The behavioural diversity of Atlantic cod: insights into variability within and between individuals

Meager, Justin J.; Fernö, Anders; Skjæraasen, Jon Egil

doi:10.1007/s11160-017-9505-y

Cited by 23 publications

(16 citation statements)

References 232 publications

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“…Cod seemed to take advantage of the time-window when the combination of light levels and prey distribution was optimal for efficient visual hunting. Previous studies have shown that the diel feeding rhythms of cod are flexible (Meager et al 2018 and references therein), and optimal foraging theory predicts that predators should optimise the energy gained feeding per unit time relative to the energy spent for food search, capture and digestion (MacArthur & Pianka 1966). Cod diel cycle behaviour is most likely a reflection of such an optimisation (Løkkeborg et al 1989, Løkkeborg 1998).…”

Section: Discussionmentioning

confidence: 99%

Diel vertical movements determine spatial interactions between cod, pelagic fish and krill on an Arctic shelf bank

Skaret

Johansen

Johnsen

et al. 2020

Mar. Ecol. Prog. Ser.

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Predator-prey spatial interactions are essential to understand ecosystem processes like predation rates and trophic interaction strength. In marine systems, such spatial interactions are highly dynamic and difficult to observe, as predators, prey and resources are mobile and responsive to each other, and also since shifting vertical light gradients strongly affect the space use of visual predators and their prey. We visited a bank area in the northern Barents Sea with cold bottom waters (~1°C), and combined conventional trawl and acoustic sampling with broadband hydroacoustics to obtain long-range, fine-scale observations of interactions between cod, their planktivore prey (capelin and polar cod) and krill. We caught cod in demersal trawl hauls but could not detect them with the vessel acoustics. However, broadband acoustics mounted on a submersible probe allowed us to track individual cod, revealing that they remained mostly within 10 m of the bottom throughout the diel cycle. In the morning, cod lifted slightly from the seabed indicating feeding activity, which corresponded with more fresh prey in cod stomachs in the morning. During daylight, krill pushed towards the bottom, sharing habitat with cod, while the planktivores aggregated in pelagic schools at the cost of lost feeding opportunities, overlapping with their krill prey only during twilight hours. The diel light cycle was an important driver of the spatial movements and aggregations, and krill appear to hide from capelin among the cod near bottom, while cod take advantage of descending pelagic fish after dawn to feed with a minimum of effort.

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Section: Discussionmentioning

confidence: 99%

Diel vertical movements determine spatial interactions between cod, pelagic fish and krill on an Arctic shelf bank

Skaret

Johansen

Johnsen

et al. 2020

Mar. Ecol. Prog. Ser.

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“…We observed a higher mean C resp for the NEA cod stock relative to the Icelandic stock. NEA cod is known for its intensive migratory behavior [ 20 , 85 ]. The long-term physiological state of NEA cod associated with its migratory nature (i.e.…”

Section: Discussionmentioning

confidence: 99%

Differences in metabolic rate between two Atlantic cod (Gadus morhua) populations estimated with carbon isotopic composition in otoliths

et al. 2021

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The isotopic composition of inorganic carbon in otoliths (δ13Coto) can be a useful tracer of metabolic rates and a method to study ecophysiology in wild fish. We evaluated environmental and physiological sources of δ13Coto variation in Icelandic and Northeast Arctic (NEA) cod (Gadus morhua) over the years 1914–2013. Individual annual growth increments of otoliths formed at age 3 and 8 were micromilled and measured by isotope-ratio mass spectrometry. Simultaneously, all annual increment widths of the otoliths were measured providing a proxy of fish somatic growth. We hypothesized that changes in the physiological state of the organism, reflected by the isotopic composition of otoliths, can affect the growth rate. Using univariate and multivariate mixed-effects models we estimated conditional correlations between carbon isotopic composition and growth of fish at different levels (within individuals, between individuals, and between years), controlling for intrinsic and extrinsic effects on both otolith measurements. δ13Coto was correlated with growth within individuals and between years, which was attributed to the intrinsic effects (fish age or total length). There was no significant correlation between δ13Coto and growth between individuals, which suggests that caution is needed when interpreting δ13Coto signals. We found a significant decrease in δ13Coto through the century which was explained by the oceanic Suess effect-admixture of isotopically light carbon from fossil fuel. We calculated the proportion of the respired carbon in otolith carbonate (Cresp) using carbon isotopic composition in diet and dissolved inorganic carbon of the seawater. This approach allowed us to correct the values for each stock in relation to these two environmental baselines. Cresp was on average 0.275 and 0.295 in Icelandic and NEA stock, respectively. Our results provide an insight into the physiological basis for differences in growth characteristics between these two cod stocks, and how that may vary over time.

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“…The study of personality allowed us to work on behavioural differences between individuals and look for differences between cannibal fish and their conspecifics (Torres et al, 2017;Meager et al, 2018).…”

Section: Discussionmentioning

confidence: 99%

Is a cannibal different from its conspecifics? A behavioural, morphological, muscular and retinal structure study with pikeperch juveniles under farming conditions

Colchen

Gisbert

Ledoré

et al. 2020

Applied Animal Behaviour Science

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The behavioural diversity of Atlantic cod: insights into variability within and between individuals

Cited by 23 publications

References 232 publications

Diel vertical movements determine spatial interactions between cod, pelagic fish and krill on an Arctic shelf bank

Diel vertical movements determine spatial interactions between cod, pelagic fish and krill on an Arctic shelf bank

Differences in metabolic rate between two Atlantic cod (Gadus morhua) populations estimated with carbon isotopic composition in otoliths

Is a cannibal different from its conspecifics? A behavioural, morphological, muscular and retinal structure study with pikeperch juveniles under farming conditions

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