Its been squashed by the line above it being tighter caused by when you wind a fish in the line is stretched and it carries the stretch onto the spool.Have seen spools collapse because the pressure blows the sides off the spool and usually the end plates off the reel.
End for ending the line helps get rid of it

End for ending the line helps get rid of it? Sorry, what does this mean?

A little off topic but does anyone use braid backing on their game outfits?

Carnarv's spot on, it does happen but I've found some lines are better at maintaining "body" ie Berkey Biggame mono!

I wouldnt use braid backing at all, "if" i had to use a backing (not my prefered) it would be dacron!

It means taking the line off the reel,winding it onto a spool,then winding it on to another spool then putting it back on to your reel.This puts what was the line on top of the spool onto the bottom and the un used line from the bottom of the spool now sits on top.
Another way is to tie the line to the back of your boat and feed the line out as you move along.When you get all the line out cut it off the spool and tie the end you secured to the back of the boat onto the spool then wind it all back on

Ryan, I will definitely be re-spooling with the big game stuff but it comes in either 500m or 1000! So my question now is should I just go with the 1000m spool and try to fit on as much as I can on or go with the 500m spool and some sort of backing? My guess is that my reel will fit approx 7-800m of the 15kg. Any ideas?

No too sure what reel you have mate but i always fill my game reels top to bottom. Any joins are a week spot so no backing for me!

The spools are either 600m or 1200m, go the 1200m spool & fill top to bottom!

I'd go for the thousand metre spool and try to get as much on as you can.That way it leaves you with some left over to top up the spool at a later date and the peace of mind knowing if you've got a big fish on there isn't a join to the backing coming up

Leave a bit of space for a wind-on leader, a must for trolling!

All taken onboard.

Off topic again but what brand names make quality wind-on leaders and are they reliable? Is it just better to make them up yourself?

Buy richters, but change them regularly! Guys like Bernie on Mahi Mahi change them after every good fish apprently!

I use the Richter Wind-ons. You can make them yourself but unless your going through a shit load not worth it imo!

I replace mine before a game trip as they're a disposable product and if i'm gamefishing everyday constantly i'll replace it after 5 days or as mentioned a big fish!

I was lucky on my last trip to exmouth, we didn't do much trolling so one lasted me the whole trip =)

Best or strongest connection between mono and wind-on leader?

Thanks in advance.

Cats Paw knot, 3 times through as a minimum and wet before pulling the paw tight!

Cheers Ryan, always helpful!