Game Fish Migrations in a Changing Climate

Schools of good-size bluefin tuna crashing bait off Washington State. Anglers up there hooking California yellowtail, finding packs feeding around flotsam. Mahi, Sierra mackerel and croakers in the Pacific Northwest too. Hordes of blacktip sharks invading Long Island Sound. On and on it goes, around the world.

As Buffalo Springfield sang in the ’60s: There’s something happening here.

And, the long-haired rock trio added prophetically, what it is ain’t exactly clear.

But the point remains: It is happening, and while the ocean has been heating up for decades, the pace of warming has begun accelerating dramatically.

The “it” here refers to migrations of fishes worldwide moving toward the poles, expanding their historic ranges, in order to continue living in their respective comfort zones.

Those comfort zones refer to the narrow range of water temperatures in which most marine species must exist in order to thrive. Heating up the ambient water by a few degrees can put entire populations at risk.

So they move, at least those that can do so.

And make no mistake: Many species of fish and even invertebrates (including corals) are moving.

As noted, gamefish normally found in Southern California were encountered in numbers off Washington state, and large schools of blacktip sharks now summer as far north as New York.

Widely labeled the poster child for relocating fishes, the center of black sea bass populations has in a few years shifted from North Carolina some 200 miles north to New Jersey (and is projected to continue shifting north in coming decades). Summer flounder have made a similar shift.

Sockeye salmon, suffering in warming Alaska waters, have been moving into Arctic waters, where they’ve never been seen previously.

Divers report tropical fishes such as butterflyfish and seahorses along the coast of Nova Scotia.

Ditto in the southern hemisphere. For example, a tropical sea snake turned up recently for the first time off Australia’s once-chilly southern coast.

Corals also appear to be relocating, ­particularly where torrid tropical waters are leading to bleaching events and dying reefs. Larvae, moved by ocean currents, are setting up shop in what had been subtropical coastal waters. For example, for the first time ever, elkhorn corals have lately shown up off Texas. (Unfortunately, rates of colonies establishing in new waters more favorable to development don’t begin to keep up with the rate of decline among historic reefs.)

However, not all species of marine fishes are capable of relocating long distances; many have begun to suffer declining populations.

There are still people for whom terms such as “global warming” or “climate change” remain politically explosive and who vehemently deny that ocean waters are warming. But the behavior of fish, which don’t understand nuances of politics, leaves no doubt of the oceans’ rising temperatures.

Where such trends historically might have occurred over many centuries or longer, our global greenhouse means these changes are now taking place in mere decades. And this raises profound questions such as, how will this affect the ecology and ecological balance of our coasts and oceans? And what will be the effect on fisheries and coastal communities where vital fisheries are changing?

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Unfortunately, nothing in our history has really prepared scientists to answer such questions. There is no baseline against which to measure or plan. Making predictions is difficult and uncertain; scientists’ opinions vary not in whether the world—including our oceans—is getting warmer, but in forecasting the speed and extent of that trend.

What all this means for us, as avid sport-fishing enthusiasts, remains to be seen. While the upshot for coastal communities and commercial fisheries might spell significant and painful long-term disruption, for anglers, there are likely to be short-term winners and losers—the former in previously cooler coastal waters as more new species of ­gamefish show up. But the long term appears to be coming much quicker than we ever expected, so find a grab rail and hold on for the confused seas ahead.