triggerfish

Photo provided

Every fish species has its own special challenges. Triggerfish have proved particularly challenging over the last few years.

Last week’s column on sheepshead included a mention of the fact that the bag limit on sheepshead has been changed significantly by the FWC. Our new daily bag limit on these popular fish is eight fish per harvester, which is a reduction of almost half from the old daily bag limit of 15. The old bag limit had been in place for more than 20 years — since 1997 — before being changed last summer.

As you can imagine, there was some grumbling among anglers about such a sharp reduction in the bag limit on a fish for which such a generous harvest had been allowed for such a long time.

One angler observed that the FWC must think sheepshead are in pretty big trouble if they are cutting the catch almost in half. It is true that cutting the harvest of a fish species in half would be something that would be done for a species that was judged to be overfished — but the recent change in sheepshead bag limit will not cut the landings by anywhere near 50 percent.

Why not? Because relatively few fishing trips resulted in 15 fish being harvested by one angler. Sure, there are sheepshead experts who haul them off jetties, piers and bridges by the bucketful, but these highly efficient anglers are in the minority and most of the rest of us won’t be affected by the new bag limit very often. I have not seen numbers which quantify the estimated impact but I would not be surprised if the actual reduction to the total annual harvest of sheepshead works out to be less than 10 percent.

So how does the FWC or any other agency tasked with managing fish stocks decide what needs to be done? The first step is to figure out how many fish there are — not an easy thing to accomplish. They could ask fishermen how many fish they are seeing, but that seldom works. For every response of, “There aren’t as many fish here as in the good old days and you need to do something about it,” there will probably be another angler who replies with. “There are plenty of fish here if you know how to catch them, we don’t need no stinkin’ regulations.”

Since we know we’ll never be able to count every fish in the sea, fisheries managers are stuck with the task of coming up with estimates of fish populations based on a variety of clues. They look at recreational angler creel surveys and commercial landings numbers and compare the current results to the results from past years. They may be able to do their own sampling using nets or other gear, especially for young fish. Sometimes they do visual surveys using divers, and there are other bits of data that they assemble as best they can. It’s definitely guesswork, but at least it’s educated guesswork.

It’s not sufficient to simply know how many fish there are. Fishery managers also need to know if there is a good mix of smaller and larger fish. A healthy population includes plenty of young fish which will grow into larger, harvestable fish in the coming seasons. There also must be enough larger breeders on hand to ensure that lots of little ones will be produced to keep the cycle going. This is a complicated balance, and it’s different for each species based on lifespan, growth rates and other traits.

Fishery managers often try to gauge the health of a fish stock by calculating the Spawning Potential Ratio (SPR) for that fish. SPR is essentially the ratio between the number of eggs being produced by the current population of that species and the number of eggs that would be produced if there was no human-related harvest of those fish.

So if a fish stock has an SPR of 50 percent, it means that the populations has been fished down to the point where they can produce half (50 percent) of the eggs that they could produce if we weren’t harvesting them. The FWC sets SPR targets for many of the species that they manage, and then adjusts fishing regulations to achieve those targets. SPR targets can vary from species to species, but targets in the range of 40 percent are commonly used by the FWC.

So, the FWC might be happy if less than half the egg production is possible for a species of fish? Isn’t that pretty low? Not really — some agencies manage a few species with SPR goals as low as 20. People are often surprised to learn that our targets are set so low. But that’s not irresponsibility on the part of our fishery managers. Rather it’s part of a calculated strategy to give us good fishing.

In that theoretical world where humans don’t catch any fish and plenty of eggs are produced, lots of those eggs would fail to produce adult fish because the environment would already be supporting its carrying capacity of just about every fish species. It turns out that if you want to produce as many fish as possible for harvest on an ongoing basis, the best way to do it is to control the population of fish so that there are fewer of them than there are resources to support.

Think of it like gardening. If you want your bushes to grow full and lush, what do you do? You prune them back, and the bushes respond by using their resources to produce a spurt of lush new growth.

Fish stocks work kind of the same way. If a stock of fish is nearly at its carrying capacity, then not so many youngsters grow up to be big fish. But if that fish stock is reduced a bit, nature responds by producing more young and growing fish. The scenario which results in the most fish being available for harvest by anglers on an ongoing basis is if the fish stock is kept below the maximum possible level for that fish species. Fishery managers use terms such as “maximum sustainable yield” and try to manage most fisheries to produce it.

Of course, there is a lot of guesswork (and sometimes a lot of trial and error) involved with reaching this goal. And just when things seem to be balanced out and the fishing is getting good, something dramatic can happen to affect fish. Hurricanes and other major weather events can damage habitat. Severe cold weather or red tide can kill large numbers of fish. Fishery managers struggle to account for the effects of these types of events because it’s usually not until years afterward that we really understand the impact on fish.

As for our Gulf stock of sheepshead, the last study done on them — a stock assessment which was released in 2015 — indicated an SPR of around 46 percent. That’s a pretty good number. But many anglers are reporting that there are fewer sheepshead around than in the past, so a reduction in the bag limit which results in a nominal reduction in harvest is probably a good idea and represents an effort by the FWC to look out for us. Good job, guys (and gals).

Let’s go fishing!

Capt. Ralph Allen runs the King Fisher Fleet of sightseeing and fishing charter boats located at Fishermen’s Village in Punta Gorda. He is an award-winning outdoor writer and photographer, and is a past president of the Florida Outdoor Writers Association. Call him at 941-639-2628 or email Captain@KingFishFleet.com.

Capt. Ralph Allen runs the King Fisher Fleet of sightseeing and fishing charter boats located at Fishermen’s Village in Punta Gorda. He is an award-winning outdoor writer and photographer, and is a past president of the Florida Outdoor Writers Association. Call him at 941-639-2628 or email Captain@KingFishFleet.com.

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