Shocking Results!

BY: QLIA President Dave Neuswanger, 9/25/17

On Tuesday night, September 19, I was privileged to help WDNR with their annual fall evaluation of juvenile walleye survival on Lost Land Lake. Fisheries Biologist Max Wolter and Technicians Scott Braden and Evan Sniadajewski met me at the public boat ramp at dusk. After launching their electrofishing survey boat, we spent the next 5 hours traveling slowly through the shallows around the entire 8-mile shoreline, capturing electrically stunned fish for immediate processing and release. A few curious residents waved greetings from their docks, but we were unable to hear or respond to their questions or comments over the roar of the onboard generator. Survey results were disappointing in some respects, yet hopeful in others.

WDNR Fisheries Biologist Max Wolter (center right) prepares waterproof data tablet while WDNR Fisheries Technician Scott Braden (back left) checks out the controls prior to our nighttime electrofishing survey.

Survival of 6,955 walleyes stocked by WDNR in August of 2017 at an average length of 3.5 inches was very low. We captured only 9 fish 6-7 inches long that were either stocked in August or hatched naturally last spring (1.1 per mile of shoreline). Follow-up genetic analysis will reveal the origin of those few fish. Regardless, we have a very weak 2017 year-class of walleyes in Lost Land Lake. On the bright side, we captured 44 walleyes (5.5 per mile) between 10 and 14 inches long that probably originated as fingerlings stocked by WDNR in fall of 2015 at lengths of 6-7 inches.

Young walleyes like this one, hatched in 2017, were the primary target of our nighttime electrofishing survey on Lost Land Lake. But very few were captured.

We will never know exactly why the 3.5-inch walleyes stocked in August survived in such low number. But our fall electrofishing survey revealed there are still enough largemouth bass to have an impact as predators on and competitors with young walleyes. Max reported that our catch rate of largemouth bass 8 inches and longer was almost 9 per mile of shoreline. That is down from 17 per mile captured in spring of 2014 (spring data may not be comparable with fall data), but still too close to the 10-per-mile threshold for largemouth bass, above which some biologists (including the retired author of this post) believe juvenile walleyes will rarely survive to adulthood.

The largemouth bass we captured were quite robust, indicating they had plenty to eat in recent weeks. I was also encouraged by the reduced proportion of largemouth bass in the 10-13 inch range. Formerly the most dominant size group, anglers at Lost Land Lake may finally have harvested enough of these 10-13 inch largemouth bass to reduce their numbers to levels conducive to overall fish community balance. The proportion of larger bass seems to have increased somewhat, possibly due to the thinning effect of angler harvest (more food for survivors). But there is now a big cohort of largemouth bass in the 7-9 inch range (probably born naturally in 2015) that anglers will need to harvest heavily in the next year or two in order to facilitate increased survival of stocked walleyes.

Even smaller largemouth bass are opportunistic predators capable of eating and competing with walleyes. The photos above were taken in late September 2009 on Nelson Lake, where 13 of 28 bass captured within 0.1 mile of extended-growth walleye stocking sites 32 hours post-stocking were found to contain walleye remains in their stomachs.

Smallmouth bass were as rare as juvenile walleyes (1.1 per mile of shoreline), but the adult fish we captured were very robust. The biggest smallmouth (19.1 inches long) was shaped like a football! I believe a decline in largemouth bass will facilitate an increase in smallmouth bass, provided anglers continue to release even legal-size smallmouths (14 inches and longer) voluntarily. And because smallmouth bass are not known to eat or compete significantly with walleyes, we can have a great bass fishery. We just need to be selective about which bass we keep (largemouths) and which ones we release (smallmouths). See our new Bass ID poster in an earlier post for more info.

Fall electrofishing is not an effective method for assessing muskellunge population abundance or size distribution, but a few muskies are always captured incidentally to the primary target species. Two of the fish we captured were small enough (19.6 and 23.2 inches) to be natural recruits, which bolsters confidence in spawning habitat quality and the genetic integrity of our musky population. Two of the fish (34.0 and 37.8 inches) had PIT (Passive Integrated Transponder) tags embedded in them, indicating they had been stocked as 13-inch fingerlings in fall of 2012 – the last time muskies were stocked in Lost Land Lake. These fish had grown faster than the average northern Wisconsin musky during their first 6 growing seasons. A 42.3-inch female had been tagged as an adult in 2008 when it was 35.1 inches long. Max reported this is the third time this fish has been recaptured! It was caught in 2012 at 40.4 inches, in 2013 at 40.8 inches, and now in 2017 at 42.3 inches. Slow growth of larger fish points out the continuing importance of voluntary catch-and-release of legal-size fish 40 inches and longer if we are to maintain a trophy aspect to the musky fishery.

WDNR Fisheries Technician Evan Sniadajewski prepares to release a tagged 37.8-inch musky that WDNR had stocked in fall 2012 when just 13 inches long.

Northern pike were captured at a low rate (1.5 fish per mile of travel along the entire shoreline). Fish ranged from 5.1 inches (hatched this year) to 31.1 inches long. As with muskellunge, fall electrofishing is not the best way to assess population abundance or size distribution of pike, but the low capture rate of various sizes of fish indicates we do not have an over-population of small “hammer-handle” pike that plague many other lakes. Still, a good approach for Lost Land Lake anglers would be to continue harvesting mid-size pike (21-28 inches) so they do not become numerous enough to have a negative impact on survival of juvenile muskellunge or walleyes. Larger pike (28 inches and longer, which are relatively high in mercury content) can be released voluntarily in order to thrill another angler, another day.

The author’s wife, Sandy Neuswanger, with her biggest pike ever — a 32-incher caught in August of 2017.
The big pike was gently lowered into the water…
And with one impressive thrust of its long, strong body, it bolted to freedom!

Thanks to Max and crew for letting a lake association representative tag along so we could understand and support what WDNR is doing to make fishing better in our lakes. Max plans to conduct a more thorough baseline monitoring survey for fish on Lost Land and Teal lakes in spring of 2018. Results from those surveys will be used to fine-tune angler harvest guidance going forward.