Open net pen fish farming of any carnivorous fish has NO future!
Not only is it the spreading of diseases killing BC's wild salmon... until those carnivorous fish learn how to eat soybeans open net pen fish farming of any carnivorous fish, be it Atlantic or Pacific salmon – has NO future! It is NOT sustainable.
Now along with that, for those who think or want to or are farming Pacific salmon, you might want to reconsider that, as that has the potential to being more devastating to the wild Pacific salmon than those Atlantics!
Sperm trait differences between wild and farmed Chinook salmon
(Oncorhynchus tshawytscha)
Sarah J. Lehnert a, Daniel D. Heath a,b, Trevor E. Pitcher b
a Great Lakes Institute for Environmental Research, University of Windsor, Windsor, Ontario, Canada N9B 3P4
b Department of Biological Sciences, University of Windsor, Windsor, Ontario, Canada N9B 3P
The expansion of salmon aquaculture, coupled with fish escaping from those sites, has raised concerns about the possible impacts of escaped farmed fish on wild fish populations. The potential for hybridization through reproductive interactions between escaped farmed and wild salmon can have significant impacts on the fitness and genetic composition of the natural population. Reproductive success of farmed male salmon in the wild will depend on their ability to compete for mates; however, it will also depend on their relative sperm performance, given that sperm competition is known to contribute to salmonid reproductive success. Farming practices, including the hormonal sex-reversal of females to create homogametic (XX) males, may have effects on sperm traits in salmon. We therefore analyzed sperm traits of XX farmed, XY farmed and wild Chinook salmon males during the spawning season. No significant difference was found between XX and XY farmed males for all sperm traits, except sperm density, which was significantly higher in XY males than XX males. XX and XY farmed males had significantly higher sperm motility and sperm velocity compared to wild males. In addition, wild males had lower sperm longevity and sperm density compared to farmed males. Our results indicate that farming practices may lead to increased sperm performance in Chinook salmon males. While we did not evaluate reproductive success resulting from spawning interactions in the wild, our results do highlight the potential for substantial introgression resulting from male–male competition between farmed and wild Chinook salmon in the wild.
Introduction
Salmon aquaculture is an economically important industry; however, there are increasing concerns about the potential impacts of interactions between farmed and wild fish (Hindar et al., 1991; Naylor et al., 2005; Skaala et al., 1990). These interactions are of major concern when considering escapes from aquaculture sites, because the unnatural and controlled aquaculture setting provides an especially different environment for fish to evolve in compared to the wild, resulting in phenotypic and genetic differences in the farmed populations (Heath et al., 2003; Skaala et al., 1990). The genetic changes occurring in aquaculture involve the loss of genetic diversity as well as the divergence of farmed stocks from the original wild population (Hindar et al., 1991; Skaala et al., 1990). Additionally, homogametic male fish (XX males) are used for commercial production of all female stocks, and if such fish escape and reproduce successfully in the wild they would skew the sex ratio in the wild population. Hybridization through reproductive interactions between escaped farmed and wild salmon is an immediate threat to the fitness and genetic composition of natural populations (Hindar et al., 1991; McGinnity et al., 2003; Naylor et al., 2005). For example, McGinnity et al. (2003) showed that farmed-wild hybrid offspring have lower survival compared to wild offspring, and that competition from farmed and hybrid offspring reduces wild smolt production in Atlantic salmon (Salmo salar).
The potential for hybridization between wild and farmed salmon will depend on numerous factors, although primarily on the reproductive success of escaped farmed individuals in the wild (Fleming et al., 1996). The effect of artificial rearing on salmon reproductive behavior and success has been widely studied showing, under experimental conditions, farm-raised, transgenic and hatchery salmon have reduced competitive and reproductive success compared to wild salmon (Berejikian et al., 2001; Fitzpatrick et al., 2011; Fleming and Gross, 1993; Fleming et al., 1996; Moreau et al., 2011; Weir et al., 2004). Although artificially reared males and females both experience lower reproductive success when in competition with wild fish, the lower reproductive success is more pronounced in males relative to females (Fleming and Gross, 1993; Fleming et al., 1996). Specifically, males show less aggression and partake in fewer spawning events than wild males; as well, they display inappropriate mating behavior resulting in females denying access to the oviposition site (Fleming and Gross, 1993; Fleming et al., 1996). In addition to those behaviors, Webb et al. (1991) reported that escaped farmed and wild Atlantic salmon spawn in different reaches of the river, further reducing the likelihood of hybridization. Nevertheless, escaped farmed salmon do successfully reproduce and hybridize with wild fish (Crozier, 2000; Lura and Sægrov, 1991). In a study of 16 Scottish rivers, escaped Atlantic salmon females contributed up to 7% of the fry in some rivers (Webb et al., 1993), furthermore the experimental release of farmed Atlantic salmon in a Norwegian river revealed that 55% of farm escapes contributed 19% of the genes to the next generation of adult salmon (Fleming et al., 2000). While behavioral interactions play a key role in breeding success, salmonids are external fertilizers allowing several males to simultaneously fertilize the eggs of a single female. Consequently, relative sperm performance will also be an important contributing factor to the reproductive success of farmed salmon in the wild (Gage et al., 2004). This is because subdominant males can offset behavioral inferiority through enhanced sperm traits (Birkhead and Møller, 1988; Hutchings and Myers, 1988). Farmed males could achieve higher fertilization success by having faster swimming sperm, as Gage et al. (2004) found males with higher sperm velocity had greater fertilization success even when competing male had a greater number of sperm.
In conclusion, our study shows that farmed males had greater sperm performance compared to wild males. Irrespective of condition factor, spawning stage and age, our data shows that if escaping farmed salmon males entered nearby rivers during the spawning season they would have an advantage in sperm competition with wild salmon. From an ecological perspective, the ability of farmed males to outcompete wild males can have significant impacts on natural populations, ranging from outbreeding depression and loss of genetic diversity to extirpation (Fleming et al., 2000; Hindar et al., 1991; McGinnity et al., 2003). However, despite sperm competition playing an important role in male–male interactions in salmonids, behavioral interactions are also critical for reproductive success (Fleming et al., 1996). While farmed Chinook salmon males may have greater sperm performance, it is possible that these farmed males have lost much of their behavioral ability to compete for mates and gain access to females due to domestication, and thus would not be reproductively successful in the wild. Currently, we are examining the semi-natural spawning competitions between wild and farmed Chinook salmon to test this possibility.
http://web2.uwindsor.ca/biology/pitcher/Pitcher lab/Publications_files/Lehnert et al. 2012.pdf
Just giving some things to think about and with this, I am done for the day!
