Newsletter 4 - Marine Mammal Institute - Oregon State University

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Untangling the mystery of entangled Steller sea lions: first steps toward a solution A followup story by Kim Raum-Suryan Since 2005, we have been collecting data about Steller sea lions entangled in marine debris and derelict fishing gear off two haul-out sites in Oregon, Sea Lion Caves and Cascade Head. We noticed that many of the younger sea lions (1 to 3 years-of-age) had thick black bands around their necks. As the animals grow, these bands start cutting into the neck, eventually causing severe injury and death if the bands do not break off (very unlikely). At first, we were unsure about the source of this entangling debris. However, we realized that these black rubber bands are the same bands that are used on commercial and sport crab pots. We have subsequently found some of these bands washed up on Oregon beaches. The mystery is how these sea lions are getting these bands around their necks and what we can do to help prevent this problem. The loose ‘replacement’ bands are either being lost overboard vessels at sea or the sea lions are somehow becoming entangled in the bands while on the crab pots. We suggested cutting the loops, making them into ‘strips’ so if they come off the crab pots, they lose the loop and are no longer an entanglement hazard to marine animals. Another idea is to better secure the ‘replacement’ bands while on board the vessels so they don’t accidentally go overboard and present an entanglement hazard. We contacted the Oregon Dungeness Crab Commission (ODCC) about this problem. At first, we met with resistance, that there is “no way” these bands could be coming from the commercial crab fishery. However, after observing newly entangled young sea lions each year for the past 4 years, presenting the data and photos at a meeting with the director of the ODDC, crab fishers, Oregon Department of Fish and Wildlife biologists, and Oregon Sea Grant personnel, there was a change of heart and the ODDC agreed to help us bring awareness of this issue to the crab fleet. As part of this effort, the ODCC has printed laminated copies of a photo of a Steller sea lion with a black rubber band around its neck and has listed ways crab fishers can help reduce the problem of entanglements. They plan to post these at ports throughout Oregon. They also presented our findings at the recent 2009 Oregon Dungeness Crab Summit held in Newport, Oregon. We are pleased that the ODDC has agreed to help us bring awareness about this problem, but we have a long road ahead of us to solve this problem. New study of Steller sea lions suggests death by predation may be higher (Source - Mark Floyd, OSU) A pioneering project that implants lifelong monitors inside of Steller sea lions to learn more about why the number of these endangered marine mammals has been declining – and remains low in Alaska – is beginning to provide data, and the results are surprising to scientists. Four out of five of the data sets that researchers have recovered indicate that the sea lions died from traumatic causes – most likely, attack from transient killer whales. This comes as a surprise to many scientists and resource managers who previously thought that recent sea lion population trends are largely attributable to depressed birth rates, a loss of fecundity, or poor nutrition, according to Markus Horning, a pinniped specialist with the Marine Mammal Institute at Oregon State University and principal investigator in the study. “This obviously is a very small sample so we cannot overstate our conclusions,” Horning said, “but the fact that four out of five deceased Steller sea lions that we received data from met with a sudden, traumatic death is well beyond what conventional thought would have predicted. It could be coincidence…or it could mean that predation is a much more important factor than has previously been acknowledged.” Results of the study are being published in the journal Endangered Species Research and results were presented at a meeting of the Society for Marine Mammalogy in Quebec City. The science behind the discovery is a story within itself. The researchers worked with Wildlife Computers, Inc., in Redmond, Wash., to develop a tag that could be implanted in the body cavity of sea lions and remain there during their life span. Conventional externally applied tags rarely have the battery power to transmit data for longer than a year and are shed during the annual molt – thus information about sea lion mortality is difficult to obtain. These new tags, however, stay within the sea lion until its death, recording temperatures for as long as eight to 10 years. When an animal dies, and either decomposes or is torn apart by predators, the tags are released and send a signal to a satellite that transmits it to Horning’s lab at OSU’s Hatfield Marine Science Center in Newport, Ore. “We can tell whether an animal died by acute death through the temperature change rate sensed by the tags and whether the subsequent transmission of a signal is immediate or delayed,” said Horning, who is an assistant professor of fisheries and wildlife at OSU. Horning and his collaborator, Jo- Ann Mellish, have tested cooling and decomposition rates of sea lions on animals that have died from stranding or other causes. They’ve also inserted tags within those animals to see how long it would take before the signal would transmit based on whether an animal was on the beach, was deep at sea, or was torn apart by predators. continued on page 7 MMI Newsletter December 2009 6 OREGON STATE UNIVERSITY
Their protocol for inserting tags within live Steller sea lions was developed from initial deployments on non-threatened, stranded California sea lions at the Marine Mammal Center in Sausalito, Calif. “We wanted to make sure there was no adverse impact on the animals,” Horning said, “and there wasn’t.” Since 2005, Horning and his colleagues at the Alaska Sea Life Center in Seward have implanted tags into 27 Steller sea lions that were captured and released off the coast of Alaska. Since that time, they have received data from five animals – at least four of which appeared to die from traumatic deaths, based on the rate of tag cooling and immediate signal transmission. Horning said the tags can precisely identify the moment an animal died from temperature data. And while they are confident in their ability to determine whether the death was caused by predation or non-traumatic causes, identifying the actual predator is admittedly a bit of guesswork, Horning says. “There are only a couple of species that are known to target sea lions as prey,” he pointed out. “Orcas are not only common in that region of Alaska, they also have been observed preying on sea lions. Some species of sharks are known to attack sea lions, but they aren’t as common in those waters and there haven’t been any observations of predation in the study area.” If predation of Steller sea lions is more prevalent than previously thought, Horning said, there are implications for management. “If the proportion of sea lions killed by predation in our study was applied to population models, we estimate that more than half of the female Steller sea lions would be consumed by predators before they have a chance to reproduce,” Horning said. “We recognize that this is a very coarse estimate based on a small sample size. “But we hope this serves as a wakeup call to begin looking more closely into the actual role of predation as a determinant in Steller sea lion populations.” These newly developed tags were also featured in a brief newsclip in the Oct 23 2009 issue of the journal SCIENCE (Vol. 326, p. 505). ‘Bycatch’ whaling — a growing threat to coastal whales (Source - Science News - June 29, 2009) Scientists are warning that a new form of unregulated whaling has emerged along the coastlines of Japan and South Korea, where the commercial sale of whales killed as fisheries “bycatch” is threatening coastal stocks of minke whales and other protected species. Scott Baker, associate director of the Marine Mammal Institute at Oregon State University, says DNA analysis of whalemeat products sold in Japanese markets suggests that the number of whales actually killed through this “bycatch whaling” may be equal to that killed through Japan’s scientific whaling program – about 150 annually from each source. Baker, a cetacean expert, and Vimoksalehi Lukoscheck of the University of California-Irvine presented their findings at the recent scientific meeting of the International Whaling Commission (IWC) in Portugal. Their study found that nearly 46 percent of the minke whale products they examined in Japanese markets originated from a coastal population, which has distinct genetic characteristics, and is protected by international agreements. Their conclusion: As many as 150 whales came from the coastal population through commercial bycatch whaling, and another 150 were taken from an open ocean population through Japan’s scientific whaling. In some past years, Japan only reported about 19 minke whales killed through bycatch, though that number has increased recently as new regulations governing commercial bycatch have been adopted, Baker said. Japan is now seeking IWC agreement to initiate a small coastal whaling program, a proposal which Baker says should be scrutinized carefully because of the uncertainty of the actual catch and the need to determine appropriate population counts to sustain the distinct stocks.Whales are occasionally killed in entanglements with fishing nets and the deaths of large whales are reported by most member nations of the IWC. Japan and South Korea are the only countries that allow the commercial sale of products killed as “incidental bycatch.” The sheer number of whales represented by whale-meat products on the market suggests that both countries have an inordinate amount of bycatch, Baker said.“The sale of bycatch alone supports a lucrative trade in whale meat at markets in some Korean coastal cities, where the wholesale price of an adult minke whale can reach as high as $100,000,” Baker said. “Given these financial incentives, you have to wonder how many of these whales are, in fact, killed intentionally.” In Japan, whale-meat products enter into the commercial supply chain that supports the nationwide distribution of whale and dolphin products for human consumption, including products from scientific whaling. However, Baker and his colleagues have developed genetic methods for identifying the species of whale-meat products and determining how many individual whales may actually have been killed. Baker said bycatch whaling also serves as a cover for illegal hunting, but the level at which it occurs is unknown. In January 2008, Korean police launched an investigation into organized illegal whaling in the port town of Ulsan, he said, reportedly seizing 50 tons of minke whale meat. Other protected species of large whales detected in market surveys include humpbacks whales, fin whales, Bryde’s whales and critically endangered western gray whales. The entanglement and death of western or Asian gray whales is of particular concern given the extremely small size of this endangered populations, which is estimated at only 100 individuals. It will be published in a forthcoming issue of the journal Animal Conservation. the wholesale price of an adult minke whale can reach as high as $100,000 MMI Newsletter December 2009 7 OREGON STATE UNIVERSITY
Page 1 and 2: HATFIELD MARINE SCIENCE CENTER, NEW
Page 3 and 4: number just 130 animals. Amazingly,
Page 5: Three large cetacean strandings occ

Newsletter 4 - Marine Mammal Institute - Oregon State University

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