USFWS Mathematical statistician Ken Newman - Photo Credit: USFWS Photo/Steve Martarano

USFWS Biologists trawl for Delta Smelt on the Sacramento River. - Photo Credit: USFWS Photo/Steve Martarano

Captive Delta Smelt at the Livingston Stone National Fish Hatchery at Shasta Dam - Photo Credit: USFWS Photo/Steve Martarano

By Steve Martarano

Editor’s note: the Delta Smelt, only found in California’s Sacramento-San Joaquin Bay-Delta Estuary, are on the brink of extinction, and scientists in the San Francisco Bay-Delta and Lodi Fish and Wildlife offices are battling to save the indicator species on several fronts. These are their stories. First in a series:

Mathematical statistician Ken Newman knows trying to reverse the decline of Delta Smelt may be the biggest fight of his 30-year-plus career. It’s a career that has taken him to such diverse places as Scotland, the states of Idaho and Washington and finally California, applying statistical methods to assist fish and wildlife populations of all shapes and sizes.

Now, he’s using that unique skill-set to help a species that is vital to the overall health of the Bay-Delta ecosystem, but is struggling mightily. It’s not a coincidence that when Delta Smelt numbers started to plunge in the early 2000s, so did just about every other native fish in that estuary. And the elusive nature of the species has always made it a challenge to study.

“There are definitely challenges to working with, capturing and studying Delta Smelt,” Newman said, citing their 2-to 3-inch size as “too small and too fragile for acoustic tags that would allow real-time information on individual fish location and movement“

Newman added that there’s also a lack of large scale mark and release studies of wild fish, which would provide information on individual fish survival probabilities in contrast to what has been done with salmon, though improvements in technology may eventually make that possible, he said.

”As a result,” he said, “we don’t have that much solid info on how they move and die. They’re short-lived at about a year, and are rare and getting rarer, which makes it them even harder to catch and find out where they are.”

In a career filled with complicated management projects that apply statistics to problems in natural resources and ecology, Newman works quietly out of cubicles at the Lodi and the Bay-Delta Fish and Wildlife offices on a problem that he terms as the most complex he’s ever encountered.

With Delta Smelt numbers at their lowest levels in history, Newman heads a group – made up of Lara Mitchell at the Lodi office, Will Smith in the Bay-Delta office, and consultant Leo Polansky – that is developing models that can estimate population numbers – not just indices – of Delta Smelt. These models use existing data from several of the California Department of Fish and Wildlife’s (CDFW) long-running surveys, including Spring Kodiak Trawl (SKT). Newman is able to estimate how many adults were alive at the start of each spawning season, in this case in January and February 2016. The estimates are not exact numbers, rather a range, but it’s a start in the right direction.

“ We’re trying to bring in not just fish data but also abiotic measures like water temperature, or salinity, and we’re using data from several different long-term surveys to build these models,” Newman said.

Those calculations estimated the current population of adult Delta Smelt to be about 13,000 fish, compared to January/February 2015 when there were an estimated then-low of 112,000 fish. As an integral part of these estimates, Newman’s group is also working with the CDFW on a gear efficiency study to help determine if current ways data are collected are effective.

“It’s been a great collaboration; Ken’s interest in and desire for gear efficiency data has pushed us to do more than we might have done otherwise on answering some important questions on how our gear works,” said Randy Baxter, CDFW’s supervising Senior Fisheries Biologist, who has worked with Newman and USFWS since 2011, most of that time on the gear study.

The state operates numerous key fish surveys on the Delta, such as the Fall Midwater Trawl, Summer Townet, and SKT surveys, which in turn collect data for several species like Delta Smelt, Longfin Smelt and Sacramento Splittail. Those data are used by USFWS’ Bay-Delta office to help manage key programs including developing incidental take levels on Delta pumping operations for Delta Smelt, as well as developing population estimates.

“We always knew that some of our gear is more effective than others for catching certain Delta Smelt life stages: the Kodiak trawl is good at catching older Delta Smelt, or that many of the Delta Smelt in the Fall Midwater Trawl were slipping through the mesh early in the sampling season, for example,” Baxter said. “But Ken’s evaluation work is directly related to the types of catch efficiency relationships he needs for his models and we need to understand how our gear works.”

Newman reiterated that studying gear efficiency with CDFW “has never been done on this scale before.”

The data generated by CDFW and studied by Newman are also assisting in efforts towards another key project – a lifecycle model for Delta Smelt that promotes a better understanding of the species that could ultimately help recover it.

“We’re trying to use the survey data that’s been in place to come up with absolute abundance numbers, not indices, in a scientific and sound way,” Newman said. “By linking those estimates together at the various life stages – looking at environmental factors and management actions that affect survival rates and reproduction, and including particle tracking model output to characterize larval movement – we are coming up with a lifecycle model. All bundled together, we have the bricks to build a lifecycle house and tools that will help us evaluate various management actions.”

Newman has been interested in applications of statistics to natural resource problems since his undergrad days at Ohio State University. After five years working as a biometrician for tribal fisheries programs in western Washington, he went back to school, receiving a PhD in statistics at the University of Washington. Newman was a professor of statistics at the University of Idaho for 10 years, and then a Senior Lecturer in statistics at the University of St Andrews, Scotland, Program, where he has worked ever since on statistical problems involving salmon and Delta Smelt.

A frequent author, in April 2010 Newman was an expert witness for the defense in the Federal District Court hearings for the Delta Smelt Consolidated Cases. He was the lead author on a book titled “Modelling Population Dynamics,” published in 2014, which is centered on a statistical procedure called state-space modeling that underlies much of the life cycle modeling work. Since 2009, he has annually co-taught a week-long course on developing a long-term Biological Monitoring Program for FWS personnel.

One product of this course is a “Road Map for Developing a Biological Monitoring Program” which will appear in the journal Environmental Monitoring and Assessment. “I’m quite excited about the Road Map as it is a way to help ensure that resource agencies collect data in a scientifically sound manner and that that the resulting data can be used to assist resource managers in making decisions,” he said.

“I get a lot of satisfaction understanding existing technical statistical theory and methods, and enjoy the creativity of coming up with something that hasn’t been done before,” Newman added. “I feel strongly about doing what we can to sustain and preserve our natural resources, and that the public is getting something of value from me.”

Steve Mararano is the public affairs officer for the S.F. Bay-Delta Fish and Wildlife Office, in Sacramento, Calif.