Category: Fish/Shellfish Research
Author(s): James West, Sandra O'Neill, Dan Lomax and Lyndal Johnson
Rockfish (Sebastes spp) are long-lived demersal predators that are distributed widely in Puget Sound marine habitats, usually associated with rocky substrate (Matthews 1989; Matthews 1990). Because of their longevity1 and high position in the benthic food chain (see Murie 1995), their probability of exposure to persistent bioaccumulative toxins like polychlorinated biphenyls (PCBs) is high. The Puget Sound Ambient Monitoring Program (PSAMP) has monitored the presence and severity of toxic contaminants, including PCBs, in three closely related Sebastes species: quillback rockfish (Sebastes maliger), brown rockfish (S. auriculatus) and copper rockfish (S. caurinus) in Puget Sound from 1989 to the present (West & O'Neill 1995; West & O'Neill 1998). These species are ecologically and economically important in the Pacific Northwest (Schmitt and others 1994), and they have been petitioned for protection under the Endangered Species Act (U.S. Department of Commerce 1999) because of declines in their population abundance in Puget Sound over the last three decades.
We estimated exposure of rockfish to PCBs by measuring PCB concentration (as the sum of Aroclors 1254 and 1260) in their skeletal muscle tissue (skin-off fillets). We sampled muscle tissue taken from 115 individual quillback, brown, and copper rockfish in Puget Sound from 1995 to 1998. We subjectively classified three location types from which rockfish were sampled: (1) highly polluted urban and industrialized habitats, termed ÂgurbanÂh locations (Sinclair Inlet and Elliott Bay), (2) areas in Central Puget Sound relatively near to urban areas (termed Âgnear-urbanÂh), and (3) relatively pristine habitats such as the San Juan Islands and Admiralty Inlet, situated far from urban or industrialized areas (termed Âgnon-urbanÂh).
Transfer of lipophilic toxic compounds such as PCBs from mother-to-egg via lipids or yolk have been reported for other fish species (Niimi 1983; Miller 1993; Miller 1994), providing a mechanism for reduction of PCB concentration in females. Related to this, we hypothesized that female rockfish from contaminated habitats should accumulate PCBs at a slower rate than males. In this study we compared accumulation patterns of 115 rockfish to PCBs among three location types (urban, near-urban, and nonurban) and between the sexes, while accounting or adjusting for the effects of variability in fish age.
We also present results of a pilot study investigating potential reproductive impairment of male rockfish (effects) related to their exposure to hormone-mimicking toxics, a group of contaminants that may include some PCBs. We sampled blood serum from eleven male quillback rockfish taken from Elliott Bay in 1998 for the presence of vitellogenin. Vitellogenin is a lipoprotein normally associated with the production of eggs in female fish (DeVlaming et al. 1984), and is normally not found in wild male fish. The presence of vitellogenin in the blood serum of male gonochoristic2 fish is considered an indicator of exposure to an exogenous estrogenic hormone or hormone-mimicking contaminant (see Lomax and others in press, this conference). When such compounds enter the male body they can function as the reproductive hormone ÂÃŽ- estradiol, triggering the production of vitellogenin. This process of feminization can cause significant disruption in normal reproductive physiology.
- Age of oldest rockfish collected by PSAMP was estimated at 60 years.
- Separate sexes â€" no hermaphroditism