Science Spotlight

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  • February 15, 2019

Scientific Journal cover with photo of bird sitting in wooden pole

The latest two issues of California Fish and Game, CDFW’s long-running scientific journal, are now available online.

Issue 104(3) features a rather dignified-looking desert spiny lizard (Sceloporus magister) on the cover. It is one of 15 species captured and documented by Cummings et. al in Biodiversity of amphibians and reptiles at the Camp Cady Wildlife Area, Mojave Desert, California and comparison with other desert locations. The paper’s eight authors spent months in the Mojave desert location, trapping and identifying its inhabitants. The finding were combined with a review of scientific literature to document the biological diversity of the area in comparison to other desert habitats.

Also in Issue 104(3):

  • Annual and seasonal variation, relative abundance, and effects of managed flows on timing of migration in Brown Trout (Salmo trutta) in the upper Trinity River, by Sullivan and Hilemen, challenges a previous study suggesting that brown trout populations are increasing in the upper Trinity River and are having a negative impact on native juvenile anadromous salmonids. The authors assert that previous trapping data suggest a behavioral response to managed flow regimes rather than an increasing population. Further, they provide management recommendations to determine whether the removal of brown trout—an important economic sport fishery resource—is necessary and has the potential to be successful.
  • Geographic range and biology of Spinyeye Rockfish (Sebastes spinorbis Chen, 1975), an endemic species to the Gulf of California, Mexico, by Acevedo-Cervantes et. al. The authors add to the existing knowledge of a marine species that is currently not a fishing target and about which little is known.

Issue 104(4)’s cover photo illustrates the article Ground-nesting great horned owl in Suisun Marsh, California. Skalos et. al provide vivid descriptions and photographs of great horned owl nest sites, ranging from non-native eucalyptus trees to man-made structures (such as the dock piling shown in the cover photo) and even ground nests. Though great horned owl nest sites are known to be diverse, little documentation exists to support some of these observations. In fact, Skalos et. al’s ground nest observation is the first documented case in California.

Also in Issue 104(4):

  • Prey of neonate leopards Sharks in San Francisco Bay, California by R. Russo. The leopard shark has been the focus of several studies documenting the diet of juvenile through adult stage animals. The author examined the stomach contents of neonate leopard sharks and found that small, easily accessible prey items such as bay shrimps and polychaete worms are important for rapid growth of leopard sharks during the first year of life.
  • Within-Talus temperatures are not limiting for pikas in the Northern Sierra Nevada, by Wright and Stewart. Pikas are small herbivores related to rabbits that live in fields of broken rock (talus) in the mountains of western North America. Researchers examined potentially suitable talus habitats at various elevations in the northern Sierra Nevada. Their findings suggest that the cooler temperatures provided by talus is not sufficient to sustain pikas. The aboveground air and surface temperatures, rather than temperatures within talus, pose a greater challenge to pika survival.

California Fish and Game provides important contributions to the existing body of scientific knowledge. First published in 1914, California Fish and Game is the longest continuously published scientific journal. For more information and other back issues, please visit CDFW’s website.

CDFW Photos.

Media Contact:
Lorna Bernard, CDFW Communications, (916) 322-8911

Categories: California Fish and Game Journal
  • February 7, 2019

Flocks of sea birds flying above large bay with boats, bridge, and hills in distant background
Circling birds indicate an offshore herring spawning event near Alameda.

Hundreds of sea birds floating on water with docks and homes on hills in background.
Bird activity after a spawning event.

Long, green aquatic plant material covered in thousands of tiny clear balls.
Heavy spawn on eelgrass.

On a drizzly winter day in San Francisco Bay, you might find CDFW Environmental Scientist Ryan Bartling surveying the shoreline on the research vessel Smoothhound in search of Pacific Herring (Clupea pallasii) eggs. Bartling is one member of a team of state biologists who monitor the San Francisco Bay Herring fishery in the winter months, counting eggs and using those numbers to estimate the size of the Herring population that enters the Bay each season. CDFW Environmental Scientists Tom Greiner and Andrew Weltz are the other members of the Herring Team who lead the collection of biological data and management of commercial take of Herring in San Francisco Bay.

“We see, on average, about 50,000 tons of Herring come into San Francisco Bay during the spawn events that occur about 12 times each year,” Bartling explains. “The fish typically show up from November through March, so that’s when we’re out there counting eggs and collecting biological information on adult Herring.”

Even before the spawning season starts, Bartling and Weltz, with assistance from other CDFW divers, perform SCUBA surveys in the Bay to estimate how much vegetation is present. In-season, Greiner runs weekly trawl surveys, using the 28-foot research vessel Triakis to catch adult Herring before they spawn. This catch provides information on size, weight and age of the adult herring, it also provides information on general health and condition.

Once the spawning begins, the biologists concentrate on spawn deposition surveys – which involves finding and counting egg masses wherever the fish lay them. Eelgrass (Zostera marina) and red algae (Gracilaria species) are common vegetation types for spawning Herring, but the fish will also gravitate to hard surfaces or man-made structures near the shoreline – pier pilings, boat bottoms and even submerged shopping carts, anything in the vicinity of a spawn is fair game. Although the eggs are tiny (about the size of the tip of a pencil), they’re laid in mass.

How do the biologists know where to look? There’s a dead giveaway. “The key indicators are the birds and marine mammals – they always find them first!” Bartling says. Using the circling birds as his guide, Bartling walks along the shoreline at low tide to do a visual count of eggs, or, if aboard the Smoothhound, he uses a rake to pull up vegetation from below.

When a spawning event is occurring, the actual survey time varies. CDFW scientists could be counting eggs for as little as four hours, or as long as 12 hours at a time depending on the size of the Herring school. Using the egg count numbers (which are typically in the billions or trillions), they can calculate estimates of Herring tonnage. “An estimate could be as small as one ton of Herring per spawn event up, or might be as high as 15,000 tons,” Bartling says. “It depends on time of year and the overall stock size.”

The estimates are necessary for CDFW to set quotas for California’s commercial Herring fishery, which runs from January through mid-March. Quotas are typically set at around 5 percent of the total tonnage the biologists calculated from the previous season.

CDFW Herring fishery management staff maintain a blog, link opens in new windowCDFW Pacific Herring Management News, to keep the public apprised of the health and status of the fishery. More information about the commercial Pacific Herring fishery can be found on CDFW’s website.

CDFW Photos. Top Photo: CDFW Environmental Scientist Ryan Bartling looks at herring eggs after a spawning event.

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Media Contact:
Kirsten Macintyre, CDFW Communications, (916) 322-8988

Categories: Wildlife Research
  • February 1, 2019

Concrete fish ladder along hillside and river. Hills in background.

Blue sign with red spray-painted text reading 'house spawning'

Fish splashing in water between gate and metal examination chute.

Two people in yellow rain jackets in hatchery facility alongside fish chute filled with fish.

At Iron Gate Hatchery in Hornbrook, the fall 2018 spawning operation has just concluded. Iron Gate spawns both Fall-Run Chinook Salmon and Coho Salmon from the Klamath River. For Chinook, the hatchery staff manually collect the eggs and mix it with the milt immediately after the fish come into the facility. CDFW environmental scientists also collect heads from adipose fin clipped salmon, in order to retrieve implanted tags in the snout. The retrieved tags tell the biologists which hatchery the fish is from, and when it was released. They also collect scales, which enable them to determine the age of the fish.

For Coho Salmon, the process is a little more involved. The Coho are measured and samples taken, but the samples are sent off to a National Oceanic and Atmospheric Administration (NOAA) laboratory in Santa Cruz for analysis. While the samples are processing, the fish are kept in individually-numbered holding tubes at the hatchery. They will be spawned after the tissue analysis determines which fish are the best genetic match.

CDFW Photos

For more information about Iron Gate Hatchery, please visit: www.wildlife.ca.gov/Fishing/Hatcheries/Iron-Gate.

Media Contact:
Kirsten Macintyre, CDFW Communications, (916) 322-8988

Categories: General