Condition of Atlantic cod Gadus morhua larvae after the transition to exogenous feeding: morphometries, buoyancy and predator avoidance

Abstract

The condition of Atlantic cod Gadus morhua L. larvae reared in densities of 0, 2, 5 and 10 zooplankton ml-l was examined after the transition to exogenous feeding. Fulton's K (weight/length3) was not correlated with prey density in which larvae were reared, indicating that this index of condition is inappropriate for larvae immediately after yolk sac absorption. Fulton's K was also not positively correlated with the ability to avoid a simulated predator. However, predation avoidance was positively correlated with higher prey density. A second measure of condition, body height standardized for length, appeared to be a more sensitive indicator of condition but also did not correlate with the ability of larvae to avoid predation. The results of a buoyancy experiment indicated that poorly fed larvae may occur higher in the water column, and thus may be more vulnerable to predation or cause a sampling bias in ichthyoplankton studies.

Influence of starvation on the critical swimming behaviour of the Senegalese sole (<i>Solea senegalensis</i>) and its relationship with RNA/DNA ratios during ontogeny

“…Larvae with a low nutritional status will consequently be smaller, weaker and less developed with regard to sensory and locomotory capacities than well-fed larvae of the same age, thus being more susceptible to predation (but see Billerbeck et al, 2001). For a variety of fish species (herring, hake, cod, flounder, anchovy, striped bass), it has been shown that starved larvae are more susceptible to predation than fed larvae (Bailey, 1984;Neilson et al, 1986;Yin and Blaxter, 1987;Booman et al, 1991). Several studies indicate that high larval condition can be correlated with increased growth rate and enhanced recruitment or juvenile survival under natural conditions (Searcy and Sponaugle, 2001;Sponaugle et al, 2006), but few attempts have been made to correlate larval condition with any behavioural function critical for larval survival, such as swimming behaviour (e.g.…”

Effects of starvation on swimming performance and body condition of pre-settlement Sparus aurata larvae

“…Predation and starvation are considered to be the 2 major causes of mortality in larval fishes (Miller et al 1988, Bailey & Houde 1989. These 2 factors can act together to increase mortality rates, as starved or underfed larvae may be more susceptible to predation (Neilson et al 1986). Some evidence suggests that general activity or vertical migratory activity declines in starved larvae of several species (Laurence 1972, Blaxter & Ehrlich 1974.…”

Production of fish larvae and their prey in subarctic southeastern Hudson Bay

“…Negative residuals indicated larvae in poor condition relative to the overall average condition of the population during the sampling season. Comparative studies have shown that morphometric indices are generally good indicators of true condition as measured by histological or biochemical indices or of the known condition of starved larvae (Ehrlich et al 1976, Nielson et al 1986, Theilacker 1986, Yin & Blaxter 1986, SetzlerHamilton et al 1987.…”

“…To avoid a systematic bias in morphometric measurements, all larvae were measured within an interval of 6 to 8 wk after capture and fixation. The residuals of the linear regression of body height above the anus (a dimension sensitive to starvation) against total length (a dimension less sensitive to starvation) were used to assess the relative emaciation of the yolk-sac larvae and postlarvae of a given species (Wyatt 1972, Ehrlich et al 1976, Koslow et al 1985, Nielson et al 1986, Yin & Blaxter 1986. Negative residuals indicated larvae in poor condition relative to the overall average condition of the population during the sampling season.…”