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Merit McCrea – WHEELHOUSE SCOOP

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Thursday, September 20, 2018
Name that spot


Where are them keepers?
Where are all those 14-inch-plus calico then Fish and Game Com­mission President Mike Sutton promised us back in 2014? We would let them go and let them grow. Then there would be more and bigger bass he promised.

Well, the DFW biologists had actually recommended a 13-inch limit, so they kinda knew a 14-inch limit would likely come with some fishery costs. But back then, Sutton, a biologist himself and a brilliant one at that, advocated strongly against the staff recommendation and for going the “extra mile” — 14 inches! And the rest of the commissioners heard him and supported it.


Legalcalico
LEGAL CALICO BASS caught near Two Harbors, Catalina, aboard the Triton out of L.A. Harbor Sportfishing. WON PHOTO BY MIKE STEVENS


The abundant science on kelp bass pins the average 12 incher — the previous minimum size limit, at 6.5 years old. A 14 incher averages 8.5 years old. So the expectation might be a couple years down the road, say by 2016 or 2017, the hit the local party boat fleet and anglers took to let them grow would be over, or at least clearly showing signs of getting over.


Now here it is 2018, fully 4 years later and we’re still keeping very few, yet releasing them by hundreds daily. The only area where 1/2- and 3/4-day anglers are keeping very many in local waters is San Diego, finally. Even there though, the ratio of 14-inch and over bass to those 12 to 13.99 inches is perhaps 1 in 5 at best.


The way the biologists figure out the maximum return for forbearance — that is, releasing smaller fish so they can grow, involves modeling with math. Conceptually it’s easy, but quickly gets complicated in practice.


Basically one figures out how many die from one year to the next, applies that loss, adds the growth for the year to the survivors and heads on to doing the same for the following year.


So say you start with 100 bass, and that’s okay because we just want to figure out the best size limit. We want the size limit that gives us the most weight of fish in the bag, given starting with a set number of fish.


We determine the death rate due to “natural causes” — almost always due to being eaten by something else. This is reduced to a formula which varies by the fish’s age. That’s because the small ones have a higher chance of getting eaten than the bigger ones.


Then you consider your 100 bass, and apply this likelihood of getting chomped — we’ll call it “M” because that’s what we always call natural mortality when it comes to fish. And you roll with that scenario through several seasons as your babies grow, until you decide to tinker with adding fishing. We’ll call getting caught and kept “F,” for the same reason.


Applying M and F together after a certain age, year after year allows you to add up the total weight of bass you sack before all 100 are gone. By trying different size limits you can easily figure out the right age and size to get the most pounds out of the fishery.


There is one thing that instantly pops out at you about this. It’s the clear scientific understanding and acceptance of the competition with all the perpetrators of “natural mortality” — seals, sea lions and so forth. That’s exactly the way it’s modeled. There is no sea lion-angler kumbaya harmony involved when it comes to fishery science.


There’s another more subtle thing about this that drives sea lion lovers absolutely wild. The primary assumption being made is the goal to maximize sustainable fishery production while treating “M” as a loss to be avoided.


Therein lies the crux dividing conservation minded fishers from “the conservationists,” — or, in more formal terms, utilitarian conservation from natural ecosystem conservation. “Natural” means without humans.


But back to nuts and bolts. The solution to this calculus, and it actually is calculus for once, is 12 or 13 inches. That provides the most meat. Any larger the minimum size and we start to give more calico bass to the harbor seals and such than we get back.


With a 12-inch limit we keep more fish at a smaller average size. At 13 we keep fewer but bigger ones, but the total weight of bass bagged is similar. At 14 inches, average bass are bigger yet but the competing charismatic megafauna end up with more pounds and anglers less.


Modeling gets more challenging and less precise with regard to estimating the total bass biomass in the Bight. Fortunately, the minimum size keeps bass growing regardless. It’s a powerful conservation tool, provided released fish live. Bass do.


The 5-fish possession limit keeps the harvest rate F in check for those fish of legal size. It prevents absolute slaughter when the bite is on.


Then there’s the question of keeping enough spawning age fish in the population to provide baby fish for the future. Bass first spawn at about 11 inches, and of course only a fraction of the keepers are caught each season, so there should be plenty of larger ones in the population.


Here’s the deal, and most hardcore watermen have a sense of it already. Bass, as well as many other marine creatures, are broadcast spawners, sending out hundreds of thousands, even millions of eggs or larvae per female each season. Survivorship is both incredibly small — less than 1 in 1,000 survive their first season, and highly variable from season to season. Larval survivorship is often dictated by things as capricious as the timing and intensity of spring winds.


While doubling the biomass of spawning age bass might double egg production, natural conditions might swing survival to the 1-inch size a hundred fold. Spawning population biomass ends up being somewhat trivial, unless it gets so low the boys can no longer find the girls reliably (Allee effects).


When it comes to sand bass, many arrive from Mexico, sporadically leaving settlers behind on our local coastal reefs. Bay bass went along for the regulatory ride simply because our regulations cover all bass together.


Why 14 inches then? It seems DFW biologists may have been more right than even they themselves had imagined when they called for a 13-inch limit. Now 4 years later, party boat anglers bag a few keepers at 14-plus and release 12- to 13-inch shorts by the hundreds. More keepers next year? Maybe not.


It was the political will of marine megafauna conservationists that put now-retired Commissioner Sutton on the Commission in the first place. Political power matters and marine mammals had an advocate at the table.


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Merit McCrea is saltwater editor for Western Outdoor News. A veteran Southern California party boat captain, he also works as a marine research scientist with the Love Lab at the University of California at Santa Barbara’s Marine Science Institute. He can be reached at: merit@wonews.com.


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Reader Comments
I was originally for the bump in size limit and the 5 fish limit, the hopes of catching more big fish in the near future though have not proven to be so. I fish for calico bass very regularly and it seems that releasing more fish has hurt the size. there is only so much food and habitat for the fish so having more fish means the average size is smaller. We need to keep more fish in order to allow the others to grow.
Brian Wilson
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