Why does inbreeding not occur in fish?

patsman07

-How is it that the salmon don't end up inbreeding when they go back to the exact same location that they were born in to spawn? Surely the chances of mating with a close relative are greatly increased with this ritual? I've asked several angling friends this question and the best answer i've heard is that the salmon can smell their own relatives, in much the same way as they can 'smell' their own river.

The same question also applies to many other species of fish, who, in an evolutionary sense live on 'an island,' a place in which they are confined e.g. small lake.

norrie rugger

patsman07 wrote: »

-How is it that the salmon don't end up inbreeding when they go back to the exact same location that they were born in to spawn? Surely the chances of mating with a close relative are greatly increased with this ritual? I've asked several angling friends this question and the best answer i've heard is that the salmon can smell their own relatives, in much the same way as they can 'smell' their own river.

The same question also applies to many other species of fish, who, in an evolutionary sense live on 'an island,' a place in which they are confined e.g. small lake.

Ask any aquarium keeper and they will tell you that inbreeding can and does occur.

Often the spawn will not be sterile though. There have been reports of physical defects, through strangled genetic lines (often occurs in shop tanks that can have generations of inbreeding occur)


The sheer numbers of fish that return would (versus the huge number that do not make it past the fry stage) mean that the chances of spawning with a close relative would be very slim

yank_in_eire

Go to any stocked trout lake and you will see firsthand the effects of fish inbreeding - big fat stupid fish that couldn't get out of their own way!:D