Foraging behaviour of larval cod (Gadus morhua) at low light intensities
نویسندگان
چکیده
The ability to forage at low light intensities can be of great importance for the survival of fish larvae in a pelagic environment. Three-dimensional silhouette imaging was used to observe larval cod foraging and swimming behaviour at three light intensities (dusk ~1.36 × 10-3 W/m2, night ~1.38 × 10-4 W/m2 and darkness ~3.67 × 10-6 W/m2) at 4 different ages from 6 to 53 days post-hatch (dph). At 6 dph, active pursuit of prey was only observed under dusk conditions. Attacks, and frequent orientations, were observed from 26 dph under night conditions. This was consistent with swimming behaviour which suggested that turn angles were the same under dusk and night conditions, but lower in darkness. Cod at 53 dph attacked prey in darkness and turn angles were not different from those under other light conditions. This suggests that larvae are still able to feed at light intensities of 3.67 × 10-6 W/m2. We conclude that larval cod can maintain foraging behaviour under light intensities that correspond to night-time at depths at which they are observed in the field, at least if they encounter high-density patches of prey such as those that they would encounter at thin layers or fronts.
منابع مشابه
Modeling growth of larval cod (Gadus morhua) in large-scale seasonal and latitudinal environmental gradients
Spawning of Northeast Arctic (NA) cod stretches from late February to early May over 1500km along the Norwegian coast. Hatching occurs from late March to late May, a period when the number of daylight hours increases from 11 to 17. Larval feeding opportunities are constrained by prey abundance and environmental variables such as light, while temperature determines the maximum growth potential. ...
متن کاملProcess-based models of feeding and prey selection in larval fish
Feeding success is essential to larval fish survival. We present detailed mechanistic models of the foraging processes (prey encounter, approach, pursuit, and capture) in larval fish, where all parameters have explicit physical or biological meaning. The model is a unification of the processes believed to be important to prey selectivity and environmental regulation of feeding in fish. We inclu...
متن کاملEffect of food deprivation on distribution of larval and early juvenile cod in experimental vertical temperature and light gradients
How and when food limits the growth and survival of larval fish are essential questions which link oceanography and fisheries science, and theory suggests that food availability may affect survival through behavioural responses. We tested the effect of food deprivation on the vertical distribution of larval cod Gadus morhua in light and temperature gradients during larval and early juvenile sta...
متن کاملImpacts of regular and random noise on the behaviour, growth and development of larval Atlantic cod (Gadus morhua)
Anthropogenic noise impacts behaviour and physiology in many species, but responses could change with repeat exposures. As repeat exposures can vary in regularity, identifying regimes with less impact is important for regulation. We use a 16-day split-brood experiment to compare effects of regular and random acoustic noise (playbacks of recordings of ships), relative to ambient-noise controls, ...
متن کامل