What's the rationale for the walleye slot limit on Balsam Lake (none between 37-55 cm / 14.6'-21.7') the opposite of the slot limit on other Kawartha lakes (must be between 35-50 cm (13.8'-19.7')? I would think that what is good for Balsam should be good for the other Kawartha lakes too.

Suggest you read the Ontario fishing regulations by the MNR. It lists all slots for the zone.
I don't recall any exception for walleye. Especially the one suggested in your post. Doesn't make sense.
Again, check the regs.

You are correct about the exemption for Balsam Lake. However I have no idea why it is there. All the walleye I ever catch are in the slot size.

It is to protect the walleye in that watershed, basically they want you to keep none of the healthy breeding stock and I think the limit is 3. Restrictions imposed probably due to overfishing and loss of habitat/spawning grounds.

I get it that a slot limit protects spawning populations. I just don't understand why the Balsam Lake slot is the inverse of the other Kawartha lakes' slot. Is the intention to have fewer but bigger walleyes??

The regulation is clear - see pg. 85 of the 2014 Recreational Fishing Regulations. The exception for Balsam walleyes is at the bottom of the page under 'Exceptions to Zone 17 Regulations'. I agree it doesn't make sense.

I asked the MNR about the different slot limit on Balsam Lake. Here's their answer: ' The walleye regulations were changed on Balsam Lake and Mitchell Lake in 2001, in response to concerns from local anglers to declines in walleye population. The MNR in cooperation with the Kawartha Fisheries Association (no longer in existence) conducted shoreline spawning surveys, creel surveys, netting surveys and laboratory analysis of samples to identify the cause(s) of the decline and prescribe appropriate management actions for walleye.
The surveys confirmed the suspected decline in walleye stocks and also established that female walleye on Balsam Lake mature much later than on other Kawartha Lakes. According to the data, female Balsam Lake walleye require 6-7 years to achieve a size sufficiently mature to spawn (36- 43 cm, or 14'-17'), compared to only 4-5 years on other lakes.
At the same time, creel surveys on Balsam revealed that the majority of fish harvested from Balsam Lake were less than 6 years old. This information suggested that >75% of the walleye harvested from Balsam had likely never spawned. This implicated harvest as a major factor in walleye declines, over say recruitment or habitat factors. Protecting these slow growing fish from harvest once they reach sexual maturity provides them the opportunity to spawn 4-5 times and produce future generations of walleye, before they would again reach a harvestable size. That was the rationale behind implementing the 'protected slot' (37-55cm, 14.6'-21.7') on Balsam and Mitchell lakes in 2001, along with reduced harvest limits (from S-6, C-2 to S-3, C-1).'

Thanks muskyteer. That makes perfect sense.
My cottage is on Kashagawigamog in Haliburton, I wish they would implement the same regulation there for walleye. Horrible overfishing and lack of conservation over the last 15 years has led to a huge decline there.

Great info Muskyteer you have help me understand it a lot better now . Thanks

I had always wondered that as well. Thanks for clarifying!