Temporal and geographic differences in feeding and nutritional condition of walleye pollock larvae Theragra chalcogramma in Shelikof Strait, Gulf of Alaska

Abstract

ABSTRACT. Feeding and nutritional condition of first-feeding walleye pollock larvae Theragra chalcogramma were compared to available prey levels measured during early spring (late April-early May) and mid-spring (mid-May) 1989. In early spring, feeding intensity, mean RNNDNA values of larvae, and microzooplankton abundance were higher within a large patch of larvae compared with areas outside the patch. In mid-spring, microzooplankton prey abundance, feedmg levels and RNA/DNA of larvae m and out of the previously defined patch were higher, indicating better overall conditions for growth than in early spring. The results suggest that limiting food densities may occur during spring over spatial and temporal scales that affect feeding and growth of larval pollock.

Parental effects in the European sardine Sardina pilchardus

“…Limitation of food is one of the most important factors determining survival during the larval stage (Cushing 1975). Canino et al (1991) demonstrated that when the spawning is not linked to an abundance of food, the lower concentrations of available food are insufficient to maintain optimum growth rates of larvae beginning to feed. This has considerable implications for the feeding rate and, therefore, the survival rate.…”

“…In natural populations, starvation is thought to be one of the main causes of larval mortality when the larvae move towards exogenous feeding (Canino et al 1991, Bailey et al 1995. Hence, the quantity and composition of vitellus that the egg and/or larva possesses can be of considerable importance as an eventual determinant of larval condition in the first days of life and, therefore, may influence mortality in situations of food limitation (Srivastava & Brown 1991, Brown & Taylor 1992, Riveiro et al 2000.…”

The effect of food availability, age or size on the RNA/DNA ratio of individually measured herring larvae: laboratory calibration

“…The RNA/DNA ratios of herring larvae of unknown condition can be compared with ratios found in fed larvae or with RNA/DNA ratios determined in starving larvae. Since it is easier to define starvation situations under laboratory conditions in which food is withdrawn completely rather than to define good Hovenkamp 1990Clemmesen 1987Richard et al 1991Canino et al 1991 feeding conditions, it seems advisable to compare RNA/ DNA values from larvae caught in the field with ratios found in larvae deprived of food in the laboratory. It is also more important for the recruitment problem to show food limitation or badly nourished larvae than to define well fed larvae.…”

Small-scale patterns in distribution and feeding of Atlantic mackerel ( Scomber scombrus L.) larvae in the Celtic Sea with special regard to intra-cohort cannibalism

“…In these larger length classes larval fish are the most important prey type, contributing substantially more to the larval gut weight and, thus, to an increased estimate for the daily ration. In addition, daily ration estimates were obtained using a variation of Bajkov's model (Bajkov 1935;Canino et al 1991). In the present study we used Elliott and Persson's (1978) model, as in a comparison of different models used to estimate daily ration, they concluded that Bajkov's model, even though widely used, cannot be recommended since it grossly underestimates daily food consumption.…”