It's Too Early To Judge Young-of-year Tally


August 18, 1991|By Capt. Bob Spore

Recent news accounts about the striped bass or rockfish young-of-year survey have painted a dismal picture and ended with dire warnings about so-called "disastrous" decisions the state may make based on thelatest number.

The Department of Natural Resources surveys the rockfish nursery areas each year to get an idea of the rockfish spawning success. This survey is not terribly accurate, but it is the only scientific tool on the whole East Coast to measure whether the rockfish is making a comeback.

The survey is conducted in July, August and September and the results are reported as a YOY index. This index is obtained by dividing the number of baby rockfish caught in a 100-foot net by the number oftimes the net is fished.

The index was used to open the striped bass fishery in Maryland and liberalize the severe striped bass fishing regulations along the whole East Coast, from Maine to North Carolina.

The problem with the recent news accounts is that they miss thesubtleties of the rockfish situation and that makes for a misleadingstory.

For example, Maryland cannot unilaterally decide the minimum striped bass size limit or number of pounds to be harvested. Theseissues and others must be settled by the Atlantic States Marine Fisheries Commission of which Maryland is but one member. The ASMFC has no direct authority, but its directives are backed by federal law. Anystate not in compliance with these directives can lose its entire striped bass fishery. New Jersey has tested this authority and lost.

The DNR has completed the second round of the 1991 YOY survey, but will not be releasing the data until the survey is completed next month.

However, early indications are this year will be better than last, but not the barn-burner we were seeking.

The YOY index has another function. It will help determine the harvest quotas when the fish meet minimum size requirements. Some of the 1991 rockfish may become a legal 18 inches in 1995, therefore the 1991 index will influence the 1995 harvest restrictions.

Why didn't we have a better year? Idon't know, and the biologists can't say which ingredient or ingredients were left out of the equation or if there was too much of something. The biologists do know that the spawning stock on the spawning grounds were plentiful and they consisted of about the right year-classes, a very important element.

Spawning activity took place duringthe normal times and there were a lot of eggs. Under normal conditions, more than 99 percent of the eggs do not develop into juvenile rockfish. That's not a significant base to build on, and Lord knows the Chesapeake Bay cannot be considered a friendly environment.

Rockfish eggs produce larvae, which hatch with an oil globule attached thatsustains the larvae for a short period before the critter has to find food. The baby rockfish is dependent on the food to be where it is,otherwise it dies.

If we have a cold snap and the water temperature drops a couple degrees, the larvae can die. If we get a good spring shower, also known as an acid rain event, a high pH spike in the water can mobilize minute aluminum particles in the water, killing the baby rockfish.

Baby rockfish, which have no fins or tail, cannot swim away from predators and they get eaten.

There are hundreds, ifnot thousands of reasons why the egg does not produce a juvenile rockfish, a critter with fins, tail and stripes. Once the fish reaches this stage, the biologists say the year class is pretty well established.

It doesn't look as if 1991 will have an outstanding striped bass year class, but don't become disheartened. We have large numbers of spawning fish producing large numbers of eggs, which means we are getting closer.

The fishery managers will adjust the harvest based on the year classes. We probably fish on six- to eight-year classes.

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