jpsdad, what would you suggest for culling? All of the >14" or 16" or judge by RW up to 16" ? Or cull some of the bigger ones? I know I need to cull and am absolutely not opposed to eating a bunch of fresh fish.
Before I suggest the remedy that I would employ were I the owner of the BOW, I would like to lay some ground work. First, your lake supports a remarkable standing weight of trophy fish. Assuming 50% survival of the original stock, there may well be 21 to 22 female fish/acre averaging say 5 lbs each. This maybe too rosy, maybe there are 16 or 10 left along with some surviving males too. If the latter is the case it is worth asking why so much mortality? One possible reason for that scenario is that some fish made maintenance and survived while others succumbed to competition and made room for the survivors to grow by dying. There is a pretty good chance the latter possibility of 20 surviving LMB of the original stocking remain. Assuming the girls weigh twice as much as the boys and equal numbers of each 20 per acre corresponds to around 75 to 80 lbs of LMB per acre(where 10 of the population are female). Now this a good standing weight of LMB ... most waters don't support that weight but I think yours does and can ... possibly more. It makes sense that recruitment is subdued particularly because abundant BG hamper spawning and because LMB YOY grow very slowly where the BG standing weights are high. A combination of competition and the length of time LMB recruits spend as forage for the big LMB greatly impacts survival of those LMB YOY that swim up. For a trophy pond, this not bad because the environment favors large LMB. This, is why you presently have a trophy pond. The head start the BG had created numbers that prohibited recruitment and the stocking rate of LMB at 43/acre limited LMB competition for prey.
Of course you can't maintain this population structure indefinitely. The original stockers will be nearly all gone by the fall of 2028 and what you would have if you do nothing is those LMB that have recruited. A sustainable trophy track would be recruitment of 2 (possibly 3 fish) into the 12 to 15" range per acre per year. Based on your earlier comments, this may not be happening. For example, for you to select 3 fish per acre year for trophy track (essentially marking the fish with a fin clip) you would need to catch 105 12" to 15" female fish per year ... something which may require catching 210 mixed sex fish per year. So if you are not recruiting at that level, you may not be able to depend on your lake for recruitment. If this is so, then the standing weight of LMB would plummet starting in earnest in about 3 years.
I haven't seen your lake and only know what you have already described. I have inferred that you stocked the ASF Tiger F1s and that the excellent catchability is related to their program of selection of aggressiveness in the Northern piece of the hybrid. I have also inferred that your recruitment of LMB into adult sizes has been muted. But to whatever extent the water is unable to recruit into adult size I do think that 1.5 year old Tiger F1s that fall into 12"-15" range would be excellent recruits. An advantage of sourcing 1.5 year old fish for this size recruit is that they have a lot of life left in them. It likely takes a minimum of 3 years possibly 4 to grow equivalent sized recruits in the lake. I think you must stock adult fish as the survival and growth of smaller fish would be very uncertain in your lake. These should be sexed where a high proportion of females are supplemented. How available are these? I don't know but you only need enough to supplement what you are able to select from your own recruitment to meet the recruitment goal. By marking fish with a fin clip or tag, you ensure their release for continued growth knowing you have sexed the fish to be female with 90% probability of correctness of the sex determination. Broom straw is a good method to make the determination. It is quick and relatively simple and is more than 90% effective.
So there is my case for recruitment and selection for trophy track ... but now about harvesting. First, yes, you need to harvest some of the large LMB. Within 5 years they will be mostly gone anyway. I think a pretty good plan would be to harvest the estimated 5 year mortality spread across 5 years of fishing. I think you probably have in the neighborhood of 10 female trophies per acre and so I would suggest harvesting up to 2 per acre per year. I would say harvest 2 fish over 20" per acre per year for the next 5 years. Restrict harvest to unmarked fish over the entire period. Let's say these fish average 5.5 lbs this year. 11 lbs of LMB will be harvested per acre. It takes 55 lbs of forage to maintain 11 lbs of LMB so this will free up that forage and the remaining LMB trophies will grow into that maintenance. Spread across 8 females trophies averaging 5.5 lbs there is potential to grow the surviving trophies by more than 1 lb per individual over the course of the next year.
I would keep good records of the weights harvested and over the next five years and in every year I would harvest no more than 18 lbs of LMB per acre but I would try to harvest at least 15 lbs per acre per year filling this remaining quota with fish less than 20" but greater than 12" that have been determined male by straw method. After 5 years of recruitment and this harvest regime I would reevaluate based on population dynamics. At this point you may be in a position to harvest only unmarked fish and allowing selected recruits to go through a full life cycle as catch and release. Of course selection and recruitment efforts will be on going along with the 18 lb/acre harvest limit. Growth of recruits may suggest the recruitment rate should be increased/decreased or that harvest should be increased. I think your lake has a pretty good chance to maintain trophy status because the BG population appears to be restricting LMB recruitment and providing forage that can support in excess of 70 lbs/acre of adults. So long as the number of adult LMB/acre remains less than 20/acre, and provided BG produce 350 to 450 lbs of forage annually the water will remain conducive to growing trophy LMB.
