Finally, the post I promised concerning the impacts on a fishery that just a few people can have. This really, at its heart, stems from the old saying that 10% of the anglers catch 90% of the fish. It is what is commonly referred to as a 'Pareto-ism", which I have also touched on in a previous post. Here's another: Ninety percent of the fish are located in 10% of the water. You've all heard these two sayings before, and a brief search of the Internet failed to produce any generally accepted origin of these two sayings. But is there any scientific basis to support either of these two commonly stated principles?
My curiosity on this subject was recently piqued by a paper concerning harvest rates of tagged channel catfish in small impoundments: "Effects of Stocking Rate, Stocking Size, and Angler Catch Inequality on Exploitation of Stocked Channel Catfish in Small Missouri Impoundments". The authors didn't go into a ton of detail on this particular aspect of the research, but they did summarize the details in the following paragraph:
"Fluctuations in the exploitation of channel catfish can occur within a small lake simply from small changes in angling clientele. As in other studies (Smith 1990; Baccante 1995; van Poorten and Post 2005), the distribution of catch that we computed was highly skewed among anglers. We found that one to three anglers were responsible for about one-third or more of the tag returns in over one-half of the lakes. We may even have underestimated the importance of these anglers because in several cases other family members also returned tags. If these successful anglers had not fished, their families would probably have not fished as well. The relative influence of these few successful anglers declined with increases in the total number of anglers returning tags. Thus, for lakes with few anglers wide fluctuations in exploitation are likely."
So I tracked down the referenced paper in this article, Seasonal Fishery Dynamics of a Previously Unexploited Rainbow Trout Population with Contrasts to Established Fisheries to learn more. In this study, they assessed the catchability of fish in a previously unexploited population (not fished for) and documented some very interesting findings.
- Large fish are more likely to be caught and harvested than small fish. This makes sense if you believe that large fish get that way by being the aggressive or more dominant individuals in a population. Remember, we're talking about unfished populations. So the first anglers in, even if only a few, can do significant damage if they choose to keep a majority of what they catch.
- Catchability in the unexploited populations are intially high, in other words, the pickings are easy or as I like to say, everybody looks like a pro. But the population as a whole (based on catchability) quickly mimics a traditional pressured fishery within a matter of weeks. This could partly be explained by harvest, and partly explained by conditioning, but those two don't explain the entire reason. The authors suspect there is something else at play driving part of this observation
- "...a small portion of the anglers catch the largest proportion of the catch and the largest portion of the anglers catch no or few fish. Early in the development of the Cabin Lake fishery, the catch was more evenly distributed among anglers, which is often indicative of high mean catch rates. This rapidly changed towards the highly skewed distribution of catches among anglers towards that more commonly seen."
Reading this paper reminded me of a couple other pieces of research that I had years before and was able to track down:
Arkansas Game & Fish Commission Largemouth Bass Management Plan - Scroll down to page 15 for the stats on 'Frequency Distribution of Angler Harvest from Arkansas Lakes'.
To Harvest or Not To Harvest: That is the Question - From the Iowa DNR concerning angler concerns over 'fish hogs' as relates to the population dynamics of the states panfish fishery. Again, the theme of a minority of the anglers who catch their limits while most others don't fare as well. Given the size and reproductive capacity of a panfish population, no detrimental effect to the overall population is believed in this case, though another post for another time could discuss just the effect on a subset of the population, the high end of the panfish size distribution.
Finally, tracking down a commonly referenced paper from the trout study, I came across "Assessing Catch Inequality in Walleye Angling Fisheries". Here they used Lorenz curves and Gini coefficients, typically an economics measurement of wealth distribution, and modified them to fit angler harvest distributions. Their basic findings concluded that catch equality is much greater among anglers when there is a large population of fish to be caught. However, in smaller populations, catch inequality reigns. Have you ever heard the saying that the easiest tournaments to win are the toughest ones (the ones with the least amount of overall catching going on)? That one I attribute to Rick Clunn, and Gini coefficients back that statement up nicely.
Other things that they found to affect these curves were bait choices (artificial anglers in one particular lake were significantly outfished by live baitfish anglers), harvest limits (the tighter the harvest restrictions, the greater the percentage of the catch attributed to those that can regularly catch their limits and subsequently the steeper the Lorenz curve), and whether a target fishery was composed of larger, schooling fish or smaller, more widely dispersed fisheries (tighter groups of fish in more discreet and fewer locations or widely scattered fish in all environments).
So regardless of the exact ratio, there is ample evidence that a minority of all anglers account for a majority of all fish caught, or at least harvested in many situations. Much of this information can be adapted to fish bass fishing scenarios that we all commonly experience. Keep this in mind when viewing reports and tourney results, and strive to become one of the elite 'few' when it comes to catching.
Indiana Weather Sucks
I can't believe this is happening again this year. The graph above tells the story. I don't remember the exact year this happened last, and I've been too lazy to look it up, but I remember the overall story line well. We get one good warm week of weather at the start of November and then the temperatures tank. Outside of a little bubble of warm air that hit us on the 13th and 14th, our highs have rarely exceeded 45 degrees and our lows have been at freezing or below, especially this past week. Needless to say, our waters went from surface temps in the low to mid-50's to the point where lakes are now starting to freeze up, all in a 2 week period. Most every small body of water (<20 acres) is now froze solid with a layer of ice. On the bigger waters, Cataract remains open, but Geist anglers had to break about 200-300 yds. of skim ice to get out to open water yesterday. Morse is freezing over in the back ends of coves, but the larger main lake water remains open. Waters to the south are probably still fine.
So we've reached the precipice of open water fishing for 2008 and it's not even Thanksgiving yet. Did I mention how much Indiana weather sucks! Long range forecast isn't showing any signs of relief yet, so I'm not overly optimistic about a warming trend moving in in time. I plan to hit the water Friday with partly sunny skies and a high of 44 on the agenda. Might get a trip in Saturday also as clouds and a chance of showers move in, but the low 40's holds. By Sunday they say back around freezing for the highs, so all bets are off the table from that point on. We'll see what happens.
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