When the subject of fish management comes up, whether the species being discussed is striped bass, fluke or whatever the flavor of the day is, many often turn to the concept of a slot limit as a way to help rebuild the species. From there I see rather arbitrary numbers thrown around in which different user groups would support, but often there is little science behind the numbers to back them up. Unfortunately, it’s the “science” in which the managers usually fall back upon when making decisions. Well, at least that is what they say motivates their actions.
For those unfamiliar with the term, a slot limit is a method of fishery management which regulates the size of a fish for legal harvest within a determined length range, or “slot.” Fish that fall below or over the range must be released, while fish that fall within the range are eligible for harvest. There is also a “protected slot limit” in which any fish that fall within a certain length range must be released, while those that fall outside the range would be eligible for harvest. Depending on the intended result, fisheries managers have used the slot limit and the protected slot limit at different times on different species.
One of several species commonly used to support the concept that a slot limit would work on striped bass, for example, is the redfish/red drum fishery in Florida. According to the Florida Fish and Wildlife Conservation Commission (FWC), “In the late 1980s red drum was overfished, thus several emergency closures were established to reduce fishing pressure. In 1989, the slot limit of 18-27 inches, the bag limit of one fish per person and a closed season from March-May were put in place. Red drum stocks have rebounded and are currently meeting or exceeding the FWC’s management goal of 40 percent escapement in most parts of Florida. Escapement is the proportion of fish that survive through age four relative to the fish that would have survived if there was no fishery.”
I am somewhat familiar with the success of the slot limit on the Florida red drum, but I never knew the story of how it came to be. Well, while in Orlando in early July at ICAST, I had the good fortune to be able to spend some time talking to several local captains who had fished through the lean years of red drum. My primary goal of our conversations was to figure out if and how what they did could be applied to our beloved striped bass in the Northeast. Knowing there has to be some science behind the numbers, I asked how the slot was determined.
Well, as it turns out, redfish generally begin spawning when they reach 26 inches in length, roughly the same length at which they make a move from primarily inshore waters to those further offshore. By setting the maximum harvest length at 27 inches for redfish, the spawning stock is protected. Sure the fish might be harvested prior to reaching spawning size, but any fish that are successful in dodging an army of hooks and nets to reach spawning size can basically do so moving forward free of any unnatural harvest.
So applying all of this to striped bass, we would need to look at minimum lengths for reproduction to begin with. It is also good to note that almost all striped bass in excess of 40 inches are females, and it is well-documented that when the end goal is species recovery, it is best to remove the males and leave the females, so first and foremost leaving all fish in excess of 40 inches in the population at large is a good thing by this logic. The science behind this concept is that it only takes one male to fertilize many females so by reducing the male population you do little to hurt reproduction. Further, as a striped bass gets larger, so does its ability to produce eggs. For example, a 12-pound female can produce in the range of 850,000 eggs while a 55-pounder can produce about 4,200,000 eggs. Now here’s where there enters some discussion and debate as to the viability of those eggs on the larger fish, but to the best of my knowledge no such definitive data exists at this time.
Striped bass reach sexual maturity somewhere between age 4 and 8, and that age range equates to a fish of anywhere from 21 to 32 inches long. So by applying the same concept as seemed to work on redfish, one would assume that we would need to protect striped bass in excess of 32 inches on the high end. If you look at the way today’s regulations are set up across New England, we basically do the opposite of this in that harvest is prohibited on fish below 28 inches, smack dab inside the range of when they reach sexual maturity, which means we basically ONLY harvest sexually-mature fish. Further, with the emphasis on taking the largest fish possible by tournaments and egos alike, we are further targeting the large females of the species. This all seems counter-productive to ensuring a healthy, robust and self-sufficient stock. Is it any wonder why the striped bass population is in as poor of a state as it is?
So where does this lead us? Now I am only speculating and throwing ideas out there, but if we were to take the redfish as an example of a similar species’ success story, then anglers would have to be willing to accept a slot limit somewhere in the range of 16 to 24 inches (somewhat random numbers but this falls inside the range as outlined above.) To be honest I’d be quite surprised if anything like this ever comes to fruition in my lifetime, but I can’t say that I’d be totally opposed to it, either. How about you? How would you feel about a slot limit like what I’ve outlined here? As always, feel free to email me your thoughts at firstname.lastname@example.org; I’ll try to respond as much as I can, and if some of your comments are well thought out, perhaps you’ll see them printed later this fall.