Diesel Spill
Dear Editor: There is currently a serious diesel spill in Sitka Sound amounting to something like 9,000 gallons. ADF&G appears prepared to conduct a large-scale sac roe herring fishery fully ignorant of the ecosystem effects of the spill. The department has indicated that they will continue to pursue fishing opportunities in northern Sitka Sound in coming days so long as diesel is not present at the time and place of fishing. That approach insulates consumers and fishermen from the spill, but it does nothing for the herring. I don’t believe it is a reasonable application of the precautionary principle. Rather, it is reckless, cavalier, entirely the wrong way to approach this local disaster. I believe that ADF&G should stand down for 3-5 days until a respectful and precautionary risk assessment can be conducted.
Scientists know that even low amounts of the diesel compound polycyclic aromatic hydrocarbon in marine environments can cause intense harm to herring of all life stages, but particularly in early life. It is understood that herring embryos do not form properly when exposed to low-level PAH contamination. Extensive studies by the Northwest Fisheries Science Center indicate that “the heart fails to pump properly and fluid accumulates in this space [which the heart normally fills] (a condition called edema), “inflating” the overlying skin and displacing the yolk mass.” (Incardona et al, 2010). An oil spill in San Francisco bay in 2007 is the known cause of massive herring embryo mortality there in that year.
A study by Langangen et al., from the Marine Pollution Bulletin in 2017, cited a number of good reasons for caution when oil spills near herring spawning grounds: “Fish stocks may be especially vulnerable to oil spills close to the spawning grounds or egg and larval drift areas (Hjermann et al., 2007, Rooker et al., 2013). Fish eggs and larvae are typically vulnerable to toxic oil compounds due to their small size, poorly developed membranes and detoxification systems as well as their position in the water column. A number of laboratory studies have shown that oil or oil compounds (mainly polycyclic aromatic hydrocarbons, PAHs) at low concentrations can kill or cause sub-lethal damage to fish eggs and larvae (Carls et al., 1999, Hicken et al., 2011, Meier et al., 2010, Scott and Sloman, 2004, Sørhus et al., 2015). Sub-lethal effects include, e.g., morphological deformities, reduced feeding and growth rates, and are likely to increase vulnerability to predators and starvation. The few existing in situ studies of fish mortality at spill sites indicate sub-lethal effects or elevated mortality of eggs and larvae (deBruyn et al., 2007, Hose et al., 1996, Incardona et al., 2012, McGurk and Brown, 1996).”
It is important to note that ADF&G herring studies lose track entirely of larval & juvenile herring (age 0-3). After egg deposition surveys occur, ADF&G has no way of knowing how those young herring are doing. In the wake of the 1989 Exxon Valdez spill, ADF&G allowed fishing to continue despite this knowledge gap, and was caught by surprise by successive recruit failures throughout the 1990’s, contributing to cascading ecosystem effects. PWS herring have not recovered.
A 2008 paper by Thorne and Thomas in the ICES Journal of Marine Science reviewed some of what went wrong in Prince William Sound: “Behaviour of adult herring makes them especially vulnerable to damage from oil spills, something that was either unknown or misunderstood at the time of the spill. […] Acoustic observations made 17 years ago suggest that Pacific herring make routine migrations to the surface at night to gulp air (Thorne and Thomas, 1990). Subsequently, this behaviour has been comprehensively documented using infrared and visual technologies (Thomas and Thorne, 2001). Recent research shows that herring also release gas bubbles and break the water surface in response to predation (Thomas et al., 2007). These behaviours make herring highly vulnerable to contact with a surface toxicant such as an oil spill. Adult herring are also highly aggregated during late winter, although juveniles are more cosmopolitan (Stokesbury et al., 2000; Thomas and Thorne, 2003). The 13 years of survey data reveal occasions where 90% of the adult herring population was in a few large aggregations distributed within a total area of 10 km2. Such behaviour places the adult herring in a situation where even a small oil spill could affect most of the spawning stock.”
We now know beyond a doubt: cautious management is essential when this sort of thing happens. Please urge local ((907) 747-6688) and statewide ((907) 465-2376) ADF&G staff to stand down the fishing effort for at least 3-5 days or until a serious and legitimate risk assessment can be conducted, and make sure your political representatives are taking the issue seriously as well.
Peter Bradley, Sitka
