Monitoring Adult Steelhead on a “Shoestring:” Fact or Fiction?
by Richard W. DeHaven, Fish and Wildlife Biologist (Retired)
Occasionally, after surfing here, someone will ask--or thinks it, but doesn’t ask: “So, Richard, you
float down the river a few times each season in your little boat and count fish. Do you really
believe that population estimates that are anywhere close to reality can be derived this way?”
My answer, coalesced after nearly 10 years on the river floating several hundred hours (a lot of
quiet time for thinking...) and close to two thousand miles, is a resounding “Yes!”–and “No!” It
It depends on rainfall and flows during any given season. There are certainly years, mainly (but
not necessarily) high rainfall years, when the methodology breaks down. There are just too many
periods–or one long period in the heart of the spawning season–when turbidity prevents decent,
well-spaced surveys. On the other hand, some seasons have a more moderate, uniform mix of
rainfall events, flow spikes and short-term rises in turbidity; these seasons do allow one to see and
count a representative sample of the fish coming upstream to spawn. I am becoming more and
more confident that in such “good” survey seasons, reasonably good population estimates are
When my field work ends in another year or two, a fresh examination of all the data and
population estimates will occur, with an eye towards how they were affected inter-seasonally by
annual rainfall, flows and turbidity. This should allow the “good,” “not so good,” and “poor”
annual population estimates to be identified, perhaps using some sort of annual spawning-survey
efficiency rating index.
Until then, one critical caveat (already expressed in several places on this site) needs to be
reemphasized again: Regardless of rainfall and flows, “good” survey years can only be achieved
if the surveyor commits unequivocally to “going with the flow (let’s just call it “flow-going”).”
Consider an example. As I am writing this, the 2010 spawning season has been roughly one-third
wetter than either the 2009 or 2008 seasons. In addition, 2010 springtime rainfall continues to be
well above average. Although conditions allowed me to conduct the fourth survey of the season
on March 21st, rainfall and steady high flows (and related turbidity) precluded another survey for
about 4 weeks. Finally, on April 25-26, the river again came into shape–albeit marginally–for
another survey. But the weather service was predicting 3 days of rainfall for April 27th through
29th that could easily blow the stream back out for days or weeks. Thus, the survey “window” was
April 25th and 26th. There was no leeway to this window. Those were the 2 days that flow-going
dictated a survey; thus, any scheduling conflicts would have to be put aside to do the survey.
And that’s an example of why, in 10 years, I have been out on the river alone on numerous
holidays and too many assorted “family obligation” days to recount. Obviously, such adherence
to a flow-going schedule can be especially difficult for government workers (I know, having been
one.) to adopt, given all the rules, regulations and institutional roadblocks constraining them.
Nonetheless, flow-going remains the single most important underlying key to success of the
population monitoring system I have developed and use.
Flow-going can make or break the scientific value of a season’s surveys and does truly open the
door to “monitoring on a shoestring (i.e., low-cost monitoring).” Other common adult population
monitoring alternatives (e.g., weirs, traps, mark-recapture programs, etc.) are almost always going
to be much more expensive and time-consuming, albeit perhaps more precise.
Nevertheless, achieving the benefit of flow-going requires attention to other details as well. One
detail that cannot be overemphasized is sunglasses. I have gone through dozens (and always carry
an extra pair) over the years, as they were lost, broken or scratched. Sunglasses don’t necessarily
have to be expensive (some under $20 have worked as well as those costing $200), but they must
be polarized and the “wrap-around” style. I have found it amazing that over the years, it has not
been uncommon for my colleagues to arrive for a survey with me either without the obligatory
glasses or without knowing whether the ones they have brought are indeed polarized. Also,
remember that under different conditions, different lens colors and shades of darkness (generally,
dark lenses on full-sun days and lighter ones [which let in more light] on low-light days) affect
your ability to see fish. And keep in mind that full sun at a low angle in front of you (i.e., early in
the season and/or early and late in the day) is your enemy when it comes to seeing fish, whereas
diffused sunlight (e.g., with high, thin cloud cover) from the sun overhead or behind you (best) is
your friend. In either case, and for all possible lighting conditions in between, good, clean
polarized sunglasses are a must for seeing and counting fish effectively.
A baseball-style cap with a well-rounded bill is also important. Such a hat is best for reducing
your main enemy–glare. Nevertheless, it is surprising how many of my friends and colleagues
have shown up with various assorted “dork” hats–or no hat or cap at all. I always bring a spare
baseball cap along for them.
Standing up in the boat (i.e., the specific boat I use) as you pass over fish-holding spots can be
tricky and takes practice, but is equally important. Elevation is another way of reducing glare at
the water’s surface by reducing (or increasing, depending upon your viewpoint) the angle at which
your eyes meet the water; this can be really important over the deepest pools and holding spots
(and is, of course, why kayaks and canoes–in which you cannot safely stand up–are not nearly as
Standing, when going over the main fish-holding spots becomes exponentially more important as
the flow increases. Higher flow means more turbulence. With both turbulence (which causes
light refraction) and surface glare working against you, without standing, you may otherwise be
hard-pressed to see any fish at all.
Pushing (with the oars) the boat downstream faster than the current is also an important technique.
The rule is: come up on fish quickly, or they will see you before you see them. If they do, they
often hide or get “pushed” downstream in front of you. The count can be reduced–or you may not
see any fish at all.
In fact, I have learned that it is important to keep the boat moving briskly downstream at all times,
thus I am constantly pushing with the oars. I am not talking about hard, all-out rowing, but just a
moderate, steady cadence. If you do this in concert with stream flow and current (that means you
need to learn the stream’s hydraulics), you won’t become nearly as tired. But when you do get
tired, pull the boat up on a beach and rest. Resting by floating leisurely along with the current
(while continuing the survey) is not a recipe for efficiently counting fish.
Familiarity with the survey reach of the stream is also essential. The observer needs to know not
only all the favored fish-holding places (more important at lower flows), but any potential danger
spots (which often change with changing flow) to navigation. After all, how can you be pushing
the boat continuously downstream, alternately sitting and standing, and always looking down and
ahead of you to spot fish, if you are worried about dumping the boat, losing your gear, or maybe
becoming a “floater?” Familiarity goes a long way towards alleviating these issues.
During early years of my work, I was foolish to not consider this when I sometimes sent friends
and colleagues on survey down a stream reach they were not familiar with (“Well..., they’re
biologists, they’ve done this kind of stuff before, so they must know what they are doing.” ...was
my naive reasoning.). We are lucky none of those early adventures resulted in more than just
some lost or ruined gear (one camera, a binoculars, and a pistol, on different occasions) dinged
boats, and minor body bruises.
Today, I wouldn’t consider sending a greenhorn down the stream alone until she had several
closely supervised surveys with me to her credit. To tell the truth, none of my greenhorn friends
have, to date, been willing to step up and make that kind of commitment (to multiple surveys).
And that is why, at least for the last few years, I have done nearly every survey alone (at least in
terms of the fish-counting, that is).
Now, if you have surfed this site before, you probably know that everything I have just discussed
has been presented earlier here in various forums, including my Annual Reports (click here), the
Secrets of Steelhead Biology Essential to Study Planning document (click here), and the piece
titled Counting Adult Steelhead in “Favored” Pools and Runs (click here). You may find it
useful to review these again now. That may help you make your own decision about whether the
decade of monitoring I have done on the Gualala River’s steelhead population is generating facts
(about the population)–or just useless background noise. It may also help you decide if a survey
protocol similar to mine might work on your particular steelhead stream.
Meanwhile, I’m sticking with what my preliminary analyses and “gut” are telling me: not only is
monitoring on a “shoestring” possible, it is (at least some of the time) providing useful facts about
the adult steelhead population of the Gualala River.
Nevertheless, next I need to corroborate and validate the population estimates using weir counts
and/or other methods. Preparations for this work are underway. Stay tuned for updates...RWD.