A Spawning Success?
The Young of Year Survey for striped bass spawning success in the Chesapeake Bay for 2011 is a whopping 34.6, the fourth highest on record since the Department of Natural Resources began this statistical measurement 58 years ago. Since our resident rockfish population has declined by approximately 30 percent over the last decade, this is great news indeed.
Twenty-two survey sites are visited monthly from July through September each year by DNR biologists, who collect fish samples with two sweeps of a 100-foot beach seine. The species captured, their numbers and ages are recorded. The results are then calculated by species as the Geometric Mean Catch per Haul. Essentially, that’s the average number of fish born that year caught in each net drag.
Angling for rockfish and perch remains inconsistent. Good bites in an area have been quickly followed by no bites at all. Water quality is the main factor, as releases from the Conowingo Dam have frequently fouled the Bay with silt and debris.
Frosting on the cake of renewed rockfish spawning success is an increase in juvenile blueback herring, a particularly threatened species that is a nutritive food fish for striped bass in their spring spawning migration up the Bay.
White perch have also experienced near-record reproduction. This is excellent news because perch, the most numerous and popular fish on the Chesapeake, are heavily exploited both commercially (two million pounds per year) and recreationally (one million pounds).
Spawning success for all species of Bay fish, DNR has noted, is influenced by many factors, including water temperature, winter snowfall, spring flow rates and prevailing weather conditions. This list, curiously, omits one factor that is at least as important as all the others: human interference.
Last winter, Maryland’s Natural Resources Police discovered miles of illegal commercial gill nets laden with tons of captured rockfish. The resultant headlines and the intense police attention seemed to curtail the practice, at least for the rest of the pre-spawn months.
Spring provided excellent and long-lasting spawning conditions. It was also particularly harsh, so that severe weather — coupled with some astute marine police work — prevented much of the human interference with our spawning fish.
The Susquehanna Flats Catch and Release Season was also virtually a non-event. Endless rain, wind, ice and discharges from the Conowingo Dam made the Flats unfishable for the entire spring season. The weather, in fact, made almost all early-season catch-and-release fishing rare.
It stands to reason that the stress to released rockfish has a negative effect on their spawning success. This year, that interference was almost eliminated by the weather.
The long-term freezing temperatures, ice, more ice, rain and high water also made the setting and operation of commercial pound nets (and similar fish traps) virtually impossible until late spring. Pound nets are long nets strung out on stakes from the shore into the rivers, streams and Bay that lead fish swimming along the shoreline into a circular trap from which they cannot escape.
It is a common commercial method of harvesting certain fish ascending these bodies of water to spawn. Rockfish, shad, herring and similarly illegal-to-harvest species are also captured in these devices but are required to be set free. This past year, because of the bad weather, this, too, was mostly a non-factor for much of the spawn.
There is no doubt that the rockfish, perch and herring reproduction numbers for 2011 are a cause for celebration and perhaps, even, optimism. However, two questions remain: How much of this year’s success was due to the great conditions for the fish? And how much was due to the absence of human interference?
The latter may be much more significant than the commercial and recreational communities care to admit.