Gualala River Steelhead Spawning Run Increases in 2007 April 23, 2007 The 2007 spawning run of steelhead in the Gualala River appears to have risen to the highest level this investigator has recorded since surveys began 7 years ago. Through mid-April 2007, surveys of the Index Reach of the Wheatfield Fork yielded 762 adult steelhead (i.e., a population index, not a total count). This compares with previous high seasonal totals along this 18.7-mile river reach of 433 and 377 adults, respectively, in 2005 (seven surveys) and 2002 (eight surveys). With 2007 surveys starting in mid-December 2006, adult steelhead (6-157) were recorded on each of nine surveys conducted over the 5-month spawning season. Moreover, the four surveys conducted during March alone recorded more adult fish (532) than the surveys of any previous spawning season. Sizes of groups of adult fish also increased. Two groups of fish numbering in the mid-40s and several in the 30s were recorded in 2007, whereas during the six previous seasons, the two largest groups numbered in the low 30s. In addition, increased numbers of smaller-size adult fish–another indicator of a robust spawning return–were evident in 2007 surveys. The 2007 and earlier results suggest that the total adult return to the river was probably at least several thousand fish, with up to about two thousand returning to the Wheatfield Fork (derivation and refinement of these conclusions will be part of the 2007 Annual Report to be posted on this website in March 2008). The Wheatfield Fork is the largest (37 percent) of the river’s five primary branches. It probably supports the largest segment of the river’s steelhead spawning run. It is also the only branch currently being systematically surveyed (for spawning), although in 2008, surveys from helicopter of other selected river reaches will likely be initiated (see Helicopter Survey page, above). Recording such a robust spawning return in 2007 leads to an obvious question: Does it indicate a river ecosystem and steelhead population in good health? The unfortunate answer in both respects is “no.” The upsurge of spawning adults in 2007 is the likely product of recent climatic anomalies which may not recur again for decades. The first anomaly was an usually early start to the 2004-2005 rainy season in mid-October 2004. Heavy rains restored surface flows to main-stem river reaches which had become dewatered over summer. Juvenile steelhead (JSH) thus gained relief from hostile in-stream conditions, including lack of surface flows (and associated connectivity) and massive stranding (and mortality) in drying pools. A large proportion of the surviving JSH population then apparently made a relatively early seaward exodus from the river. With a more normal start to the rainy season in November or early December (i.e., when flow increases normally occur), many more JSH would likely have perished before smolting and migrating to sea. A second, even more fortuitous climatic anomaly appeared in the spring of 2005. Both March and May had above-average rainfall, with May far above average. Late-season precipitation of such magnitude, even when overall yearly precipitation remains average or below, greatly benefits watershed hydrodynamics. Ground and surface water is replenished just before the onset of summer, thus reducing and delaying inevitable summertime declines of surface stream flow. With higher summertime flows, little or no main-stem dewatering occurs (which was true in 2005) and rearing conditions for JSH (especially with respect to water temperature) are markedly improved. Improved summertime rearing results in both more and healthier JSH ultimately emigrating to sea. Thus, a strong case can be made that 2007's robust spawning return was largely a product of 2005's unusually wet spring. Moreover and despite low odds, the wet-spring anomaly recurred yet again in 2006, when April rainfall far exceeded average. In addition, annual rainfall for 2006 was also far above average. Thus, just as in summertime 2005, flows, temperatures, and JSH rearing conditions were greatly improved in summertime 2006. The resulting improved production of JSH may have played a role in the robust 2007 spawning run, but is more likely to be expressed as increased spawners in 2008-2009. Nevertheless, short-term benefits to steelhead of rare back-to-back wet spring seasons cannot negate serious and extensive habitat problems facing the river and its salmonids (i.e., also including coho salmon–which appear to have already been extirpated). Excessive sediment, extensive summertime dewatering (including large, main-stem reaches), and water temperatures elevated to lethal levels, not only persist in most years, but are likely incrementally worsening. A return of extensive summertime dewatering and hostile (to JSH) water temperatures is inevitable with recurrence of average-to-below annual rainfall–or particularly low springtime rainfall. Just as inevitably, fewer JSH will then be produced, with fewer adult spawners returning 1-3 years later. Currently (as this is written), 2007 precipitation, with a dry spring and only about half the overall rainfall as occurred in 2006, is tracking towards just such a scenario. Only unusually high rainfall in the few remaining weeks of the rainy season can ameliorate the inevitable outcome. Nevertheless, there is reason for optimism. A robust spawning return for 2007 shows that the steelhead population is still quite resilient and capable of marked positive response, when favorable habitat conditions driven by climatic anomalies improve JSH rearing and production. And the jump in numbers lends credence to the thesis that man-made habitat improvements may benefit steelhead equally as well (as natural acts). The “window of opportunity” is clearly limited, however. Effective solutions to the river’s habitat problems must begin soon or population viability will eventually be compromised, possibly sending steelhead down the same path as the river’s coho salmon. (Note: Several issues addressed here are more fully discussed and explained in the 2001-2007 Annual Reports and other pages of this web site. The reader may wish to review these for more insight.)