Monitoring serves two essential purposes when it comes to fish and wildlife conservation. First, it informs our understanding of the status and trend of populations that we want to conserve and recover. Second, it informs the design and implementation of conservation measures to benefit those populations and allows resource managers to assess the effectiveness of such measures.  Absent monitoring, we are guided by intuition, surmise, or plain faith in determining whether we should intervene to protect a species and how we should go about doing so. While delta smelt have been protected under the California and federal Endangered Species Acts for almost three decades and federal and state regulatory agencies have implemented many millions of dollars of management actions intended to protect the species, a monitoring scheme to fulfill those two core purposes has proven inexplicably elusive. It is high time to overcome institutional resistance and move ahead with the development of a monitoring scheme for delta smelt, both for the sake of the imperiled species and to stop wasting our limited conservation dollars on ill-informed measures.

You wouldn’t know it from articles and blog posts detailing the demise of delta smelt. You wouldn’t know that nobody knows how many delta smelt — the San Francisco Estuary’s tiny but headline-grabbing fish – survive in the Delta’s turbid and troubled waters. Estimates of the size of the only population of delta smelt vary by two orders of magnitude or more, reflecting the inadequacy of existing data collection efforts. Maybe 13,000 delta smelt survive in the entire San Francisco Estuary, as the U.S. Fish and Wildlife Service asserted in 2016. There might be 20,000 delta smelt in the western Delta and lower Sacramento River, the number the Service estimated from two captured individuals in the second week of October 2017. Or there might be nearly one million delta smelt in the lower Sacramento River alone, the agency’s estimate just one week later when 38 of them were caught there. But the following week no delta smelt were captured in the lower Sacramento River. And then, in the third week of November 2017, no delta smelt were caught anywhere in the Delta.


Thankfully delta smelt had not disappeared. But now, four years and something like 40 million dollars later, delta smelt appear only occasionally in five long-term fish surveys. As a result, resource managers are left guessing how many delta smelt exist, where their habitat remains, and what needs to be done to conserve and recover the species – or, for that matter, whether recovery is even possible.  


You see, the federal and state wildlife and water-resource agencies are not implementing a monitoring plan for the imperiled delta smelt that reflects contemporary practices. The agencies have never identified, much less implemented, an effective sampling scheme from which delta smelt abundance might be estimated, a reliable assessment of delta smelt habitat conditions might be provided, or the effectiveness of delta smelt management actions might be assessed. Rather the agencies record infrequent delta smelt captures from general fish surveys, and then guess at what the recorded occurrences of delta smelt could possibly mean.


Those fish surveys, administered by California’s Department of Fish and Wildlife and initiated at different points in time dating back as far as 1959, were designed and are employed to serve overlapping but distinct purposes. The first of them was exclusively intended to “monitor” striped bass from trawlers dragging nets across fixed, open-water locations in the upper estuary, including much of the Delta. The surveys differ by sampling period, sampling frequency, number of stations, and type of gear used — but all are open-water surveys. They do not sample fish in the species-rich near-shore littoral zone. The surveys can deliver certain limited facts to information-hungry resource managers and decision-makers, but they cannot provide reliable and supportable answers to the Delta’s most pressing questions — what is causing declines in the abundance delta smelt and other listed species, and are management actions and measures intended to contribute to the conservation of those species serving that purpose?


In contrast, well-designed, appropriately targeted monitoring regimes of the sort that numerous protected species enjoy elsewhere across the nation do address those pressing questions. Actual monitoring — rather than the generalized fish surveys conducted at present in the Delta — requires an “experimental” sampling design. Data that are gathered in a targeted, rigorously designed monitoring scheme in representative potential habitats can be used to evaluate our hypotheses about how imperiled species are affected by the many stressors in their environments and the conditions of essential resources. Accordingly, monitoring can be described as the most fundamental form of research on listed species. 


Designed appropriately, monitoring can produce abundance estimates for species of concern, it can document patterns of species’ distributions across environmental gradients, it can generate an understanding of species-habitat relationships, and, importantly, it allows conservation planners to make robust inferences about management actions that are likely to benefit targeted species. Monitoring is the fundamental source of information in adaptive resource management, which is widely acknowledged as the most effective means of generating and implementing a successful management agenda for imperiled species. Delta smelt and the other half-dozen endangered and threatened fish species that reside in or migrate through the Delta are not being subjected to the rigorous monitoring they deserve. 


So, why now point to this long-missing element of a responsible conservation program targeting delta smelt, the embattled flagship species of the Delta? Because the federal and state governments under their separate Endangered Species Acts have identified nearly 80 species-specific conservation actions and landscape restoration projects that the resource agencies think will contribute to the recovery of those listed species in the Sacramento and San Joaquin rivers, their tributaries, and the Delta — delta smelt, longfin smelt, steelhead, and multiple Chinook salmon runs. A 2020 Incidental Take Permit for Long-term Operations of the State Water Project from the California Department of Fish and Wildlife requires the Department of Water Resources to employ “adaptive water management” in “a manner protective of fish listed under the state’s endangered species law” and to do so “based on scientific monitoring.” But with the State in the lead in a federal-state conservation effort, instead of targeted species-specific monitoring that could allow for ongoing, real-time assessment of the status of the delta smelt and trends in its numbers, and the fish’s responses to management actions targeting it, the State is relying on the old data collection schemes that cannot inform the new management agenda. 


A state-sponsored Biological Monitoring Survey Design Review proposes that the ongoing fish surveys (and the limited information that they generate) can be “redesigned” to meet long-unmet needs for ecological information on the listed fishes in Bay-Delta. The survey re-design effort implicitly promises to produce fish sampling schemes that will meet the specific information needs called out in the 2019 Biological Opinion and 2020 Incidental Take Permit. It would do so by enhancing the five individual fish surveys (one by one) to become the monitoring plan that is required to assess conservation measures proposed and currently being implemented and identifying the conservation measures (among alternatives) that are efficacious, that is, likely to provide anticipated benefits for the listed species, and efficient, that is, capable of providing the desired benefits at least cost. 


The charter for the Biological Monitoring Survey Design Review justifies the survey re-design — in lieu of an explicitly targeted monitoring design — by asserting that the standing fish surveys already “fulfill three broad management needs.” According to the charter, the ongoing fish surveys provide: (1) the data required to assess the effects of real-time water-export operations on “listed species and other important indicator species,” (2) the information necessary to understand the “status and trends” of the listed species in the Bay-Delta, and (3) the basis for “special management studies,” that can serve to evaluate the performance of directed outflow actions, habitat restoration efforts, and focused habitat enhancement efforts targeting delta smelt. These assertions regarding the standing fish surveys are flat wrong. And the surveys do not and cannot, even with adjustments, provide the necessary data to meet the information needs of the aggressive management agenda in the new state and federal permits and plans.  


Limited by the spare information derived from the standing fish surveys, as noted above, there is no reliable estimate of the size of the delta smelt population. Limited by the footprint of the fish surveys, it took separate, targeted sampling only three years ago to finally understand where longfin smelt spawn in the Bay-Delta system. And limited by those same fish surveys, the information necessary to help managers understand the magnitude of the effects of predation by invasive fishes on delta smelt and longfin smelt is non-existent. It can be fairly argued that the current fish surveys in the upper San Francisco Estuary have been effective in raising a red flag over declines in the abundances of a number of species, but those surveys have done virtually nothing to identify the reasons why certain species are in decline or steer planners to the necessary conservation agenda to respond to those declines. 


An effective monitoring design for delta smelt recognizes that the fish has specific habitat requirements that should guide the sampling footprint. The species almost certainly frequents shoals along the bathymetric gradient of Delta’s channels and adjacent bays and is not confined to the open waters of the deep channels and bays that the existing fish surveys sample. Sampling must cover all habitat strata (or types) that are occupied by delta smelt. To estimate abundance, the monitoring scheme must sample the whole “closed” delta smelt population in order to account for the fish’s seasonal and daily movements, not just certain parts of it that are convenient and accessible to the long-employed trawlers and gear. Importantly, a monitoring scheme for delta smelt, like for all fish and wildlife that require attention from resource managers, must use the best available science to inform discrete, sequential steps to a competent data-collection design. Those include articulation of the spatial and temporal domain of sampling, selecting appropriate monitoring variables, determining desired sampling precision, estimating uncertainty, and a raft of other obligatory design components that have never been and are not now adequately considered in the State’s surveys and re-design endeavor. 


It is understood that designing a monitoring scheme for an imperiled fish is challenging under any and all circumstances. Nonetheless, the resource agencies have a responsibility to clearly articulate the purposes and objectives for monitoring delta smelt and follow well-established sampling design protocols if we have any hope of informing a successful conservation agenda for the species. Failure to do so amounts to abdication of our collective responsibility to conserve the species and the Delta ecosystem that supports it and to manage responsibly the State’s over-stretched conservation resources. And it is simply an unacceptable outcome of the current survey redesign process.

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