Recovering predators create new wildlife management challenges

Contributed by Michael Milstein, NOAA Northwestern Fisheries Science Center
from The Fishing Wire

Researchers suggest multi-species approaches to address tensions around rebounding predators

The protection and resurgence of major predators such as seals, sea lions and wolves has created new challenges for wildlife managers, including rising conflicts with people, other predators and, in some cases, risks to imperiled species such as endangered salmon and steelhead, a new research paper finds.

The study by scientists from NOAA Fisheries’ Northwest Fisheries Science Center and the University of Washington examines recovering predator populations along the West Coast of the United States and in the Greater Yellowstone ecosystem, and the conflicts surrounding them. The study was published today in the journal Conservation Letters.

In the Pacific Northwest, for example, California sea lions that have increased under the Marine Mammal Protection Act have increasingly preyed on endangered salmon. Wolves reintroduced to Yellowstone in 1995 have since cut into elk herds, reducing human hunting opportunities.

“Increases in predators can be seen as successful in terms of efforts to recover depleted species, but may come at a cost to other recovery efforts or harvest of the predators’ prey,” said Eric Ward, a NOAA Fisheries biologist and coauthor of the paper.

The scientists describe three types of conflicts that can emerge as predators rebound under the protection of the Endangered Species Act and Marine Mammal Protection Act:

-Increased competition with humans for the same prey. For instance, sea lions eating fish also pursued by anglers and wolves preying on livestock and reducing elk numbers.
-Predators consuming protected or at-risk prey species, such as sea lions eating salmon and grizzlies consuming Yellowstone cutthroat trout.
-Protected predators competing with each other for prey. For example, sea lions consuming the same fish as killer whales, with wolves and grizzly bears also preying on the same species.

Pacific Northwest waters include many such conflicts, largely because many top predators such as sea lions, elephant seals and several whales are increasing in number and prey upon salmon, steelhead, rockfish and other fish protected by the Endangered Species Act.

Conservation conflicts have also emerged elsewhere: On California’s San Clemente Island, a threatened island fox species preys on an endangered shrike, while protected golden eagles prey on both the fox and the shrike. Also in the Pacific Northwest, protected barred owls are moving into forest habitat long important to threatened spotted owls and double-crested cormorants, like sea lions, have been targeted for culling to reduce predation on Columbia River salmon.

The scientists call for improved monitoring and modeling to better anticipate interactions between predators and prey, and assess whether steps to manage predators may be warranted.

Where conflicts continue, the scientists suggest developing multi-species recovery plans that consider the tradeoffs between increasing predators and other protected species.

“Predators such as bears, wolves and whales are charismatic creatures often seen as bellwethers of ecosystem health,” said Kristin Marshall, a postdoctoral researcher at NOAA Fisheries who completed graduate research in Yellowstone and lead author of the paper. “We’re fortunate to have places such as Yellowstone and the Northeast Pacific where they can recover, but in protecting one species you have to be thinking ahead to account for cascading effects that may impact other species too.”

The Endangered Species Act and Marine Mammal Protection Act do recognize larger ecosystem needs. For instance, the first purpose of the Endangered Species Act is “to provide a means whereby the ecosystems upon which endangered species and threatened species depend may be conserved,” and the Marine Mammal Protection Act seeks to “maintain the health and stability of the marine ecosystem.” Both NOAA Fisheries and public land managers in the Yellowstone region are increasingly pursuing ecosystem-based management with those goals in mind. Research has also found ecological benefits from the reintroduction of wolves in Yellowstone.

Both the Endangered Species Act and Marine Mammal Protection Act also provide safety valves by allowing limited control of recovering predators to manage their impacts under certain circumstances.

NOAA Fisheries has authorized states under the Marine Mammal Protection Act to remove sea lions known to be preying on endangered salmon, for instance. An “experimental” designation under the Endangered Species Act allowed for removal of wolves that attacked livestock, although wolves are no longer listed as endangered in Montana and Idaho and are now subject to hunting.

But the scientists note that resolving conflicts by culling predators may itself have unintended consequences and will face public and legal opposition that may limit management options.

“Thirty years ago scientists predicted that increases in predator populations would cause more of these conflicts to emerge,” Ward said. “We’ve largely seen these predictions come true, and there’s no indication of these conflicts decreasing.”

Maps from the 1930s Help Find Potential Fish Habitat in the Digital Age

A total of 1.4 million National Ocean Service (NOS) bathymetric soundings from 98 hydrographic surveys represented by smooth sheets in Cook Inlet were corrected, digitized, and assembled in order to produce this interpolated depth surface for Cook Inlet, Alaska.

For years, researchers, fishermen, and policy makers have had to rely on low-resolution navigational charts with limited fish habitat information to analyze fish habitat in Alaskan waters. But now, with the help of technology, detailed survey data from the 1930s may help to improve fish habitat analysis and help us learn more about important fish stocks.

“We now have a much more detailed picture of the seafloor in some areas,” said Mark Zimmermann, research fish biologist with NOAA Fisheries’ Alaska Fisheries Science Center. “We can see variations in depth between areas and unique features like troughs and banks. We will also be studying how fish and other marine life use these different habitats.”

The challenge was to translate the old data that were documented by hand on large flat, one-dimensional sheets of paper called smooth sheets, into a form that would be useful to modern scientists without having to spend millions of dollars.

These smooth sheets exist for many nearshore areas of Alaska. Nearshore areas are important as nurseries for rearing of young fish. Being able to pinpoint where these nursery areas are enables fishery managers to better define and protect essential fish habitat for commercial species of Alaska.

How did the scientists translate the data?

Inshore cartographic features of rocks, reefs, kelp patches and islets from smooth sheet H05152. Depth soundings in fathoms are shown as numbers, some with fractions.
NOAA Fisheries scientists developed a new methodology to transform the one-dimensional data on the smooth sheets, into three-dimensional digitized layers of data. They used a geographic information system (GIS) to do this.

Smooth sheets provide 10 times as much bathymetry or seafloor depth than traditional nautical charts. They also provide other data such as; shoreline location, seafloor sediment type, and various features such as kelp beds, rocky reefs, and islets.

What can we learn using digitized maps?

Scientists used the digitalized maps to compare five inshore study areas known to be important habitat for juvenile Pacific halibut and flathead sole. They were able to quantify differences and similarities between bottom type and depths at each of the sites to determine, which ones would provide preferred habitats for these fish.

Scientists in the Gulf of Alaska Project sponsored by the North Pacific Research Board (NPRB), are using these same data sets to predict the preferred habitat across the central Gulf of Alaska for juveniles of five other important species: walleye pollock, Pacific cod, Pacific ocean perch, arrowtooth flounder and sablefish. This knowledge could help design more focused research surveys in the future, saving valuable resources.

Smooth sheets are available for free through NOAA’s National Geophysical Data Center in Boulder, Colorado. For more information on the Alaska Fisheries Science Center’s use of smooth sheets and the study of Alaska bathymetry please visit the AFSC website.

As Horseshoe Crabs Near Mating Season, A Bit of Background

Editor’s Note: Today’s feature comes to The Outdoor Wires from the Florida Fish and Wildlife Commission (FWC).
from The Fishing Wire

Ancestors of horseshoe crabs date back over 450 million years–long before the age of the dinosaurs.

Four species of horseshoe crabs exist today. Only one species, Limulus polyphemus, is found in North America along the Atlantic and Gulf coasts from Maine to Mexico. The other three species are found in Southeast Asia. Horseshoe crabs are not true crabs at all. Horseshoe crabs are more closely related to arachnids (a group that includes spiders and scorpions) than to crustaceans (a group that includes true crabs, lobsters, and shrimp). Horseshoe crabs are often called “living fossils” because fossils of their ancestors date back almost 450 million years–that’s 200 million years before dinosaurs existed.

Despite inhabiting the planet for so long, horseshoe crab body forms have changed very little over all of those years.

The strange anatomy of the horseshoe crab is one of this animal’s most notable aspects. Unfortunately, the long, thin, spike-like tail of horseshoe crabs has given this species an unfavorable reputation. Many people view horseshoe crabs as dangerous animals because they have sharp tails. In reality, horseshoe crabs are harmless. Their tails are used primarily to flip themselves upright if they are accidentally overturned.

Horseshoe crabs nesting on Florida BeachHorseshoe crabs nest on beaches in Florida and mid-Atlantic states.

Horseshoe crabs are known for their large nesting aggregations, or groups, on beaches particularly in mid-Atlantic states such as Delaware, New Jersey and Maryland in the spring and summer. Horseshoe crabs can nest year-round in Florida, with peak spawning occurring in the spring and fall. When mating, male horseshoe crabs move parallel to the shoreline on sandy flats and intercept females as they pass by. A male attaches himself to the top of a female’s shell by using his specialized front claws, in a position known as amplexus, and together they crawl to the beach. The male fertilizes the eggs as the female lays them in a nest in the sand. Some males (called satellite males) do not attach to females but still have success to fertilizing the female’s eggs as they swarm around the amplexed pair. Most of this nesting activity takes place during high tides in the three days before and after a new or full moon.

Horseshoe crab larvae emerge from their nests several weeks after the eggs are laid. Juvenile horseshoe crabs resemble adults except that their tails are proportionally smaller. The young and adult horseshoe crabs spend most of their time on the sandy bottoms of intertidal flats or zones above the low tide mark and feed on variousinvertebrates.

Why are horseshoe crabs important?

Horseshoe crabs are an important part of the ecology of coastal communities. During the nesting season, especially in the mid-Atlantic States, horseshoe crab eggs become the major food source for migrating birds. Over 50 percent of the diet of many shorebird species consists of horseshoe crab eggs. Many bird species in Florida have been observed feeding on horseshoe crab eggs. In addition, many fish species rely on horseshoe crab eggs for food.

Horseshoe crabs are extremely important to the biomedical industry because their unique, copper-based blue blood contains a substance called Limulus amebocyte lysate. The substance, which coagulates in the presence of small amounts of bacterial toxins, is used to test for sterility of medical equipment and virtually all intravenous drugs. Research on the compound eyes of horseshoe crabs has led to a better understanding of human vision. The marine life fishery collects live horseshoe crabs for resale as aquarium, research, or educational specimens, and the American eel and whelk fisheries use horseshoe crabs extensively as bait along many parts of the Atlantic coast.

Threats to horseshoe crabs and research efforts

Horseshoe crab numbers are declining throughout much of the species’ range. In 1998, The Atlantic States Marine Fisheries Commission developed a Horseshoe Crab Fishery Management Plan that requires all Atlantic coastal states to identify horseshoe crab nesting beaches. Currently, with the help of the public, biologists at the Fish and Wildlife Research Institute are trying to document nesting sites of horseshoe crabs throughout the state. If you are interested in becoming more involved with the horseshoe crab survey, please visit the Survey for Horseshoe Crab Nesting Beaches in Florida for more information.

Tracking Fish Oil Supplements to the Source

Baitfish—forage—are at the base of the food chain that culminates in many species of gamefish. Here’s a take on protecting this overlooked resource, from Lee Crockett of Pew Charitable Trusts.

by Lee Crockett of The Pew Charitable Trusts in Ocean Views
from The Fishing Wire

Are fish oil supplements really improving our health but hurting our oceans?

That’s one question New York Times bestselling author Paul Greenberg is exploring for his next book, due out next year, The Omega Principle: The Health of Our Hearts, the Strength of Our Minds, and the Survival of our Oceans All in One Little Pill.

Global demand for forage fish is surging. The small species are used to make products such as fertilizer, cosmetics, and fish meal for aquaculture and animal feed.
Fish oil pills are made from forage fish, some of the most important species in ocean food webs. These small fish, including menhaden and sardines, are a vital food source for many marine animals, including whales, dolphins, seabirds, and fish that people eat, such as grouper, snapper, and salmon. At the same time, forage fish are also used to make products such as fertilizer, cosmetics, and fish meal for aquaculture and animal feed. As a result, in some parts of the world, overfishing has caused forage fish populations to plummet.

Greenberg has made a career out of seeing a story behind almost every fish. In his popular books Four Fish and American Catch, the lifelong angler examined the forces that get seafood from the ocean to our dinner plates. He related tales of greed, hunger, politics, international affairs, and crime on the high seas, stories that raise questions about how we treat the oceans to serve ourselves.

His ability to see the stories behind seafood began as a teenager. He grew up fishing in Long Island Sound, a pastime his mother encouraged because, he recalls, she considered it a “manly, character-building activity.” Similarly, his film critic-writer-psychiatrist father saw it as a way to entertain his son on weekend visits, and eventually encouraged him to submit an article about fishing to the weekly angling magazine New England Fisherman. Later, after earning a bachelor’s degree in Russian studies from Brown University and then spending six years working to establish independent media in Eastern Europe, Greenberg launched his writing career by returning to where he started: writing articles about fish.

Now the award-winning New York City-based writer is investigating the push and pull between human demands on forage fish, the impact on the ocean, and the responsible stewardship of this precious resource. His work comes during his three-year tenure as a Pew marine fellow.

He’s taking a hard look at fish oil—which, he recently told me, is the third-largest-selling supplement in the United States and a $34 billion-a-year global industry. In this case, he’s also stepping squarely into the debate about heart health.

“I’m a middle-aged guy. I have all the issues: cholesterol, forgetting things, anxiety, sleeplessness,” said Greenberg, 47, who takes the fish oil supplements containing omega fatty acids. “These omega-3’s do come across as the fountain of youth.” But as he’s swallowed his daily dose, Greenberg’s thoughts have wandered toward the sea. Beyond their usefulness as ingredients, these small fish are the lifeblood of the oceans that sustain us: “Maybe [they’re] the elixir of life itself.”

Atlantic menhaden are caught by the hundreds of millions each year.

Greenberg’s work comes as forage fish are making headlines—despite not being well-understood by the public. Recently, fishery managers along the West Coast of the United States agreed to prohibit commercial fishing on seven groups of forage fish unless scientific analysis shows it won’t harm marine ecosystems or compromise fishing for valuable predators such as salmon. In June, Florida wildlife managers will discuss the management of forage fish in that state’s waters.

And in May, East Coast fishery managers might consider changing catch limits on menhaden. Dubbed “the most important fish in the sea” by author H. Bruce Franklin, these fish are captured by the hundreds of millions every year and ground up to make fish oil, fish meal, animal feed, and other products. Managers reduced menhaden catch limits for the first time in 2012 to keep more fish in the water to feed the many animals that depend on them, such as striped bass, ospreys, and humpback whales. A recent assessment shows some improvement in the health of the menhaden population, although the number of fish remains near a historic low. The industrial menhaden fleet wants catch limits increased, so fishery managers need to employ the most up-to-date and comprehensive ecological and biological analysis to help pinpoint how many menhaden should stay in the water as food for marine animals.

Predators like this tarpon make meals of forage fish. Forage species are critical food sources for animals, including whales, dolphins, seabirds, and larger fish such as snappers and groupers.

But in many ways, these challenges are not new. Greenberg points out that forage fish have been used to make products for thousands of years, dating to the Roman Empire, when some species were ground up to make a product called garam, which could be considered something close to today’s ketchup. Now, millenniums later, both Greenberg and I think it’s time to finally consider forage fish in a broader sense.

“The real question is, where does a fish like a menhaden have its value? As fish meal and oil or in a matrix of the food web?” asks Greenberg. After decades of research, he believes—as I do—that when managing our fish resources we should pay more attention to the diverse ecological roles fish play in marine environments, rather than setting rules that consider only one species at a time. “What are these rules doing,” Greenberg asks, “to the other fish?”

“With seafood you’re dealing with hundreds if not thousands of species that interact with human destiny in different ways at different times,” Greenberg told me. “People say they relate to the ocean through seafood. I try to tie ocean issues to people. I want to put positive, science-based ideas into the world.”

Ocean Views brings new and experienced voices together to discuss the threats facing our ocean and to celebrate successes. We strive to raise awareness worldwide to the benefits of restoring fisheries and creating marine reserves. We inspire people to take better care of the oceans and leave a legacy of pristine seas to future generations.
The blog is hosted by Enric Sala, Explorer-in-Residence with National Geographic.

Opinions expressed are those of the blogger and/or the blogger’s organization, and not necessarily those of the National Geographic Society. Bloggers and commenters are required to observe National Geographic’s community rules.

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Gill nets for TVA Lakes are a bad idea

By Frank Sargeant
from The Fishing Wire

COMMENTARY:

A gillnet, like a handgun, is not inherently evil. The problem arises when it becomes the wrong tool in the wrong place at the wrong time.

The idea of permitting gill nets in North Alabama’s TVA lakes apparently has some appeal to somebody, otherwise it would not have been made into a bill, HB 258, and passed by the Alabama House of Representatives recently.

But thousands of recreational fishermen (and women) as well as homeowners and fishing/boating/resort industry execs in the affected areas are pretty much universally opposed to bringing this highly effective gear to the river lakes, which include Lake Guntersville, frequently cited as one of the top bass fishing lakes in the nation.

Not that the netters or the legislators who backed them propose to net bass commercially–state laws prohibit net harvest of gamefish. The targets would be shad, drum and other “rough fish” that some say are currently going to waste in the fertile waters of the big river.

But one issue that must surely concern anglers is the fact that gill nets do not work well for catch and release in many cases. They’re called “fish chokers” in saltwater, for good reason. They function via squares of mesh that slide over the head of a fish and then jam tight right behind the gill plates–they’re locked in place.

Getting a fish out of the mesh without killing it is not easy, particularly when it’s being done rapidly and/or at night, both of which conditions often apply in net fishing because that’s the nature of the fishery.

While the nets presumably would not be set around the grass beds where the majority of bass hang out for a part of the year, they might well be set around the bars, humps and other offshore structure where shad and drum are most abundant. And in the TVA lakes, this structure is also where huge schools of bass gather, both in the dead of summer and the chill of winter.

Crappies also gather in schools of hundreds around these offshore ledges in winter and again in July, August and September.

Both these species of gamefish would very likely be caught, occasionally in large numbers, as a by-catch of the nets, which can extend for hundreds of feet, forming a sort of “wall of death” around anything on the inside. While the commercial netters could not legally land them, they very likely would be killed in the process of being shucked out of the mesh–they’d wind up as buzzard bait along the shores. The bill as written has no limitations on net length or square footage–whole feeder creeks could be “stop netted” with a damming effect from shore to shore.

Gill nets of a given mesh size catch fish of a given size–it’s one of the reasons netters like them, because they let small fish swim through while trapping the larger ones. But the mesh that would be appropriate for a big gizzard shad would also be about right for a 1 to 2 pound bass or crappie, and the mesh that would catch a 5 pound drum or buffalo would also choke a 5 pound largemouth.

The bill also permits trammel nets, which catch pretty much everything that hits them–a large mesh net is suspended in front of a small mesh net, and the fish “pocket” in the folds when they hit the net. Again, accidentally-caught gamefish would suffer.

At the last meeting of the Conservation Advisory Board in Guntersville recently, a commercial hook-and-line catfish angler complained to the board that Tennessee commercial fishermen are already taking unlimited quantities of catfish out of the river, and requested relief. How much worse will this issue become if gill nets are added to the mix?

Once this fishery gets underway and working fishermen have invested in their nets, it will be no easy matter to shut it down–in Florida, it took a constitutional amendment to get rid of gillnets in coastal use. The people of the state rose up and passed the amendment, and the fisheries have improved steadily ever since. But the state–i.e. the taxpayers–was put on the hook for millions to buy back nets from the netters. Allow this gear again in Alabama? Why?

Bottom line is, this is a bill that has benefit for very few in the state of Alabama, and a potentially enormous downside. It’s hard to imagine how any caring legislator could pass it, and if it manages to get past the Senate, how Governor Bentley, who reportedly enjoys recreational fishing, could sign it. But stranger things have happened in politics.

Anglers and conservationists would do well to keep an eye on this effort, and to bring it to a halt if possible by making their feelings known to their legislators. You’ll find contact info on state senators at http://www.legislature.state.al.us/aliswww/SenatorsPicture.aspx

(A word of advice–like most folks, the legislators take council better from a polite, well-reasoned letter, email or phone call rather than angry bluster.)

Frank Sargeant can be contacted at [email protected].