Monitoring Adult Steelhead on a “Shoestring:” Fact or Fiction?

by Richard W. DeHaven, Fish and Wildlife Biologist (Retired)

--June 2010--

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 all depends.

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 generated.

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 effective).

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.


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