Atlantic cod Gadus morhua

Meager

Skjæraasen²,

Fernö³

et al. 2009

Mar. Ecol. Prog. Ser.

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Rapid development of fish mariculture and efforts to restock depleted populations have raised concerns about the effects on wild populations and the risk of genetic introgression from hybridisation. Reproduction of many marine fish species involves substantial vertical movements, but nothing is known of the vertical dynamics of farmed fish in spawning shoals. We combined laboratory observations and field biotelemetry to examine the depth-related reproductive behaviour and vertical dynamics of individual farmed and wild Atlantic cod Gadus morhua (L). We first tested the prediction that the depth distributions of male and female wild cod differ both in the laboratory and in the field. We then tested the prediction that farmed cod have a shallower depth distribution than wild cod and thus lack the sex-based vertical dynamics of wild cod. In both the laboratory and field, male farmed and wild fish tended to be located deeper than females, and wild fish were deeper than farmed fish. In the field, wild males were near the seafloor, considerably deeper than wild females and farmed fish. Residency on the spawning ground was longer for wild fish, but a substantial proportion (61%) of farmed fish remained for more than 3 d. Our study reinforces the idea that vertical dynamics play a key role in reproduction of an important fisheries species, and demonstrates clear differences in vertical distribution between farmed and wild fish on a spawning ground. The results suggest that escaped farmed cod, and in particular, farmed females, are likely to hybridise with wild cod.

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Section: Vertical Dynamics and Reproductive Behaviourmentioning

confidence: 65%

Vertical dynamics and reproductive behaviour of farmed and wild Atlantic cod Gadus morhua

Meager

Skjæraasen²,

Fernö³

et al. 2009

Mar. Ecol. Prog. Ser.

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“…comm.). Furthermore, the survival estimates are likely to be overestimates as sperm quality, and subsequent fertilisation success, is reduced for farmed males compared to wild males (Skjaeraasen et al 2009, Butts et al 2011.…”

Section: Survival Of Eggs From Farmed Atlantic Codmentioning

confidence: 99%

Extent and ecological importance of escape through spawning in sea-cages for Atlantic cod

Uglem¹,

Knutsen²,

Kjesbu³

et al. 2012

Aquacult. Environ. Interact.

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The culture of certain fish species to sizes at which they can reproduce has led to the escape of fertilised eggs or 'escape through spawning'. To investigate the extent and ecological importance of spawning in sea-cages for Atlantic cod Gadus morhua (L.), we (1) evaluated the extent, frequency and timing of spawning in cod culture; (2) analysed the quality of eggs released from farms in terms of variation in fatty acids; (3) modelled the distribution of eggs and larvae from a commercial cod culture site; and (4) predicted the post-escape survival of eggs through summarizing existing knowledge on survival rates of different life stages. Collectively, our results indicate that cod farming has the potential to produce large amounts of eggs and larvae through spawning in cages, with numbers of eggs spawned being 4 to 5 times higher in the second than in the first year. Our scenarios suggest that a typical sea-cage with 60 000 fish may produce 1.4 to 21 tons of 3 yr old first generation farmed cod through spawning in sea-cages. The quality of escaped eggs and larvae is likely to be sufficient for larvae to survive until the first feeding, while survival until adulthood, though difficult to predict, may be high under favourable conditions. Simulations indicate that eggs and larvae from farms may mix with those of wild fish during the spawning season, and thus experience comparable larval environments. However, several implementable management measures exist that will diminish the extent of egg escape in future cod farming.

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“…Such traits include sperm swimming velocity, sperm viability (the proportion of live sperm in a male's ejaculate) and sperm length-all of which have been shown to predict competitive fertilization success or fertility in several taxa. For example, differences in sperm swimming velocity between competing ejaculates is the primary determinant of competitive fertilization success in some birds (Birkhead et al, 1999;Denk et al, 2005) and fishes (Gage et al, 2004;Liljedal et al, 2008;Skjaeraasen et al, 2009), and is associated with fertility (non-competitive fertilization rates) in mammals (Gomendio and Roldan, 2008). Similarly, sperm viability predicts competitive fertilization success in insects (García-González and Simmons, 2005) and is associated with the strength of selection from sperm competition across insect taxa (Hunter and Birkhead, 2002).…”

Section: Introductionmentioning

confidence: 99%

Patterns of genetic variation and covariation in ejaculate traits reveal potential evolutionary constraints in guppies

Evans

2010

Heredity

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Ejaculates comprise multiple and potentially interacting traits that determine male fertility and sperm competitiveness. Consequently, selection on these traits is likely to be intense, but the efficacy of selection will depend critically on patterns of genetic variation and covariation underlying their expression. In this study, I provide a prospective quantitative genetic analysis of ejaculate traits in the guppy Poecilia reticulata, a highly promiscuous livebearing fish. I used a standard paternal half-sibling breeding design to characterize patterns of genetic (co)variation in components of sperm length and in vitro sperm performance. All traits exhibited high levels of phenotypic and additive genetic variation, and in several cases, patterns of genetic variation was consistent with Y-linkage. There were also highly significant negative genetic correlations between the various measures of sperm length and sperm performance. In particular, the length of the sperm's midpiece was strongly, negatively and genetically correlated with sperm's swimming velocity-an important determinant of sperm competitiveness in this and other species. Other components of sperm length, including the flagellum and head, were independently and negatively genetically correlated with the proportion of live sperm in the ejaculate (sperm viability). Whether these relationships represent evolutionary trade-offs depends on the precise relationships between these traits and competitive fertilization rates, which have yet to be fully resolved in this (and indeed most) species. Nevertheless, these prospective analyses point to potential constraints on ejaculate evolution and may explain the high level of phenotypic variability in ejaculate traits in this species.

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Sperm characteristics and competitive ability in farmed and wild cod

Cited by 41 publications

References 68 publications

Vertical dynamics and reproductive behaviour of farmed and wild Atlantic cod Gadus morhua

Vertical dynamics and reproductive behaviour of farmed and wild Atlantic cod Gadus morhua

Extent and ecological importance of escape through spawning in sea-cages for Atlantic cod

Patterns of genetic variation and covariation in ejaculate traits reveal potential evolutionary constraints in guppies

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