Fish science v/s experience collide on Lower Marmion

[Lee Borgersen]

Science and experience collide on Lower Marmion
by Atikokan Progress on January 19, 2012

M. McKinnon

Fish science and anglers’ experience are not matching up when it comes to walleye in Lower Marmion Lake.

In a detailed presentation to the Atikokan Sporstmen’s Conservation Club on Wednesday, MNR biologist Brian Jackson showed the results of ten fish population studies conducted on the lake over the past 15 years. They indicate the walleye in the lake have rebounded strongly, and now have the same population characteristics as most other walleye lakes in the region.

But the ten or so club members on hand, most of whom regularly fish the lake, say that isn’t what anglers have experienced over the past year. Small walleye are scarce, they say. Fishing regulations limit anglers to possession of one walleye of over 46 cm (18.1 inches – the slot size) in length; this applies to both regular and conservation fishing licences. And Lower Marmion anglers are having a hard time catching fish under the slot size.

The most comprehensive recent fish population survey in Lower Marmion was conducted in June, 2010, as part of the zone-wide broadscale monitoring survey. All those results indicate the walleye population in Lower Marmion is healthy, with good numbers of fish in all age classes.

The study looked specifically at the size and age mix of the walleye. It found that about half the walleye in the lake were under the slot size. The data does suggest that walleye seem to grow a little faster than average in Lower Marmion, but that rate of growth is nowhere near enough to account for the frustration anglers are experiencing.

Another factor could be in play. In an unfished lake, the percentage of older (and thus larger) fish is always significantly greater than in a lake that is subject to regular fishing pressure. This makes sense – the chance of a fish living five years or more is far greater when there are no anglers around.

And while the moratorium on Lower Marmion was not universally adhered to, it may be that the ten-year walleye ban has resulted in a lake with more older fish than what anglers are encountering in more typical lakes.

Stocking?

The findings of the broadscale monitoring survey are consistent with the trend shown in a series of studies on the lake that started in 1996. The walleye fishery in the lake had collapsed then, apparently as a result of the warm water being emitted by the Atikokan Generating Station. A series of remedial actions, including the establishment of a weir and a sluiceway, spawning bed improvements and the ten-year moratorium on walleye fishing, helped the species re-establish in the lake.

The studies included netting surveys in 1996, 2001, 2003, 2006, 2007 and 2010, telemetry surveys in 2001, 2002 and 2003 (these involved putting radio transmitters in 14 fish and monitoring their movement throughout the lake), and a trap netting study in 2001. Positive results from those surveys led to the lifting of the walleye moratorium in January, 2009.

The Sportsmen’s Club proposed conducting its own fish survey in the lake, but Jackson was not keen on the idea, saying it would be hard to compare that data with that of the previous studies. He did note that Lower Marmion would be surveyed again in 2015 under the broadscale monitoring program, and that if there is something radically wrong with the surveys of the past 15 years that it should show up then.

This led to a wider discussion about the value of stocking the lake with fry produced in the club’s hatchery.

The science regarding stocking lakes with fry suggests that it doesn’t help in lakes where walleye are already well-established and have good spawning habitat. A healthy walleye population produces plenty of fry; adding more does not seem to increase the number that make it through the first winter.

As a result, the MNR has encouraged the ASCC to look to lakes where walleye are not present, or have died out. Stocking those lakes, with both fry and adult walleye, has been shown to help re-establish healthy walleye populations as long as the lake has suitable conditions for the species.

There is another issue at play with stocking, said Jackson. In southern Minnesota, where angling pressure is typically ten times or more than what it is here, fisheries managers have turned to stocking to support fish populations. And while the effectiveness of those efforts are questionable, they have had a pretty clear effect on the approach anglers take: the conservation ethic has taken a beating.

“Stocking a lake changes attitudes,” said Jackson. “[Anglers worry less] about letting fish go, because the hatchery will just put them back in. That’s been the experience in Minnesota.”