Science Spotlight

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  • November 2, 2018

California Fish and Game, Volume 104, Issue 2, is now available online! California Fish and Game is CDFW's official, quarterly, scientific journal devoted to the conservation and understanding of the flora and fauna of California and surrounding areas, and the eastern Pacific Ocean.

A mallard in flight appears on the cover of the newest installment of the journal. With its iridescent green head and school bus yellow legs, the male mallard is one of the most recognizable species of duck in California. It is also the most abundant breeding species of waterfowl in the state. However, California’s mallard population estimates have generally declined since the mid-1990s. In California mallards: a review, Feldheim et. al synthesizes volumes of research in an effort to identify long-term research needs and monitoring activities to help improve management of this iconic species.

In another paper, entitled Abundance, habitat and occupancy of Roosevelt Elk in the Bald Hills of Redwood National Park, Tolliver and Weckerly seek to understand the relationship between a species’ occupancy-abundance rate and its habitat use. Using elk sign surveys (i.e, counting tracks and feces at standardized locations) researchers found that, as population density increases, Roosevelt elk will move into other (lower quality) habitats. This was true for two herds of vastly different sizes, although the occupancy rate remained comparable.

Finally, Hiney et. al looks at recruiting experienced anglers and using citizen science to help document and survey the native Coastal Rainbow Trout population of Grass Valley Creek Reservoir. The authors look at methods of overcoming the time and resource limitations of assessing wild trout populations.

Also included in this issue are reviews of two books that make meaningful contributions to the field of wildlife research.

As it has for the past 104 years, California Fish and Game continues to publish high-quality, peer-reviewed science that contributes to the understanding and conservation of California’s wildlife. We look forward to witnessing the contributions of the next installment.

Categories: California Fish and Game Journal
  • April 5, 2018

The latest issue of California Fish and Game, the California Department of Fish and Wildlife’s scientific journal, is now available online! Issue 103(4) features articles that add to the knowledge base for three marine species, all of which face potential threats from overharvesting, incidental take and loss of habitat: Thorny stingray, Chinook salmon and green abalone. 

The link opens in new windowThorny stingray (Urotrygon rogersi) (PDF) is common in the eastern Pacific, from the Gulf of California south to Ecuador, and is frequently a by-catch of commercial shrimp trawlers. Little is known about its life history and movements. It was thought to occupy relatively shallow depths ranging from two to 15 meters, with a maximum recorded depth of 30 meters. In their published research, Acevedo-Cervantes et al. report the discovery of specimens at a depth of 235 meters—an indicator that the Thorny stingray has the capacity to survive beneath the disturbance of commercial shrimping activity. According to the authors, this new information is “of vital relevance” for the management of the species.

Adams et al. examined the effects of link opens in new windowEl Niño on adult Chinook salmon as they migrate through the Gulf of the Farallones (PDF). Researchers found that the dressed weight of commercial landed Chinook was lower during El Niño compared to non-El Niño years, a reduction attributed to a disruption in the normal feeding cycle in the Gulf of the Farallones. The analysis suggests that management agencies need to give more consideration to ocean conditions as risk factors in planning the recovery of endangered and at-risk Chinook salmon spawning runs.

link opens in new windowGreen abalone (Haliotis fulgens; Philippi) (PDF) were once part of a large recreational and commercial fishery, but are now estimated to be at less than 1% of their baseline density. Past attempts at restocking wild populations using juvenile farm-raised green abalone have resulted in high mortality rates. In “Outplanting large adult green abalone (Haliotis fulgens) as a strategy for population restoration,” author Caruso explores the efficacy of using adult specimens—at least 10 years old—to augment wild populations. The resulting 40 percent survival rate is much higher than the survival rates of previous projects that used juveniles. Although it is costly to raise green abalone to adult size, it may be the best method, given the decades of past unsuccessful restocking attempts.

These articles provide information useful to fisheries managers and should be helpful for future recovery efforts.

Cover photo © Peter Hemming

Categories: California Fish and Game Journal
  • August 15, 2017

The latest issue of California Fish and Game, CDFW’s scientific journal, is now available online. This century-old quarterly journal contains peer-reviewed scientific literature that explores and advances the conservation and understanding of California’s flora and fauna.

The endangered salt marsh harvest mouse (Reithrodontomys raviventris) graces the cover of California Fish and Game, Volume 103, Issue I. Researchers ventured into the pickleweed to study the tiny mouse, which is endemic to the marshes surrounding the San Francisco Estuary Bay and its tributaries. The mice were fitted with tiny radiotelemetry collars and tracked for three years. Researchers documented some curious behavior in the resulting paper, “Potential evidence of communal nesting, mate guarding, or biparental care.” The accompanying photos provide a fascinating glimpse into an active nest.

Another paper, “Documentation of mountain lion occurrence and reproduction in the Sacramento Valley of California,” explores the potential for mountain lions to exist in fragmented habitats if there is adequate connectivity with larger blocks of suitable habitat and sufficient prey. The study used camera traps to document populations of mountain lions in the Sacramento Valley’s Butte Sink, which is made up of relic riparian habitats interspersed with managed wetlands. The photos show healthy mountain lions moving through habitat that has long been considered unsuitable due to extensive agricultural and urban development.

The article, “Mussels of the Upper Klamath River, Oregon and California,” reports on sampling efforts that expand existing baseline population data on freshwater mussels in the Upper Klamath River. The sampling efforts may ultimately assist with protection, mitigation and enhancement efforts for large bi-valve species.

The final paper provides insights into the benefits deer and elk derive from licking mineral rocks. Researchers took samples of “lick sites” that were used by California black-tail deer (Odocoileus hemionus columbianus) and Roosevelt elk (Cervus canadensis roosevelti) in the Klamath Mountains, Siskiyou County. After performing a detailed analysis of the elemental content of each lick site, the researchers concluded that each lick site offers a different smorgasbord of minerals, and in varying concentrations. The study’s objective is to begin identifying, classifying, and analyzing important mineral lick sites to benefit future ungulate management efforts.

As it has for the past 103 years, California Fish and Game continues to publish high-quality, peer-reviewed science that contributes to the understanding and conservation of California’s wildlife. We look forward to witnessing the contributions of the next installment.

Download the link opens in new windowentire Winter Issue 103 (PDF) in high resolution, or browse individual articles in low resolution.

Categories: California Fish and Game Journal, Wildlife Research
  • April 25, 2017

The latest issue of California Fish and Game, CDFW’s scientific journal, is now available online. This century-old quarterly journal contains peer-reviewed scientific literature that explores and advances the conservation and understanding of California’s flora and fauna.

A photo of the world’s first radio tagged tricolored blackbird (Agelaius tricolor) graces the cover of this issue of California Fish and Game. The bird was tagged as part of a study, the results of which are published as “Breeding chronology, movements, and life history observations of tricolored blackbirds in the California Central Coast” by Wilson et al. The tricolored blackbird is currently under review for listing under both the California and Federal endangered species acts.

Also in this issue, Overton et al. offers a fascinating observation of predation by Peregrine falcons on an endangered California Ridgway’s rail (Rallus obsoletus obsoletus), the result of environmental extremes and a series of species interactions.

Other papers published in this issue look at a predictive model for commercial catch of white seabass (Atractoscion nobilis); fecundity and reproductive potential of wild female Delta Smelt (Hypomesus transpacificus); and updated information on the length-weight relationships (LWR) and length-length relationships (LLR) and condition factors for pelican barracuda (Sphyraena idiastes) in the Gulf of California.

New in this issue is a section called “From the Archives,” which reprints articles from past issues to provide historical perspective on topics still relevant today. The first article in this series comes from Volume I, Issue I, dated 1914. It asserts that natural resources must be conserved for the use and enjoyment of the public.

Download the entire Fall Issue 102 in high resolution, or browse individual articles in low resolution.

Categories: California Fish and Game Journal
  • February 7, 2017

California’s recreational fishery resource provides a huge benefit to the state’s economy. In the latest issue (102-3) of the scientific journal California Fish and Game, Reid et. al tackles the difficult task of quantifying the economic value of California’s recreational red abalone (Haliotis rufescens) fishery.

Using data for the 2013 season at more than 50 sites in Sonoma and Mendocino counties, the authors used the travel-cost estimation method to determine a value. According to their findings, the 31,000 people who fish for red abalone provide an economic benefit to California of between $24M and $44M annually.

The lower figure was derived solely by determining the costs involved in driving to the fishing locations, while the higher figure considers the time spent on the fishing activity. The data reveal three dominant criteria used to select fishing sites: 1) the presence of a harmful algal bloom — and the resulting stricter fishing regulations — in Sonoma County; 2) protection from ocean swells; and 3) the presence of recreational conveniences such as restrooms and boat launches.

Determining the economic value of the red abalone fishery puts into perspective the importance of managing it for sustainability. Other articles in this issue focus on management implications for California halibut (Paralichthys californicus) and Olympia oysters (Ostrea lurida).

Lesyna and Barnes report that California halibut reach physical maturity at different sizes and ages, depending upon location. Macroscopic examination of specimens revealed that, although all halibut were mature before reaching the commercial and recreational minimum legal size limit, central California halibut are larger and older by the time they reach physical maturity than their southern California counterparts.

Moore et. al studied the sexual development and symbionts of Olympia oysters (Ostrea lurida) that settled naturally on artificial clutches placed in San Francisco Bay. The results of the study suggest that Olympia oysters have the capacity to flourish when suitable habitat is available.

Collectively, these articles demonstrate the importance of studying natural resources for their consumptive and non-consumptive value.

According to California Fish and Game Editor-in-Chief Armand Gonzales, the articles provide critical direction for resource management. “It is therefore incumbent upon us as scientists, to keep working, keep studying and keep reporting what we see and find.

Categories: California Fish and Game Journal