Swallow This!

The hunter is the "alert man" according to Jose Ortega y Gasset, author-philosopher whose "Meditations on Hunting" has become the de facto standard to explain the intrinsic human instinct to hunt. This applies, of course, to the aquatic hunter, or fisher, who is constantly seeking cues to the activity and whereabouts of her/his quarry. 

The question arises, alert to what? Alert to anything;  especially, able to think clearly; intellectually active. And so, when I emerged from the house one mid-May morning and saw the swallows swarming over the river, I suspected that a hatch was on.

While the swallows were visible enough, their prey was not. Nor was there a conspicuous cloud or swarm of insects over the river. I concluded that the swallows were feeding on very small insects, perhaps midge-sizes, certainly not mayflies larger than tricos.  

I seldom carry an insect net afield when I am fishing, but I often swipe my hat at nearby flying insects, to see first-hand what they are, or, at least, how big and what color they are.  Skittering insects on the surface of the water frequently indicate egg-laying is in progress. Empty shucks (exoskeletons) of insects attached to plant stems at riverside are further indicators of what kind of trout food is present, or, recently risen.

Just as the hunter is attuned to the squawk of crows or ravens, sometimes heralding the approach of ground-roving creatures, so too does the fisher remain alert to the actions of birds and other riparian indicators of trout food in the making.

Lampreys Suck; and, so does the Budget

We seldom have better evidence of the perils of eating the seed corn than appears in the continuing resolution budget. Last March, in the congressional frenzy to appease the 'baggers while trying to appear responsible in allowing the gov'mint to stay open for business, both the White House and congressional "leaders" recommended spending cuts of 15-20 per cent for the Great Lakes lamprey control program. A reduced lamprey control budget penalizes the scientists and fisheries managers of the international control agencies for one of the most cost-effective, ingenious and diverse integrated pest control programs anywhere in the world, and it threatens to set back by decades the rehabilitation of lake trout, whitefish and the coldwater fish community of the upper Great Lakes. Not to mention reneging on an international agreement with Canada.
The unparalleled effectiveness of the lamprey control program hinges upon control strategies that exploit the unique life history of sea lampreys. These exotic invaders gained access to the upper Great Lakes following the 1935 expansion of the Welland Canal, enlarged to allow maritime shipping to bypass Niagara Falls in eastern Lake Erie.

Ammocoete larva, bottom; transformer, middle;
car keys for size comparison, top.

A female lamprey will spawn with an individual male by depositing eggs in gravel nests in large and small streams tributary to the Great Lakes. Like Pacific Salmon, sea lampreys spawn only once in their lifetime, and then die. The eggs hatch into larvae known as ammocoetes which form burrows in the fine sediments in the bottom of the stream. There, they filter water through their gills, extracting fine particles of detritus and algae, and grow, over a period of several years, to a size of about 120mm. Soon after attaining this size threshold, the ammocoetes undergo a morphological transformation in which they form a true "camera" eye, develop a sucking mouth with a rasp-like tongue, and dorsal fin and tail. The transformed larvae now migrate downstream and begin a parasitic life in which they attach to fish, rasp a hole in the skin and suck the bodily fluids out of the fish.

Fresh lamprey mark on Great Lakes coho salmon.

Parasitologists have known lampreys for years as "parasites", because they don't often kill their host fish in their natural marine environment. But, in the Great Lakes, the lampreys frequently do kill their host if the fish they attach to is small relative to the rate at which lampreys suck out their fluids. Great Lakes sea lampreys are easily capable of killing a 2-pound trout, burbot, or whitefish during a single feeding attack. After feeding for 14-18 months, the lampreys migrate to a stream to spawn and die. A single lamprey will kill an estimated 40-50 lbs. of fish during its "parasitic" stage.


The life history segment when ammocoete larvae are living in streams is their "Achilles heel" ably exploited by the lamprey control program. Because it usually takes at least 3 years to grow to a size large enough to "transform" into a parasitic stage lamprey, the streams occupied by ammocoetes need to be treated to kill these larval lampreys only once every 3 years, or even less frequently if the larvae are growing more slowly. A single treatment with a selective toxicant, TFM, can then remove several year-classes of lampreys at once, making the control program one of the most effective fishery management programs anywhere in North America. In combination with low-head barrier dams, sterile-male release programs, selective-release toxicants for lake bottom application, and pheromone attractants to lure mature lampreys into fish traps, the sea lamprey control program has gradually allowed the restoration of the cold-water fisheries of the upper Great Lakes.

It took more than 30 years of intensive stocking and lamprey control to begin to see the rehabilitation of naturally self-sustaining stocks of lake trout in Lake Superior. Lake Huron is only just beginning to show lake trout year-classes produced by natural spawning, and Lake Michigan is still lagging behind in natural reproduction of lake trout. Meanwhile, the steelhead, salmon and whitefish have also benefitted greatly from the lamprey control program. A cut-back in funding now will have very far-reaching consequences in continuing to restore these lakes to fishable self-reproducing populations.

The upper lakes fishery is estimated to be worth from 8-12 billion dollars in annual economic activity. At current budget levels of about $20 million, the sea lamprey control activity generates a $200 return for every dollar spent. That's approximately the cost of one Apache attack helicopter, as used in last Sunday's raid against Osama Bin Laden's compound in Pakistan.

There is no reason not to invest just a little more in higher taxes rather than accept long-term damage to one of the nation's greatest fishery resources.

Cross-posted to the Renaissance Post