March 14, 2024 — The following was released by NOAA Fisheries:

Restored salmon habitat should resemble financial portfolios, offering fish diverse options for feeding and survival so that they can weather various conditions as the climate changes, a new study shows.

The researchers looked at threatened spring-run Chinook salmon in tributaries of the Sacramento River. They found that restored sites that produce lots of fish may be especially vulnerable to changes such as drought. Such sites should be coupled with other varying sites that support the salmon population in diverse ways.

“The fish need all the different opportunities,” said Flora Cordoleani, a NOAA Fisheries and University of California Santa Cruz researcher who led the research published this week in Ecosphere. “Fish with one life history that favors certain habitat are not going to save the population in the long term. We need diverse habitats to support diverse life histories that help provide resilience.”

Life history refers to salmon traits such as their juvenile migration timing, growth rates, and food preferences. For instance, some juvenile salmon migrate to the ocean in their first year, while others may spend the year growing in freshwater first. That timing may benefit them in some years, but leave them more vulnerable in others, such as during drought.

Spring Chinook salmon were once found across the state and formed the backbone of California’s commercial salmon fishery. They are now greatly diminished and survive in only a few key watersheds with worsening trends in numbers. State and federal biologists last fall collected a few remaining spring-run Chinook salmon to begin a captive broodstock that will safeguard the genetic heritage of the species.

Habitat Mix Benefits Fish

Fish benefit most when they have access to a mosaic of interconnecting habitat from streamside vegetation to open floodplains, the research found. Young salmon may grow rapidly when wet years inundate floodplains and produce plentiful food, “but that happens pretty rarely,” Cordoleani said. “The key is for the fish to have access to all those habitats, so if something happens to one of them, the fish don’t all disappear.”

The new research goes beyond earlier studies showing that later-migrating fish had better survival rates. It shows how that played out on the landscape of three creeks that feed the Sacramento River, one of the biggest salmon-producing rivers on the West Coast.

Cordoleani and her team examined Butte Creek, the focus of extensive restoration that produced a large increase in fish numbers that had access to the floodplain. They examined salmon otoliths – small ear bones – that record clues about each fish’s life history. They found few later-migrating fish, which made the fish there more vulnerable to sharp declines during drought years that may become more common with climate change.

Two other nearby streams, Mill and Deer Creek, offered different conditions and hosted more fish that migrated later as yearlings (juveniles oversummering in freshwater). While they did not see the big increases in fish abundance that Butte Creek did, their salmon better survived droughts. Combining the three sites that complement each other increases the resilience of the Central Valley spring run stock complex—the term for all the individual populations combined.

“The sum of the parts is much greater, because they are doing different things and supporting the fish in different ways,” said Rachel Johnson, the senior author of the research and scientist at NOAA Fisheries’ Southwest Fisheries Science Center. “Some of those qualities may turn out to be more or less important as the climate changes.”

But relying on these three creeks is not enough. “Spring-run Chinook are already playing the climate stock market with only a few stocks in their portfolio,” Johnson said. They were once found in every major watershed. She said a lesson of the research is that more habitat options help fish survive a volatile climate by providing more opportunities to survive and thrive.

Providing that array of options requires restoring diverse habitat areas that complement each other at the landscape scale and returning salmon to historical habitats that had long vanished. Cordoleani and her team hope that this research encourages restoration planners to implement projects that create a mosaic of different habitats across watersheds that support diverse fish survival strategies. These actions will also balance each other to help stabilize numbers in the long term.

March 14, 2024 — Read the full article at NOAA Fisheries: 

For more than 50 years, NOAA Fisheries has issued permits for research on marine mammals to improve our management and understanding of our ocean neighbors. The Marine Mammal Protection Act, authorizes NOAA Fisheries to issue special permits that allow research on marine mammals and improve our understanding of marine mammals in the United States. This research, authorized under the Marine Mammal Protection Act, helps us so we can manage these species more effectively.

Northern Elephant Seal Research in California

One group of seal biologists from the University of California Santa Cruz have held research permits for almost as long as NOAA Fisheries has been issuing them. Over five decades, these researchers have tracked thousands of northern elephant seals at Año Nuevo, a state park in California south of San Francisco. Northern elephant seals are extremely large brown seals known for the large-nosed males, who can grow up to 13 feet long and weigh 4,000 pounds.

Each year thousands of elephant seals return to Año Nuevo to give birth, raise pups, and breed. And each year, the scientists from UCSC study the seals to learn more about them and to better understand their behavior, physiology, and ecology. Over the past decades, researchers documented:

• Which females had pups
• How large those pups were when they weaned from their mothers
• Whether the pups were male or female
• If the female pups grew up and went on to raise pups of their own

Weighing and Tagging

Researchers keep track of seals using flipper tags. These plastic tags with unique identification numbers—like you might see on the ear of a cow—are attached to the back flippers of the seal. When the researchers observe a mom and pup pair, they record the seals’ identities and link them in the database. This allows them to identify which pups belonged to which mothers, especially after the nursing period is over and the animals separate.

After the pups wean, at about a month old, researchers carefully capture the pups and weigh them. Elephant seal pups are heavy—270 pounds on average —so picking them up and stepping on a scale is not an option. The researchers use a tripod and scale to help lift the animal into what looks like a canvas bag to obtain an accurate weight. The weighing process lasts only a few minutes. The data can be used to ask important questions about how different seal moms vary in their ability to raise pups.

Learning from the Data

The researchers then observe the flipper-tagged animals throughout their entire lives. They use binoculars and cameras to identify individual animals and record data about where they go and what they do. This includes information about survival, reproductive success, as well as pup ID.

UCSC researchers analyzed the weaned pup weights for several generations of seals. They discovered that certain seal moms always produced heavier pups, even accounting for the age of the moms and whether the pups were male or female. When those heavy female pups grew up and had their own pups, those grand-pups went on to become the heavier pups raised that year. Of all the pups weighed during weaning, the heavy pups were also the most likely to return to Año Nuevo as breeding adults. They did not necessarily live longer or produce more pups than the pups that weighed less at weaning.

Benefits of Long-Term Research

Studying seals over time and looking at traits that may be passed from mothers to pups is only possible through continuous, long-term data collection. This research by marine mammal researchers is authorized by scientific research permits.

Research permits cover projects including capturing, sampling, tagging, and releasing seals to find out how deep they dive and what they eat. They also cover remote biopsy sampling and tagging large whales to study their migrations. As scientists conduct permitted research, they expand our knowledge of the abundance, distribution, and health of these animals.

Resource managers use that data to inform their decisions. Rigorous studies of these long-lived species often require years, even decades, of data collection.