Factors influencing distribution of juvenile yellowtail flounder ( Limanda ferruginea) on the grand bank of Newfoundland

Abstract

On the Grand Bank, off the coast of Newfoundland, yellowtail flounder is at its northern limit in abundance. The population is relatively sedentary and has formed the basis of a traditional trawler fishery since the middle 1960s. However, very little is known about this species' early life history stages and ecology. Beginning in 1985, bottom trawl surveys have been conducted annually to determine distribution and abundance of juvenile yellowtail flounder on the Grand Bank. It was found that both juveniles and adults maintained their shallow water depth distribution despite wide fluctuations in temperature. Based on the analyses of the distribution of age-1 group and older juveniles (up to 4 years) and incorporating historical information on egg and larval surveys, physical oceanography and substrate type in the region it was found that all early life history stages were retained in the same geographic area, on and adjacent to the Southeast Shoal on the southern Grand Bank. It is suggested that passive retention of eggs and larvae is related to a weak current regime on the southern Grand Bank. Age-1 group and older juveniles were consistently found on a sandy substrate in the same area, indicating that sediment size is an important factor influencing distribution. These observed patterns of distribution of eggs, larvae, and juveniles points to the Southeast Shoal area as being an oceanic nursery site for Grand Bank yellowtail flounder. But unlike the well-published North Sea coastal nurseries, this oceanic nursery also contains newly settled juveniles, older juveniles, and adults.