http://steelheadvoices.com/?p=590 Over many years in the fisheries business I’ve witnessed more predictions regarding salmon returns than I care to remember. One thing I’ve not forgotten, however, is my overriding impression – if you want to be wrong, just make a prediction. British Columbia is replete with examples of that this year. I don’t think I’m overstating it to say the batting average was so low there wouldn’t be a glimmer of hope for a new contract for any of the predictors if they were ball players. I don’t see that as a lack of available information as much as I do failure to look for it and/or apply it. The business of predicting steelhead returns involves much greater uncertainty than for salmon. Steelhead have so many combinations of freshwater and ocean ages and repeat spawning frequencies that confidence in anything other than broad scale forecasts is probably not something most managers want to think about. That aside, here’s some information that should be top of mind. The warm water intrusion (“the blob”) that befell virtually the entire ocean migration and rearing area for steelhead, especially those originating from British Columbia, during 2015 and well into 2016 clearly had major impacts on the returns to our streams in 2017. That was 100% predictable but I see no evidence of anything but surprise on the part of fisheries managers when it happened. Lots of head scratching after the fact but no acknowledgement of the science that predicted it. Now there is even more science that is sounding alarms for 2018 and even beyond. The National Oceanic and Atmospheric Administration (NOAA) is my go to source for research results on happenings in the ocean environments occupied by North American origin salmon and steelhead. NOAA has been at it for a very long time and their people have published more highly instructive findings and reports on steelhead at sea than everyone else combined. Dr Nathan Mantua, a prominent member of NOAA as well as a steelhead angler, is the presenter of the prestigious Peter Larkin Lecture at the University of British Columbia for 2017. They don’t extend that invitation to just anyone! (Dr. Peter Larkin was the very first chief fisheries biologist appointed to serve the provincial government in 1948. He passed away in 1996 after a long and distinguished career in the science community, mostly at UBC.) Dr. Kate Myers, another remarkable high seas researcher (recently retired) out of the University of Washington’s School of Aquatic and Fisheries Sciences was a frequent research colleague of Mantua. Together they have provided a tremendous amount of quality information on steelhead. Here’s a bit of a synopsis of what some of the research they have been directly involved in over recent years has been telling us. Steelhead migrate and feed in the surface and near surface layers of the ocean (usually 6m or less). The high end of their preferred temperature range is 13-15C. The ocean rearing area most frequented by North American origin steelhead is bounded on the south by what is known as the Sub-Arctic boundary, the area south of which water temperature becomes a barrier to steelhead. To the north, the ocean feeding area includes the Gulf of Alaska and all the areas westward through the central north Pacific to well past the mid-point between North America and Asia. The northern boundary, the Aleutain Islands chain, is physical rather than temperature determined. The area within these physical and temperature controlled limits is the one that will lose the most thermally suitable steelhead rearing habitat under increased ocean temperatures whenever that Sub-Artic temperature dependent boundary shifts north. Whereas the blob has largely dissipated now, don’t bet the farm on a return to broad scale cooler ocean temperatures any time soon. The temperature issues are, by no means, straightforward but the pathways through which they manifest themselves are becoming reasonably understood. One of the important points related specifically to steelhead at sea and elevated temperatures is the influence on their metabolic requirements. As temperature warms metabolic requirements increase while the energy supply from preferred food items is reduced through a combination of less of them and their lower size and quality. The companion feature out there in the central north Pacific is ocean acidification or, as Kate Myers once parroted, ocean warming’s evil twin. Squid, that preferred steelhead food item, are particularly sensitive to acidification. The predictions around trends in ocean acidification are consistent. It isn’t going away. I spoke to some of the research findings with respect to steelhead and chinook way back in February (“Science Messages”, February 1). A couple of points made then deserve repeat. The numbers of enhanced pink and chum salmon being pumped into the North Pacific ecosystem are outstripping its capacity to grow sufficient food supplies to sustain everything feeding on them. Massive numbers of enhanced pink salmon, from both Alaska and Asia, prey heavily on the same squid that are the food item of choice for maturing steelhead and chinook. Those enhancement programs are about as likely to go away as ocean acidification. All things considered we’re looking at more fish competing for less food of lower quality than needed to sustain the once known survival and growth of steelhead in their main ocean feeding grounds. Fishers and managers need to lower their expectations on the supply side of the picture. The fact that the abundance of steelhead from Alaska to California this year was nowhere near what everyone wanted and expected ought to have been a wake up call but I still don’t see any evidence of concern for next year and beyond. Another aspect of ocean conditions I wonder about is the distance between the river of origin of steelhead smolts and the high seas rearing areas they are known to occupy. It seems logical that smolts from rivers closest to those areas would not be subjected to the inhospitable conditions for as long as those that had to migrate greater distances to arrive at the same destination. This is obviously pure conjecture but it might explain at least part of the increasingly negative steelhead abundance trend as one moves from north to south down the B C coast. Some recent results of NOAA’s near shore sampling of coho and chinook illustrate more of the problems now confronting us. What their people are telling us is the research and standard sampling they have been conducting off the Pacific Northwest coast for more than 20 years turned up the fewest juvenile coho and chinook salmon ever in 2017. Here is their graphic: Couple that with the markedly increased incidence of species known to prey on salmon and it is delusional to believe there won’t be consequences.