Occurrence of Eggs of Bass Dicentrarchus Labra X on the Southern Coasts of Ireland

Extract

During April-June, 1967, tow-netting for bass eggs was carried out at four places on the Irish coast. Small numbers of bass eggs were obtained at two of these places, namely the Splaugh Rock, near Greenore Point, Co. Wexford and Youghal Harbour, Co. Cork. They were taken near the surface, in water of the salinity range 30–34.5%, and of surface temperature range 10.5–13.2°C.

The Irish material was larger than described by Bertolini (1933) from the Mediterranean, but smaller than described by Jackman (1954), who hatched eggs spawned in the Plymouth Laboratory Aquarium and described the larvae.

Introduction

Bass have spawned in the aquarium at Naples, and their eggs have been found in plankton in the Mediterranean (Raffaele, 1888; Bertolini, 1933). Bass have also spawned in the aquarium at Plymouth, and their eggs and the resulting young stages have been described by Jackman (1954).

Hitherto, however, the eggs of bass do not appear to have been found on the coasts of Britain or Ireland. The only young stages recorded were 14 post-larvae from 4 to 7.5 mm long, taken in the Eddystone area in the years 1925, 1926, 1931 and 1933, with dates of capture between 17 March and 4 June (Russell, 1935).

As part of a programme of research on the biology of bass in Irish waters, tow-netting was carried out in 1967 at the Splaugh Rock off the Wexford coast; at Dungarvan, Co. Waterford; at Youghal, Co. Cork; and at Baltimore, Co. Cork (Fig. 1). The Splaugh, Dungarvan and Youghal are places where bass ‘shoal’; that is, frequently gather in shoals to attack sand-eels, herring fry or sprats at the surface.