3,387 research outputs found
A resolution to the blue whiting (Micromesistius poutassou) population paradox?
No full textWe provide the strongest evidence to date supporting the existence of two independent blue whiting (Micromesistius poutassou (Risso, 1827)) populations in the North Atlantic. In spite of extensive data collected in conjunction with the fishery, the population structure of blue whiting is poorly understood. On one hand, genetic, morphometric, otolith and drift modelling studies point towards the existence of two populations, but, on the other hand, observations of adult distributions point towards a single population. A paradox therefore arises in attempting to reconcile these two sets of information. Here we analyse 1100 observations of blue whiting larvae from the Continuous Plankton Recorder (CPR) from 1948-2005 using modern statistical techniques. We show a clear spatial separation between a northern spawning area, in the Rockall Trough, and a southern one, off the Porcupine Seabight. We further show a difference in the timing of spawning between these sites of at least a month, and meaningful differences in interannual variability. The results therefore support the two-population hypothesis. Furthermore, we resolve the paradox by showing that the acoustic observations cited in support of the single-population model are not capable of resolving both populations, as they occur too late in the year and do not extend sufficiently far south to cover the southern population: the confusion is the result of a simple observational artefact. We conclude that blue whiting in the North Atlantic comprises two populations
The rise and fall of the NE Atlantic blue whiting (Micromesistius poutassou)
No full textThe Northeast Atlantic blue whiting (Micromesistius poutassou) stock has undergone striking changes in abundance in the last 15 years. The stock increased dramatically in the late 1990s due to a succession of eight unusually strong year classes and dropped again equally dramatically after 2005 when the recruitment collapsed to former levels. The North Atlantic subpolar gyre has previously been shown to have a strong influence on the behaviour of this stock: synchronous changes in the gyre and recruitment suggest a causal linkage and the possibility of forecasting recruitment. A range of mechanisms are reviewed that may explain these observed changes, with two major candidate hypotheses being identified. One hypothesis suggests that the large mackerel (Scomber scombrus) stock in this region may feed on the pre-recruits of blue whiting, with the spatial overlap between blue whiting and mackerel being regulated by the subpolar gyre. Alternatively, variations in the physical environment may have given rise to changes in the amount, type and availability of food for larvae and juveniles, impacting their growth and survival and therefore recruitment. It was not possible to draw firm conclusions about the validity of either of these hypotheses: nevertheless, forecasting recruitment to this stock may be possible in the future if the underlying mechanisms can be resolve
Is meaning fraught with ought?
No full textAccording to Normativism, what an expression means has immediate implications for how a subject should or may (not) employ that expression. Many view this thesis as imposing substantive constraints upon theories of linguistic meaning. In this paper, I shall not consider that view; instead, I shall address the prior issue of whether or not one should accept Normativism. Against certain recent prominent lines of attack common to a number of different anti-Normativist discussions, I shall defend both the Normativist thesis and an attempt to appeal to a certain platitude in its support
Letter from B. C. Whiting and J. B. McIntosh to E. S. Parker with letter from Henry Orman, 1869
No full textEnclosed letters from B. C. Whiting, J. B. McIntosh and Henry Orman Jr. in regards to James Haight's claim for services as blacksmith for Indian services in California
What is the normativity of Meaning?
No full textThere has been much debate over whether to accept the claim that meaning is normative. One obstacle to making progress in that debate is that it is not always clear what the claim amounts to. In this paper, I try to resolve a dispute between those who advance the claim concerning how it should be understood. More specifically, I critically examine two competing conceptions of the normativity of meaning, rejecting one and defending the other. Though the paper aims to settle a dispute among proponents of the claim that meaning is normative, it should be of interest to those who challenge it. After all, before one takes aim, one’s target needs to be in clear view
Comparisons between the biology of two species of whiting (Sillaginidae) in Shark Bay, Western Australia
No full textGolden-lined whiting Sillago analis and yellow-fin whiting Sillago schomburgkii were collected from waters within Shark Bay, which is located at ca 26ºS on the west coast of Australia. The number of circuli on the scales of S. analis was often less than the number of opaque zones in sectioned otoliths of the same fish. Furthermore, the number of annuli visible in whole otoliths of S. analis was often less than were detectable in those otoliths after sectioning. The magnitude of the discrepancies increased as the number of opaque zones increased. Consequently, the otoliths of S. analis were sectioned in order to obtain reliable estimates of age. The mean monthly marginal increments on sectioned otoliths of S. analis and S. schomburgkii underwent a pronounced decline in late spring/early summer and then rose progressively during summer and autumn. Since these trends demonstrated that opaque zones are laid down annually in the otoliths of S. analis and S. schomburgkii from Shark Bay, their numbers could be used to help age this species in this marine embayment.
The von Bertalanffy growth parameters, L_, k and to derived from the total lengths at age for individuals of S. analis, were 277 mm, 0.73 year-1 and 0.02 years, respectively, for females and 253 mm, 0.76 year-1 and 0.10 years, respectively. Females were estimated to attain lengths of 141, 211, 245 and 269 mm after 1, 2, 3 and 5 years, compared with 124, 192, 224 and 247 mm for males at the corresponding ages. The maximum ages recorded for females and males were 6 and 8 years, respectively, and the maximum lengths for females and males were 320 and 283 mm, respectively. The von Bertalanffy growth parameters derived from the total lengths at age of individuals of S. schomburgkii were 346 mm, 0.47 year-1 and -0.09 years, respectively, for females and 294 mm, 0.59 year-1 and -0.06 years, respectively, for males. Females initially grew at a similar rate as males, attaining total lengths of 139, 216, 265 and 296 mm after 1, 2, 3 and 4 years, compared with 136, 206, 245 and 266 mm for males at the corresponding ages. The maximum ages recorded for females and males were 10 and 9 years, respectively, and the maximum lengths for females and males were 383 and 299 mm respectively. The likelihood ratio test demonstrated that the growth curves of the females and males of both S. analis and S. schomburgkii in Shark Bay were significantly different (P < 0.001). Since, throughout the full range of ages, the differences between the estimated lengths at age for S. schomburgkii in the subtropical environment of Shark Bay and those recorded previously for this species over 800 km further south in temperate waters never exceeded 5%, any differences in the estimated lengths at age are too small to be of any biological significance.
Monthly trends exhibited by the gonadosomatic indices and prevalence of the different gonad maturity stages demonstrate that S. analis and S. schomburgkii both have protracted spawning periods from October to April and from August to March, respectively. Hyndes and Potter (1997) found females and males of S. schomburgkii with mature and spent ovaries at stages V-VII in six months, i.e. October to March, in temperate waters over 800 km further south on the lower west coast of Australia. Higher average water temperatures are thus accompanied by a longer spawning period.
Since the distributions of the oocyte diameters in the ovaries of mature females of both S. analis and S. schomburgkii in Shark Bay are essentially continuous, and as mature ovaries contain oocytes at different stages in development, including “intermediate” stages such as the cortical alveolar stage, these species have indeterminate fecundity. Thus, implicitly, S. analis and S. schomburgkii are also multiple spawners.
The females and males of S. analis typically attain maturity (L50) at 216 and 184 mm, respectively, and maturity is typically reached by the end of their fourth years of life. The L50s for female and male S. schomburgkii were 237 and 192 mm, respectively, and maturity is typically attained by the end of their fourth and third years of life, respectively. The above L50s for the females and males of S. schomburgkii in Shark Bay are very similar to those estimated by Hyndes and Potter (1997) for this species in temperate waters on the lower west coast of Australia. There are indications that the length at maturity for S. analis and S. schomburgkii in Shark Bay may have decreased during the last 30 years, which may represent a response of these two Sillago species to fishing pressure. Preliminary mortality estimates suggest that, in Shark Bay, S. analis is more heavily fished than S. schomburgkii
Inferentialism, representationalism and derogatory words
No full textIn a recent paper, after outlining various distinguishing features of derogatory words, Jennifer Hornsby suggests that the phenomenon raises serious difficulties for inferentialism. Against Hornsby, I claim that derogatory words do not pose any insuperable problems for inferentialism, so long as it is supplemented with apparatus borrowed from Grice and Hare. Moreover, I argue, derogatory expressions pose difficulties for Hornsby’s favoured alternative theory of meaning, representationalism, unless it too is conjoined with a similar Grice/Hare mechanism. So, the upshot of the discussion is that, contra Hornsby, focus on derogatory expressions alone does not provide grounds for deciding between competing theories of meaning, but nevertheless serves to highlight important features that any such theory must acknowledge and incorporate
Spatio-temporal patterns of whiting (Merlangius merlangus) in the Adriatic Sea under environmental forcing
No full textUnderstanding how environmental factors affect species distribution is crucial for the conservation and management of marine organisms, especially in the face of global changes. Whiting (Merlangius merlangus) is a demersal cold-temperate fish, considered a 'relict species' in the Adriatic Sea. Despite its significance to commercial fisheries in the region, the specific drivers behind its spatial and temporal patterns have not been thoroughly examined. Here, we fitted a set of Generalized Linear Mixed Effects Models to data collected in the Northern and Central Adriatic from 1999 to 2019 during the Mediterranean International Trawl Survey to investigate the potential influence of depth, seafloor temperature and seafloor dissolved oxygen on the annual biomass density and spatial distribution of whiting in the spring-summer season. Our results showed that depth, and to a lesser degree temperature and oxygen, are important predictors of whiting distribution in this period, with preferences for depths of ~ 45 m, temperature of ~ 15.4°C and dissolved oxygen > 5.5 ml L-1. We predicted a persistent core area of distribution in front of the Po River Delta, in the Northern Adriatic Sea, while the density progressively declined towards the Central and Southern Adriatic Sea along the Italian coast. Additionally, the temporal trend exhibited high fluctuations over the years, occurring in cycles of 3 to 4 years. Finally, by comparing the biomass density estimates obtained under optimal conditions with those derived from the actual values for each variable, our analysis revealed that temperature had a pronounced and general impact on biomass density in the northern survey area (predictions revealed a density reduction of approximately two-thirds), while oxygen displayed a minor and more localized influence. This work deepens the current knowledge about the ecology of whiting in the Adriatic Sea and provides support for the conservation and management of this species
Habitat selection in whiting
No full textGiven a choice of habitats in a laboratory experiment, whiting preferentially spent most time over sand, then gravel and least time over a habitat with emergent structures. The introduction of a predator stimulus increased the preference for the sand habitat for large whiting, whereas small whiting had an increased preference for the habitat with emergent structures
It's not what you said, it's the way you said it: slurs and conventional implicatures
No full textIn this paper, I defend against a number of criticisms an account of slurs, according to which the same semantic content is expressed in the use of a slur (e.g. 'chink') as is expressed in the use of its neutral counterpart (e.g. 'Chinese'), while in addition the use of a slur conventionally implicates a negative, derogatory attitude. Along the way, I criticise competing accounts of the semantics and pragmatics of slurs, namely, Hom's 'combinatorial externalism' and Anderson and Lepore's 'prohibitionism'
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