Interpretations of Physical Habitat Analysis

Edited by
Charles D.D. Howard

March 19, 20, 21, 1984
Victoria, B.C. Canada

Preface

Instream flow discussions are often polarized around seemingly irreconcilable points of view. In actual fact, a private conversation with biologists from both sides of an issue will often reveal a mutual desire for getting at the truth of the matter and escaping the frustrating circumstances which surround most instream flow discussions. Interagency negotiation, public hearings, and courtrooms, which are the normal arenas for these discussions thwart scientific enquiry. This workshop was a planned escape from this environment - an opportunity for experts to speak frankly with others working in similar situations. For this reason the written record here does not identify the speakers or the agencies and institutions which they represent. This represents a departure from some instream flow discussions in which the reputation of an individual and the prestige of his agency can be factors which influence acceptance of ideas. Here, the ideas must stand or fall on their own.

My company sponsored this workshop because that seemed to be the best way to get this diverse, international group together into one room. The local arrangements were handled by Clem Wehner and my secretary, Paula Samson, who also typed this manuscript. Charles Newcombe of the British Columbia Department of Environment provided many good ideas before, during and after the workshop, and he also read and commented on this manuscript. However, if these proceedings have lasting merit it will be primarily because of the participants themselves, the invited speakers, and the discussion leaders.

Charles D.D. Howard
Victoria, British Columbia
Canada
January, 1985

Table of Contents

Attachment A - Steps in Office IFG Methodology Analytical Process
Attachment B - Workshop Participants
Attachment C - Workshop Discussion Papers

Section 17: Working Group Conclusions

On the last day the participants got together in working groups. This chapter records their conclusions.

Group A:

Our group decided that there was evidence which supported, to certain degrees, the positions of both the pro-fish and the pro-development positions. We found some common, neutral ground here at the workshop, and have come to a clearer understanding. We decided that we should not become committed to a method because it was an explicit method. Like a man in the water grasping at a rope maybe we should try to paddle around and swim and see if we can find something else. We decided that there was little or no evidence that habitat indices, whatever they might be, are clearly related to fish abundance or biomass, before or after changes in instream flows. Nor is there a very clear relationship between habitat indices and production(in grams per metre per year) before changes in flow. We are still having difficulty calibrating indices of habitat with observed fish and with what the populations are doing.

We felt that there were problems simulating habitat after perturbation of streamflows if it was predicted that the perturbation was going to cause a change in the channel morphology. Some people here said that it could be done and others said that it could not be done. Our group was not convinced that calculations could simulate habitat changes.

As far as deciding what method to use to determine instream flow needs is concerned we agreed that the method is generally based on what the proponent and the agency perceive at the time to be the best method available for that situation. There was some discussion about how do we select a method. Some people said that we should take the method we think is best for each particular application and obviously some methods appear better in some situations than others. We agreed that it is a very desireable and noble thing for people to strive for the best method - if it doesn't do the job absolutely perfectly, they should not be criticized.

We talked about what are the best habitat criteria for fish and we agreed that velocity appears to be one, pool-riffle ratio appears to be another, and finally, the third one was the availability of water. We had difficulties describing what the availability of water is but we said that if there was no water that was a pretty serious thing to have happen.

We talked about changes in fish behaviour and thereby the consequences that make it difficult to model changes in habitat with changes in stream flow. That is, if changes in stream flow alter the behaviour of a fish then my estimate of the amount of habitat, and the fish's perception of the available habitat may not be related.

There was general agreement that none of the methods that we use to assess instream flows necessarily work to protect fish. We were concerned that our methods don't do the whole job. We did agree that the insteam flow exercise was still a very worthwhile one because it forces the proponent and the agency to focus attention on the consequences of decisions pertaining to stream flow. Thus, and instream flow method becomes a forum which encourages discussion and maybe talking is better than not talking. So maybe we're still not doing the whole number for the fish but this is still taking us some distance.

We said that this IFG modelling exercise is only worthwhile if everyone believes that there is a relationship between habitat and fish. If you don't believe that that relationship exists, then you shouldn't do the analysis. We also agreed that there is no evidence that this relationship between habitat and fish is linear. We do agree that the numbers of fish, or biomass, increases with habitat, but we don't know how you get from weighted usable area to fish. That goes back to earlier points.

We agreed that having done an objective analysis of instream flow needs one then needs to superimpose a subjective analysis on top of the first analysis to form an opinion of what the objective analysis means. How much confidence we have in it is another matter. In other words, we suggested a cautious interpretation of any method.

We also discussed possibilities for future meetings like this one. our conclusion is that there should be future meetings because they benefit the water and fish resources. It is also beneficial to the proponent and to the agencies, and as a consequence, it is beneficial to North American society for us to get together for future meetings.

We were, however, unclear about who should carry the burden (the effort and considerable cost) of bringing together all of these people to get their viewpoints. our group wants to express our confidence and appreciation to the person and the agencies and the people who went to all the effort to make this workshop happen. It was above and beyond the call of duty and we acknowledge this. we did not come to any agreement as to who should bring us together in the future. We did talk about maybe it should be a joint sponsorship. If we are going to have multi-disciplinary participants, maybe we should have multi-disciplinary sponsorship.

We agreed that the meetings should be issue oriented. In other words future meetings should concentrate on what is currently controversial about instream flow needs. Pick the hottest controversial potato that you canfind and that you have disagreement on, and lets talk about that because that's where weire going to make the strongest advances in our field.

We agreed that if the meeting is large, such as this is, then we should have key note speakers to start each session, identifying the issue, setting it into perspective, and then leading us on to discussion by the group. In other words, very similar to what we did in this meeting but a little bit more focused. It was an opinion of the group that this was required if we are really going to have a bona fide workshop. Some topics to help us that we should include in future meetings are: What are the methods, what are their advantages, what are their problems, and what advances have been made since the last meeting on those methods in those areas? Have new problems with those methods come up? Have new advantages come up since the last meeting?

We also thought that some case histories, more explicitly discussed, would be helpful. We felt that future meetings should be documented in some type of proceedings. There should be some written record of this event so that people confronted with these problems could benefit from this workshop in the future. The document should include the important existing knowledge which we discussed. We should include in it some of the fundamental things that we are dealing with that are generally accepted. Some people suggested that there be an annotated bibliography of key reference material. The proceedings should document any unique aspect of the workshop - what advances occurred, new concepts, new ideas developed during the meetings. A statement of where we are now should be recorded so that we can measure progress in the future. And then, of course, we strongly endorse the idea that the meeting should produce a list of the participants, i.e, that some of these people who are here now are the main actors in this problem. This list of participants should include their agencies and their mailing addresses.

Group B:

I would like to go back to Escher's triangular diagram of a moibus strip, an impossible configuration that is the symbol of this workshop. I think it is an appropriate symbol because we really do have people from various disciplines - engineers, biologists, hydrologists etc. - all coming together. One problem is that we do not have a common set of assumptions, beliefs or experience. What is becoming clear to me is that there is still a need to develop a common language so that we can talk, with each of us understanding what the other has said. Another problem that confronts us is that there is an immense lack of knowledge about how to deal with instream flow needs. One of the constructive suggestions that came out of our group discussion was that we need to keep some kind of a post-project record about the outcomes following the predictions made by various computerized models or subjective assessments and so on. This would help us to find what works and figure out why it works. Then we need to tell the world about it so that we can start filling in these areas of ignorance.

I worked for a year and a half corresponding with the Federal Government suggesting that we should meet to discuss instream flow needs. Everyone I wrote expressed the belief that it was a good idea to have a meeting and that I should try to make it happen; in all this governmental inertia, we never did get to meet. What we needed was a catalyst and perhaps a neutral ground. This workshop here was long over due and it should set in motion a series of such meetings in order for us to advance our understanding.

One of the people in our group suggested that we had omitted discussion of ecological appraisal of instream flow needs and that we tend to be overly computer oriented and abiotic, and too busy measuring depth and velocity.

There was another question about the validity of probability of use curves. I personally disagree that there is any doubt about the validity of them. The question simply points out the need to use them intelligently or to develop new ones when necessary. In a particular case, where rainbow trout can be found in two seemingly utterly different areas, the question is to use the probability of use curves appropriatly to account for the trout's presence in such different parts of the stream.

There was another question about what a major stocking program does to your analysis of habitat use. There are unpredictable variables that can mislead one into believing that an analysis has been conducted correctly, but perhaps it has not and you just stock fish in the stream instead.

There was also the observation that biologists are very conservative. Although the subject was raised, it was not examined in great detail. The hydro engineer sees a river flowing down a gradient as potential energy to be captured from now until eternity and it doesn't matter whether he waits five years to get it. The biologist really has got something to lose while the engineer has got something to gain. If a biologist makes a mistake at this stage, he has lost a resource forever. And this is a reason for a biologist's conservativeness.

We also talked a little about the perception of value of tiny little sloughs that are rectangular in shape and that have virtually no water flowing through them but are suitable habitat for immense numbers of fish. The point that comes to mind, is that we tend to worry about the arteries and forget about the veins. It is worth remembering that tiny little sloughs so overgrown that they are almost impossible to see, really are the life blood of our fisheries.

Another relevant point raised was that we need to spend a good deal of effort scoping a project and deciding what needs to be done before we expend a lot of time and energy in studies.

A question was raised about the suitability of using a habitat index to design new habitat. I personally believe that it should be possible to do that and that we c an learn from experience with habitat enhancement and turn it back into wildlife evaluations.

I asked the question whether the concept of weighted usable area for habitat could be infused into some sort of larger model that takes into account some of the ecological relationships. I got the impression from the group that it might not be possible. In the future we might have to discard the idea of weighted usable area or habitat index if we are going to include ecological relationships in our modelling.

Group C:

Our group took the approach, initially, of reviewing the agenda, summarizing the various aspects of the workshop, and discussing what we have learned under each of the topics. But it soon became apparent that it would be of more value to put into perspective the definitions of instream flow methodologies, particularly incremental methodology. We discussed the idea that there may be perceived a conflict between water managers and resource managers, but there really is not a conflict. It is more that we all share a common responsibility among different user groups, and have not yet developed the language or the experience to know how to go about it in an organized manner. We are all trying by various means to make these decisions and we have set in motion a methodology which is referred to as the incremental methodology which is really a water management tool

it is a means or a mechanism by which people can get involved and make these kinds of decisions. There is a large body of consistency within that methodology for making decisions at various levels, along the line of the four levels of analysis that were introduced in this workshop. Where there seems to be confusion now is that definitions of what occurs at each of the four levels of analysis are perceived as being of a different value, and because of the way that developments happen, often one group, usually the engineering water development group, is well along at about a well established "level two" and perhaps getting into the "level three" type of analysis before they bring the resource managers in. At that point what they are really asking for is a "level four" answer from the resource people. A very important thing to establish is that these levels are a sequential process. They all become part of the planning, the scoping, and the up front work. The resource managers should come in early on and we need to recognize basically what can be done at a "level one", and then to proceed through to level two. We tried to summarize then, what could be done at these various levels.

Under level one we are trying to define the opportunities for all parties and what the compromises might be. From the biological perspective, what you are asking is "Does this stream have fish in it?".

Under a level two type of analysis, we are trying to decide what ought to be studied with regard to making an evaluation of fish habitat. There are various components of an analysis that one should undertake to establish the effects of a project or the opportunies presented by a project to do something for fish habitat and these components cover a very broad spectrum. For example, we have food relationships, we have water'quality, temperature, hydraulic relationships, channel stability, as well as ice. These are all relevant at level two and we should be going through some type of systematic procedure to decide whether or not the proposed development would require analysis at the various levels.

Beyond that, one could drop into a level three in which you basically try to provide a well focused qualitative type of assessment. It is sort of a macro habitat type of evaluation. If you were to change flow regimes by some order of magnitude, what is likely to occur? Or should you put an impoundment on this reservoir and change the thermal regime, what would the opportunities presented or the consequences likely be.

Finally, you get down to level four where you try to provide a quantitative description of what is going on, and that is where the different, detailed micro habitat type of analysis would come into play. The development of the criteria - should criteria curves be drawn in shape A, B or C. How do you calibrate your hydraulic model, how much detail do you have to have in your water chemistry analysis, how would you interpret these things? One should not really be embarking on the level four analyses until having gone through the entire heirarchial process.

The utilization of computer modelling is a very appropriate tool which can be brought to bear at several levels. But most important is that you completely recognize right up front that the level of detail assigned to your computer simulation is dictated by the quality of input information, not by the type of computational output that can be presented. We have very f ine computerized simulations which operate at level two which help us figure out what to study; but just because they are computerized and have good graphics they should not be used or presented as level 4 answers.

Group D:

The title of the workshop is primarily why I attended, but we have not discussed it specifically to this point. The title is "Interpretation of Physical Habitat". I am fairly familiar with the calculation of physical habitat. I have been very interested for five or six years in what you do with it once you get it.

We have discussed the various levels of analysis before us. I think we made some good distinctions during the workshop that it might be valuable to bring up again. Physical habitat is not everything and we need to make a good distinction. Physical habitat can be basically broken down into micro habitat and macro habitat. We did not talk about macro habitat at all during the discussions and I think it was probably just as well.

Micro habitat elements are noted to change as you go downstream. When you get into physical micro habitat, talking about the things that do vary within a short reach of stream as flow changes, the depth, velocity, substrate. I do not think we can get to the point of interpreting physical, micro habitat values unless we @do something about system review. Systems vary from the point of view of physical and chemical parameters and biological parameters. At no time can you forget one or the other. Certain systems have a much higher influence from physical or chemical aspects and other systems are much more biologically oriented. We have concluded that you are probably going to be much more successf ul in carrying your physical habitat interpretations through some kind of meaningful analysis and recommendations for water managment schemes if you deal primarily with systems that are predominately inf luenced by physical and chemical parameters. If there are chemical and macro habitat elements, you can deal with them in another way, but if there are physical micro habitat elements, then we probably have some kind of an approach, a credible approach to handling these things that was discussed in the workshop.

The description of the system in these terms before you even get started is something that a lot of people don't do. The continuation of that description down to the refinement of limiting factors placed on physical micro habitat components is absolutely necessary before you can really get going into all of these time series and frequency analyses that computers can to put together. Pinpointing the system in this manner, before we really get started with the whole thing is very crucial.

Once you have determined what physical micro habitat influence is, it is very easy to measure it. We have all the engineering tools we need and we talked about the refinements, and how well we believe in the models. We talked to some degree about the biological response criteria - our ability to talk about various aspects of biological preference. We can always do that and with velocity and depth the computer models that we have will always result in a discharge versus habitat curve - the functional limit of what we are trying to do here. We concluded then that the step that most people seem to be looking at more than any other, is that this thing is equally interpretable across its entire range. A very good example is a situation in which streamflows are limiting the population because of limited habitat and a high velocity. We should not use curves like this under the assumption that they are equally meaningful across the entire flow range. In the case of high velocities limiting the population the habitat chain may really be in another part of the curve ... small fish just as an example, might not be handled meaningfully at all. They can be crowded intensively and not really die off in spite of what the preference curves seem to say. You might not be buying a great deal at one time because you are only offering space for a limited spawning population at another time. A physical and biological habitat balance type of approach is needed as you go into the analysis. So the limiting factors on fish production we have concluded are very important.

As a final note on what we came up with, the physical habitat relation techniques, the computer models - the capabilities that we have seen demonstrated here - have been around in a basic form for nearly ten years now. I am a little dismayed that they have led us to side-step what is probably the most fascinating challenge of all the biological sciences and that is stream aquatic biology. It is the biggest bug out of the whole bunch because of the variation. You can handle the marine environment because it is fairly stable. You can handle the lake environment because it is nearly as stable, but we scientists have not handled the physical biological relationships in the stream environment to the extent that we should have. If we had, we would have made generalizations and categorizations and hypotheses that would have pushed us to go on to the next step and make some of the necessary experiments to verify our hypothethis. So, do not lose site of stream ecology as a science that is still alive and one that does not have to be supplanted simply because of the relative ease of doing the physical habitat simulation that you can put into a computer.

Workshop Participants

For a list of participants, please email us at info@cddhoward.com.