2021: Is this the year that wild delta smelt become extinct?

by Peter Moyle, Karrigan Börk, John Durand, T-C Hung, and Andrew L. Rypel

Misty sunrise over former delta smelt habitat, Cache Slough, December, 2014.  Peter Moyle

2020 was a bad year for delta smelt. No smelt were found in the standard fish sampling programs (fall midwater trawl, summer townet survey). Surveys designed specifically to catch smelt (Spring Kodiak Trawl, Enhanced Delta Smelt Monitoring Program) caught just two of them despite many long hours of sampling. The program to net adult delta smelt for captive brood stock caught just one smelt in over 151 tries. All signs point to the Delta smelt as disappearing from the wild this year, or, perhaps, 2022. In case you had forgotten, the Delta smelt is an attractive, translucent little fish that eats plankton, has a one-year life cycle, and smells like cucumbers. It was listed as a threatened species in 1993 and has continued to decline since then. Former President Trump made it notorious when he called it a “certain little tiny fish” that was costing farmers millions of gallons of water (not true, of course).

Delta smelt, photo by Matt Young.

As part of the permitting process for Delta water infrastructure, the USFWS issued a Biological Opinion (BO), written by biologists, that found that increased export of water from the big pumps of the State Water Project and the Central Valley Project would further endanger the smelt. The BO was then revised by non-biologists to conclude that increased pumping would not hurt the smelt. The reason given was that large-scale habitat improvement efforts, plus the development of a facility for spawning and rearing of domesticated smelt, would save the species. We have written a short, fairly readable, article for a law journal that describes why the revised BO will not save the smelt. We will not write further about the paper in this blog but encourage readers to give the full article a read (it is a free download).

So, is this the year the smelt becomes extinct in the wild? Frankly, we are impressed by its resilience (see previous California WaterBlogs on smelt status) but small populations of endangered pelagic fish in large habitats tend to disappear, no matter what we do, partly the result of random events.

Looking for delta smelt

We trawl clear Delta water

And find emptiness.

Further Reading

Baumsteiger, J. and P.B. Moyle 2017. Assessing extinction.  Bioscience 67: 357-366. doi:10.1093/biosci/bix001

Baumsteiger, J, and P. Moyle 2017. Facing Extinction II: Making hard decisions. UCD Center for Watershed Sciences California WaterBlog   May 7, 2017

Börk, K.S., P. Moyle, J. Durand, T-C. Hung, and A. L. Rypel. 2020. Small populations in jeopardy: a Delta Smelt case study. Environmental Law Reporter 50 ELR 10714 -10722 92020. https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3749669

Bork, K. A. Rypel, and P.B. Moyle. 2020. New science or just spin: science charade in the Delta.  California WaterBlog. https://californiawaterblog.com/2020/03/15/new-science-or-just-spin-science-charade-in-the-delta/

Hobbs, J. and P. Moyle. 2018. Will delta smelt have a happy new year?  California WaterBlog  January 14, 2018. https://californiawaterblog.com/2018/01/14/will-delta-smelt-have-a-happy-new-year/

Hobbs, J.A, P.B. Moyle, N. Fangue and R. E. Connon. 2017. Is extinction inevitable for Delta Smelt and Longfin Smelt? An opinion and recommendations for recovery.  San Francisco Estuary and Watershed Science 15 (2):  San Francisco Estuary and Watershed Science 15(2). jmie_sfews_35759. Retrieved from: http://escholarship.org/uc/item/2k06n13x

Moyle, P. 2015. Prepare for extinction of delta smelt.  California WaterBlog, March 18, 2015. https://californiawaterblog.com/2015/03/18/prepare-for-extinction-of-delta-smelt

Moyle, P., K. Bork, J. Durand, T-C Hung, and A. Rypel. 2019. Futures for Delta smelt. December 15. California WaterBlog. https://californiawaterblog.com/2019/12/15/futures-for-delta-smelt/ Moyle, P.B., J. A. Hobbs, and J. R. Durand. 2018.  Delta smelt and the politics of water in California.  Fisheries 43:42-51. https://doi.org/10.1002/fsh.10014

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