UPDATED 12-17: Laboratory testing shows that when you feed young salmon and steelhead eggs cured in some bait products that contain sodium sulfites, some die.
So says a study by the Oregon Department of Fish & Wildlife and Oregon State University released Wednesday afternoon and sure to stir up the industry.
“Specific mortality levels varied among products and ranged from 0 to 30 percent,” a press release from ODFW says.
While the work has not yet been formally peer reviewed, egg-cure makers are said to be committed to solving the problem, according to ODFW.
No company’s products are mentioned by name, but Scott Amerman of Amerman’s Eggs was briefing anglers on Ifish about it. He writes:
The tests have shown that hatchery raised smolts whose diet is changed to 100% cured eggs (egg cures high in sodium sulfite) have shown mortalityin some smolts in a small hatchery basin test. As of so far we have no idea how this translates to the real world and if smolts in the wild suffer these same effects. It is very unlikely that any fish in the wild will ever be forced to eat 100% eggs only.
Eggs are among the most effective baits for steelhead, Chinook and coho, and are used numerous ways — drift-fished, under a bobber, plunked, back-trolled, with a diver, etc. Anglers use cures to make their eggs last longer on the hook, and to change its color and texture. Prawns are also cured.
According to ODFW, a random sample of commercially available cures were tested. Researchers found that “some juvenile fish died after ingesting some brands. Specific mortality levels varied among products and ranged from 0 to 30 percent. In a second round of studies at OSU, researchers identified sodium sulfite as the ingredient causing the fish to die.”
The investigation was sparked in 2008 “by a group of anglers who were concerned that some of these cured eggs may be toxic to juvenile salmon.”
According to an email sent by Rob Russell last night to the heads of three Northwest fishing magazines and the operator of a popular chat board, as well as posted online on the Oregon Fly Fishing Blog, Western Oregon salmon, steelhead and trout fly fishing guide Jeff Mishler is cited as the angler who approached ODFW with concerns.
Mishler is quoted as saying:
“I had heard stories of trout dying from eating cured eggs. Then one day while I was bobber fishing with my Dad, I noticed swarms of young-of-the-year steelhead pecking at our baits. Then we noticed the shoreline. Bait anglers had disposed of their old bait along the beach, creating a fuzzy pink margin along the river bank. Baby steelhead were eating them like crazy, and cutthroat hung behind waiting for an easy meal. It suddenly occurred to me that the poisons in cured eggs could be having serious impacts.”
Sulfites became a common ingredient in egg cures in the 1980s, says ODFW. However, the agency says that it can’t extrapolate the data to say if sulfites have a “significant effect on the overall health of salmon and steelhead populations.”
A study summary reads:
“The researchers initially tested the effects of 4 or 5 commercially available cures in a laboratory setting. This represents a limited sample of the commercially available cures. The cured eggs were fed to groups of juvenile chinook and steelhead held in tanks over a period of 23 days. The researchers also examined whether there were any differences among pre-smolts (juvenile salmon or steelhead that have not yet reached the physiological state known as a smolt) and smolts (juvenile salmon that are undergoing physiological changes to migrate from fresh to salt water). Mortality was assessed following each feeding and all dead fish were autopsied.
The results of these experiments confirmed that some of the commercially available cures caused mortality in both steelhead and chinook juveniles (Figs. 1 and 2). In any given tank mortality ranged from 0-30% during the 23 day period. However, researchers also found that there was considerable variability in the individual sensitivity of the juvenile fish. Some fish died after apparently eating a single egg whereas most were able to persist after 23 day of (presumably) consuming the eggs.
The researchers then focused on determining the likely cause of this mortality. Based on a list of ingredients supplied by several of the manufacturers, sodium sulfite was identified as the most likely cause. Researchers tested this by removing the sodium sulfite from two of the cures that were used in the first round of experiments. Groups of fish were fed eggs that were cured with or without the inclusion of sodium sulfite in the cure. Mortality was again recorded daily. Removal of sodium sulfite appeared to eliminate the mortality (Fig. 3). To confirm this, the researchers also injected cured eggs directly into the stomach (to ensure consumption of a known amount). Injection of eggs cured with sodium sulfite caused 30-35% mortality within a 10 day period. Removal of sodium sulfite eliminated the mortality (0%).
Researchers also tested whether the effect could be minimized by pre-soaking the eggs prior to feeding, as might occur in the wild. The cured eggs were soaked for 0, 30, or 60 seconds, or 10 minutes prior to feeding. There was no difference in mortality for the pre-soaked eggs as compared to the unsoaked eggs.
Conclusions. Based on these results the researchers concluded that some commercially available cures caused elevated mortality in juvenile chinook and steelhead. The mortality is most likely cause by the inclusion of higher levels of sodium sulfite in the cures. It is also highly likely that fish that consume these particular cures in the wild will respond similarly. However, we have no data to suggest that this may be significant at a population level.
ODFW Deputy Administrator of Inland Fisheries Bruce McIntosh says the agency is talking with several of the product manufacturers to address the issue.
“Our emphasis will be on informing anglers, guides and other manufacturers about the risks sulfites pose to juvenile fish,” he says in the press release.
Amerman, the bait-cure maker, adds this advice:
Be aware that there will be groups out there that will want to take these preliminary test results to push for total bait bans or to prove a great impact by the sports fisherman rather than waiting for continued testing to see if these results translate over to the wild which right now no one knows. For now what we as fisherman can do is avoid throwing your fished out baits back in the water after you change it. Small salmon and steelhead are much more likely to eat the small discarded bait chunks than the larger bait chunks many people fish. Discarding any used cured eggs in a safe manor instead of back into the water until more testing is done will be a safer alternative either way for now.
And in bolded text he declares:
Please know that if something in our products is significantly impacting juvenile salmon in the wild, then we the cure companies will whole heartedly take on the responsibility to change these ingredients, the way they are used and hopefully regulated.
Adds Mishler: “The smart manufacturers will simply design new cures that are not poisonous to our fish … Anglers want to do the right thing, and will undoubtedly move toward products that are safe for salmon.”
That said, to some it’s just another example of “death by a thousand cuts,” as Auntie M on piscatorialpursuits wrote. This year, loon advocates proposed a partial ban on lead fishing weights on a dozen lakes in Washington, which some took to mean the beginning of a wholesale attack on the cheapest, best way for anglers to target moving and stillwater species.
Then again, as other anglers have noted, there’s always good ol’ borax for curing eggs.