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Pacific razor clam shell growth was examined using data provided by the Alaska Department of Fish and Game containing 235,606 length-al-age records based on visible annuli on the shell from 57,534 individual clams measured from 1966 to 2021 at nine locations in Cook Inlet, AK. Shell growth was modeled via the von Bertalanffy Growth Function treating each individual clam as a random effect. Asymptotic mean length at time infinity (LJ varied considerably between sites, from 121.35 to 186.58 mm, as did the growth coefficient k which ranged from 0.28 to 0.54 [y.sup.-1]. When both [L.sub.[infinity]] and k were examined collectively via a growth performance index ([empty set]'), all Cook Inlet sites were similar ([empty set]' range: 3.80-4.02). The growth performance of Pacific razor clams in Cook Inlet was also compared with summary statistics from previously published mean length-at-age estimates for Pacific razor clams across their distribution. Growth performance estimates from Alaska and British Columbia sites were largely similar, whereas sites in Washington, Oregon, and California were generally characterized by faster growth and smaller maximal lengths. Although this study did not attempt to quantitatively identify predictors of variation in growth parameters and performance within and outside of Cook Inlet, AK, this manuscript concludes with speculations on possible correlates to growth and recommendations for future work. KEY WORDS: Pacific razor clams (Siliquapatuld), von Bertalanffy growth function, Alaska, INTRODUCTION The Pacific razor clam, Siliqua patula, is a large bivalve that inhabits fine to medium-grain sandy beaches from southern California to the Aleutian Islands, AK (Weymouth et al. 1925, [...]

Beaches along Cook Inlet, AK, historically supported commercial, sport, and personal use fisheries for the Pacific razor clam (Siliqua patula). In 2015, east Cook Inlet beaches were closed to sport and personal use harvests, however, due to low abundances of adult clams with concomitant decreases in average length and percentages of large-sized razor clams. Meanwhile, razor clams in west Cook Inlet have not experienced the same decline, and west Cook Inlet beaches remain open to harvest. The universality of the trends in east Cook Inlet suggests post-settlement mortality as a primary driver, but changes in source-sink population dynamics or oceanographic processes may also differentially influence productivity. Given the differences in productivity between east- and west-side beaches, a key question is the degree to which razor clams around Cook Inlet are genetically connected. To answer this question, RAD-seq was used to discover and successfully genotype 44,040 single nucleotide polymorphisms in 37-48 razor clams collected from 11 sites around Cook Inlet and one site on the Alaska Peninsula. Pairwise [F.sub.ST] estimates indicated a lack of neutral population genetic structure across the sampled range, with no evidence of genetic isolation among samples, between east and west Cook Inlet, or between 2y classes with sufficient sample sizes, and less than 0.1% of loci were deemed [F.sub.ST] outliers. Despite the lack of neutral and putatively adaptive variation, these results provide insights into the biological and ecological processes that may influence dispersal, recruitment, and stock productivity among Cook Inlet razor clam aggregations. Moreover, the knowledge gathered can assist resource managers in evaluating harvest strategies for Cook Inlet sport and commercial razor clam fisheries and provides information salient to abundance and demographic survey design. KEY WORDS: Pacific razor clam, Siliqua patula, Cook Inlet, population genomics, restriction site-associated DNA sequencing, single nucleotide polymorphism, INTRODUCTION Pacific razor clams (Siliqua patula Dixon 1789; hereafter 'razor clams') are large marine bivalves in the family Pharidae found on sandy intertidal beaches along the west coast of North [...]

Since 2000, information to support the sustainable management of the weathervane scallop Patinopecten caurinus in the Gulf of Alaska is largely derived from fishery-dependent observations from a small fleet ([less than or equal to] vessels total). As a supplement to this information, the Alaska Department of Fish and Game collected more than one million high-resolution underwater photographs of the sea floor in five previously unsurveyed scallop beds off Kodiak Island during the spring of 2014. Weathervane scallop distribution, abundance, and size composition in these beds were assessed by analyzing more than 150,000 images subsampled in 50-image strips (stations) using a 100-m grid. In addition, the influence of local abiotic habitat features, including depth, substrate, and shell remains, on weathervane scallop distributions was explored. An estimated 26.8 [95% confidence interval (CI) = 23.5-30.7] million scallops in the five beds, with densities ranging from 0.08 (95% CI = 0.067-0.084) to 0.26 (95% CI = 0.221-0.297) ind.*[m.sup.-2] among the beds. Shell size compositions differed significantly despite the relative proximity of the beds. Weathervane density was positively related (in order of influence) to gravel, shell debris, shell hash, mud, and cobble. Optical assessment of these five previously unsurveyed scallop beds in the Gulf of Alaska demonstrates the efficacy of this approach for weathervanes and suggests that the expansion of optical survey coverage to include other known beds as a viable path to overcoming the limitations of fishery-dependent information for scallop assessment and management in Alaskan waters. KEY WORDS: weathervane scallops, Patinopecten caurinus, Gulf of Alaska, density, abundance, optical assessment, INTRODUCTION The continental shelf east of Kodiak Island is a diverse and productive region of the Gulf of Alaska, which supports commercial harvests of the weathervane scallop Patinopecten caurinus (Gould, [...]

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 [[delta].sup.13]C and [[delta].sup.15]N values between size-at-age categories for each sex, with larger-size-at-age fish consuming diets with higher [[delta].sup.15]N 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. Les mecanismes ecologiques a l'origine de la baisse observee de la taille moyenne selon l'age des fletans du Pacifique (Hippoglossus stenolepis) adultes dans l'est de l'ocean Pacifique nord ne sont pas encore etablis. Nous presentons les resultats d'une etude conque pour etudier la relation entre un mecanisme possible--l'alimentation--et la taille selon l'age, qui repose sur l'analyse des isotopes stables du carbone et de l'azote. Nos resultats font ressortir des differences significatives des valeurs de [[delta].sup.13]C et [[delta].sup.15]N des muscles squelettiques entre les differentes classes de taille selon l'age pour chaque sexe, les plus grands poissons aun age donne ayant une alimentation caracterisee par des valeurs plus grandes de [[delta].sup.15]N, indiquant un plus haut niveau trophique. L'analyse d'aires d'ellipses standards bayesiennes montre que, pour les femelles, les classes intermediates de taille selon l'age sont caracterisees par la plus grande diversite alimentaire. Pour les males, la plus grande diversite alimentaire est observee pour la plus grande classe de taille selon l'age. Nos resultats semblent indiquer une stratification basee sur la taille des strategies d'alimentation pour le fletan du Pacifique qui serait reliee aux baisses observees des tailles selon l'age., Introduction Since peaking in the 1970s, mean size-at-age of adult Pacific halibut (Hippoglossus stenolepis) in the eastern North Pacific Ocean has dropped by ~50% for both sexes (Stewart and Webster [...]

Abstract: Despite frequent observations of gray wolves (Canis lupus L., 1758) using nonungulate prey, the seasonal and interannual variation in the use and relative importance of alternative prey sources to [...]

Electron-phonon coupling was believed to govern the carrier transport in halide perovskites and related phases. Here we demonstrate that electron-electron interaction enhanced by Cs-involved electron redistribution plays a direct and prominent role in the low-temperature electrical transport of compressed CsPbI3 and renders Fermi liquid (FL)-like behavior. By compressing δ-CsPbI3 to 80 GPa, an insulator-semimetal-metal transition occurs, concomitant with the completion of a slow structural transition from the one-dimensional Pnma (δ) phase to a three-dimensional Pmn21 (ε) phase. Deviation from FL behavior is observed upon CsPbI3 entering the metallic ε phase, which progressively evolves into a FL-like state at 186 GPa. First-principles density functional theory calculations reveal that the enhanced electron-electron coupling results from the sudden increase of the 5d state occupation in Cs and I atoms. Our study presents a promising strategy of cationic manipulation for tuning the electronic structure and carrier scattering of halide perovskites at high pressure. Halide perovskites display physical properties that are of both practical and fundamental interest. At high pressure, the low-temperature electrical transport in one such compound, CsPbI3, is now shown to be due to Cs-mediated electron-electron interactions resulting in Fermi-liquid-like behaviour. [ABSTRACT FROM AUTHOR]

Pacific Halibut Hippoglossus stenolepis captured in directed commercial longline fisheries in Canada and the USA that are below the legal minimum size for retention must be returned to the sea without incurring additional injury. Estimates of mortality caused by discarding sublegal‐sized fish are included in annual estimates of total mortality from all sources and affect the results of stock assessment and the yield available to fisheries. Currently, an average discard mortality rate (DMR) of 16% is applied to all sublegal‐sized longline discards. These discards consist of fish that suffer injuries ranging from minor to severe. The 16% DMR that is currently applied was derived by averaging injury‐specific DMRs that in turn assume 3.5% mortality of Pacific Halibut that are released to the sea with only minor injuries. The latter has been derived experimentally but only in captivity. Here, we used acceleration‐logging pop‐up archival transmitting tags to infer individual survival outcomes for Pacific Halibut that were released in situ following capture on longline gear. Postrelease behavioral data were evaluated for 75 fish that were at liberty for 2–96 d. Three fish were confidently inferred to have died after periods at liberty of 41–80 d, and another three fish may have died 96 d after release, resulting in minimum and maximum estimated 96‐d postrelease DMRs of 4.2% (range = 0.0–8.7%) and 8.4% (range = 1.7–14.6%), respectively. These ranges are consistent with the currently applied value of 3.5%. However, the observation that no mortalities occurred until after 40 d postrelease departs from the findings of captive studies, in which the majority of capture‐induced mortality occurred within 20 d of release. [ABSTRACT FROM AUTHOR]