Sitka, AK, United States
Sitka, AK, United States

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Straley J.,University of Alaska Southeast | O'Connell V.,Sitka Sound Science Center | Liddle J.,University of Alaska Southeast | Thode A.,University of California at San Francisco | And 4 more authors.
ICES Journal of Marine Science | Year: 2015

In Alaskan waters, depredation on sablefish longline gear by sperm whales increases harvesting cost, negatively biases stock assessments, and presents a risk of entanglement for whales. The Southeast Alaska Sperm Whale Avoidance Project (SEASWAP), a collaborative effort involving industry, scientists, and managers, since 2003 has undertaken research to evaluate depredation with a goal of recommending measures to reduce interactions. Prior to 2003, little was known about sperm whale distribution and behaviour in the Gulf of Alaska (GOA). Although fishers were reporting increasing interactions, the level of depredation varied with no apparent predictor of occurrence across vessels. Between 2003 and 2007, fishers were provided with fishery logbooks and recorded information on whale behaviour, whale presence and absence, during the set, soak, and haul for 319 sets in the GOA. Data were evaluated for a vessel, area, and seasonal (month) effect in the presence and absence of sperm whales. Using catch per unit effort (cpue) as a metric, in kg/100 hooks, results indicated that depredation depended on both the vessel and the area. More whales associated with vessels from April to August. Sperm whales were also likely to be present when cpue was high, revealing that whales and fishers both knew the most productive fishing areas, but confounding the use of cpue as a metric for depredation. Using a Bayesian mark-recapture analysis and the sightings histories of photo-identified whales, an estimated N=135 (95% CI 124, 153) sperm whales were associating with vessels in 2014. A spatial model was fitted to 319 longline sets and quantified a 3% loss in cpue, comparable to other global studies on sperm whale depredation. Through all phases of SEASWAP, our understanding of depredation has gained significantly. This successful collaboration should be considered as a model to create partnerships and build collaborations between researchers and fisherpeople encountering marine mammal interactions with fishing gear. © 2015 International Council for the Exploration of the Sea 2015. All rights reserved. For Permissions, please email: journals.permissions@oup.com.


O'Connell V.,Sitka Sound Science Center | Straley J.,University of Alaska Southeast | Liddle J.,University of Alaska Southeast | Wild L.,Sitka Sound Science Center | And 3 more authors.
ICES Journal of Marine Science | Year: 2015

In Alaska, sperm whale (Physeter macrocephalus) depredation on longline sets has increased since implementation of the Individual Fishing Quota programme in 1995. A collaborative effort (SEASWAP) between longliners, scientists, and managers has undertaken research to evaluate this depredation with a primary objective to develop and test a passive deterrent that would reduce depredation without reducing catch rate of sablefish (Anoplopoma fimbria). Commercial longliners, fishing for their own sablefish quotas during the regular season, deployed beaded gear (25 mm lucite beads attached to gangions) with control gear and set recorders to collect acoustic data. Beaded and control gear were randomly assigned by skate quad (672 hooks) with 5 quads in each longline set. Acoustic recorders were used to document sperm whale creak-pause events, representative of depredation of the longline gear. Although there were more sablefish per skate quad on the beaded gear and there was a decrease in depredation events on the beaded gear compared with the control, neither effect was significant (p = 0.205 and 0.364, respectively). The SEASWAP project is testing other deterrent strategies including gear modifications and the establishment of a sighting network to improve avoidance. © 2015 International Council for the Exploration of the Sea 2015. All rights reserved. For Permissions, please email: journals.permissions@oup.com.


Thode A.,University of California at San Diego | Mathias D.,University of California at San Diego | Straley J.,University of Alaska Southeast | O'Connell V.,Sitka Sound Science Center | And 8 more authors.
ICES Journal of Marine Science | Year: 2015

Since 2003, a collaborative effort (SEASWAP) between fishers, scientists, and managers has researched how Alaskan sperm whales locate demersal longline fishing activity and then depredate sablefish from gear. Sperm whales constantly produce relatively low-frequency biosonar signals whenever foraging; therefore, over the past decade, passive acoustic monitoring (PAM) has become a basic tool, used for both measuring depredation activity and accelerating field tests of potential depredation countermeasures. This paper reviews and summarizes past published PAM research on SEASWAP, and then provides a detailed example of how PAM methods are currently being used to test countermeasures. The review covers two major research thrusts: (i) identifying acoustic outputs of fishing vessels that provide long-distance "cues" that attract whales to fishing activity; and (ii) validating whether distinctive "creak" sounds can be used to quantify and measure depredation rates, using both bioacoustic tags and statistical comparisons between visual and acoustic depredation estimates during federal sablefish surveys. The latter part of the paper then provides an example of how PAM is being used to study a particular potential countermeasure: an "acoustic decoy" which transmits fishing vessel acoustic cues to attract animals away from true fishing activity. The results of an initial 2011 field trial are presented to show how PAM was used to design the decoy signals and monitor the efficacy of the deployment. The ability of PAM to detect both whale presence and depredation behaviour has reduced the need to deploy researchers or other specialists on fishing cruises. Instead, volunteer fishers can deploy "user-friendly" acoustic recorders on their gear, greatly facilitating the testing of various deterrents, and providing the industry and regulators a convenient and unobtrusive tool for monitoring both the scale and long-term spread of this behaviour across the Alaskan fishery. © 2015 International Council for the Exploration of the Sea 2015. All rights reserved. For Permissions, please email: journals.permissions@oup.com.


PubMed | Sitka Sound Science Center, University of Alaska Southeast, National Oceanic and Atmospheric Administration, University of California at San Diego and 2 more.
Type: Journal Article | Journal: The Journal of the Acoustical Society of America | Year: 2016

False killer whales (Pseudorca crassidens) depredate pelagic longlines in offshore Hawaiian waters. On January 28, 2015a depredation event was recorded 14m from an integrated GoPro camera, hydrophone, and accelerometer, revealing that false killer whales depredate bait and generate clicks and whistles under good visibility conditions. The act of plucking bait off a hook generated a distinctive 15Hz line vibration. Two similar line vibrations detected at earlier times permitted the animals range and thus signal source levels to be estimated over a 25-min window. Peak power spectral density source levels for whistles (4-8kHz) were estimated to be between 115 and 130dB re 1Pa


News Article | December 22, 2016
Site: www.eurekalert.org

A team of researchers and fishermen has directly observed for the first time how Hawaiian false killer whales remove fish from longline fishing gear. The team, coordinated by Scripps Institution of Oceanography at the University of California San Diego scientist Aaron Thode, used video and audio recordings to observe false killer whales removing fish from a longline fishing hook, a behavior known as depredation. They gained new insight into a behavior that has caused false killer whales to entangle with fishing gear at rates deemed unsustainable by the U.S. National Marine Fisheries Service. False killer whales dine on popular game fish like yellowfin tuna and mahi-mahi. Their foraging efforts take them to the same open-ocean regions where commercial fishermen set 30-60 kilometer (19-37 mile)-long fishing lines to catch the same fish. This competition for fish has led false killer whales, actually a member of the dolphin family, to occasionally end up as an unintended catch of the fishing operations. To observe false killer whales removing fish from hooks, the Alaskan and Hawaiian research team deployed an underwater camera, sound recorder, and vibration detector on long-line fishing gear deployed by fishing vessels off Hawaii. The researchers were interested in learning more about the animals' behavior, such as what attracts them to the gear, whether they make sounds as they approach, and if they removed bait or the targeted species from the hook. They were also interested in measuring how far away the animals could be heard to provide new information into future passive acoustic surveys of the population. "This study addresses some important questions about the nature of this depredation, and whether underwater sound can be used to study or possibly alleviate the issue," said Thode, a researcher with the Scripps Marine Physical Laboratory and lead author of the paper recently published in the Journal of the Acoustical Society of America. During the 30-second encounter captured on video, the scientists found that the false killer whale made distinct clicks and whistles as it approached the longlines and took baitfish off the hook. Vibrations on the fishing line when the animal removed three fish also helped the researchers estimate how far away the animal was from the recorder to calculate how loud the animal's sounds were. The research team, part of a collaborative effort between the Southeast Alaska Sperm Whale Avoidance Network (SEASWAP), the National Marine Fisheries Service, Pacific Islands Fisheries Science Center, and members of the Hawaii Longline Association, has collectively been studying marine mammal and fishery interactions for more than a decade. Entanglements between fishing gear and offshore false killer whales, which are typically found in groups of 10 to 50 individuals, have occurred in Hawaii often enough that the population has been designated a "strategic stock" under the Marine Mammal Protection Act. This designation led to a federal take-reduction strategy for reducing the negative impact to the population from the unintentional catch of the threatened species. "Further acoustics studies could help us understand more about these animals' behavior, which could be used by fishermen to hear the animals make these whistles or echolocation noises before they deploy their gear," said Thode. "The study can also be helpful in designing future experiments to estimate the actual number of animals in the region." Thode also suggests that the tugs and jerks that a given species makes on the fishing line could differ from other species, and might lead to new ways to recognize and reduce bycatch, protecting both animals and fishermen from unintentional encounters. "This was a true collaborative effort with fishermen, fisheries managers and scientists from across the North Pacific working together that made this project a success," said Janice Straley, professor of biology at the University of Alaska Southeast and a coauthor of the study. "Fishermen modified techniques used for depredation in Alaska for use in Hawaii and everyone worked on design and implementation." The research team hopes that this study may help test the concept of a so-called "smart hook" to reduce the impacts to the animals and fishing operations. The work was supported by the National Oceanic and Atmospheric Administration (NOAA) Bycatch Reduction Engineering Program in close collaboration with NOAA's Pacific Islands Fisheries Science Center and SEASWAP, a group that includes members from the University of Alaska Southeast, the Alaska Longline Fishermen's Association, the Sitka Sound Science Center, the Central Bering Sea Fishermen's Association, and the Hawaii Longline Association. Scripps Institution of Oceanography at the University of California, San Diego, is one of the oldest, largest, and most important centers for global science research and education in the world. Now in its second century of discovery, the scientific scope of the institution has grown to include biological, physical, chemical, geological, geophysical, and atmospheric studies of the earth as a system. Hundreds of research programs covering a wide range of scientific areas are under way today on every continent and in every ocean. The institution has a staff of more than 1,400 and annual expenditures of approximately $195 million from federal, state, and private sources. Scripps operates oceanographic research vessels recognized worldwide for their outstanding capabilities. Equipped with innovative instruments for ocean exploration, these ships constitute mobile laboratories and observatories that serve students and researchers from institutions throughout the world. Birch Aquarium at Scripps serves as the interpretive center of the institution and showcases Scripps research and a diverse array of marine life through exhibits and programming for more than 430,000 visitors each year. Learn more at scripps.ucsd.edu and follow us at: Facebook | Twitter | Instagram. At the University of California San Diego, we constantly push boundaries and challenge expectations. Established in 1960, UC San Diego has been shaped by exceptional scholars who aren't afraid to take risks and redefine conventional wisdom. Today, as one of the top 15 research universities in the world, we are driving innovation and change to advance society, propel economic growth, and make our world a better place. Learn more at http://www. .


Sreenivasan A.,Sitka Sound Science Center | Heintz R.,National Oceanic and Atmospheric Administration
Deep-Sea Research Part II: Topical Studies in Oceanography | Year: 2016

Pacific cod (Gadus macrocephalus) are generalist predators in the Gulf of Alaska (GOA), and are an important predator on other commercially important species. Efficient management of this species can benefit by knowing how these fish adapt to changing environmental conditions, with a focus on how growth and condition are affected by changes in temperature and diet. We conducted a feeding study to understand the relationship between growth, ration, and temperature, and how these factors interact to affect energy allocation strategies. Since growth and condition of juveniles can determine recruitment into the population, this study focused on growth and consumption of age 1+Pacific cod held over 4 temperature treatments (4. °C, 8. °C, 12. °C, and 16. °C) and 3 ration levels (unlimited ration, medium ration, and low ration). We also compared cellular nucleic acid (RNA/DNA) ratios, an instantaneous growth index, total-body lipid, and proximate composition between fish. At 4. °C, 8. °C, and 12. °C, fish at medium and low rations had higher growth rates relative to fish at high rations. Higher food consumption appears to negatively affect digestive ability, assimilation efficiency, and nutrient utilization. RNA/DNA was clearly correlated with growth rates at 4. °C and 8. °C, but this relationship did not hold at higher temperatures. A secondary growth study was conducted to test the reliability of the growth/consumption models derived from the main growth study. Temperature influenced energy reserves (lipid) while tissue growth (protein) was influenced by ration level. Average lipid values were higher at 4. °C than at 8. °C or 12. °C, suggesting a predisposition to heightened lipid synthesis at colder temperatures. Longer durations of warmer water temperature in the GOA could consequently affect energy allocation strategies, with dietary changes in the field potentially amplifying this effect in cold and warm years. This energy allocation strategy could be detrimental with warmer temperatures predicted in the GOA. © 2016 Elsevier Ltd.

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