there are alot of factors. And the primary factor is, how mature are the eggs you are getting. If your salmon is off a boat or just entering a trib, chances are the eggs are not as mature as one holding in a pool. Simply put, more mature eggs are far stronger.
That could be first problem. Roe tight in skiens is not mature. The scraping that occurs to remove the skien, wears away the membrane of the eggs to become loose. When this happens, the egg doesn't have the same retention and will mush/pop easier. Simply put, the easier eggs scrape off a skien, the more mature they are. If you find your eggs are tight in the skien, I would reccommend using a cure to harden them,
So, due to nature alone, you can blame the fish if your eggs are mature or not, lol. I have some eggs I recently milked that are almost as strong as bouncy balls (ok not quite, but I have NO goop after tying and in my canister). Just try to keep a fish with stronger more mature eggs and you will have a hand up on the results you wish to obtain.