Per Lusk, fish don't "prefer" forage fish types over another, but are more successful at predation with some species over others. If I (TJ) understand his position correctly, BG and YP are likely to both be targeted with the same frequency, however due to the fusiform shape of a YP it will be successfully preyed upon with higher frequency vs the taller BG, leading us [erroneously] to refer to the YP as the "preferred" forage species.
I would debate this comment with Lusk. I have performed some fish feeding studies in college and when I was in an animal behavior class. I contend a predator can learn from experience that fusiform was an easier meal. Thus I say the predator will often choose or prefer a food if given a choice. Give the predator a little credit. Granted “prefer” is an anthropomorphic term (human attributes). Although at least some educated animal behaviorists use the terms choose and prefer when describing animal behavior. See Preferred Animal Behavior in the link below.
Predatory fish including those eating meat, even in terms of panfish preying on invertebrates, have numerous times been shown and reported to selectively choose, prefer or key-in on a certain type of forage food item despite other foods being readily available. This I think is where "match the hatch" phrase came from. Choice of lure size shape and or color that resembles the current food being eating by the targeted fish is another confirmation that predators will key-in on and choose, prefer or select certain foods compared to other similarly easily available items.
Trout have been shown to select a certain insect shape and color versus another insect each side by side and each being the same effort to capture. This may and may not be closely related to relative abundance of food items. I have fished many times were you need to match what the fish are eating on that day to catch a fish or more fish than your partner !. Walleye in Lk Erie during the mayfly hatch gorge solely on mayflies despite small fish and shiners being very abundant also eating mayflies among the walleye. Walleye stomachs were full of mayflies rarely fish. So were walleye more successful eating mayflies or were they focused on eating mayflies? I say, that day, walleye were choosing and preferred to eat mayflies and not the just as easy to catch small fish among the walleye. Plus those choosey WE had to expend more energy and time to eat a lot of mayflies to equal the weight reward of eating one small fish.
Also what about pellet eating fish, such as lets use a 12" LMB as an example. The bass will choose / eat and expend more energy eating several pellets instead of expending less energy / effort of sucking in a 1.5" or 3" BG right beside or in front of the bass. I also see same type of behavior in pellet feeding my big yellow perch and my snapping turtle. You may have also seen similar fish behavior in your pond. Sit still, watch and learn.
See Case Study 2 using honeybees. Choice – Preference behavior
https://www.nature.com/scitable/kno...references-and-choice-behavior-23590718/Commentary. However in my comment above about GSF eating lots of YP, the GSF are not necessarily selectively choosing to eat YP over another food. The GSF are basically eating anything that fits into their mouth and at certain times of the year, YP fry are abundant and mostly the only or primary food available so it gets aggressively and heavily consumed. Amount of refuge habitat can minimize the losses. Aggressive, competitive, greedy and availability being the main behaviors of the predatory nature of GSF and IMO not so much choice or preferred feeding as it relates to YP living with GSF.
