Welsh Journals

NOTES ON THE BIOLOGY OF THE LEOPARD-SPOTTED GOBY IN WALES P. WIRTZ. R. HOARE. K. HISCOCK INTRODUCTION The Leopard-spotted Goby Thorogobius ephippiatus (Lowe) was first discovered in Britain in 1955. With the further use of diving for biological work, the number of records of the species increased and in 1969 Miller recorded 31 localities in the British Isles indicating that the species has a widespread distribution and is locally common. Thorogobius ephippiatus is easily recognised by its characteristic coloration of conspicuous orange or brick-red spots evenly dispersed on a light brown background. The species attains a maximum size of 13 cm. and an age of 9 years and feeds mainly on a variety of small benthic invertebrates. Typically, it occurs in or near crevices associated with vertical rock faces from LWST to 40 m. (Miller 1969). Investigations over the past three years from the Marine Science Laboratories at Menai Bridge have determined the distribution of T. ephippiatus in North Wales and have added to the information available on the habits and habitat of the species. Observations were made whilst diving and individual specimens were collected with the aid of the anaesthetic quinaldine (Gibson 1967). DISTRIBUTION Fig. 1 shows the recorded distribution of the species in North Wales. At most sites, only two or three specimens were observed during the course of a dive (usually about 30 minutes). On a thorough search at two sites (Llanbadrig and Porth Ysgadan) up to 40 specimens were counted during a 60 minute dive. Absences have only been included in Fig. 1 where the species has not been recorded during a large number of dives or during a thorough search. The distribution is discontinuous and T. ephippiatus appears to be absent from the south-east coast of Anglesey and from the Menai Strait around to Llanddwyn Island. The discontinuous distribution does not correspond to that described by Crisp and Knight-Jones (1954) for intertidal species, many of which do not occur east of the Carmel Head region (NW Anglesey). The higher turbidity, lower wave action, and lower winter temperature of the east coast of Anglesey compared to the west coast are not considered important, since the species does occur at Ynys Moelfre. The vigorous tidal streams within the Menai Strait might be unsuitable for the species, but T. ephippiatus has been found in Bardsey Sound where the tidal streams reach a similar velocity. The influence of a reduced water quality cannot be ruled out: water affecting the area of Puffin Island, entering the Menai Strait and leaving via Llanddwyn Island is partly derived from the polluted Liverpool Bay area. HABITAT One of the reasons why this fish, although very common, was not