Green Lake fish hatchery site of extensive salmon-tagging project

DATE:03/31/90 LENG:12 EXTR:

An unusual spring ritual is under way at the Green Lake fish hatchery. It could be called the rite of the snoozing smolt. TEXT:KEYWORD-HIT.

An unusual spring ritual is under way at the Green Lake fish hatchery. It could be called the rite of the snoozing smolt.

Each day, 20,000 anesthetized Atlantic salmon smolts are subjected to a scientific production-line process that ultimately will allow fisheries biologists to better understand the mysteries surrounding the life cycles of these anadromous fish.

Before the ritual is over, 200,000 1-year-old Atlantic salmon will be fin-clipped, equipped with coded wire micro-tags and returned to their ancestral habitat, the Penobscot River.

The process works like this:

The hatchery-raised smolts are pumped through a large pipe from holding pools into the hatchery’s main building.

There the smolts are put to sleep and parceled out to a production line of workers. The workers then clip the dazed smolt’s adapose fin and place the fish’s snout against a machine that automatically injects a miniature piece of coded wire.

To the trained eye, the coded wire will one day identify the retrieved salmon’s country of origin, as well as its river of origin.

The processed smolts, still asleep, are pumped back into the sheltered holding pools in preparation for their release into the Penobscot in a few weeks.

According to U.S. fisheries biologist Paul Gaston, who manages the Green Lake hatchery, the main goal of the micro-tagging project is to stock 50,000 coded smolts between each main stem dam on the Penobscot River and evaluate their rate of return. Fish caught by commercial fishermen in the high seas off Greenland will be readily identifiable by their clipped adapose fin and micro-tag.

Similar tagging projects are under way at other federal hatcheries elsewhere in New England. Gaston says that the Green Lake hatchery, in cooperation with the Craig Brook Hatchery in Orland, will raise more than a million Atlantic salmon a year, most of which wind up in the Penobscot, St. Croix, Saco and a number of rivers Downeast.

The hatchery also ships 1.5 million eggs to other New England hatcheries for restoration programs in the Connecticut and Merrimack rivers.

According to Gaston, only about half of 1 percent of the salmon returned to the rivers will actually spawn. A female salmon will produce about 800 eggs for every pound of body weight.

Gaston operates the Green Lake hatchery with an annual budget of $450,000. The hatchery is producing stocking smolts at a cost of 75 cents apiece. According to Gaston, the cost of producing salmon smolt commercially is about $2.50 per smolt.

Gaston is quick to point out that the overall aim of the restoration project for Atlantic salmon is “small gains in lots of places.”