Recent accomplishments of CDFW's scientific community
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 Thorny 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 El 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.
Green 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
The latest issue of California Fish and Game, 103-3, makes a significant contribution to the body of research related to longfin smelt in California. A paper titled, “Historic and contemporary distribution of Longfin Smelt (Spirinchus thaleichthys) along the California coast (PDF)” analyzes and presents observation data for this species from a variety of published and unpublished sources dating from 1889 to 2016. This anadromous fish, which is listed as threatened under the California Endangered Species Act, has been documented in a diverse range of habitats, including coastal lagoons, bays, estuaries, sloughs, tidal freshwater streams and nearshore habitats. In addition to providing a comprehensive look at the existing information available for longfin smelt along the California coast, this paper identifies additional information needed to improve management and enhance recovery of the species within the state.
In “Distribution and derivation of dabbling duck harvests in the Pacific Flyway (PDF),” the authors look at abundance, banding and harvest data from throughout the Pacific Flyway and other important source areas in the Central Flyway to estimate the distribution and derivation of Pacific Flyway dabbling duck harvests during 1966−2013. The Pacific Flyway has long been considered an important wintering area for dabbling ducks. Better knowledge of the origins of these birds could assist in both harvest and habitat management.
The authors of “Distribution of Amargosa River pupfish (Cyprinodon nevadensis amargosae) in Death Valley National Park, CA (PDF)” endured harsh environmental conditions to document the occurrence of Amargosa River pupfish along the lower Amargosa River drainage where the species has not been previously documented. The downstream-most location of Amargosa pupfish captured in this study extends the previously recorded geographic range approximately 49 river km. The findings not only determine the distribution of Amargosa River pupfish within Death Valley National Park, but will help identify suitable locations at which to establish long-term monitoring sites.
California Fish and Game has published high-quality, peer-reviewed science for the past 103 years, making important contributions to the understanding and conservation of California’s wildlife.
Cover photo courtesy of Gerald and Buff Corsi © California Academy of Sciences.
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