by Carmen Macdonald
It seems that at this point, every couple of months I see another article published by notable researchers like Michael Blouin, Mark Christie and Michael Ford. To cut right to the chase, these studies conclude that the Relative Reproductive Success of hatchery fish is lower than that of wild fish. In other words if 100 wild fish (50 pairs) can produce 100 returning adults in the next generation, hatchery fish will produce fewer. In the case of wild broodstock steelhead, that number might be 85 returning fish instead of 100 with an RSS value of 85% for these fish.
What follows these articles is a wholly political discussion with those vehemently against hatchery fish standing on the position that hatchery fish are bad, hatchery fish are bad and hatchery fish are bad.
On the research side, what I read is a call for more money for more research so that the components causing this 15% reduction can be dissected.
While all of this is taking place, hatchery programs are (perhaps by design) thrown into turmoil. We have lawsuits, lost participation, lost economics and what will amount to a lost connection between the population and the resource if the trend continues.
While an 85% RRS value for steelhead seems to be a source of condemnation, I believe exactly the opposite. Looking at some layman-understood components that affect spawning success, 85% is one heck of a good number.
What follows here is an email I wrote to Michael Blouin at Oregon State University on the first of August. I did not receive a response from Mr. Blouin, but wanted to share the concepts involved. The italic components were not part of the original email...I've added them here in an attempt to further flesh out the concepts.
Dear Mr. Blouin,
As an angler I've read with great interest the number of Relative Reproductive Success studies that you've been involved with publishing over the last years. Within each, I see quick references to what appear to be some critical concepts that we'd want to understand, but then not much in regards to follow up.
A couple of them are:
a. High level of variation in spawning success between adults. I'd believe most interested in salmon and steelhead would expect progeny to be spread more or less evenly across the spawning adults that preceded them, but that's not the case as you've mentioned. Certain spawners are highly successful, others are not at all- which is true across both wild and hatchery spawners. On Hood River, genetic studies found that the parents of any given run year were not evenly spread across the population with every two wild spawners replacing themselves. Instead, some spawning events produced many fish, some one or two, and many none at all. To me this suggests that on a given year X, Y or Z tributary might hit those perfect conditions and others experience just the opposite. Think about our hatchery programs. We no longer scatter-plant fish. We apply them to select locations in order to greater expose them to fisheries and minimize their influence on wild spawners.
b. Spatial distribution of spawners. You've referenced spatial distribution of spawners being different for wild and hatchery fish. Generally, I understand that wild fish, especially steelhead, are found higher in systems and better disbursed through spawning tributaries. Hatchery fish are generally planted lower in systems and returning adults tend to hang around the area of their liberation and the spawning tributary nearest upstream.
Within these two concepts alone I see great reason for differences in reproductive success. With regard to variation in spawning success, my thoughts would lead me to believe that to be successful in spawning and returning the next generation, the conditions where spawning, emergence and early life history take place have to be just right. When it's great, it's really great. When it's not good, nature comes down hard. Couple that with greater spatial distribution of wild spawners, usually higher in systems and my thoughts quickly wonder how we can ask that hatchery fish and wild fish be equally successful?
Wild fish are the progeny of a wild event. Hatchery fish have to be applied to a wild river. They cannot be a wild event. Their point of liberation is chosen by humans, not nature.
Is anybody asking or contemplating whether the question of hatchery fish equaling wild fish productivity is even legitimate to ask? It doesn't seem so. And the further thought here is that wild broodstock steelhead have been shown to perform at 85% of their wild ancestry. With that number and the fact that within fishery programs we're actively trying to minimize interaction while maximizing harvest, how has the result been allowed to be characterized as a negative?
One other component that intrigues me is the issue of capacity. From what I can gather, the first three years of the Hood River study release numbers of hatchery smolts numbered no more than 5,000. Consequently, those were also the years that returned the best relative reproductive success from hatchery fish. From what I believe I've read, the years that followed included releases in the range of 45,000 smolts.
We know a capacity exists in our rivers. We can go beyond capacity by adding smolts that use little resources before they exit the system. However, when they return as adults and try to spawn, they're 100% subject to all forms of natural selection, and capacity. What I see within the studies appears to be the expectation of an infinite upside. To be equal to the productivity of wild fish, hatchery fish would have to be there in numbers (and the aforementioned locations) that are capable of delivering successful reproduction equal to that of wild fish. And because we're applying hatchery fish to streams in a manner that will limit their spatial distribution and utilization of the best habitat, rational thought would conclude that the stream's capacity will come down hardest on these fish.
As I consider steelhead, they were made a game fish in the late 1970's. By the early 1990's sport harvest was ended. With only a small level of tribal harvest and sport release mortalities, by what mechanism would Hood River steelhead be below capacity?
With regard to the work you've done, do you have spatial distribution information of where successful and unsuccessful spawners were found? Were the hatchery fish applied to areas that also produced successful wild spawning or were they in low success areas? Is there any information with regard to capacity of Hood River and the stream segments used?
In all of this it appears that the conventional wisdom says that to be of benefit, the RRS of hatchery fish needs to equal that of wild fish. Is anybody asking if that goal is at all reasonable?
And finally, from a population level. If first generation broodstock steelhead have a relative reproductive success that is 85% of wild fish, does the hypothetical math below work?
a. Wild run= 1,000 fish
b. Remove 50 pairs to create broodstock
c. Produce and release 100,000 smolt at 1% return
d. 900 wilds (1,000 minus the 100 removed) return plus 1,000 broodstock
If the Relative Reproductive Success of the broodstock fish are 85% of the wilds, am I in a better population position with 100% of a 1,000 fish run, or 100% of 900 wild and 85% of the additional 1,000 broodstock?
I'd greatly appreciate your insight.
As we move forward with management programs, there is a reason we have some separation between science and policy. And with regard to Relative Reproductive Success, a difference in raw value does not immediately mean damage to wild populations.
To me some in-depth discussion and transparency within these concepts from the leadership at our management organizations would do much to advance trust within ongoing processes.