Building a little bit upon our discussion from the other day, I'd like to take a minute and describe how some of these fishery statistics relate to what anglers actually experience when out on the water.
One of the stats you'll see repeated in this post is the CPUE of both bass and bluegill in the form of numbers of fish captured via electrofishing per hour. The other is Proportional Stock Density (PSD). Proportional Stock Density is calculated as a number based upon percent of fish over a quality length, divided by the percentage that are over a stock length, times 100. The lake in this example will be West Boggs.
In this first graph dealing with largemouth bass, you'll see the CPUE in blue and labeled on the right, with the PSD in magenta and labeled on the left. In particular, notice the red circled values around the recent and contined low (~50) CPUE values, and the trend arrow for CPUE continuing to rise, and now up around 90. What this means is that the overall population of bass has dropped, most likely due to poor recruitment, so that anglers are catching fewer fish overall. However, the tradeoff is that the remaining bass tend to grow large, hence the really high PSD numbers. In the case of W. Boggs, electrofishing surveys have shown that more than 55% of all bass surveyed are over the 14" minimum length limit, a much higher than normal number.
In this next graph, the same stats are applied to the lake's bluegill population. Here the trends are exactly reversed (see red arrows), with the CPUE of over 1000, and the PSD now down to less than 10. So you have a large population of bluegills that have become slow growing due to their numbers relative to the amount of food available. What's this all mean?
What has most likely happened is that as shad got introduced into the lake after the renovation, bass started to preferentially feed on them over the bluegill, and the bluegill population could no longer be kept in check. Bluegill are best managed by a very high population of small bass, and what you now actually have is a very low population of large bass. Part of this problem is also likely exacerbated by high shad biomass that tends to negatively affect recruitment of bass, though there is some mixed opinions on this in the literature. The kicker is that once this happens, it is very hard to reverse, and the word I've heard is that the liklihood of another renovation at Boggs in the next couple years is high.
From a more practical standpoint, anglers can get a very good idea of the fishing potential of a lake by studying this type of information before ever visiting. If you're a bass angler, by looking at this data, you could expect to not catch a lot of fish if you were to make a trip, but the ones you did catch are likely to be a very good size. Tournament anglers can then make a good guess as to game plan or strategy based upon this information. On the other hand, if you're a pan fisherman, it probably wouldn't be worth your time to go, because while you would most likely catch a ton of fish, very few of them are going to be of a harvestable size.
Don't be like most anglers and overlook this valuable information. It's all easily accessable via the IDNR website, with much of the information in downloadable .PDF files that you can ultimately save to your computer for future reference.
The Biggest Lie In Bass Fishing
Go to the seminars, read the magazine and Internet articles, query the pros and you'll hear one mantra repeated over and over again..."Catching fish is easy; finding them is the hard part."
Bull crap!
Now, I'm not going to say this is the case all the time, or even everywhere, but for bass fishing here in Indiana, which is what a lot of this blog is about, by and large, it just isn't true. In fact, it's actually the reverse, and you know I have some data to share with you to support this opinion.
First, a quick fishery terminology lesson. 'CPUE' or "catch per unit effort." It's a very common term that you'll find in most every lake survey dealing with fish populations. The 'catch' in this case will be bass, particularly numbers of bass 'caught' during a lake survey. The 'unit effort' in most instances is 1 hour, which comes from the total length of time spent electrofishing, and then adjusted using some simple math to get a catch rate per hour, or CPUE. For example, you shock up 300 bass in 2 hours of surveying, and your CPUE is 150. So lets look at the CPUE from the most recent data available for many of the popular Indiana bass waters.
The first thing you'll notice is that for the most part, every lake listed falls into just 1 or 2 basic categories. They are either in the higher range with CPUE's around 150, or they are in the lower range with CPUE's around 50. So what does this actually mean? It means when a team of biologists pulls along a bank on one of those listed lakes and does their survey, they are shocking up, on average, either 50 or 150 bass every hour. Now when you consider that a survey boat is moving along pretty slowly so that all the fish shocked can be netted and counted, you're really talking about hundreds, more likely hundreds and hundreds of bass down any given mile or two of shoreline. It means finding the fish is easy - they're concentrated pretty well on most every bank you might think of pulling up to to fish.
The fact that you're not whacking them doesn't mean they're not there. They don't bite for lots of reasons. Many are probably neutral or negative - only a few may be feeding at any given time. Perhaps you scared them with your sloppy approach or your poor casting. Maybe they're not impressed with your new $50 swim bait. Who knows exactly why. The point is, the fish are there, around you, under you...you've found them - it's the catching that is difficult!
Need some more data? IDNR biologists recently completed a lake survey and population estimate of the number of potentially catchable bass (those >8") in Lake Monroe. Do you really want to know what their models came up with?
22,797 bass! That's right. There are over 20,000 bass swimming in Lake Monroe at any given moment, and you can't even catch 5 of them to bring to the scales. Want more data from smaller lakes? Surveys and modeling combined to give an estimate of 16,754 bass swimming around in Hardy Lake down to the southeast. Over to the west, Sullivan Lake has an estimated 12,243 bass roaming its waters. Still not convinced? At Brookville Res., there are about 137 smallmouth bass per mile of shoreline, and another 307 largemouth in that same 1-mile stretch. That's over 400+ bass per shoreline mile at a lake fondly known as "the Dead Sea." Still having a hard time finding those bass?
So lets look at the catching side of the axiom. IDNR has researched catch rates for all the reservoirs that are part of the tournament permit system. Here are some of the results. The catch per unit effort (in this case number of legal bass caught per hour) was highest at Hardy Lake (0.42), followed by Lake Wawasee (0.21), and Brookville Reservoir (0.19). The lake with the lowest CPUE for legal bass was Salamonie Reservoir (0.04).
If you want to think of these numbers in a different context, the number of hours needed to catch a legal bass was lowest at Hardy Lake (2.4 h), followed by Lake Wawasee (4.8 h), and Brookville Reservoir (5.4h). The lake with the highest number of hours to catch a legal bass was Salamonie Reservoir (23.0 h).
When you look at not just tourneys, but instead creel survey data for all anglers fishing for bass at many of these lakes, you get very similar catch rates. For example, at Monroe, the most recent creel survey showed a catch rate for all bass anglers for all sizes of bass caught at 0.13 bass per hour. Even in some of the best waters such as the Bluegrass F&W area, overall bass catch rates only run in the 0.5-0.7 fish per hour rate.
The bottom line is, catching bass really is the hardest part of the equation. It's why we're so focused on purchasing new and better lures. The tackle manufacturers thrive on this same set of data. If catching was so easy, we wouldn't need to be buying the latest and greatest holographic, sexy, japanese-imported, Touring Pro touted 'whatchamacallits'. Would the brand of rod or the type of line truly matter? Isn't it why we attend seminars, go to bass university, subscribe to magazines and read everything we can on the Internet from all the newest and greatest sites?
The fish are right there in front of you, every time you pull up to the ramp, or set down on a bank. You found them when you arrived at the lake. Now you just need to figure out how to catch them!
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