Making Sense of Slot Limits

Steve with a nice bass

Steve with a nice bass

Finally, I am going to share my thoughts on slot limits for striped bass and on some management measures that should go along with slot limits to make sense out of that management process. My fellow blogger John McMurray thinks that slot limits concentrate the catch in one segment of the striped bass population. I happen to think that raising the size limit concentrates the catch in one segment of the striped bass population. Who is correct?

I will say that I agree with John’s main premise that there has to be a reduction in the overall mortality. How to accomplish that reduction, and in the process use some existing natural and manmade mortality and physical stock makeup to best play into sustainable management, is the question.

First, I am not suggesting a slot limit regime could replace the existing two fish at 28 inches or above. That would simply not work. There needs to be reasonable conservation equivalency. The state of Maine made a case for conservation equivalency years ago and ended up with a one fish slot between 20 and 26 inches or a trophy fish over 40 inches. If I were king, I’d get rid of the trophy category. Catch a big one, measure it, snap a pic and return it to the water. Those big fish are barely edible, in my estimation. I’d rather eat an old piece of cardboard soaked in menhaden oil. As far s a trophy, 99 percent of all mounts are reproduction mounts that do not use any of the actual catch, beyond pictures and measurements. I digress.

So, my suggestion would be to drop the limit to one fish per angler per day at a slot limit somewhere in the range of 20 to 28 inches. Maybe the correct slot is 22 to 28 or 20 to 26 or 24 to 28. A population dynamics specialist would be better at determining that than I am. Do I think that a “set it and forget it” mentality will work with striped bass? No, I do not. This will always be a work in progress, and additional steps may have to be taken to ensure that the stock biomass remains above the threshold. A unique advantage of slot limits is that they can be adjusted up or down each year in order both to protect poor year classes and at the same time take advantage of the good ones. Constant adjustment will be the case as long as there are habitat impacts and ever-increasing coastal populations.

Why the slot limit in the first place? It has been determined, by folks a lot smarter than I am, that the big old females (BOFs) are the most valuable segment of any fish species. Per pound, they contribute more eggs that are more viable and produce stronger juveniles than less mature females. So McMurray’s suggestion that managers simply raise the minimum size as one mechanism to drop manmade mortality makes little sense to me. Why would you put all the fishing pressure on the very segment of the population that you need to sustain the species? Also, if one thinks of the perfect size and age composition of any fishery it will be shaped in the classic bell curve. The BOFs are past the peak or to the right of the bell curve. They have a lower natural mortality level than smaller fish, which also adds to their value.

Also, fish that are at the 28 inch limit or larger are 95 percent or better females. The males tend to be smaller, so dropping the size limit to spread the mortality between both sexes makes some sense. The females are the more important, and I am constantly reminded of that by my wife, daughter and four granddaughters.

Probably the major aspect of why slot limits could work has to do with the current statistics for release mortality. The current percentage used to estimate the mortality of released striped bass is 8 percent. In Massachusetts alone, the release mortality exceeds the commercial harvest.

If we look at the catch by size for 2006, which is similar in distribution to more current years, 39 percent of the total annual catch was 27 inches or less. Again for 2006, that amounted to 1,152,850 fish. Of that catch 92,000 died from release mortality. Of that number, 58 percent would have been in the slot of 20 to 28 inches. So, approximately 58,000 fish that were wasted could have been used to offset the recreational landings. At the same time, hundreds of thousands of BOFs would have been left in the water to help produce more strong year classes. Yes, I realize that in the past the correlation between numbers of BOFs and the spawning success as measured by the young-of-the-year survey is not a direct correlation. In fact, if you go back to 1986, the spawning biomass was at an all-time low, but the environmental conditions were perfect. Subsequently, the rebuilding process worked because annually adjusted measures protected the BOFs and allowed them to spawn. The current management regime focuses all the pressure on the very heart of the spawning stock. Somehow that needs to be spread around. And when the conditions are right, it makes more sense to me that one would maximize the potential spawning success.

One of the other factors is that there are a number of participants in the fishery who are simply interested in catching a fish to take home. Once they catch it, they will move on to another species or head to the beach. Making it easier for them to achieve their goal means that they will not have to catch and release a number of fish in an effort to get one to take home. That should reduce the release mortality and waste.

It seems to me that the current management regime has the drawbacks pointed out above, while the concept of a slot limit resolves a number of those drawbacks. I’ll be the first to say that a slot limit for striped bass may not be the perfect answer. However, I also think that the current management regime is not the perfect answer.

Slot limit management for striped bass has the benefit of protecting BOFs, mitigating release mortality by turning a percentage into landings and moving some anglers off striped bass when they have caught what they want for consumption. It also improves the chances for anglers to catch that trophy of a lifetime. The main drawback of the slot limit is the fact that fishing pressure gets concentrated on one or two year classes. Without doubt, that will require careful, real-time catch accounting and analysis with an understanding that changes may have to be made.

What I know does not work is the current management regime and the general proclivity of the Atlantic States Marine Fisheries Commission to kick the can down the road. Oh, yes, and since we are near the end, I’ll throw in my thoughts that having gamefish status for striped bass also would help by changing the attitude of managers from managing for maximum sustainable yield to managing for a quality experience. ’Nuff said.


"Rip" Cunningham, who owned, published and edited Salt Water Sportsman for 32 years, is also an accomplished writer and photographer. Cunningham has received several awards from the Outdoor Writers Association of America. His work has appeared in such magazines as Field and Stream, Rod and Reel, Gray's Sporting Journal, Australian Boating and the Boston Globe Magazine. Among his many accomplishments, Rip was recognized as the Conservationist of the Year from both the International Game Fish Association, the Coastal Conservation Association of Massachusetts, The Billfish Foundation and Federation of Fly Fishers. "I've earned a living from fishing, and I believe strongly that people with an interest in a given area should give something back,” he says. “It's rewarding every single day." Cunningham received his MBA from Babson College in Wellesley, MA and his BA from Rollins College in Winter Park, FL. He has two grown children and four grand children and lives with his wife and hunting dogs in Dover, MA and Yarmouth, ME. When he's not fishing or working through the items on his wife's "honey-do" list, Cunningham does some hunting and skiing.

Posted in Conservation
3 comments on “Making Sense of Slot Limits
  1. avatar Ross Squire says:

    I appreciate the comments that you raise. Clearly the slot size option is one that ASMFC Board members seemed very interested in considering as a large amount of time at the last meeting was spent on a variety of motions to include a slot fish (which in most cases also included a BOF).

    My greatest fear with the slot option is that since 2006 we have experienced poor recruitment classes. Only two years were above target – one was marginally above and the 2011 class was the fourth best on record. Rarely cited is the 2012 class which is the worst on record. Any new regulation should protect this YoY class and quite frankly, based on Maryland’s easing of size limits to capitalize on the 2011 class, I just don’t trust the ASMFC.

    Your referencing of 2006 may be misleading. In the 8 years preceding 2006 there were 6 YoY classes that were above target. The variety of fish in 2006 had to be much different than the fishery we see today just based on recruitment levels.

    I would love to see more emphasis placed on promoting best practices for the release of fish. The 8 or 9% figure that is used as the basis for release mortality is reduced significantly when anglers crush their barbs, use circle hooks, avoid the use of gaffs, and minimize the time that fish are kept out of water.

    And I agree with you wholeheartedly that the time for kicking the can down the road MUST end now.

  2. As far as I can tell we have the best opportunity to set our own slot limit right now. With 28″ min size we can let all the fish go over 34″ or 32″ whatever you choose. I try to encourage everyone every day to put the big fish back. Let’s set the slot ourselves and keep the state out of it.

  3. I have to admit that I’m in John McMurray’s corner on this one. While slots can be useful for some species, and might even be useful for striped bass if very carefully created, used and followed, as a practical matter, they are unlikely to work in the bass fishery.

    I’ll start by saying that, with respect to the question asked in the first paragraph, both sides are correct–slots concentrate harvest on one or two year classes at a time, a serious consideration when few strong year classes are being produced, and high size limits concentrate the kill on larger fish. The question is, which is the greater evil.

    So let’s first look at how biologists deal with slots.

    The Maine slot that was mentioned is a good example. We should first acknowledge that it was not adopted as a conservation measure; instead, at the time that it was put in place, the 1993 year class, the first really dominant year class since the stock collapsed, was not yet 28 inches long, so Maine put the slot in place to allow some harvest of those fish before they reached the coastal minimum length. In doing so, and adopting the 20-26 or 40+ limit, which put a lot of pressure on immature fish that had not even spawned once (there weren’t many 40-inch-plus fish around at that time, although there were some), the biologists found that they did a lot more harm to the stock than they would have with 2 @ 28 inches, so in return for the slot, Maine had to surrender one fish from its bag limit–going to just a one fish bag–to compensate for the harm done.

    We saw the same thing in New York, where the commercial quota was cut by about one-fourth due to New York’s 24-36″ commercial slot (adopted to reduce the amount of PCBs that the commercial fish bioaccumulate before being caught). New York had to give up quota to account for the harm done by the slot.

    So, if we accept the current advice provided by ASMFC’s Striped Bass Technical Committee, which has said that the bag limit needs to be dropped to a single 28″ fish (or two 33s) in order to achieve the needed harvest reduction and have a 50-50 chance of reducing mortality to the target level within two years, we have a problem.

    You can’t reduce the bag limit below 1 fish in order to compensate for the harm done by a slot which allows the harvest of immature stripers. That means a season, and the season reduction needed to reduce landings by 25% (above and beyond the reduction achieved by going to 1 @ 28″), a figure I based on New York’s commercial experience, is pretty severe. I did a back-of-the-envelope calculation not too long ago, when I was taling about this to someone else, and this is what I came up with based on the last three years of MRFSS/MRIP estimates (remember that fall 2012 and, to a lesser extent, spring 2013 were disrupted by Hurricane/Superstorm Sandy).

    If all of the 25% reduction was put at the front end of the season (admittedly unlikely), and the season ended on December 31, based on 2011 landings patterns it would have begun around Memorial Day. Based on 2012 patterns it would have started around July 1 and based on 2013 patterns, on June 7.

    If all of the 25% reduction came off the end of the season (perhaps even more unlikely), and the season began on January 1, based on 2011 landings patterns, the season would end around October 20. 2012 landing patterns would have seen it end around August 20, and 2013 patterns would have led to a September 1 closing (all dates are approximate, but close enough for purposes of this discussion).

    I didn’t work out what would happen if half of the reduction was put at each end of the season, but something like May 15-November 1 is probably pretty close.

    A lot of folks, particularly in the lower Mid-Atlantic, wouldn’t care for that very much. If we want to say that a slot is the right way to go, that’s fine, but we need to look at what the consequences would be.

    We also need to ask how much such a slot would reduce real-world mortality of larger fish.

    Although there are exceptions (and Rip Cunningham may be–and probably is–one of those exceptions, most of the ardent slot advocates fall into one of two diametrically opposed categories. One one hand, there are the ratcatchers–fly fishermen and the like–who don’t catch that many really large bass, don’t understand the trophy-hunting mentality at the gut level, and release all or at least the great majority of the fish that they catch. On the other hand are the tackle shops, party boats and even some folks who call themselves striped bass conservationists, but vehemently fight for the anglers’ ability to take “a fish home for dinner,” either because they make more money when anglers can reliably find fish to kill, or because they just believe that it’s the right way to manage. Because of the latter group of folks, allowing anglers to kill immature fish may actually incease mortality, and bring more people into the fishery.

    And I don’t buy the notion that people will stop fishing once they have a bass to take home. If you watch the clam chummers in Long Island’s inlets, they’ll keep fishing so long as their bait and chum holds out, even when they’ve got fish in the box. And even when the J-hooks that far too many use are killing fish after fish.

    But one of the biggest attractions of the striped bass is that it is the largest fish caught in the inshore waters off New England and the upper Mid-Atlantic. A lot of striped bass fishermen are looking for a big fish, and that leads directly to the release mortality problem.

    While it is correct to say that the official release mortality rate is 8%, it’s important to note that the studies used to come up with that rate tended to base mortality of fish hooked with single-hooked lures (I know that was the case in a Massachusetts study), in cool water and released quickly. A New York study done in the Hudson River, which tried to reproduce the way anglers normally catch and handle fish came up with a number closer to 30%, while a Maryland study found that even a small fish, if dragged out into air temperatures in excess of 90 degrees, is almost certain to die. And, of course, all studies show that fish hooked in the gills or gut are likely to die.

    So given the prevalence of bait fishing among those seeking large stripers, the 8% release mortality number probably significantly understates the number of fish that die after release; bass that swallow a bunker chunk, or even a large bunker head-rigged with a treble hook (a very common technique here in New York) are not prime survival candidates. Couple that already-lowered survival opportunity with the stresses caused by fighting a larger fish, then hanging it from a Boga for a photo, and leaving it waving around in the air while the hero who caught it waits for his buddy to dig a camera out of the cabin, and survival rates go way down.

    Yes, a slot could still work–if you coupled it with mandatory circle hooks in bait, barbless hooks on lures and borrowed Florida’s tarpon rules that make any fish lifted out of the water to be “in possession” and thus require large fish to be released and photographed next to the boat, rather than in it (the rule they have up in Alaska that requires you to stop fishing for king salmon immediately after retaining your limit would also be a big help). As a rule, I don’t bring bass home, nor do I bait fish for them, but I like the idea of being able to keep a fish that isn’t going to survive the fight.

    Rip Cunningham is also correct in saying that that a “set it and forget it” slot wouldn’t work; a slot would have to be reset to match the existing biological conditions. That’s fine from a biological perspective, but from a practical perspective, it has problems. A lot of fishermen don’t stay on top of changes in the law, and compliance rates always drop when new rules go into effect; while changing slots to match the conditions is the right thing to do, a good number of anglers will always be fishing on the last year’s rules, at least at the beginning of the season, and thus would water down the effectiveness of shifting the slot to meet the needs of the stock. Here in New York, the rule has been one fish at 28-40 and one over 40 since 2005 or so, but a lot of the fishermen–perhaps most–still don’t get it, and will take two over 40″ and still think that they’re within the law.

    The bottom line is what we all agree on–that we need to reduce mortality. If we can get a good estimate of discard mortality in the recreaational fishery, then keeping F<0.18–and remember that F includes discard mortality–should get us where we need to go. It's unfortunate that some fish will be wasted, but waste–and discard mortality on fish of all sizes–is always going to happen. A slot may not reduce it as much as we think, and killing fish before they have a chance to spawn even once is not a good idea.

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