Gas secretion and resorption in the swimbladder of the codGadus morhua

Jones, Frank; Scholes, P.

doi:10.1007/bf00687474

Cited by 71 publications

(81 citation statements)

References 31 publications

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“…The model is based on calculations of the swimbladder volume, the maximum rates of gas secretion and absorption (Harden Jones and Scholes 1985), and the rate of leakage through the swimbladder wall (Lapennas and Schmidt-Nielsen 1977). If the cod moves vertically faster that the swimbladder can accommodate by secretion or absorption of gases, the cod will experience a buoyant force (Archemdes' principle), working either upwards (floating) or downwards (sinking).…”

Section: Swimbladder Regulationmentioning

confidence: 99%

“…Other factors may indirectly constrain the behavior of cod. For example, cod has a closed swimbladder with slow gas exchange (Harden Jones and Scholes 1985). Swimbladder gas content puts restrictions on the distance and speed at which cod can change depth, as the swimbladder will be damaged or will burst if the pressure is decreased by 50%-70% (Tytler and Blaxter 1973).…”

Section: Introductionmentioning

confidence: 99%

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Vertical migration in adult Atlantic cod (Gadus morhua)

Strand¹,

Huse²

2007

Can. J. Fish. Aquat. Sci.

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Abstract:We investigate the trade-offs associated with vertical migration and swimming speed of Atlantic cod (Gadus morhua) using an adaptive individual-based model. Simulations with varying distribution and occurrence of prey, with and without swimbladder constraints, and visual predation were performed. Most simulations resulted in cod migrations between the bottom and pelagic zones. In simulations with high probability of encountering pelagic prey, the cod spent the daytime in the pelagic zone, moving to the bottom to feed only when no pelagic prey were encountered. At night the cod stayed in the pelagic zone to attain neutral buoyancy. In simulations with low occurrence of pelagic prey or high visual predation pressure, the cod remained at the bottom feeding on the consistently present benthic prey. If the pelagic prey occurred far above the sea floor or there were no benthic prey, the cod abandoned all bottom contact. The study thus predicts that the probability of encountering energy-rich pelagic prey is the key factor in driving vertical migration in adult cod. Buoyancy regulation is further shown to be an important constraint on vertical migration. Résumé :Nous examinons les compromis associés à la migration verticale et la vitesse de nage chez la morue franche (Gadus morhua) à l'aide d'un modèle adaptatif basé sur l'individu. Nous avons procédé à des simulations comprenant des répartitions et des présences variables des proies, avec et sans contraintes sur la vessie natatoire et une prédation visuelle. Le résultat de la plupart des simulations comprend une migration des morues entre le fond et la zone péla-gique. Dans les simulations avec une forte probabilité de rencontre de proies pélagiques, les morues passent la journée dans la zone pélagique et se déplacent vers le fond pour se nourrir seulement s'il ne trouvent pas de proies pélagiques. La nuit, les morues demeurent dans la zone pélagique pour maintenir une flottabilité neutre. Dans les simulations avec une faible présence de proies pélagiques ou avec une forte pression de prédation visuelle, les morues restent sur le fond à se nourrir des proies benthiques qui sont toujours présentes. Si les proies pélagiques se trouvent loin du fond de la mer ou s'il n'y a pas de proies benthiques, les morues abandonnent tout contact avec le fond. Notre étude permet donc de prédire que la probabilité de rencontrer des proies pélagiques riches en énergie est le facteur essentiel qui régit la migration verticale chez les morues adultes. Elle montre aussi que le contrôle de la flottabilité constitue une contrainte importante pour la migration verticale.[Traduit par la Rédaction] Strand and Huse 1760

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Section: Swimbladder Regulationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Vertical migration in adult Atlantic cod (Gadus morhua)

Strand¹,

Huse²

2007

Can. J. Fish. Aquat. Sci.

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“…As a further restriction on H cod , the depth at which pressure was 75% of the pressure at the bottom was used as the upper boundary of the free vertical range. Cod that are neutrally buoyant at bottom depth would have to use energy to maintain depth outside this free vertical range (Harden-Jones & Scholes 1985). Potential encounter volumes were obtained using the same integration method as that for H cod , but using the threshold values for herring and sprat.…”

Section: Methodsmentioning

confidence: 99%

Environmentally driven predatorprey overlaps determine the aggregate diet of the cod Gadus morhua in the Baltic Sea

Neuenfeldt¹,

Beyer²

2006

Mar. Ecol. Prog. Ser.

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Aquatic ecosystems are environmentally heterogeneous with features such as fronts or clines of temperature and salinity. This heterogeneity varies over time and is likely to cause changes in predator-prey overlaps, which will affect the diet composition of the predators. We investigated how inflows of oxygenated and saline deep water alternating with stagnation periods affect the consumption rates of the herring Clupea harengus L. and the sprat Sprattus sprattus L. by the cod Gadus morhua in the Bornholm basin of the Baltic Sea. We developed conceptual models for the effect of predator-prey overlaps on the aggregate diet of the predator population to test the hypothesis that the effects of inflows on the aggregate diet are mediated by changes in cod -clupeid overlaps. After estimating salinity and oxygen thresholds of the spatial distributions of cod and clupeids and calculating cod -clupeid overlaps from March 1958 to 2004, we applied the models relating cod -clupeid overlaps to observed numbers and masses of herring and sprat in cod stomachs. Our study indicated that (1) the ratio of consumed herring to sprat increases faster than proportionally to the ratio of cod -herring to cod -sprat overlaps, and (2) the ratio of consumed herring to sprat increases slower than proportionally to the ratio of herring to sprat in the sea. The latter is most pronounced at the low ratios of overlaps that occur during stagnation periods, which destabilise the clupeid populations, and may have contributed to the drastic increase in the sprat abundance during the late 1980s.KEY WORDS: Predator-prey overlap · Salinity threshold · Oxygen threshold · Aggregate diet · Apparent negative switching · Atlantic cod · Baltic SeaResale or republication not permitted without written consent of the publisher

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“…Ocean currents can provide a transport mechanism and/or directional clues to marine ®shes that undertake long distance migrations (Harden Jones, 1968;Arnold, 1981;Rose, 1993;Arnold and Metcalfe, 1995). Swimming with currents provides energetic bene®ts to ®sh migrating to their spawning ground, theoretically saving energy which can be used for reproduction (Weihs, 1978;Metcalfe et al, 1990).…”

Section: Introductionmentioning

confidence: 99%

“…Cod adapted to deep water and raised to the surface may have greatly expanded or ruptured swim bladders, losing the ability to maintain neutral buoyancy (Harden Jones and Scholes, 1985;Arnold and Greer Walker, 1992). Therefore, only ®sh that appeared uninjured in the holding tank were selected for tagging.…”

mentioning

confidence: 99%

Response of individual shoaling Atlantic cod to ocean currents on the northeast Newfoundland Shelf

et al. 2000

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The movements of sonically-tagged Atlantic cod swimming within a large (80,000 mt) shoal of post-spawning ®sh on the northeast Newfoundland Shelf were related to the acoustically determined position of the shoal and event structure in the local ocean currents. For the ®rst several days of the study, a period when currents were unfavorable for shoreward transport, the tagged ®sh maintained station. There was little net movement of individual ®sh and no change in the geographical location of the shoal. Then, apparently in response to a shoreward current event, the cod moved with the¯ow. The tagged cod behaved as members of the shoal, in that their net movement was similar to that of the shoal itself. These observations further support the hypothesis that cod on the northeast Newfoundland Shelf selectively use currents for transport during their shoreward feeding migration. The cue to initiate migration by post-spawning cod is apparently an organized onshore¯ow exceeding a threshold velocity and duration. #

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Gas secretion and resorption in the swimbladder of the codGadus morhua

Cited by 71 publications

References 31 publications

Vertical migration in adult Atlantic cod (Gadus morhua)

Vertical migration in adult Atlantic cod (Gadus morhua)

Environmentally driven predatorprey overlaps determine the aggregate diet of the cod Gadus morhua in the Baltic Sea

Response of individual shoaling Atlantic cod to ocean currents on the northeast Newfoundland Shelf

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Gas secretion and resorption in the swimbladder of the codGadus morhua

Cited by 71 publications

References 31 publications

Vertical migration in adult Atlantic cod (Gadus morhua)

Vertical migration in adult Atlantic cod (Gadus morhua)

Environmentally driven predatorprey overlaps determine the aggregate diet of the cod Gadus morhua in the Baltic Sea

Response of individual shoaling Atlantic cod to ocean currents on the northeast Newfoundland Shelf

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Environmentally driven predatorprey overlaps determine the aggregate diet of the cod Gadus morhua in the Baltic Sea