November 15, 1999

In the fall of 1980, Mattole Salmon Group workers were in the river waiting for the mouth to open, preparing for our first attempt to trap adult salmon for enhancement purposes. The 1999-2000 trapping season marks the 20th anniversary of our continuous efforts to save native runs of Mattole chinook and coho salmon. For a more extended report about this anniversary year, including details of our surveys, on-the-ground restoration work, and about what we have learned in 20 years of work, visit our web site at www.humboldt.net/~salmon or write to us at P.O. Box 188, Petrolia, California 95558.

The annual autumnal opening of the Mattole’s mouth, the event that both allows and announces the return of the salmon, can be vastly different from year to year. This season’s mouth opening, on October 28, 1999, coincided with a series of very high tides and tidal fluctuations (a 9.1-foot differential between high and low tides) and a 28-foot swell. Considering how dry the summer had been, it is questionable whether the total of 2.7” of rain that fell on the night of October 27-28 could have forced open the mouth if it hadn’t been for the tide and the big waves. The overwashing by the surf of the entire length of the berm caused the estuary/lagoon to swell at least as much as did the runoff from the rains. (Formally speaking, the lowest stretch of the river, where it falls under tidal influence, is an estuary only when the mouth is open and there is a direct connection to the sea. When the mouth closes for the summer, the ‘estuary’ becomes a lagoon, a lake-like body of fresh water bordering the sea but not directly connected to it.)

Observers first noted a channel into the sea at first light on the 28th of October. It was far to the north end of the estuary. Because of the overwash, though, and backing up of waters trying to flow through the new mouth, the estuary drained very slowly during the course of the day. Still, fish watchers along the river saw adult salmon, some of them six and seven miles upstream, within a day of the mouth’s opening.

As tradition and necessity dictate, the Salmon Group goes into an especially high gear once the mouth opens. Summer projects are quickly wrapped up and put to bed, preparations for the adult trapping program intensify and surveyors begin to organize themselves and gather gear for the long, cold days they’ll spend walking the streams in efforts to estimate the size and distribution of the year’s run – where the fish spawn and how many of them there might be. It’s an exciting time. Knowing that big fish are in the river again renews our energies and sense of purpose. It marks the onset of our working year, the beginning of our annual calendar.

One thing we have learned by occasional underestimation is how quickly fish can move upriver given enough water to do it. With steady, non-cataclysmic rainfall after the mouth opens, salmon, usually smaller ones, can reach our trap at Ettersburg within 5 days of entering the mouth. And that’s 43 river miles from the ocean.

Our trapping crew, led by Colum Coyne, set a new record for preparedness this year. The trap at Ettersburg was in place by November 11th. Then the crew waited. The first salmon to show up this anniversary and millennial season was a coho female, on November 15th. The first chinook came into the Ettersburg trap four days later. It is interesting that the last salmon our surveyors observed this season were also coho – carcasses of two recently spawned-out females seen on January 27th in Thompson Creek, a major spawning and rearing stream in the Mattole headwaters area, upstream from Whitethorn. The two coho carcasses had a distinctive mark – a clipped right maxillary – that indicated they were fish we had reared, marked and released as juveniles.

It turned out to be a good year for our trappers and a relatively good year for the salmon. Trapping was conducted on a one-night-off and one-on basis up until December 10th. That last night, 4 male and 2 female chinook swam into the trap. By then, we had caught a total of 25 chinook, 6 coho and one steelhead. It was enough for our program goals so we stopped fishing. As it turned out, because of a December drought followed by heavy storms in January, we never resumed trapping.

We spawned 7 of the female chinook and distributed a total of 16,000 “eyed” eggs to 2 hatchbox facilities in early January. Slightly more than half of the eggs were taken to our Arcanum hatchbox facility in the Mattole headwaters area, and the remainder to our Solitude site on the upper South Fork of Bear Creek. The Solitude chinook will be held until fall rains while those at Arcanum will be released in mid-spring. Another 125 chinook eggs were distributed to five classroom aquaria throughout the Mattole, as part of an educational program initiated in 1986.

Our annual spawner surveys began on November 24, l999, and ended January 27, 2000. Between these dates, our surveyors covered 150 stream miles and counted 173 redds (spawning nests), 39 salmon carcasses and 122 live fish. Of the redds, an estimated 89 were made by chinook, 36 by coho and 48 by steelhead. Of the carcasses, 32 were chinook, while among the live fish count, there were about 60 chinook, 40 coho and 22 steelhead. It should be noted that the numbers reported for steelhead are not indicative of their overall abundance, since our surveys are completed well before the end of the steelhead run.

Staff biologist Gary Peterson, who organizes the surveys and has been walking Mattole streams for 20 years, feels that this year’s salmon run was a marked improvement over last year and as good as, or better than, the 1997-98 run. In both of the last 2 seasons, El Niño negatively affected salmon in the ocean. Last year, especially, we saw the results of El Niño’s impacts. Most salmon were stunted, egg counts were down and overall numbers were the fifth lowest in the 19 years we’ve been counting. (The lowest count was in the l990-91 season, when an estimated 100 chinook and 100 coho returned to the Mattole.) Our best estimate, based on surveys, on trapping results and on general reports from residents of the watershed, is that approximately 700 chinook and 300 coho spawned in the Mattole during the 1999-2000 season.

These numbers, though a slight improvement, are hardly bountiful. There are, too, a couple of troubling notes. Lack of rainfall between early December and early January forced many salmon to spawn lower in the river system than they otherwise would have. Gravels are more mobile downriver and the storms, when they finally come, are likely to cause higher mortalities among eggs deposited there. Even worse conditions occurred in l994-95 when a huge storm on January 9th followed months of dry weather. Most of the salmon ended up spawning below Ettersburg, even lower than they did this season. We have reason to believe that high flows destroyed many if not most of the redds in 1995. Downstream migrant trapping this spring on Bear Creek at Ettersburg and downriver near Mill Creek will give us a clearer picture of the impacts of the December 1999 low-water conditions on Mattole salmon survival.

Another troubling note: even though we had average rainfall last winter, spring rains were scarce. By September 1999, stream flows were extremely low. Maureen Roche, MSG monitoring director, dove almost 6 miles of the Mattole headwaters near Whitethorn to evaluate projects on August 30 and September 23. Divers counted approximately 2500 coho and chinook* juveniles and almost 6,000 steelhead. On September 28, after a substantial heat wave, a spot check of ten pools in the same reaches found that fish numbers in those pools had dropped to about 20% of their former level. There is a good chance that the missing fish had died. Over the next several weeks, water levels dropped even lower. In some areas in the upper Mattole, water actually stopped flowing between pools during the day. This phenomenon seems to make it urgent that landowners throughout the watershed begin to contemplate renewed water conservation measures during the crucial late summer/early fall period.

* Until recently, we have accepted the common wisdom among biologists that juvenile chinook in northern California invariably migrate downstream to the ocean (or to oversummer in the estuary/lagoon) during their first spring of life, but divers have observed some chinook in upriver reaches of the Mattole in late summer over the past three years.


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Table of Contents for Mattole Restoration Newsletter, Issue 14 - Winter/Spring 2000