Article written by Sean Landsman
[Editor’s note: This article is the first in a series written by guest authors for this blog. This article was written by Sean Landsman, a PhD candidate at the University of Prince Edward Island. Sean is an incredible photographer and an accomplished angler. Check out his webpage for some amazing fishy photos].
Full moon. New moon.
These are two of the most important phases of the lunar cycle for anglers. Talk to just about any accomplished angler and they’ll tell you that catch rates around these moon phases often go up dramatically.
But is it a self-fulfilling prophecy? If the fishing community pushes the Kool-Aid for years and years, eventually you’re bound to drink it, right? I’m certainly guilty of leaning heavily on moon phases. I fish my best spots around moon rise/set and plan long-distance fishing trips around the moon phases.
Consider, too, the effect of lunar cycles in freshwater. Or rather, is there an effect at all? Certainly large tide swings (i.e., “spring tides”) are consistently associated with the new and full moon periods. So, for saltwater species this may have a huge impact on habitat availability and access to resources (e.g., large tidal flushing moves more food in and out of habitats).
However, in freshwater environments such as lakes, ponds, and rivers, there are no tides (Great Lakes aside). So then what is the biological effect? Is it increased light levels at full moons? If so, how would that explain higher catch rates during new moons?
Let’s examine a paper published two years ago in 2014 about moon phases and muskie (i.e., muskellunge Esox masquinongy) catch rates. For those not familiar with muskies, they are close relatives of the northern pike, sharing several similar characteristics such as large, well-developed teeth, long bodies built for speed, and a predominantly sit-and-wait foraging tactic. Muskies are native to temperate North American waters, extending south from the Carolinas up to northern Ontario.
Two scientists examined the relationship between muskie catch rates and lunar phases by studying almost 240,000 catch records from Muskies, Inc. (a conservation and fishing organization). Catch records from Minnesota, Wisconsin, Canada, and Ohio were examined. Each date a fish was caught was then related to a specific lunar phase. The authors also compiled angler effort data to address whether catch rates could be biased because anglers focus their efforts during the full and new moon periods.
After a series of complex statistical analyses, their results did indeed indicate that lunar phase has a significant impact on angler catch rates. Specifically, new and full moon periods were the best predictors (of all possible lunar phase combinations) of an angler catching a muskie. And bigger fish were also caught during these full and new moon periods.
As a default explanation for these findings, the authors’ hypothesis was that angler effort is simply more concentrated during these time periods. The authors acknowledge that this is something that cannot be ignored. However, their findings showed that lunar phase only significantly affected angling effort for one specific lake in Minnesota.
What their data point to is some sort of synchronicity occurring between muskies and the lunar cycle. The authors also noted that catch rates were similar between new and full moon periods. If this were not true (for example, if catch rates were greater during full moon periods only), then one might correctly posit that full moons lead to increased light levels and increased muskie foraging. However, the authors’ results do not support this.
So what the heck is going on then? The answer is really that we still do not understand the underlying mechanism. The authors suggest that synchronizing feeding behaviour with the lunar cycle must confer some advantage to individuals.
Of Moons and Anglers
So what does this mean for us anglers? This study certainly lends quite a bit of credence to focusing efforts around the new and full moon periods, at least for muskies. Many of us cannot afford to fish whenever we want to so maximizing our time on the water becomes important. If you feel guilty about “drinking the Kool-Aid,” as I sometimes do, I think this study should allay that guilt.
To end on a personal note, I still have a hard time understanding how moon phases affect muskie behaviour. Without a clear explanation, I will continue to be skeptical. What do you think? Do you plan your fishing trips around the new and full moon periods? Do you have any hypotheses that would explain increased catch rates – muskies or otherwise – during these moon phases? Feel free to add your thoughts in the comments.
Citation: Vinson MR, Angradi TR. 2014. Muskie Lunacy: Does the Lunar Cycle Influence Angler Catch of Muskellunge (Esox masquinongy)? PLoS ONE 9(5): e98046.
Find the paper here.