Who gets the blame for a declining salmon population off the California coast? A blog by fishery advocate Dick Pool a few days ago is typical of a popular view around the Golden State.
“The Sacramento Valley’s fall-run salmon have experienced catastrophic declines over the past eight years, falling from 769,000 returning adult fish in 2002 to 39,000 in 2009. The National Marine Fisheries Service report addresses several factors in this horrendous free fall, but you don’t have to dig very deep into the data to root out the primary culprit: the huge state and federal pumps near Tracy that send water south.”
Ah yes, let’s blame the farmers for the demise of this iconic fish.
But NOAA’s National Marine Fisheries Service (NMFS) scientists actually have a different take.
“The big decline we saw in Chinook salmon returns in 2007 and 2008 was subject to a major study that called poor ocean conditions the ‘proximate reason’ for the low numbers says Dr Michael O’Farrell Vice Chair of the Salmon Technical Team for the Pacific Fishery Management Council. Dr O’Farrell works for the NMFS in Santa Cruz who released that study about a year ago. He says ocean conditions was the “largest factor” although there were other reasons as well.
Biologists says the young fish made their way out to sea -but a virtual collapse of the food chain drastically reduced salmon survival once they got there.
The Northwest Fishery Service Centers states “As many scientists and salmon managers have noted, variations in marine survival of salmon often correspond with periods of alternating cold and warm ocean conditions. For example, cold conditions are generally good for Chinook and coho salmon, whereas warm conditions are not.”
The warm, then cold ocean conditions oscillate and can vary widely seemingly accounting for wild swings in salmon population survival.
Some Good News
Now after a disappointing three years scientists with the Pacific Fishery Management Council are forecasting an ocean abundance estimate of 245,500 Chinook adults from the Sacramento River - up from just 39,500 in 2009 (see chart).
Just north on the Klamath the Chinook forecast for ocean abundance is 330,500 adults - also markedly higher than recent years. Last year the Klamath had a river run of a little over 100,000. These are fish that went to sea in 2007/08 - just when ocean conditions were improving by several key measures. Mostly healthy returns are expected as well in the rest of the Pacific Northwest this season.
Off the California coast the Council’s preliminary estimate could change but most observers believe some recreational fishing is likely with a good chance for some commercial fishing as well - the first time in three years. The fishing community has been devastated by the moratorium.
The Council will forward its final recommendation on how much salmon fishing will be recommended to the NMFS by May 1 for final approval. The Council suggests management measures for fisheries off the Coast of California,Oregon and Washington.
Dr. O’Farrell notes the 245,000 Chinook estimate “might be optimistic” considering last year the estimate of 122,000 returning fish fell far short - numbering 39,500 by a DFG estimate. On the other hand the 245,000 for 2010 is about average over decades.Wild swings appear to be the rule rather than the exception.
Scientists say ocean conditions the Pacific Northwest were good through 2008 boosting the survival numbers of young salmon through mid 2009 when the colder waters warmed. Young salmon are born in fresh water rivers but migrate out to sea for most of their adult life returning “home” 3 to 4 years later. Some return early as young immature “jacks”.
This year’s estimate is based on in part on a doubling of the the number of jacks coming back up the Sacramento in 2009 vs the year before.
Earlier this year the state Department of Fish and Game expressed pessimism over the recovery of the Sacramento fishery in 2010 saying conditions looked no better than 2009. Some are still pessimistic.
How Much Water?
If farm pumps were not the the proximate cause of the fishery collapse - will the pumps be turned back on? That is an issue very much on the front burner with a a re-examination of a federal biological opinion pending. The opinion in turn guides not just the water agencies but the federal courts to guide water policy decisions.
On March 15th, the National Research Council (NRC) of the National Academy of Sciences is expected to issue an important report. It will detail the NRC’s evaluation of the science that has been used to determine how much water can safely be pumped out of the Delta for cities and farms while preventing the extinction of endangered salmon and other fish.
Last year’s NMFS study on ocean conditions and other factors is summarized below.
A multi-agency scientific review panel, lead by scientists at the SWFSC Fisheries Ecology group in Santa Cruz “found that poor conditions in the coastal ocean in 2005 and 2006 resulted in unusually poor survival of fall-run chinook salmon returning to the river in 2007 and 2008. These fish entered the ocean during periods of weak upwelling, warm sea surface temperatures, and scarce food. Seabirds with diets similar to juvenile chinook abandoned their nests in these years because they could not feed their chicks.
Freshwater factors were ruled out as direct causes of the collapse because conditions were normal while juvenile chinook were in fresh water, normal numbers of juvenile fall-run chinook entered the estuary, and normal numbers of juvenile fall chinook were released from hatcheries into the bay. Water exports in the summer were high but did not occur until after the vast majority of juvenile fall chinook had already left the Delta. Freshwater factors are, however, implicated indirectly. Land and water development in the Sacramento-San Joaquin watershed has destroyed or degraded the once-diverse habitats that once supported highly diverse chinook populations. The remaining fall chinook populations lack the diversity that would make them more resilient to periods of poor ocean conditions. Most fall chinook are now born in hatcheries. Hatchery practices further reduce diversity and make the SRFC increasingly susceptible to periods of poor ocean conditions, but can create very large salmon runs when oceans conditions are good.”
Sacramento Fall Chinook Salmon Estimates By Year
Source: PFMC. Numbers are in thousands. 2010 is a
preliminary estimate.
