Talk:Brown trout

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I've done this as a single page because I've never seen a case where we have different pages for different subspecies. Also I wasn't convinced, from the data to hand, that there is a hard and fast difference in their habits etc. However if anyone feels like splitting them up, go right ahead. All I've done so far is shovel some basics down from FishBase. seglea 07:18, 24 Dec 2003 (UTC)

Since we're supposed to be more of a summary of knowledge than a replacement for specialists' works, I tend to incline towards discussing types as a group, rather than breaking each out into a lot of stubly articles. I can't even think of a subspecies that has so much information unique to it that the info would add multiple pages to a species article... Stan 07:30, 24 Dec 2003 (UTC)

The reference to truly native populations being restricted to a very few places such as Corsica needs justification. As far as I am aware in the UK, nearly all Brown trout populations are native and the distriuction is only limited by pollution and by competion from other fish species. Trout introductions tend to be of Rainbow trount and for this species there are only a few succseful breeding introductions (luckily). Unless this statement can be justified I would propose that it is deleted. Velela 5 July 2005 13:13 (UTC)

The life cycle is NOTHING like an Atlantic Salmon. This needs sorting out! Malcolm Morley 23:19, 18 December 2005 (UTC)

Care to expand on that a bit? Dave 00:49, 19 December 2005 (UTC)

Because most brown trout are not anadromous whereas all Salmon are. Malcolm Morley 07:15, 19 December 2005 (UTC)

As an ichthyologist, I can assure you that all "Salmon" are not anadromous. The life cycle of anadromous brown trout populations is very similar to that of anadromous Atlantic salmon populations. Lacustrine brown trout populations are very similar to landlocked Atlantic salmon populations. There are literally thousands of landlocked Atlantic salmon populations in the world, all(?) of which are potamodromous. The only real exception to the similarity is in the fario morph of brown trout which is really, it could be argued, a form of neoteny. I'm not aware, personally, of any Atlantic salmon populations that share this stream-resident trait although it wouldn't surprise me if there were some. In any event, there is more to life history than migratory pattern. Even if we focus solely on migration, however, you are not entirely correct. Most Atlantic salmon populations and most brown trout populations are either anadromous of potamodromous. This reality, it seems to me, is a far cry from your statement that the brown trout "life cycle is NOTHING like an Atlantic salmon." Regardless, I'm not wedded to the language. Your edit is not inaccurate. I'd suggest, though, that your view is somewhat narrow. There are many places in the world where anadromous brown trout populations and anadromous Atlantic salmon populations occur sympatrically and are very similar in life cycle. There are also many places in the world where landlocked Atlantic salmon populations are in some sense sympatric with lacustrine brown trout populations and they share a very similar life cycle. Does your edit capture this? Dave 15:06, 19 December 2005 (UTC)

Dave I have made some amendments to the article. I am not an ichthyologist, merely a keen fisherman with a scientific background. Please tell me if you disagree with my changes! Malcolm Morley 22:24, 19 December 2005 (UTC)

I like the way you broke it up. I re-arranged things just a bit to keep the zoogeography in the main part of the article and the farming stuff alone in the second section. Dave 01:22, 20 December 2005 (UTC)

[edit] Potamodromous

"The lacustrine morph of brown trout is most usually potamodromous although there is some evidence of stocks which spawn on wind-swept shorelines of lakes." Do you mean by this that most lacustrine morph fish migrate into flowing water to spawn whereas some do not migrate outside the lake to spawn? It just needs a little clarification... perhaps "The lacustrine morph of brown trout is most usually potamodromous, migrating into rivers or streams to spawn, although there is some evidence of stocks which spawn on wind-swept shorelines of lakes."' Malcolm Morley 22:36, 19 December 2005 (UTC)

Yes, your version is clearer, especially to a non-specialist which is the audience Wikipedia strives to address. Dave 00:44, 20 December 2005 (UTC)

"Brown trout may live for several years although, as with the Atlantic salmon, there is a high proportion of death of males after spawning and probably fewer than 20% of female kelts recover from spawning." Absolute malarky! Can I get a source on this? I used to live immediately adjacent to a brown trout stream in Alberta. They would spawn there every year. These figures are garbage or misinformed. Freshwater browns do not fit this statement at all!

Well, you're largely correct. Jonsson in 2001 showed that brown trout post-spawning mortality is correlated with stream size and habitat quality. Presumably, longer migrations in larger and faster streams exert a high energetic toll on the fish. At the same time, this 1998 study by Berg et al says that post-spawning mortality depends on the sex of the fish and how many times the individual has already spawned. In their study, they indicate that first time female spawners essentially all survived whereas about 65% of first-time spawning males survived. For repeat spawners, about 60% of females and 40% of males survived. So, on balance, I'd say that you are correct, the 20% number is probably too high except, perhaps, for anadromous populations in large streams undertaking long migrations. I didn't insert the 20% figure — it's been in the article for some time — but I also didn't verify it during my last rewrite. Feel free to alter the text appropriately. If you care not to make the alterations, I'll do it in a couple of days when I get a bit of time. — Dave 04:11, 14 September 2006 (UTC)