Unfortunately, replacing your fishing pole will also replace your Algari Weaverline. The Weaverline is tied to the specific fishing pole it’s applied to.
So, if you switch poles, you’ll need to start building up your Weaverline progress again from scratch.
This is a bummer, why is this a limitation when considering a new fishing pole?
No you will not need to start from scratch. Weaverline progress is tied to your warband. A member of your warband just need to install a weaverline to benefit from your progress. The 100 AA cost is the reason I put the weaverline on the good fisherfriend.
People change their fishing poles?
I have the exalted with Kalu’ak fishing pole for the water breathing (useful in the two underwater delves) and never change it.
The TWW fisherfriend has +skill in TWW fishing and a ton of perception stats. Besides, Noggenfogger’s do the job in the underwater delves when I am not running it on my lock.
Please see https://www.wowhead.com/achievement=40476/10-algari-seekerthread
And
https://www.wowhead.com/achievement=40494/10-algari-anglerthread
These achievements unlock the ability to share your accumulated threads across your warband. There is an achievement every 10 threads you add.