Application of a one-dimensional model to vertical distributions of cod eggs on the northeastern Newfoundland Shelf

Abstract

A one-dimensional model is developed to describe the vertical distribution of cod eggs and larvae on the northeastern Newfoundland Shelf. The model is dependent on egg buoyancy, temperature-dependent development, and age-dependent changes in density for eggs in good and poor condition. The model was fit to physical oceanographic data from the inner and outer shelf collected in 1991. Output from the model compared favourably with field observations. Cod eggs (stages I to III) were bimodally distributed above and below 100 m depth. Late stage eggs (stage IV) and larvae (5–6 mm) were only abundant in surface waters (<50 m). There was a progression from deeper to shallower depths as cod eggs developed through to larvae. Cod eggs observed deeper in the water column were thought to be in poor condition and were probably sinking. The model demonstrates that the vertical distribution of cod eggs is sensitive to changes in water temperature, water density (salinity), and egg condition.