10/23/2012 11:13 am ET | Updated Dec 23, 2012

Of Little Fish, Cute Mammals, and the Law of Unintended Consequences

A recent statement to the California Fish and Game Commission drafted by Audubon California, Earthjustice and Oceana sounded alarms over declining Pacific herring stocks in near shore California waters. The paper also decried declines in two other small marine fishes -- anchovies and sardines.

Why such a big fuss over such tiny fish? As well as constituting the basis for idiosyncratic pizzas, sandwiches, and hors d'oeuvres, these three fish are critical forage for a great number of other marine species, including seabirds, whales, seals and sea lions, and valuable food fishes including salmon, lingcod and rockfish.

Herring, in particular, are crucial links in the marine food web. Both the fish and their roe (deposited on kelp and rocks during spawning events) are staples for several species of birds, particularly sea ducks. They are also consumed by the kiloton by marine mammals.

Pacific herring also support a small commercial fishery -- the roe is highly esteemed in Japan, and can fetch high prices. The pressure on the fish, apparently, is unsustainable. The paper notes that the stocks are "truncating" in age structure, meaning that older, larger fish -- the prime breeders -- are getting scarce; that the herring biomass in general is dwindling; and that no effective management plan exists for herring stocks.

Pacific herring don't exist in a vacuum, of course, and their decline bodes ill indeed for California's marine biome: as herring go, so go the myriad species that depend on herring. Clearly, something needs to be done. The signatories to the paper have some ideas, focusing mainly on restricting the state's already beleaguered commercial fishery. This may well be necessary, for the simple fact that it is one of the few things that can be done; options are limited.

It's highly unlikely, however, that limiting the commercial fishery will be enough. Why? Lots of things eat herring, but some things eat way more herring than everything else. I'm speaking specifically of California sea lions. The paper notes that the U.S. population of California sea lions increased 6.5 percent annually from 1983 -2003, and that almost 250,000 of these large pinnipeds are now disporting off the coast of western North America.

California's Central Coast (roughly from Big Sur to Ano Nuevo Island north of Santa Cruz) now supports about 18,000 California sea lions. This population alone consumes 8 to 10 percent of the region's herring biomass. California's coast also supports a robust population of harbor seals -- roughly 35,000 of them. They, too, are voracious consumers of herring.

These two species are the piscine equivalent of the elephant in the room that nobody is talking about. Certainly, no researcher or administrator from Audubon, EarthJustice, or Oceana -- or any other environmental group -- will state the obvious: a truly effective herring management plan would call for local culls of California sea lions, and perhaps harbor seals as well. That's understandable. The idea of killing seals and sea lions for any reason is -- from a PR perspective -- radioactive.

Both species are protected under the highly popular U.S. Marine Mammal Protection Act. Moreover, both are "charismatic megafauna" -- cute, fuzzy, highly appealing beasts with a built-in constituency among animal lovers and "conservationists" (whose grasp of the hard choices implicit in true conservation may be less than comprehensive).

Herring, of course, have no such legion of supporters. They're fish, for goodness sake: small, slippery, aquatic creatures with scales and cold, staring eyes that convey neither warmth nor deep intelligence. There is nothing cuddly about them. No wonder no one cares about them -- aside from fishermen, scientists and those environmentalists who grok their significance to the marine food web.

I've talked to fishery and seabird biologists off the record -- make that waaaaay off the record -- who felt amending the Marine Mammal Protection Act is long overdue. In other words, they were open to the idea of managing California sea lions. And not just for herring: the removal of a small number of sea lions at the mouth of the Klamath River would have a significant and salutary effect on the river's dwindling runs of salmon and steelhead. Several of the pinnipeds have developed the habit of biting out the fat-rich and roe-laden bellies of the spawning fish as they enter the river, spurning the remainder of the carcasses. This (relative) handful of sea lions kills thousands of threatened salmonids each year.

Please note no one is suggesting "management" of any other marine mammal species. Northern elephant seals are burgeoning in numbers, but they mainly eat squid. Northern fur seals remain rare off California, though their numbers are recovering. As to whales -- well several species eat a lot of herring. The 2,043 humpback whales known to ply the waters off California and Oregon are estimated to consume 817 tons of food a day; much of that is herring. But no matter how you parse them, humpbacks are few in number. From the perspective of biological diversity, they could well be worth their weight in herring.

Of course, I'm just woolgathering here: California sea lions will never be managed, for the sake of Pacific herring or anything else. Certainly, factors other than hungry sea lions and commercial fishing are exerting a malign impact on herring -- including pollution of coastal waters and estuaries and baseline shifts in the marine environment due to climate change. But as with sea lions, those issues are unlikely to be addressed. Commercial fishermen will be forced to shoulder the entire burden for the herring's recovery. It's unlikely it will make any difference. The herring will continue to decline, and everything that depends on them will decline with them. That includes the commercial fleet.