Shortfin mako sharks are in trouble, and NOAA is asking anglers who catch them — accidentally or on purpose — to voluntarily comply with new emergency rules that haven’t been enacted yet but probably will later this year.

Compliance, though public-spirited, could be difficult and risky.

For example, NOAA Fisheries asks recreational fishing-doers to self-impose minimum keeper sizes of 71 inches for male makos and 83 inches for females. They don’t say about 71 inches or 83 more or less. Those would be guesses, not data, and therefore scientifically worthless.

So let’s do the best we can. Imagine wrestling a hooked mako to boatside. Okay, now what?

You: “Please hold still while I measure you.”

Shark: “You gotta be kidding.”

You: “No, seriously, there are going to be new regulations and I have to report that information or the supporting scientific data will be skewed and it will all be for naught.” Shark: “No, seriously, I am a frantically thrashing hooked shark and d----- if I’ll hold still. Take your best guess. Reckon it against the tallest guy on the boat.” You: “I also have to report whether you’re male or female.”

Shark: “Dude, don’t even think about going there or — aw, go ahead. Make my day.”

You: “Y’know, on second thought I’ll just cut the leader and turn you loose.”

It seems like most law-abiding offshore fishing-doers would rather let a mako go than gaff it, haul it up on deck, hold it still for intimate inspection, measure it precisely and at last discover they’ve killed a 70-inch male or an 82-inch female.

Legally, they could get away with it before the size limits are enacted and penalties are set, but true sportsman would feel guilty.

Why are they being put into this predicament? Because a mako stock assessment done in 2017 by the International Commission for the Conservation of Atlantic Tunas (ICCAT) determined that North Atlantic shortfin makos had been and still were being overfished.

In the matter of makos, the stock assessors think shortfin mako catches need to be reduced to stop their population’s decline. That’s a typical prelude to revision of size and bag limits, whether for big game fish or the common mangrove snapper your kids catch with toy tackle from the seawall.

Typically, though, fish officials don’t ask us to comply in advance with limits they haven’t even created yet.

It should be said that NOAA is not asking that favor of everyone who happens to catch a mako. Its request is directed to anyone with an Atlantic Highly Migratory Species permit, as well as all tournaments. The idea is to get a head start on decreasing shark mortality sooner than later.

Even so, the casual offshore troller who might accidentally catch a mako while fishing for something else could contribute to the cause by participating anyway.

Some time in the second half of the year, ICCAT people will study reported catches from the first half. They hope to get enough info by then to decide whether to keep or change the 71 and 83-inch minimums proposed now.

If they don’t get enough, they can’t be sure the proposed rule is likely to solve the problem.

NOAA Fisheries, without explicitly mentioning the folly of measuring large sharks accurately, advises disregarding the 71-inch minimum for males. Instead, we’re told, release all sharks short of 83 inches, never mind gender.

As our imaginary mako above suggested, you can estimate its length against the height of the tallest man on the boat. If he’s 6'11 and the shark looks convincingly longer, you can keep it.

As you may expect, there’s a smartphone app available for download: www.nmfs.noaa.gov/sfa/ hms/shortfinmako/mako_app.html.