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1.
Environ Pollut ; 344: 123322, 2024 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-38211875

RESUMO

Marine vibrators are a new technology being developed for seismic surveys. These devices can transmit continuous instead of impulsive sound and operate over a narrower frequency band and at lower peak pressure than airguns, which is assumed to reduce their environmental impacts. We exposed spawning Atlantic cod (Gadus morhua) to sound produced by a prototype, but full-scale, marine vibrator, and monitored behavioural responses of tagged cod using acoustic telemetry. Fish were exposed to 10 × 3 h continuous sound treatments over a 4-day period using a randomised-block design. Sound exposure levels were comparable to airgun exposure experiments conducted previously with the same set-up ranging from ∼115 to 145 dB re 1 µPa2s during exposure. Telemetry data were used to assess 1) whether marine vibrator exposure displaced cod from the spawning ground, through estimation of residence and survival probabilities, and 2) fine-scale behavioural responses within the test site, namely swimming depth, activity levels, displacement, and home ranges. Forty-two spawning cod were tagged prior to the exposure, with 22 present during the exposure. All 22 tags were equipped with pressure sensors and ten of these additionally with accelerometers. While no premature departure from the spawning site was observed, cod reacted to the exposure by decreasing their activity levels (by up to 50%, SE = 7%) and increasing their swimming depth (by up to 2.5 m, SE = 1.0 m) within the test site during the exposure period. These behavioural responses varied by sex and time of day. Cod reactions to a marine vibrator may be more pronounced than reactions to airguns, possibly because continuous sound is more disturbing to fish than intermittent sound at the same exposure levels. However, given sample size limitations of the present study, further studies with continuous sound are necessary to fully understand its impact and biological significance.


Assuntos
Gadus morhua , Animais , Acústica , Meio Ambiente , Peixes , Gadus morhua/fisiologia , Som , Comportamento Animal
2.
Science ; 382(6675): 1181-1184, 2023 12 08.
Artigo em Inglês | MEDLINE | ID: mdl-38060630

RESUMO

The Earth's ecosystems are increasingly deprived of large animals. Global simulations suggest that this downsizing of nature has serious consequences for biosphere functioning. However, the historical loss of large animals means that it is now often impossible to secure empirical data revealing their true ecological importance. We tracked 465 mature Atlantic cod (Gadus morhua) during their winter spawning season and show that large females (up to 114 centimeters in length), which are still found in mid-Norway, were characterized by more complex movement networks compared with smaller females. Large males were sparse but displayed similar movement patterns. Our finding implies that management programs promoting large fish will have positive impacts on population resilience by facilitating the continued use of a diversity of spawning habitats and the connectivity between them.


Assuntos
Gadus morhua , Aquecimento Global , Animais , Feminino , Masculino , Ecossistema , Gadus morhua/anatomia & histologia , Gadus morhua/crescimento & desenvolvimento , Noruega , Tamanho Corporal
3.
J Anim Ecol ; 92(10): 1966-1978, 2023 10.
Artigo em Inglês | MEDLINE | ID: mdl-37485731

RESUMO

Movement diversity within species represent an important but often neglected, component of biodiversity that affects ecological and genetic interactions, as well as the productivity of exploited systems. By combining individual tracking data from acoustic telemetry with novel genetic analyses, we describe the movement diversity of two Atlantic cod Gadus morhua ecotypes in two high-latitude fjord systems: the highly migratory Northeast Arctic cod (NEA cod) that supports the largest cod fishery in the world, and the more sedentary Norwegian coastal cod, which is currently in a depleted state. As predicted, coastal cod displayed a higher level of fjord residency than NEA cod. Of the cod tagged during the spawning season, NEA cod left the fjords permanently to a greater extent and earlier compared to coastal cod, which to a greater extent remained resident and left the fjords temporarily. Despite this overall pattern, horizontal movements atypical for the ecotypes were common with some NEA cod remaining within the fjords year-round and some coastal cod displaying a low fjord fidelity. Fjord residency and exit timing also differed with spawning status and body size, with spawning cod and large individuals tagged during the feeding season more prone to leave the fjords and earlier than non-spawning and smaller individuals. While our results confirm a lower fjord dependency for NEA cod, they highlight a movement diversity within each ecotype and sympatric residency between ecotypes, previously undetected by population-level monitoring. This new knowledge is relevant for the management, which should base their fisheries advice for these interacting ecotypes on their habitat use and seasonal movements.


Assuntos
Gadiformes , Gadus morhua , Humanos , Animais , Ecótipo , Simpatria , Gadus morhua/genética , Biodiversidade
4.
J Fish Dis ; 41(12): 1909-1915, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30294909

RESUMO

This study describes radiological malformations in the vertebral column of adult sexually mature wild haddock, Melanogrammus aeglefinus collected from Masfjorden, Western Norway, in 2014 and 2015. There were seven deformed fish (33% of sampled fish), five with mild deformities and two with severe deformities. The deformity types discovered were lordosis, vertebra body asymmetry, compression, fusion (ankylosis), remodelling, and haemal spine hyperostosis. The two severely deformed fish were as follows: (a) one specimen with 29 deformed vertebrae within the region vertebrae nos. 1-30, including two sites of lordosis; (b) one specimen with 15 deformed vertebrae within the region vertebrae nos. 31-52 (most caudal vertebrae). The results of this study show that wild haddock can survive severe vertebra deformities, both in the trunk and tail region, and reach adulthood and sexual maturity. Whether normal nondeformed wild conspecifics would mate and spawn with these individuals and thereby complete the life cycle of the deformed individuals is, however, unknown. A possible link between bone fracture and fish hyperostosis is discussed.


Assuntos
Gadiformes/anatomia & histologia , Coluna Vertebral/anormalidades , Animais , Feminino , Gadiformes/crescimento & desenvolvimento , Masculino , Noruega , Radiografia/veterinária , Coluna Vertebral/diagnóstico por imagem
5.
Artigo em Inglês | MEDLINE | ID: mdl-25882085

RESUMO

Artificial triploid salmonids are sterile and therefore commercially bred to prevent genetic interactions between wild and domestic fish strains. The full biological effects of having an extra chromosome set are largely unknown, but triploids are considered to be more sensitive to sub-optimal environmental conditions and to be stressed by the presence of diploid conspecifics. Brain serotonergic and dopaminergic activity are known to regulate the stress response in vertebrates, but monoamine systems in diploid and triploid fish have yet to be compared. Here we study monoamine neurochemistry in the telencephalon and brain stem of juvenile diploid and triploid Atlantic salmon (Salmo salar) in response to stress (unstressed vs stressed individuals) and holding (separate- vs mixed-ploidy) conditions. Both diploids and triploids showed an increase in serotonergic activity following stress, but the increase was significantly greater in the telencephalon of triploids compared to diploids. Furthermore, while telencephalic dopaminergic activity was significantly increased in diploids following stress, there was no response in triploids. Holding conditions had a significant effect on dopaminergic activity in the brain stem of diploids only, with lower values in mixed- compared to separate-ploidy conditions. These results suggest artificially produced triploids experience increased reactivity and monoaminergic dysregulation following stress that may impede their welfare and performance.


Assuntos
Dopamina/metabolismo , Salmo salar/metabolismo , Serotonina/metabolismo , Adaptação Fisiológica , Animais , Tronco Encefálico/citologia , Tronco Encefálico/metabolismo , Neurônios Dopaminérgicos/metabolismo , Feminino , Masculino , Salmo salar/genética , Neurônios Serotoninérgicos/metabolismo , Estresse Fisiológico , Telencéfalo/citologia , Telencéfalo/metabolismo , Triploidia
6.
Proc Natl Acad Sci U S A ; 111(9): 3478-83, 2014 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-24550465

RESUMO

The widespread depletion of commercially exploited marine living resources is often seen as a general failure of management and results in criticism of contemporary management procedures. When populations show dramatic and positive changes in population size, this invariably leads to questions about whether favorable climatic conditions or good management (or both) were responsible. The Barents Sea cod (Gadus morhua) stock has recently increased markedly and the spawning stock biomass is now at an unprecedented high. We identify the crucial social and environmental factors that made this unique growth possible. The relationship between vital rates of Barents Sea cod stock productivity (recruitment, growth, and mortality) and environment is investigated, followed by simulations of population size under different management scenarios. We show that the recent sustained reduction in fishing mortality, facilitated by the implementation of a "harvest control rule," was essential to the increase in population size. Simulations show that a drastic reduction in fishing mortality has resulted in a doubling of the total population biomass compared with that expected under the former management regime. However, management alone was not solely responsible. We document that prevailing climate, operating through several mechanistic links, positively reinforced management actions. Heightened temperature resulted in an increase in the extent of the suitable feeding area for Barents Sea cod, likely offering a release from density-dependent effects (for example, food competition and cannibalism) through prolonged overlap with prey and improved adult stock productivity. Management and climate may thus interact to give a positive outlook for exploited high-latitude marine resources.


Assuntos
Clima , Conservação dos Recursos Naturais/métodos , Pesqueiros/métodos , Gadus morhua/crescimento & desenvolvimento , Análise de Variância , Animais , Geografia , Oceanos e Mares , Dinâmica Populacional
7.
Proc Natl Acad Sci U S A ; 109(23): 8995-9, 2012 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-22615381

RESUMO

Life-history theory suggests that animals may skip reproductive events after initial maturation to maximize lifetime fitness. In iteroparous teleosts, verifying past spawning history is particularly difficult; the degree of skipped spawning at the population level therefore remains unknown. We unequivocally show frequent skipped spawning in Northeast Arctic cod (NEAC) in a massive field and laboratory effort from 2006 to 2008. This was verified by postovulatory follicles in temporarily arrested ovaries close to the putative spawning period. At the population level, "skippers" were estimated to be approximately equally abundant as spawning females in 2008, constituting ∼24% of the females 60-100 cm. These females never truly started vitellogenesis and principally remained on the feeding grounds when spawners migrated southward, avoiding any migration costs. The proximate cause of skipping seems to be insufficient energy to initiate oocyte development, indicating that skipped spawning may partly be a density-dependent response important in population regulation. Our data also indicate more skipping among smaller females and potential tradeoffs between current and future reproductive effort. We propose that skipped spawning is an integral life-history component for NEAC, likely varying annually, and it could therefore be an underlying factor causing some of the currently unexplained large NEAC recruitment variation. The same may hold for other teleosts.


Assuntos
Gadus morhua/fisiologia , Reprodução/fisiologia , Comportamento Sexual Animal/fisiologia , Análise de Variância , Animais , Regiões Árticas , Tamanho Corporal , Análise Discriminante , Feminino , Fígado/crescimento & desenvolvimento , Oogênese/fisiologia , Tamanho do Órgão , Folículo Ovariano/fisiologia , Ovário/crescimento & desenvolvimento , Dinâmica Populacional
8.
Physiol Behav ; 106(4): 462-70, 2012 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-22465310

RESUMO

Much of the inter-individual variation observed in animal behaviour is now attributed to the existence of behavioural phenotypes or animal personalities. Such phenotypes may be fundamental to fisheries and aquaculture, yet there have been few detailed studies of this phenomenon in exploited marine animals. We investigated the behavioural and neuroendocrine responses of Atlantic cod (Gadus morhua L.), to situations reflecting critical ecological challenges: predator attacks and territorial challenges. Both hatchery-reared and wild fish were tested and behavioural profiles were compared with baseline conditions. We then used an objective, multivariate approach, rather than assigning individuals along one-dimensional behavioural axes, to examine whether distinct behavioural phenotypes were present. Our results indicate that two distinct behavioural phenotypes were evident in fish from each background. In hatchery-reared fish, phenotypes displayed divergent locomotor activity, sheltering, brain monoamine concentrations and responses to competitive challenges. In wild fish, phenotypes were distinguished primarily by locomotor activity, sheltering and responsiveness to predator stimuli. Hatcheries presumably represent a more stressful social environment, and social behaviour and neuroendocrine responses were important in discerning behavioural phenotypes in hatchery fish, whereas antipredator responses were important in discerning phenotypes in wild fish that have previously encountered predators. In both fish types, behavioural and physiological traits that classified individuals into phenotypes were not the same as those that were correlated across situations. These results highlight the multidimensionality of animal personalities, and that the processes that regulate one suite of behavioural traits may be very different to the processes that regulate other behaviours.


Assuntos
Comportamento Animal/fisiologia , Gadus morhua/fisiologia , Adaptação Psicológica/fisiologia , Animais , Aquicultura , Monoaminas Biogênicas/metabolismo , Comportamento Competitivo/fisiologia , Pesqueiros , Crescimento/fisiologia , Individualidade , Atividade Motora/fisiologia , Sistemas Neurossecretores/fisiologia , Tamanho do Órgão/fisiologia , Fenótipo , Comportamento Predatório , Análise de Componente Principal , Territorialidade
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