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Herring Pickles

Creosote-coated pilings - some perhaps more than 40 years old-may be killing the eggs of Bay herring. Researchers from U.C. Davis Bodega Marine Lab lab found that virtually all of the herring eggs collected from creosote pilings near Ft. Baker failed to develop properly and died. Eggs spawned near, but not directly on, the pilings were also affected, although not as dramatically.

Scientists collected the eggs as part of a five-year study of the factors affecting herring populations in the Bay. Herring support one of the Bay's last commercial fisheries. Between December and March, about 450 boats take turns fishing for herring, primarily to harvest the roe for export to Japan. Cal Fish & Game sets the quotas for each year based on the spawning biomass of the previous year. In addition to its economic value, herring are an important ecological species. Together with sardines and anchovies, herring supply a primary food source for salmon and other sport fish. "If you don't worry about the herring you may end up impacting the salmon," says researcher Gary Cherr.

As striking as the effects of creosote on herring eggs appear to be, Cherr and fellow researcher Carol Vines believe that it may be a much less significant factor in herring reproductive success than the salinity of Bay waters. Although they live most of their lives in the ocean, herring migrate to lower salinity environments to spawn, depositing their eggs on submerged objects, such as pilings, grasses, even boat hulls.

However, too little salinity can be as bad as too much. Cherr's lab have found that the ideal salinity for egg fertilization and embryonic development is between 12 and 20 parts per thousand (ppt). Hatching rates decrease at salinities below 8 ppt, while the number of abnormal larvae increase at above 24 ppt. The research may explain why the herring population declined during the drought, only to rebound during the recent wet years.

According to Fish & Game's Diana Watters, this year's spawning biomass was approximately 89,000 tons, the third highest on record. Ironically, however, a large spawning biomass does not necessarily guarantee a huge crop of baby herring. Because the heavy rains during the early part of this winter added so much fresh water to the Bay, the herring held off on spawning through most of January. The impact of the late spawn is not known.

As far as the creosote is concerned, Cherr and Vines say it's difficult to determine the overall effect on herring populations. However, Watters notes that "the amount of spawning that occurs on creosote pilings is substantial. In some years every piling and every pier from Ft. Mason to Hunter's Point can be covered in spawn." Many of these pilings, as well as others around the Bay, are creosote-coated, although how many is not known. Moreover, says Cherr, in laboratory experiments eggs 1 to 2 inches from creosote were affected, but "we don't know how far the effects spread under natural conditions." Cherr says the findings are interesting because of what they reveal about creosote itself. "The pilings we collected those eggs from are so old they had things growing on them," says Cherr "One might have expected the creosote to have become less toxic by now."

Contact: Gary Cherr (707)875-2051

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