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Maturity size, reproductive cycle, sex ratio and fecundity of female Nephrops were investigated at SW, S and SE Iceland for the period 1960-2010. Time series of biological parameters and fisheries data displayed significant relationships. In addition, female biological data from 20 areas in the Atlantic and Mediterranean were compared. Fifty percentage maturity estimates had an overall range of 23.9-34.4 mm CL with some anomalies in the 2000s. The reproductive cycle in Iceland has been biennial during the whole study period from mid-1960s to 2010 with minor change in phase in the 2000s. Biennial moulting retards female growth more than annual spawning, and the length of incubation and hatch time of year show significant relationships with latitude and sea temperature. Variations in sex ratio were observed and relationships found between female sex ratio and CL, CPUE and stock biomass during 1961-2010, displaying apparent fishery-induced effects on sex ratio. Potential and realized fecundity estimates in Iceland are 35-50% of those reported from more southerly waters. Biennial spawning and low fecundity limit the number of progeny in Icelandic Nephrops and necessitate lower fishing mortality. Ambient temperature in Icelandic waters has risen by 1 °C since the late 1990s, generating around 30 days shorter incubation time in the 2000s, but around 3 °C rise is necessary for possible annual spawning. [ABSTRACT FROM AUTHOR]

Effects of scallop dredging on benthic communities in Breidafjordur, west Iceland, were investigated by analysing bycatch data from scallop stock assessment surveys and effort data from the commercial scallop fishery. Bycatch constituted 28% of the total catch, with eight benthic macrofaunal taxa alone making up nearly 98% of the bycatch. Modiolus modiolus and Cucumaria frondosa dominated in terms of abundance and biomass in most of the study area regardless of intensity of fishing effort, although both have been identified as sensitive to fishing in other studies. The macrofaunal benthic community in Breidafjordur consisted mostly of hard-shelled molluscs, holothurians, crabs, and starfish. Emerging epifauna was absent in the samples taken since 1993. These results suggest that our study was carried out within an already altered community that would have suffered the greatest impact during the early years of the scallop fishery. However, the available data are not enough to endorse this assumption with complete certainty. [Copyright &y& Elsevier]

The effects of temperature on the survival and behaviour of two size classes ofChlamys islandicawas investigated in a laboratory study. The scallops were sampled in spring from three localities in Iceland, Breidafjördur (west), Húnaflói (north), and Hvalfjördur (southwest) and again in August from Breidafjördur and Hvalfjördur. Daily observations of mortality and behaviour were made over a 21-day period at sea temperatures ranging from 7 to 16°C in spring (April–May) and 11 to 14°C in August. During the spring experiment the tolerance of scallops, as expressed by mortality and behaviour, was distinctly reduced at sea temperatures above 12°C among scallops from Breidafjördur and Húnaflói and above 13°C among scallops from Hvalfjördur. During the second set of experiments, conducted in August, scallops were transported into the laboratory from a higher sea temperature than in the spring. As a result, mortality rates were much lower demonstrated by the fact that only scallops reared at sea temperature of 14°C died. This indicates thatC. islandicamay tolerate somewhat higher temperatures than have been observed in Icelandic waters in recent years. However, the gradual increase in temperature during the last 10 years has brought the mean temperature close to the species' tolerance limit. [ABSTRACT FROM AUTHOR]