Incorporation of bomb-produced14C into fish otoliths. An example of basin-specific rates from the North Pacific Ocean

2015 ◽  
Vol 72 (6) ◽  
pp. 879-892 ◽  
Author(s):  
Stephen G. Wischniowski ◽  
Craig R. Kastelle ◽  
Timothy Loher ◽  
Thomas E. Helser
Keyword(s):  
North Pacific Ocean ◽  
Deviance Information Criterion ◽  
Information Criterion ◽  
Gulf Of Alaska ◽  
Estimation Accuracy ◽  
Model Parameters ◽  
Age Validation ◽  
The North ◽  
Pacific Halibut ◽  
Hippoglossus Stenolepis

Sagittal otoliths from juvenile Pacific halibut (Hippoglossus stenolepis) of known age were used to create a bomb-produced radiocarbon reference chronology for the eastern Bering Sea (EBS) by fitting a coupled-function model to Δ14C values from each specimen’s birth year. The newly created EBS reference chronology was then compared with a reference chronology previously created for Pacific halibut from the Gulf of Alaska (GOA). Adult Pacific halibut age-validation samples from the EBS were also analyzed for14C and modeled to validate age-estimation accuracy. A Bayesian model was developed and Markov chain Monte Carlo simulation was used to estimate model parameters and adult Pacific halibut ageing bias. Differences in reference chronologies between ocean basins were reflected in a large deviance information criterion (ΔDIC) between models, supporting the hypothesis that two separate coupled-function models were required to adequately describe the data, one each for the EBS and GOA. We determined that regionally specific GOA and EBS oceanography plays a considerable role in the Δ14C values and must be taken into consideration when selecting a reference chronology for bomb-produced14C age-validation studies. The age-validation samples indicated that the current ageing methodology used in Pacific halibut assessments is accurate and has provided accurate age assignments for Pacific halibut in the EBS.

Age validation of four rockfishes (genera Sebastes and Sebastolobus) with bomb-produced radiocarbon

2020 ◽  
Vol 71 (10) ◽  
pp. 1355
Author(s):  
Craig Kastelle ◽  
Thomas Helser ◽  
Todd TenBrink ◽  
Charles Hutchinson ◽  
Betty Goetz ◽  
...  
Keyword(s):  
Age Determination ◽  
Gulf Of Alaska ◽  
Age Validation ◽  
Pacific Halibut ◽  
The Pacific ◽  
Hippoglossus Stenolepis ◽  
Deep Water Species ◽  
Growth Zones ◽  
Shortspine Thornyhead ◽  
Water Species

In rockfish (Family Scorpaenidae), age determination is difficult and the annual nature of otolith growth zones must be validated independently. We applied routine age determination to four species of Gulf of Alaska rockfish: two shallower-water species, namely harlequin rockfish (Sebastes variegatus) and redstripe rockfish (Sebastes proriger), and two deep-water species, namely shortspine thornyhead (Sebastolobus alascanus) and shortraker rockfish (Sebastes borealis). The estimated ages (counts of presumed annual growth zones in the otoliths) were then evaluated with bomb-produced radiocarbon (14C) and Bayesian modelling with Markov chain Monte Carlo simulations. This study successfully demonstrated the level of accuracy in estimated ages of redstripe rockfish (a 35% probability of underageing, and ~5% probability of overageing) and harlequin rockfish (a 100% probability that they were underaged by ~3 or 4 years). Measured Δ14C in shortspine thornyhead and shortraker rockfish otoliths was lower and increased later than expected. Hence, incorrect age determination could not be evaluated. This is likely caused by dissimilar environmental and biological availability of 14C between these two species and the Pacific halibut (Hippoglossus stenolepis) reference chronology, or underageing of these two species.

scholarly journals Assessing the relationship between diet and size-at-age in Pacific halibut (Hippoglossus stenolepis) using δ13C and δ15N analysis

2019 ◽  
Vol 76 (12) ◽  
pp. 2326-2331
Author(s):  
Nathan Wolf ◽  
Sarah R. Webster ◽  
Jeffery M. Welker ◽  
Bradley P. Harris
Keyword(s):  
North Pacific Ocean ◽  
Isotope Analysis ◽  
Δ13c And Δ15n ◽  
Pacific Halibut ◽  
Hippoglossus Stenolepis ◽  
Dietary Strategy ◽  
Mean Size ◽  
Intermediate Size ◽  
Size At Age ◽  
The Relationship

The ecological mechanisms driving an observed decline in the mean size-at-age of adult Pacific halibut (Hippoglossus stenolepis) in the eastern North Pacific Ocean have yet to be defined. Here, we present the results of a study designed to investigate the relationship between one potential mechanism — diet — and size-at-age using carbon and nitrogen stable isotope analysis. Our results indicate significant differences in the skeletal muscle δ13C and δ15N values between size-at-age categories for each sex, with larger-size-at-age fish consuming diets with higher δ15N values, indicating higher trophic level feeding. Analysis of Bayesian standard ellipse areas showed that for females, intermediate size-at-age categories have the largest dietary range. For males, the largest dietary range was observed in the largest size-at-age category. Our results suggest a size-based stratification in dietary strategy for Pacific halibut with implications for observed declines in size-at-age.

scholarly journals Research on RMB Exchange Rate Volatility Risk Based on MSGARCH-VaR Model

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Xiaofei Wu ◽  
Shuzhen Zhu ◽  
Junjie Zhou
Keyword(s):  
Exchange Rate ◽  
Value At Risk ◽  
Financial Risk ◽  
Deviance Information Criterion ◽  
Exchange Rate Volatility ◽  
Information Criterion ◽  
Model Parameters ◽  
Volatility Risk ◽  
Rmb Exchange Rate ◽  
Trade Friction

This paper captures the RMB exchange rate volatility using the Markov-switching GARCH (MSGARCH) models and traditional single-regime GARCH models. Through the Markov Chain Monte Carlo (MCMC) method, the model parameters are estimated to study the volatility dynamics of the RMB exchange rate. Furthermore, we compare the MSGARCH models to the single-regime GARCH specifications in terms of Value-at-Risk (VaR) prediction accuracy. According to the Deviance information criterion method, the research shows that MSGARCH models outperform the single-regime specifications in capturing the complexity of RMB exchange rate volatility. After the RMB exchange rate reform in 2015, the volatility is more asymmetric and persistent, and the probability of being in the turbulent volatility regime is significantly increased. The continuous escalation of Sino-US trade friction has increased the VaR of RMB exchange rate log-returns. From the evaluation results of the actual over expected exceedance ratio (AE), the conditional coverage (CC) test, and the dynamic quantile (DQ) test, we find strong evidence that two-regime MSGARCH models could forecast VaR more accurately, which provides practical value for China’s foreign exchange management authorities to manage the financial risk.

Biology of the Pacific Pomfret (Brama japonica) in the North Pacific Ocean

1993 ◽  
Vol 50 (12) ◽  
pp. 2608-2625 ◽  
Author(s):  
William G. Pearcy ◽  
Joseph P. Fisher ◽  
Mary M. Yoklavich
Keyword(s):  
Pacific Ocean ◽  
North Pacific ◽  
North Pacific Ocean ◽  
Gulf Of Alaska ◽  
Small Fish ◽  
Large Fish ◽  
The North ◽  
The Pacific ◽  
Subarctic Current ◽  
The North Pacific

Abundances of Pacific pomfret (Brama japonica), an epipelagic fish of the North Pacific Ocean, were estimated from gillnet catches during the summers of 1978–1989. Two size modes were common: small pomfret <1 yr old, and large fish ages 1–6. Large and small fish moved northward as temperatures increased, but large fish migrated farther north, often into the cool, low-salinity waters of the Central Subarctic Pacific. Lengths of small fish were positively correlated with latitude and negatively correlated with summer surface temperature. Interannual variations in the latitude of catches correlated with surface temperatures. Large catches were made in the eastern Gulf of Alaska (51–55°N) but modes of small pomfret were absent here, and large fish were rare at these latitudes farther to the west. Pomfret grow rapidly during their first two years of life. They are pectoral fin swimmers that swim continuously. They prey largely on gonatid squids in the region of the Subarctic Current in the Gulf of Alaska during summer. No evidence was found for aggregations on a scale ≤1 km. Differences in the incidence of tapeworm, spawning seasons, and size distributions suggest the possibility of discrete populations in the North Pacific Ocean.

scholarly journals Assessing the ecological importance of red tree coral thickets in the eastern Gulf of Alaska

2014 ◽  
Vol 72 (3) ◽  
pp. 900-915 ◽  
Author(s):  
Robert P. Stone ◽  
Michele M. Masuda ◽  
John F. Karinen
Keyword(s):  
North Pacific Ocean ◽  
Fish Habitat ◽  
Keystone Species ◽  
Gulf Of Alaska ◽  
Habitat Characteristics ◽  
Benthic Habitat ◽  
Logistic Regression Models ◽  
Small Areas ◽  
Bottom Contact ◽  
The North

Abstract Red tree corals (Primnoa pacifica), the largest structure-forming gorgonians in the North Pacific Ocean, form dense thickets in some areas. These thickets are a dominant benthic habitat feature in the Gulf of Alaska (GOA), yet little is known about the ecosystems they support. In 2005, we used a submersible to study the ecology of thickets inside or near five small areas of the eastern GOA later designated in 2006 as habitat areas of particular concern (HAPCs)―areas closed to all bottom contact fishing. We show that red tree corals are keystone species in habitats where they form thickets (mean density 0.52 corals m−2)—the densest and largest thickets documented anywhere. Measured sponge densities (2.51 sponges m−2) were also among the highest documented anywhere. The corals and sponges in the study areas provide essential fish habitat for some fish species, and we show with logistic regression models modified with a scaled binomial variance that bedrock, while important habitat for some fish, is even more important when paired with corals and sponges. Red tree corals were not equally distributed with regard to habitat characteristics, and we show that their presence was correlated with bedrock substrate, moderate to high seabed roughness, and slope &gt;10°. Most corals and sponges are vulnerable to disturbance from longlining, the principal bottom contact fishing in this region, but the larger corals and sponges are the most vulnerable. We observed evidence of infrequent recruitment events and a strong pulse of predation, apparently from fishing gear-induced trauma, that could exacerbate slow recovery of red tree corals from disturbance. Some red tree coral thickets are provided protection within designated HAPCs and some are not. Modifications to longline gear and an expanded network of HAPCs could help preserve these keystone species and the ecosystems they support.

Decadal changes in growth and recruitment of Pacific halibut (Hippoglossus stenolepis)

1999 ◽  
Vol 56 (2) ◽  
pp. 242-252 ◽  
Author(s):  
William G Clark ◽  
Steven R Hare ◽  
Ana M Parma ◽  
Patrick J Sullivan ◽  
Robert J Trumble
Keyword(s):  
North Pacific ◽  
Regime Shift ◽  
Assessment Model ◽  
Individual Growth ◽  
Climate Regime ◽  
Climate Regime Shift ◽  
The North ◽  
Pacific Halibut ◽  
Hippoglossus Stenolepis ◽  
The North Pacific

Since the climate regime shift of 1976-1977 in the North Pacific, the individual growth of Pacific halibut (Hippoglossus stenolepis) has decreased dramatically in Alaska but not in British Columbia. Recruitment has increased dramatically in both areas. The decrease in age-specific vulnerability to commercial longline gear resulted in a persistent underestimation of incoming recruitment by the age-structured assessment method (CAGEAN) that was used to assess the stock. This problem has been corrected by adding temporal trends in growth and fishery selectivity to the assessment model. The recent sustained high level of recruitment at high levels of spawning biomass has erased the previous appearance of strong density dependence in the stock-recruitment relationship and prompted a reduction in the target full-recruitment harvest rate from 30-35 to 20-25%. The climate regime shift affected a number of other stocks of vertebrates and invertebrates in the North Pacific. While the general oceanographic changes have now been identified, the specific biological mechanisms responsible for the observed changes have not.

Zoogeography of the parasites of Pacific halibut (Hippoglossus stenolepis) in the northeast Pacific

1998 ◽  
Vol 76 (12) ◽  
pp. 2262-2273 ◽  
Author(s):  
R B Blaylock ◽  
L Margolis ◽  
J C Holmes
Keyword(s):  
Parasite Fauna ◽  
Life Cycles ◽  
Small Scale ◽  
Parasite Abundance ◽  
Northeast Pacific ◽  
Queen Charlotte Islands ◽  
The North ◽  
Northern Bering Sea ◽  
Pacific Halibut ◽  
Hippoglossus Stenolepis

The parasite fauna of 336 adult Pacific halibut (Hippoglossus stenolepis) from 15 geographic localities along the North American coast, ranging from northern California to the northern Bering Sea, was examined to assess zoogeographic and latitudinal zonation of Pacific halibut parasites in the eastern North Pacific. Results show the existence of three zoogeographic zones in the northeast Pacific with boundaries near the southern Queen Charlotte Islands and in the vicinity of Kodiak Island. "Fuzziness" around these boundaries probably reflects small-scale fish movement and the complexity of parasite life cycles. These boundaries roughly correspond to those previously established using the fish and invertebrate faunas. Parasite species richness appears to be more directly correlated with halibut abundance than with latitude; parasite abundance appears to be correlated with temperature and therefore negatively correlated with latitude.

Sign in / Sign up

Export Citation Format

Share Document