Pacific Islands Fisheries Science Center

Honolulu, HI, United States

Pacific Islands Fisheries Science Center

Honolulu, HI, United States
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Abecassis M.,University of Hawaii at Manoa | Senina I.,Collecte Localisation Satellite | Lehodey P.,Collecte Localisation Satellite | Gaspar P.,Collecte Localisation Satellite | And 3 more authors.
PLoS ONE | Year: 2013

Habitat preferences for juvenile loggerhead turtles in the North Pacific were investigated with data from two several-year long tagging programs, using 224 satellite transmitters deployed on wild and captive-reared turtles. Animals ranged between 23 and 81 cm in straight carapace length. Tracks were used to investigate changes in temperature preferences and speed of the animals with size. Average sea surface temperatures along the tracks ranged from 18 to 23 °C. Bigger turtles generally experienced larger temperature ranges and were encountered in warmer surface waters. Seasonal differences between small and big turtles suggest that the larger ones dive deeper than the mixed layer and subsequently target warmer surface waters to rewarm. Average swimming speeds were under 1 km/h and increased with size for turtles bigger than 30 cm. However, when expressed in body lengths per second (bl s-1), smaller turtles showed much higher swimming speeds (>1 bl s-1) than bigger ones (0.5 bl s-1). Temperature and speed values at size estimated from the tracks were used to parameterize a habitat-based Eulerian model to predict areas of highest probability of presence in the North Pacific. The model-generated habitat index generally matched the tracks closely, capturing the north-south movements of tracked animals, but the model failed to replicate observed east-west movements, suggesting temperature and foraging preferences are not the only factors driving large-scale loggerhead movements. Model outputs could inform potential bycatch reduction strategies.


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. .


News Article | December 22, 2016
Site: phys.org

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. Explore further: Spate of whale entanglements could inform regulations


News Article | January 6, 2016
Site: phys.org

The technique provides more accurate estimates than other methods scientists currently use and may help shed new light on factors influencing the decline and lack of recovery of some endangered sea turtles populations. "The most basic questions of sea turtle life history are also the most elusive," said Kyle Van Houtan, fisheries research ecologist at NOAA's Pacific Islands Fisheries Science Center and adjunct associate professor at Duke's Nicholas School of the Environment. Van Houtan and his colleagues analyzed hard tissue from the shells of 36 deceased hawksbill sea turtles collected since the 1950s. The turtles either died naturally or were harvested for their decorative shells as part of the global tortoiseshell trade. The researchers worked with federal agencies, law enforcement and museum archives to obtain the specimens. The scientists were able to estimate each turtle's approximate age by comparing the bomb-testing radiocarbon accumulated in its shell to background rates of bomb-testing radiocarbon deposited in Hawaii's corals. Levels of carbon-14 increased rapidly in the biosphere from the mid-1950s to about 1970 as a result of Cold War-era nuclear tests but have dropped at predictable rates since then, allowing scientists to determine the age of an organism based on its carbon-14 content. Van Houtan and his team were able to estimate median growth rates and ages of sexual maturity in the collected specimens by comparing their radiocarbon measurements to those of other wild and captive hawksbill populations whose growth rates were known. This is the first time carbon-14 dating of shell tissue has been used to estimate age, growth and maturity in sea turtles. Previously, scientists employed other, less precise methods such as using turtle length as a proxy for age, or analyzing the incomplete growth layers in hollow bone tissue. The researchers published their peer-reviewed research Jan. 6, 2016, in the Proceedings of Royal Society B. Aside from giving scientists a more reliable tool for estimating turtle growth and maturity, Van Houtan believes the new technique sheds light on why some populations—including Hawaiian hawksbills, the smallest sea turtle population on Earth—aren't rebounding as quickly as expected despite years of concerted conservation. "Our analysis finds that hawksbills in the Hawaii population deposit eight growth lines annually, which suggests that females begin breeding at 29 years—significantly later than any other hawksbill population in the world. This may explain why they haven't yet rebounded," Van Houtan said. The bomb radiocarbon tests also indicate another red flag, he said. "They appear to have been omnivores as recently as the 1980s. Now, they appear to be primarily herbivores. Such a dramatic decline in their food supply could delay growth and maturity, and may reflect ecosystem changes that are quite ominous in the long term for hawksbill populations in Hawaii," he said. Although the new research focused primarily on Hawaiian hawksbills, bomb radiocarbon dating could be used to study other hawksbill populations, or populations from other sea turtle species, worldwide. More information: 'Time in Tortoiseshell: A Bomb Radiocarbon-validated Chronology in Sea Turtle Scutes,' Kyle Van Houtan, Allen Andrews, T. Todd Jones, Shawn Murakawa, Molly Hagemann. Proceedings of the Royal Society B, Jan. 6, 2016. DOI: 10.1098/rspb.2015.2220


Curran D.,Pacific Islands Fisheries Science Center | Bigelow K.,Pacific Islands Fisheries Science Center
Fisheries Research | Year: 2011

Sixteen vessels within the deep-set Hawaii-based tuna longline fleet tested the catch efficacy, fish size selectivity and survival on longline retrieval of large-size 18/0 circle hooks vs. Japanese style tuna hooks, size 3.6 sun and vs. size 9/0 " J" hooks. Vessels alternated hook types throughout the longline gear and maintained a 1:1 ratio of circle hooks to their existing tuna or J-hooks. Observers monitored a total of 1393 sets; 1182 sets were circle hooks vs. tuna hooks and 211 sets were circle hooks vs. J-hooks. The 18 most-caught species were analyzed representing 97.6% of the total catch by number. Two statistical methods were used to assess differences in catch (randomization test) or catch rate (generalized linear mixed models (GLMMs)). There were no significant catch or catch rate (catchability) differences among hook types for bigeye tuna (Thunnus obesus), the primary target species, with either statistical method. However, GLMMs indicated that catch rates on circle hooks were significantly lower for 16 and 8 species compared to tuna and J-hooks, respectively. There were no significant differences in mean length of bigeye tuna among hook comparisons. Caught condition at retrieval varied considerably among the 18 species. Large circle hooks had greater effects on catch rates than on fish size selectivity and fish survival. We contend that reduced catch rates are a function of 18/0 circle hook shape, where the minimum width (4.9. cm) was 57% and 25% wider than the Japanese tuna (3.1. cm) and J-hook (3.9. cm), respectively. In contrast to tuna hooks, large circle hooks have conservation potential for use in the world's pelagic tuna longline fleets for some highly migratory species, with catch rate reductions of 29.2-48.3% for billfish species and 17.1-27.5% for sharks. © 2011.


Brodziak J.,Pacific Islands Fisheries Science Center | Piner K.,Southwest Fisheries Science Center
Canadian Journal of Fisheries and Aquatic Sciences | Year: 2010

We show how model averaging can be applied to estimate the probable status of a fishery resource under assessment scenario uncertainty. This approach is applied to North Pacific striped marlin (Tetrapturus audax), an apex predator that may be vulnerable to recruitment overfishing in pelagic longline fisheries targeting tunas. In the current striped marlin assessment, two assessment scenarios were used to account for different hypotheses about the steepness of the stock-recruitment dynamics. Estimates of spawning stock and recruitment from these scenarios are used post hoc to fit age-structured production models that represent alternative hypotheses about the degree of compensation in stock-recruitment dynamics and the degree of serial correlation of environmental forcing. Model-averaged estimates of target spawning biomass to produce maximum sustainable yield (SMSY) and the associated limit fishing mortality (FMSY) characterize relative stock status (S/SMSY and F/FMSY) under each scenario. Scenario-weighted averages of relative status determine probable stock status, with weightings reflecting the credibility of each scenario. Estimates of the variance of probable status account for both model selection and assessment scenario uncertainty in risk analyses. Using model averaging to estimate probable stock status from multiple assessment scenarios is analogous to using ensemble averages from multiple predictive models to make weather forecasts.


Heenan A.,University of Hawaii at Manoa | Williams I.D.,Pacific Islands Fisheries Science Center
PLoS ONE | Year: 2013

Resilience-based management aims to promote or protect processes and species that underpin an ecosystem's capacity to withstand and recover from disturbance. The management of ecological processes is a developing field that requires reliable indicators that can be monitored over time. Herbivory is a key ecological process on coral reefs, and pooling herbivorous fishes into functional groups based on their feeding mode is increasingly used as it may quantify herbivory in ways that indicate resilience. Here we evaluate whether the biomass estimates of these herbivore functional groups are good predictors of reef benthic assemblages, using data from 240 sites from five island groups in American Samoa. Using an information theoretic approach, we assembled a candidate set of linear and nonlinear models to identify the relations between benthic cover and total herbivore and non-herbivore biomass and the biomass of the aforementioned functional groups. For each benthic substrate type considered (encrusting algae, fleshy macroalgae, hard coral and turf algae), the biomass of herbivorous fishes were important explanatory variables in predicting benthic cover, whereas biomass of all fishes combined generally was not. Also, in all four cases, variation in cover was best explained by the biomass of specific functional groups rather than by all herbivores combined. Specifically: 1) macroalgal and turf algal cover decreased with increasing biomass of 'grazers/detritivores'; and 2) cover of encrusting algae increased with increasing biomass of 'grazers/ detritivores' and browsers. Furthermore, hard coral cover increased with the biomass of large excavators/bio-eroders (made up of large-bodied parrotfishes). Collectively, these findings emphasize the link between herbivorous fishes and the benthic community and demonstrate support for the use of functional groups of herbivores as indicators for resilience-based monitoring.


Mangel M.,University of California at Santa Cruz | Brodziak J.,Pacific Islands Fisheries Science Center | DiNardo G.,Pacific Islands Fisheries Science Center
Fish and Fisheries | Year: 2010

The relationship between the biomass of reproductively mature individuals (spawning stock) and the resulting offspring added to the population (recruitment), the stock-recruitment relationship, is a fundamental and challenging problem in all of population biology. The steepness of this relationship is commonly defined as the fraction of recruitment from an unfished population obtained when the spawning stock biomass is 20% of its unfished level. Since its introduction about 20 years ago, steepness has become widely used in fishery management, where it is usually treated as a statistical quantity. Here, we investigate the reproductive ecology of steepness, using both unstructured and age-structured models. We show that if one has sufficient information to construct a density-independent population model (maximum per capita productivity and natural mortality for the unstructured case or maximum per capita productivity, natural mortality and schedules of size and maturity at age for the structured model) then one can construct a point estimate for steepness. Thus, steepness cannot be chosen arbitrarily. If one assumes that the survival of recruited individuals fluctuates within populations, it is possible, by considering the early life history, to construct a prior distribution for steepness from this same demographic information. We develop the ideas for both compensatory (Beverton-Holt) and over-compensatory (Ricker) stock-recruitment relationships. We illustrate our ideas with an example concerning bluefin tuna (Thunnus thynnus/orientalis, Scombridae). We show that assuming that steepness is unity when recruitment is considered to be environmentally driven is not biologically consistent, is inconsistent with a precautionary approach, and leads to the wrong scientific inference (which also applies for assigning steepness any other single value). Published 2009. This article is an US Government work and is in the public domain in the USA.


Weijerman M.,University of Hawaii at Manoa | Weijerman M.,Wageningen University | Fulton E.A.,CSIRO | Parrish F.A.,Pacific Islands Fisheries Science Center
PLoS ONE | Year: 2013

Three trophic mass-balance models representing coral reef ecosystems along a fishery gradient were compared to evaluate ecosystem effects of fishing. The majority of the biomass estimates came directly from a large-scale visual survey program; therefore, data were collected in the same way for all three models, enhancing comparability. Model outputs-such as net system production, size structure of the community, total throughput, production, consumption, production-to-respiration ratio, and Finn's cycling index and mean path length-indicate that the systems around the unpopulated French Frigate Shoals and along the relatively lightly populated Kona Coast of Hawai'i Island are mature, stable systems with a high efficiency in recycling of biomass. In contrast, model results show that the reef system around the most populated island in the State of Hawai'i, O'ahu, is in a transitional state with reduced ecosystem resilience and appears to be shifting to an algal-dominated system. Evaluation of the candidate indicators for fishing pressure showed that indicators at the community level (e.g., total biomass, community size structure, trophic level of the community) were most robust (i.e., showed the clearest trend) and that multiple indicators are necessary to identify fishing perturbations. These indicators could be used as performance indicators when compared to a baseline for management purposes. This study shows that ecosystem models can be valuable tools in identification of the system state in terms of complexity, stability, and resilience and, therefore, can complement biological metrics currently used by monitoring programs as indicators for coral reef status. Moreover, ecosystem models can improve our understanding of a system's internal structure that can be used to support management in identification of approaches to reverse unfavorable states.


Goldbogen J.A.,2181 2 W. 4th Ave. | Calambokidis J.,2181 2 W. 4th Ave. | Croll D.A.,University of California at Santa Cruz | Mckenna M.F.,University of California at San Diego | And 6 more authors.
Functional Ecology | Year: 2012

Diving capacity generally increases with body size both within and among taxanomic groups because of the differential scaling between body oxygen stores and metabolic rate. Despite being some of the largest animals of all time, rorqual whales exhibit very short dive times relative to other large divers because of the high energetic costs incurred during lunge feeding. This mode of filter feeding requires high drag for the engulfment of large volumes of prey-laden water, and the magnitude of both drag and engulfment volume is largely determined by the size and shape of the skull. The positive allometry of rorqual skulls increases mass-specific engulfment capacity in larger whales, but the energetic requirements of feeding are also predicted to increase and thus further limit diving capacity. To test the hypothesis that the energetic cost of a lunge is disproportionately higher in larger rorquals, we compared diving and lunge-feeding performance among three different-sized species (blue, fin and humpback whales) foraging on krill. Our hydrodynamic analyses indicate that the mass-specific energy expenditure will increase with body size if rorquals lunge at length-specific speeds (in body lengths per second) that are independent of body size, a condition that is supported by tag data. Although the absolute time required to filter each volume of water increased with body size, maximum dive duration and depth were not significantly different among species. As a consequence, the maximum number of lunges executed per dive decreased with body size. 7. These data suggest that, unlike all other true divers, adult rorqual species do not exhibit a positive relationship between body size and diving capacity. Larger rorquals forfeit diving capacity for greater engulfment capacity, a trade-off that favours the efficient exploitation of patchily dense prey aggregations. Such a trade-off may underlie different foraging strategies associated with resource partitioning, life history and ecological niche. © 2011 The Authors. Functional Ecology © 2011 British Ecological Society.

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